Human body 인체(人體)
페이지 정보
본문
인간의 몸을 뜻하는 말로, 구성요소로는 크게 내장, 근육, 뼈, 혈관, 혈액, 체액, 신경계 등이 있는데 이 중에 하나라도 없으면 절대로 살아갈 수 없다. 그만큼 인체는 연약하다. 그리고 일부 구성요소는 상처를 입거나 없어져도 다시 회복되는 경우도 있지만, 일단 한번 확실하게 절단되면 재생할 수 없다. 이는 대부분의 동물이나 식물들도 마찬가지다.
3. 구조[편집]
진화 과정 중간부터 나타난 직립보행 탓인지, 인간은 해부학적으로 상당히 기형적인 신체 구조를 가졌다. 덕분에 다른 포유동물들은 없는 질병이 상당수 있으며 출산하기도 어렵다.
인체의 세포 수는 연구나 세는 방법에 따라 큰 차이를 보이고 있는데 약 30조 ~ 37조 개 로 추정된다. 그런데 장내 세균이나 피부에사는 세균을 포함해 인간의 몸속에 있는 박테리아 세균의 총 수도 39조 개 정도로 그와 비슷해서 대체로 1:1-1:1.3 정도 비율이라고 한다. 과거에는 인체 세포 대 박테리아 비율이 1:10 이라는 설이 과학계에도 퍼졌지만 2010년대의 조사로 과학적 근거가 미약한 추정치라고 밝혀졌다.
4. 성분[편집]
external/science...
60kg의 일반인 기준 위키백과 출처
인체 성분
60kg의 일반인 기준
성분 무게[1] 원자 백분율[1]
산소 38.8 kg 25.5 %
탄소 10.9 kg 9.5 %
수소 6.0 kg 6.3 %
질소 1.9 kg 1.4 %
칼슘 1.2 kg 0.2%
인 0.6 kg 0.2 %
칼륨 0.2 kg 0.07 %
0.07 %
인체로 만들 수 있는 것 중 그나마 가장 쓸만하다는 게 다이아몬드 비누와 성냥. 일단 먹을 수가 없다는 점이 가장 큰 문제다.[1] 뭐 그래도 소처럼 알뜰하게 쓰려고 하면 피부로는 전등갓이나 손수건을, 연골로는 아교를, 뼈로는 단추를, 태우고 남은 찌꺼기로 비료를 만들 수도 있다. 2차 대전 당시 나치가 이를 현실화하지 않았냐는 의심을 받았다. 자세한 건 인체 비누 참고.
만약 시신기증이나 인체조직기증 등을 한다면 이야기는 달라진다. 시신기증은 의과대학이나 치과대학에서의 연구용으로 시신을 기증하는 것이다. 인체조직기증은 실제로 이식되기 위해 선택하는 것으로, 인간의 신체에서 뼈나 연골, 인대, 피부, 혈관, 심장판막 등[2]을 떼어낸 뒤 필요한 환자에게 이식하거나, 치료제를 만드는 데 쓰인다. 이러한 행위는 장기기증처럼 다른 생명을 살리고, 치료를 돕는 데 쓰이는 것으로 값으로 따질 수 없는 숭고한 것이지만, 굳이 돈으로 계산하자면 수백만~수천만 원 수준의 부가가치에 해당한다고 볼 수 있다.
우리나라에선 인체조직기증이 알려져 있지 않아 기증하는 사람이 매우 적어서, 이러한 부위들이 필요하면 미국이나 유럽 등에서 수입해온다.
5. 사람의 뼈대와 몸체 형성[편집]
사람의 뼈대즉 인체골격 목록(list)은 성인기준 남녀 모두 206개 이다. 태어날 때는 270개였다. 무려 64개 중 대부분이 접합된다. 한편 손가락과 발가락의 경우 마지막까지 형성된다고 본다. PCD(세포예정사,Programed Cell Death)와 소닉 헤지호그(Sonic Hedgehog) 단백질에 의해 주요하게 만들어진다.
Skeleton diagram...
인간의 뼈 중 사람의 뼈대는 척추, 어깨, 골반에서 주요하게 구분된다.
한편 천골(엉치뼈) 5개가 1개로, 미골(꼬리뼈)이 4개에서 1개로 접합된다. 뼈는 직립보행을 가능하게 하고 혈액세포를 만들며 미네랄을 저장하고 내분비계중 하나이자 이러한 맥락에서 인체의 주요한 장기이다.
[1] 타 생물과 다르게 식인은 같은 종이니만큼 피식자의 질병이 다이렉트로 옮을 위험이 크다.
[2] 이러한 부위들은 의학적으로 꼭 필요하지만, 현재의 기술력으론 인공적으로 만드는 데 시간과 비용이 많이 들고 완벽하지도 않아서 대체하기 곤란하다는 공통점이 있다.
Human body [하기웹사이트는 카피하여 인터넷에서 보십시요]
https://www.amc.seoul.kr/asan/healthinfo/body/bodySubmain.do
https://namu.wiki/w/%EC%9D%B8%EC%B2%B4
https://en.wikipedia.org/wiki/Human_body
https://www.google.ca/search?q=human+body+wikipedia&sxsrf=APwXEddyIXPZa3Hlh0aGPRcM8bhZpMUzaQ%3A1686398760070&ei=KGeEZIn2A8yt0PEPxqGQ0AQ&oq=human+bodywiki&gs_lcp=Cgxnd3Mtd2l6LXNlcnAQARgAMgcIIxCwAhAnMgYIABAHEB4yBggAEAcQHjIGCAAQBxAeMgYIABAHEB4yBggAEAcQHjIGCAAQBxAeMgYIABAHEB4yBwgAEA0QgAQyBwgAEA0QgAQ6CwgAEAcQHhDxBBAKSgQIQRgAUABYmUBg5VZoAHABeACAAXqIAbEHkgEDNy4zmAEAoAEBwAEB&sclient=gws-wiz-serp
인체
https://www.google.ca/search?q=%EC%9D%B8%EC%B2%B4&sxsrf=APwXEdeZKZn1Xhfl6dTXQl75VyC48o3_YA%3A1686399336336&ei=aGmEZMiSFIay0PEP7LOy6As&ved=0ahUKEwjI5pCL17j_AhUGGTQIHeyZDL0Q4dUDCBA&oq=%EC%9D%B8%EC%B2%B4&gs_lcp=Cgxnd3Mtd2l6LXNlcnAQDDIHCCMQigUQJzIECCMQJzIECCMQJzIHCAAQigUQQzIFCAAQgAQyBQgAEIAEMgUIABCABDIFCAAQgAQyBQguEIAEMgUIABCABEoECEEYAFAAWABgqhNoAHABeACAAZcBiAGXAZIBAzAuMZgBAKABAqABAcABAQ&sclient=gws-wiz-serp
===========================
"Anatomy of the human body" redirects here. For the textbook, see Gray's Anatomy.
Female (left) and male (right) adult human bodies photographed in ventral (above) and dorsal (below) perspectives. Naturally-occurring pubic, body, and facial hair has been deliberately removed to show anatomy.
The human body is the entire structure of a human being. It is composed of many different types of cells that together create tissues and subsequently organs and then organ systems. They ensure homeostasis and the viability of the human body.
It comprises a head, hair, neck, torso (which includes the thorax and abdomen), arms and hands, legs and feet.
The study of the human body includes anatomy, physiology, histology and embryology. The body varies anatomically in known ways. Physiology focuses on the systems and organs of the human body and their functions. Many systems and mechanisms interact in order to maintain homeostasis, with safe levels of substances such as sugar and oxygen in the blood.
The body is studied by health professionals, physiologists, anatomists, and artists to assist them in their work.
Composition
Main article: Composition of the human body
Elements of the human body by mass. Trace elements are less than 1% combined (and each less than 0.1%).
Element Symbol Percent mass Percent atoms
Oxygen O 65.0 24.0
Carbon C 18.5 12.0
Hydrogen H 9.5 62.0
Nitrogen N 3.2 1.1
Calcium Ca 1.5 0.22
Phosphorus P 1.0 0.22
Potassium K 0.4 0.03
Sulfur S 0.3 0.038
Sodium Na 0.2 0.037
Chlorine Cl 0.2 0.024
Magnesium Mg 0.1 0.015
Trace elements < 0.1 < 0.3
The human body is composed of elements including hydrogen, oxygen, carbon, calcium and phosphorus. These elements reside in trillions of cells and non-cellular components of the body.
The adult male body is about 60% water for a total water content of some 42 litres (9.2 imp gal; 11 US gal). This is made up of about 19 litres (4.2 imp gal; 5.0 US gal) of extracellular fluid including about 3.2 litres (0.70 imp gal; 0.85 US gal) of blood plasma and about 8.4 litres (1.8 imp gal; 2.2 US gal) of interstitial fluid, and about 23 litres (5.1 imp gal; 6.1 US gal) of fluid inside cells.[1] The content, acidity and composition of the water inside and outside cells is carefully maintained. The main electrolytes in body water outside cells are sodium and chloride, whereas within cells it is potassium and other phosphates.[2]
Cells
See also: List of distinct cell types in the adult human body
The body contains trillions of cells, the fundamental unit of life.[3] At maturity, there are roughly 30[4]–37[5][6] trillion cells in the body, an estimate arrived at by totaling the cell numbers of all the organs of the body and cell types. The body is also host to about the same number of non-human cells[4] as well as multicellular organisms which reside in the gastrointestinal tract and on the skin.[7] Not all parts of the body are made from cells. Cells sit in an extracellular matrix that consists of proteins such as collagen, surrounded by extracellular fluids. Of the 70 kg (150 lb) weight of an average human body, nearly 25 kg (55 lb) is non-human cells or non-cellular material such as bone and connective tissue.
Genome
Main article: Genome
See also: Genetics
Cells in the body function because of DNA. DNA sits within the nucleus of a cell. Here, parts of DNA are copied and sent to the body of the cell via RNA.[8] The RNA is then used to create proteins which form the basis for cells, their activity, and their products. Proteins dictate cell function and gene expression, a cell is able to self-regulate by the amount of proteins produced.[9] However, not all cells have DNA; some cells such as mature red blood cells lose their nucleus as they mature.
Tissues
The body consists of many different types of tissue, defined as cells that act with a specialised function.[10] The study of tissues is called histology and often occurs with a microscope. The body consists of four main types of tissues. These are lining cells (epithelia), connective tissue, nerve tissue and muscle tissue.[11]
Cells that lie on surfaces exposed to the outside world or gastrointestinal tract (epithelia) or internal cavities (endothelium) come in numerous shapes and forms – from single layers of flat cells, to cells with small beating hair-like cilia in the lungs, to column-like cells that line the stomach. Endothelial cells are cells that line internal cavities including blood vessels and glands. Lining cells regulate what can and can not pass through them, protect internal structures, and function as sensory surfaces.[11]
Organs
See also: List of organs of the human body
Organs, structured collections of cells with a specific function,[12] mostly sit within the body, with the exception of skin. Examples include the heart, lungs and liver. Many organs reside within cavities within the body. These cavities include the abdomen (which contains the stomach, for example) and pleura, which contains the lungs.
Heart
Main article: Heart
The heart is an organ located in the thoracic cavity between the lungs and slightly to the left. It is surrounded by the pericardium which holds it in place in the mediastinum and serves to protect it from blunt trauma, infection and help lubricate the movement of the heart via pericardial fluid.[13] The heart works by pumping blood around the body allowing oxygen, nutrients, waste, hormones and white blood cells to be transported.
Diagram of the human heart
The heart is composed of two atria and two ventricles. The primary purpose of the atria is to allow uninterrupted venous blood flow to the heart during ventricular systole. This allows enough blood to get into the ventricles during atrial systole. Consequently, the atria allow a cardiac output roughly 75% greater than would be possible without them.[14] The purpose of the ventricles is to pump blood to the lungs through the right ventricle and to the rest of the body through the left ventricle.[15]
The heart has an electrical conduction system to control the contractions and relaxation of the muscle. It starts in the sinoatrial node traveling through the atria causing them to pump blood into the ventricles. It then travels to the atrioventricular node which makes the signal slow down slightly allowing the ventricles to fill with blood before pumping it out and starting the cycle over again.[16]
Coronary artery disease is the leading cause of death worldwide, making up 16% of all deaths.[17] It is caused by the buildup of plaque in the coronary arteries supplying the heart, eventually the arteries may become so narrow that not enough blood is able to reach the myocardium,[18] a condition known as myocardial infarction or heart attack, this can cause heart failure or cardiac arrest and eventually death.[19] Risk factors for coronary artery disease include obesity, smoking, high cholesterol, high blood pressure, lack of exercise and diabetes.[20] Cancer can affect the heart, though it is exceedingly rare and has usually metastasized from another part of the body such as the lungs or breasts. This is because the heart cells quickly stop dividing and all growth occurs through size increase rather than cell division.[21]
Gallbladder
Main article: Gallbladder
The gallbladder is a hollow pear shaped organ located posterior to the inferior middle part of the right lobe of the liver. It is variable in shape and size. It stores bile before it is released into the small intestine via the common bile duct to help with digestion of fats. It receives bile from the liver via the cystic duct which connects to the common hepatic duct to form the common bile duct.[22]
The gallbladder gets its blood supply from the cystic artery which in most people emerges from the right hepatic artery.[22]
Gallstones is a common disease in which one or more stones form in the gallbladder or biliary tract. Most people are asymptomatic but if a stone blocks the biliary tract it causes a gallbladder attack, symptoms may include sudden pain in the upper right abdomen and or center of the abdomen. Nausea and vomiting may also occur. Typical treatment is removal of the gallbladder through a procedure called a cholecystectomy.[23][24] Having gallstones is a risk factor for gallbladder cancer which although quite uncommon is rapidly fatal if not diagnosed early.[25]
Systems
See also: List of systems of the human body
Circulatory system
Main article: Circulatory system
The circulatory system consists of the heart and blood vessels (arteries, veins and capillaries). The heart propels the circulation of the blood, which serves as a "transportation system" to transfer oxygen, fuel, nutrients, waste products, immune cells and signalling molecules (i.e. hormones) from one part of the body to another. Paths of blood circulation within the human body can be divided into two circuits: the pulmonary circuit, which pumps blood to the lungs to receive oxygen and leave carbon dioxide, and the systemic circuit, which carries blood from the heart off to the rest of the body. The blood consists of fluid that carries cells in the circulation, including some that move from tissue to blood vessels and back, as well as the spleen and bone marrow.[26][27][28]
Digestive system
Main article: Digestive system
Digestive system
The digestive system consists of the mouth including the tongue and teeth, esophagus, stomach, (gastrointestinal tract, small and large intestines, and rectum), as well as the liver, pancreas, gallbladder, and salivary glands. It converts food into small, nutritional, non-toxic molecules for distribution and absorption into the body. These molecules take the form of proteins (which are broken down into amino acids), fats, vitamins and minerals (the last of which are mainly ionic rather than molecular). After being swallowed, food moves through the gastrointestinal tract by means of peristalsis: the systematic expansion and contraction of muscles to push food from one area to the next.[29][30]
Digestion begins in the mouth, which chews food into smaller pieces for easier digestion. Then it is swallowed, and moves through the esophagus to the stomach. In the stomach, food is mixed with gastric acids to allow the extraction of nutrients. What is left is called chyme; this then moves into the small intestine, which absorbs the nutrients and water from the chyme. What remains passes on to the large intestine, where it is dried to form feces; these are then stored in the rectum until they are expelled through the anus.[30]
Endocrine system
Main article: Endocrine system
The endocrine system consists of the principal endocrine glands: the pituitary, thyroid, adrenals, pancreas, parathyroids, and gonads, but nearly all organs and tissues produce specific endocrine hormones as well. The endocrine hormones serve as signals from one body system to another regarding an enormous array of conditions, and resulting in variety of changes of function.[31]
Immune system
Main article: Immune system
The immune system consists of the white blood cells, the thymus, lymph nodes and lymph channels, which are also part of the lymphatic system. The immune system provides a mechanism for the body to distinguish its own cells and tissues from outside cells and substances and to neutralize or destroy the latter by using specialized proteins such as antibodies, cytokines, and toll-like receptors, among many others.[32]
Skin
Integumentary system
Main article: Integumentary system
The integumentary system consists of the covering of the body (the skin), including hair and nails as well as other functionally important structures such as the sweat glands and sebaceous glands. The skin provides containment, structure, and protection for other organs, and serves as a major sensory interface with the outside world.[33][34]
Lymphatic system
Main article: Lymphatic system
The lymphatic system extracts, transports and metabolizes lymph, the fluid found in between cells. The lymphatic system is similar to the circulatory system in terms of both its structure and its most basic function, to carry a body fluid.[35]
Musculoskeletal system
Main article: Musculoskeletal system
The musculoskeletal system consists of the human skeleton (which includes bones, ligaments, tendons, joints and cartilage) and attached muscles. It gives the body basic structure and the ability for movement. In addition to their structural role, the larger bones in the body contain bone marrow, the site of production of blood cells. Also, all bones are major storage sites for calcium and phosphate. This system can be split up into the muscular system and the skeletal system.[36]
Nervous system
Main article: Nervous system
Nervous system
The nervous system consists of the body's neurons and glial cells, which together form the nerves, ganglia and gray matter which in turn form the brain and related structures. The brain is the organ of thought, emotion, memory, and sensory processing; it serves many aspects of communication and controls various systems and functions. The special senses consist of vision, hearing, taste, and smell. The eyes, ears, tongue, and nose gather information about the body's environment.[37]
From a structural perspective, the nervous system is typically subdivided into two component parts: the central nervous system (CNS), composed of the brain and the spinal cord; and the peripheral nervous system (PNS), composed of the nerves and ganglia outside the brain and spinal cord. The CNS is mostly responsible for organizing motion, processing sensory information, thought, memory, cognition and other such functions.[38] It remains a matter of some debate whether the CNS directly gives rise to consciousness.[citation needed] The peripheral nervous system (PNS) is mostly responsible for gathering information with sensory neurons and directing body movements with motor neurons.[38]
From a functional perspective, the nervous system is again typically divided into two component parts: the somatic nervous system (SNS) and the autonomic nervous system (ANS). The SNS is involved in voluntary functions like speaking and sensory processes. The ANS is involved in involuntary processes, such as digestion and regulating blood pressure.[39]
The nervous system is subject to many different diseases. In epilepsy, abnormal electrical activity in the brain can cause seizures. In multiple sclerosis, the immune system attacks the nerve linings, damaging the nerves' ability to transmit signals. Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease, is a motor neuron disease which gradually reduces movement in patients. There are also many other diseases of the nervous system.[38]
Reproductive system
Main article: Human reproductive system
This section may require cleanup to meet Wikipedia's quality standards. The specific problem is: Should be cut down more to fit the length of the other systems, and some paragraphs are a bit difficult to read. Please help improve this section if you can. (June 2023) (Learn how and when to remove this template message)
The primary purpose of the reproductive system is to produce new humans in the form of children and ensure their sexual development so that they can produce new humans too. It is composed of the gonads (testicles and ovaries) which produce eggs and sperm cells (gametes) and produce hormones necessary for proper sexual development. The rest of the glands and ducts of the reproductive system are responsible for the transportation and sustaining of the gametes and to nurture the offspring.[40]
The reproductive system is first stimulated by the hypothalamus during puberty which causes the ovaries and testicles to produce testosterone (male) and estrogen and progesterone (female). Male puberty generally occurs between the ages of 13 and 15 and is characterized by beginning of sperm production and the development of secondary sex characteristics such as increased height and weight, broadened shoulders, pubic and facial hair, voice deepening and muscle development. Female puberty generally occurs between the ages of 9 and 13 and is characterized by ovulation and menstruation. The growth of secondary sex characteristics, such as growth of pubic and underarm hair, breast, uterine and vaginal growth, widening hips and increased height and weight, also occur during the female puberty process.[41]
The external male reproductive system is made up of the penis and the scrotum which is a sac containing the testicles. The penis consists of the glans, and contains the urethra and urinary meatus – the point where urine exits the penis. The rest of the penis is called the shaft and contains most of the urethra. The glans is covered by a fold of skin called the foreskin, although this can be removed through circumcision.[41]
Internal gross anatomy of the male reproductive system
Internally, the male reproductive system starts in the testes where hundreds of seminiferous tubules produce sperm which is then stored and matured into spermatozoon in the epididymis. They are then brought through the vas deferens which leads away from the testes to the seminal vesicles where the sperm cells are mixed with a fructose-rich fluid from the seminal vesicles allowing the sperm to stay alive and remain healthy. It is then brought by the ejaculatory duct through the prostate and bulbourethral gland, and mixed with fluids from said glands. The fluid from the prostate helps to neutralize the acidity of the vagina and keep the sperm alive. This mixture of sperm and accessory gland fluids is called semen and is released through the urethra during ejaculation. Almost the entire internal male reproductive system works in pairs with two testes, two epididymis, two vas deferens, two seminal vesicles, two ejaculatory ducts, two bulbourethral glands, but only one prostate and urethra.[41][42]
External female reproductive system with mons pubis highlighted
The external female reproductive system, also called the vulva, consists of the mons pubis, a fatty mass that covers the pubis, the labia majora (outer lips), the labia minora (inner lips), the vaginal opening which opens into the vagina and is where the penis is inserted during sexual intercourse and children are born. The urethral opening is for the urethra that carries urine from the bladder and the clitoris which contains the most sensitive nerve endings and in humans has no use other than sexual pleasure. Located between the anus and vulva is the perineum.[43][41]
Internal gross anatomy of the female reproductive system
Internally, the female reproductive system contains two ovaries, the uterus, two fallopian tubes and the cervix. At birth, a female has about 700,000 oocytes (the immature version of the egg cell) in both ovaries combined, although this degenerates to about 400,000 by the time puberty is reached. This is a lifetime supply, as after birth, no more oocytes are produced, compared to males where sperm cells are produced during their entire lifetime. During puberty, the menstrual cycle begins for the first time, in response to low estrogen and progesterone levels the hypothalamus releases gonadotropin releasing hormone (GnRH). This causes the anterior pituitary gland to release follicle-stimulating hormone (FSH) and luteinizing hormone (LH). FSH stimulates ovarian follicles to grow and one dominant follicle will eventually take over.
As the ovarian follicle continues to grow, it releases more estradiol which stimulates LH secretion and suppresses FSH secretion, preventing further follicular growth. When LH levels are highest, the follicle ruptures releasing the ovum in a process called ovulation where it is then moved to one of the fallopian tubes. After ovulation, the portion of the follicle that remains in the ovary is transformed into a corpus luteum which continues to produce estrogen and high levels of progesterone. The progesterone causes the endometrium to grow thick, preparing it for implantation of a fertilized egg. If fertilization occurs, the corpus luteum continues to secrete hormones until the placenta develops enough to secrete the necessary hormones for maintaining pregnancy. Eventually, the corpus luteum will turn into a corpus albicans which is essentially scar tissue. If fertilization fails, the corpus luteum will degrade into the corpus albicans and stop secreting enough progesterone and estrogen, causing the endometrial lining to break resulting in menstruation.[41][44]
Many diseases affect the reproductive system such as polycystic ovary syndrome (PCOS) which is characterized by elevated androgen levels, menstrual irregularities and/or small cysts on one or both of the ovaries. It is a common disease affecting at least 7% of adult women. Symptoms may include excess body hair, infertility, or weight gain, male pattern baldness.[45][46]
Another reproductive disease is testicular torsion, it occurs when the spermatic cord which holds up the testicle wraps around itself cutting off blood flow to the testicle. Testicular torsion is a medical emergency and can result in testicular death or infertility if not treated immediately by physically unwrapping the spermatic cord. If the testicle has suffered severe damage, it may need to be surgically removed in a lateral orchiectomy. The primary symptom of testicular torsion is severe testicular pain at rest, nausea and vomiting may also occur. Testicular torsion can occur at any age, although it is most common in 12-18 year olds.[47][48]
Sexually transmitted infections such as syphilis, HIV, chlamydia, HPV and genital warts are spread through sexual intercourse, including oral, vaginal, anal, and manual sex. Many of these infections can be lethal if left untreated though others are mostly harmless.[49][50]
Cancer can affect many parts of the reproductive system including the penis, testicles, prostate, ovaries, cervix, vagina, fallopian, uterus and vulva.[51]
Respiratory system
Main article: Respiratory system
The respiratory system consists of the nose, nasopharynx, trachea, and lungs. It brings oxygen from the air and excretes carbon dioxide and water back into the air. First, air is pulled through the trachea into the lungs by the diaphragm pushing down, which creates a vacuum. Air is briefly stored inside small sacs known as alveoli (sing.: alveolus) before being expelled from the lungs when the diaphragm contracts again. Each alveolus is surrounded by capillaries carrying deoxygenated blood, which absorbs oxygen out of the air and into the bloodstream.[52][53]
For the respiratory system to function properly, there need to be as few impediments as possible to the movement of air within the lungs. Inflammation of the lungs and excess mucus are common sources of breathing difficulties.[53] In asthma, the respiratory system is persistently inflamed, causing wheezing and/or shortness of breath. Pneumonia occurs through infection of the alveoli, and may be caused by tuberculosis. Emphysema, commonly a result of smoking, is caused by damage to connections between the alveoli.[54]
Urinary system
Main article: Urinary system
Female urinary system
The urinary system consists of the two kidneys, two ureters, bladder, and urethra. It removes waste materials from the blood through urine, which carries a variety of waste molecules and excess ions and water out of the body.
First, the kidneys filter the blood through their respective nephrons, removing waste products like urea, creatinine and maintaining the proper balance of electrolytes and turning the waste products into urine by combining them with water from the blood.[55] The kidneys filter about 150 quarts (170 liters) of blood daily, but most of it is returned to the blood stream with only 1-2 quarts (1-2 liters) ending up as urine.[56] The urine is brought by the ureters from the kidneys down to the bladder.
The smooth muscle lining the ureter walls continuously tighten and relax through a process called peristalsis to force urine away from the kidneys and down into the bladder. Small amounts of urine are released into the bladder every 10–15 seconds.
The bladder is a hollow balloon shaped organ located in the pelvis. It stores urine until the brain signals it to relax the urinary sphincter and release the urine into the urethra starting urination.[57] A normal bladder can hold up to 16 ounces (half a liter) for 3–5 hours comfortably.
Numerous diseases affect the urinary system including kidney stones which are formed when materials in the urine concentrate enough to form a solid mass, urinary tract infections which are infections of the urinary tract and can cause pain when urinating, frequent urination and even death if left untreated. Renal failure occurs when the kidneys fail to adequately filter waste from the blood and can lead to death if not treated with dialysis or kidney transplantation.[58] Cancer can affect the bladder, kidneys, urethra and ureters with the latter two being far more rare.[59]
Anatomy
Main articles: Outline of human anatomy and Anatomy
Cavities of human body
Human anatomy is the study of the shape and form of the human body. The human body has four limbs (two arms and two legs), a head and a neck which connect to the torso. The body's shape is determined by a strong skeleton made of bone and cartilage, surrounded by fat (adipose tissue), muscle, connective tissue, organs, and other structures. The spine at the back of the skeleton contains the flexible vertebral column which surrounds the spinal cord, which is a collection of nerve fibres connecting the brain to the rest of the body. Nerves connect the spinal cord and brain to the rest of the body. All major bones, muscles, and nerves in the body are named, with the exception of anatomical variations such as sesamoid bones and accessory muscles.
Blood vessels carry blood throughout the body, which moves because of the beating of the heart. Venules and veins collect blood low in oxygen from tissues throughout the body. These collect in progressively larger veins until they reach the body's two largest veins, the superior and inferior vena cava, which drain blood into the right side of the heart. From here, the blood is pumped into the lungs where it receives oxygen and drains back into the left side of the heart. From here, it is pumped into the body's largest artery, the aorta, and then progressively smaller arteries and arterioles until it reaches tissue. Here blood passes from small arteries into capillaries, then small veins and the process begins again. Blood carries oxygen, waste products, and hormones from one place in the body to another. Blood is filtered at the kidneys and liver.
The body consists of a number of body cavities, separated areas which house different organ systems. The brain and central nervous system reside in an area protected from the rest of the body by the blood brain barrier. The lungs sit in the pleural cavity. The intestines, liver, and spleen sit in the abdominal cavity.
Height, weight, shape and other body proportions vary individually and with age and sex. Body shape is influenced by the distribution of bones, muscle and fat tissue.[60]
Physiology
Main articles: Outline of physiology and Physiology
Human physiology is the study of how the human body functions. This includes the mechanical, physical, bioelectrical, and biochemical functions of humans in good health, from organs to the cells of which they are composed. The human body consists of many interacting systems of organs. These interact to maintain homeostasis, keeping the body in a stable state with safe levels of substances such as sugar and oxygen in the blood.[61]
Each system contributes to homeostasis, of itself, other systems, and the entire body. Some combined systems are referred to by joint names. For example, the nervous system and the endocrine system operate together as the neuroendocrine system. The nervous system receives information from the body, and transmits this to the brain via nerve impulses and neurotransmitters. At the same time, the endocrine system releases hormones, such as to help regulate blood pressure and volume. Together, these systems regulate the internal environment of the body, maintaining blood flow, posture, energy supply, temperature, and acid balance (pH).[61]
Development
Main article: Development of the human body
Baby being carried
Development of the human body is the process of growth to maturity. The process begins with fertilisation, where an egg released from the ovary of a female is penetrated by sperm. The egg then lodges in the uterus, where an embryo and later fetus develop until birth. Growth and development occur after birth, and include both physical and psychological development, influenced by genetic, hormonal, environmental and other factors. Development and growth continue throughout life, through childhood, adolescence, and through adulthood to old age, and are referred to as the process of aging.
Society and culture
Professional study
Further information: History of anatomy, History of medicine, and History of physiology
Anatomical study by Leonardo da Vinci
Health professionals learn about the human body from illustrations, models, and demonstrations. Medical and dental students in addition gain practical experience, for example by dissection of cadavers. Human anatomy, physiology, and biochemistry are basic medical sciences, generally taught to medical students in their first year at medical school.[62][63][64]
Depiction
Main article: Depictions of nudity
Figure drawing by Lovis Corinth (before 1925)
In Western societies, the contexts for depictions of the human body include information, art and pornography. Information includes both science and education, such as anatomical drawings. Any ambiguous image not easily fitting into one of these categories may be misinterpreted, leading to disputes.[65] The most contentious disputes are between fine art and erotic images, which define the legal distinction of which images are permitted or prohibited.
History of anatomy
Main article: History of anatomy
Two facing pages of text with woodcuts of naked male and female figures, in the Epitome by Andreas Vesalius, 1543
In Ancient Greece, the Hippocratic Corpus described the anatomy of the skeleton and muscles.[66] The 2nd century physician Galen of Pergamum compiled classical knowledge of anatomy into a text that was used throughout the Middle Ages.[67] In the Renaissance, Andreas Vesalius (1514–1564) pioneered the modern study of human anatomy by dissection, writing the influential book De humani corporis fabrica.[68][69] Anatomy advanced further with the invention of the microscope and the study of the cellular structure of tissues and organs.[70] Modern anatomy uses techniques such as magnetic resonance imaging, computed tomography, fluoroscopy and ultrasound imaging to study the body in unprecedented detail.[71]
History of physiology
Main article: History of physiology
The study of human physiology began with Hippocrates in Ancient Greece, around 420 BCE, and with Aristotle (384–322 BCE) who applied critical thinking and emphasis on the relationship between structure and function. Galen (c. 126 – c. 199) was the first to use experiments to probe the body's functions.[72] The term physiology was introduced by the French physician Jean Fernel (1497–1558). In the 17th century, William Harvey (1578–1657) described the circulatory system, pioneering the combination of close observation with careful experiment.[73] In the 19th century, physiological knowledge began to accumulate at a rapid rate with the cell theory of Matthias Schleiden and Theodor Schwann in 1838, that organisms are made up of cells. Claude Bernard (1813–1878) created the concept of the milieu interieur (internal environment), which Walter Cannon (1871–1945) later said was regulated to a steady state in homeostasis. In the 20th century, the physiologists Knut Schmidt-Nielsen and George Bartholomew extended their studies to comparative physiology and ecophysiology.[74] Most recently, evolutionary physiology has become a distinct subdiscipline.[75]
See also
3. 구조[편집]
진화 과정 중간부터 나타난 직립보행 탓인지, 인간은 해부학적으로 상당히 기형적인 신체 구조를 가졌다. 덕분에 다른 포유동물들은 없는 질병이 상당수 있으며 출산하기도 어렵다.
인체의 세포 수는 연구나 세는 방법에 따라 큰 차이를 보이고 있는데 약 30조 ~ 37조 개 로 추정된다. 그런데 장내 세균이나 피부에사는 세균을 포함해 인간의 몸속에 있는 박테리아 세균의 총 수도 39조 개 정도로 그와 비슷해서 대체로 1:1-1:1.3 정도 비율이라고 한다. 과거에는 인체 세포 대 박테리아 비율이 1:10 이라는 설이 과학계에도 퍼졌지만 2010년대의 조사로 과학적 근거가 미약한 추정치라고 밝혀졌다.
4. 성분[편집]
external/science...
60kg의 일반인 기준 위키백과 출처
인체 성분
60kg의 일반인 기준
성분 무게[1] 원자 백분율[1]
산소 38.8 kg 25.5 %
탄소 10.9 kg 9.5 %
수소 6.0 kg 6.3 %
질소 1.9 kg 1.4 %
칼슘 1.2 kg 0.2%
인 0.6 kg 0.2 %
칼륨 0.2 kg 0.07 %
0.07 %
인체로 만들 수 있는 것 중 그나마 가장 쓸만하다는 게 다이아몬드 비누와 성냥. 일단 먹을 수가 없다는 점이 가장 큰 문제다.[1] 뭐 그래도 소처럼 알뜰하게 쓰려고 하면 피부로는 전등갓이나 손수건을, 연골로는 아교를, 뼈로는 단추를, 태우고 남은 찌꺼기로 비료를 만들 수도 있다. 2차 대전 당시 나치가 이를 현실화하지 않았냐는 의심을 받았다. 자세한 건 인체 비누 참고.
만약 시신기증이나 인체조직기증 등을 한다면 이야기는 달라진다. 시신기증은 의과대학이나 치과대학에서의 연구용으로 시신을 기증하는 것이다. 인체조직기증은 실제로 이식되기 위해 선택하는 것으로, 인간의 신체에서 뼈나 연골, 인대, 피부, 혈관, 심장판막 등[2]을 떼어낸 뒤 필요한 환자에게 이식하거나, 치료제를 만드는 데 쓰인다. 이러한 행위는 장기기증처럼 다른 생명을 살리고, 치료를 돕는 데 쓰이는 것으로 값으로 따질 수 없는 숭고한 것이지만, 굳이 돈으로 계산하자면 수백만~수천만 원 수준의 부가가치에 해당한다고 볼 수 있다.
우리나라에선 인체조직기증이 알려져 있지 않아 기증하는 사람이 매우 적어서, 이러한 부위들이 필요하면 미국이나 유럽 등에서 수입해온다.
5. 사람의 뼈대와 몸체 형성[편집]
사람의 뼈대즉 인체골격 목록(list)은 성인기준 남녀 모두 206개 이다. 태어날 때는 270개였다. 무려 64개 중 대부분이 접합된다. 한편 손가락과 발가락의 경우 마지막까지 형성된다고 본다. PCD(세포예정사,Programed Cell Death)와 소닉 헤지호그(Sonic Hedgehog) 단백질에 의해 주요하게 만들어진다.
Skeleton diagram...
인간의 뼈 중 사람의 뼈대는 척추, 어깨, 골반에서 주요하게 구분된다.
한편 천골(엉치뼈) 5개가 1개로, 미골(꼬리뼈)이 4개에서 1개로 접합된다. 뼈는 직립보행을 가능하게 하고 혈액세포를 만들며 미네랄을 저장하고 내분비계중 하나이자 이러한 맥락에서 인체의 주요한 장기이다.
[1] 타 생물과 다르게 식인은 같은 종이니만큼 피식자의 질병이 다이렉트로 옮을 위험이 크다.
[2] 이러한 부위들은 의학적으로 꼭 필요하지만, 현재의 기술력으론 인공적으로 만드는 데 시간과 비용이 많이 들고 완벽하지도 않아서 대체하기 곤란하다는 공통점이 있다.
Human body [하기웹사이트는 카피하여 인터넷에서 보십시요]
https://www.amc.seoul.kr/asan/healthinfo/body/bodySubmain.do
https://namu.wiki/w/%EC%9D%B8%EC%B2%B4
https://en.wikipedia.org/wiki/Human_body
https://www.google.ca/search?q=human+body+wikipedia&sxsrf=APwXEddyIXPZa3Hlh0aGPRcM8bhZpMUzaQ%3A1686398760070&ei=KGeEZIn2A8yt0PEPxqGQ0AQ&oq=human+bodywiki&gs_lcp=Cgxnd3Mtd2l6LXNlcnAQARgAMgcIIxCwAhAnMgYIABAHEB4yBggAEAcQHjIGCAAQBxAeMgYIABAHEB4yBggAEAcQHjIGCAAQBxAeMgYIABAHEB4yBwgAEA0QgAQyBwgAEA0QgAQ6CwgAEAcQHhDxBBAKSgQIQRgAUABYmUBg5VZoAHABeACAAXqIAbEHkgEDNy4zmAEAoAEBwAEB&sclient=gws-wiz-serp
인체
https://www.google.ca/search?q=%EC%9D%B8%EC%B2%B4&sxsrf=APwXEdeZKZn1Xhfl6dTXQl75VyC48o3_YA%3A1686399336336&ei=aGmEZMiSFIay0PEP7LOy6As&ved=0ahUKEwjI5pCL17j_AhUGGTQIHeyZDL0Q4dUDCBA&oq=%EC%9D%B8%EC%B2%B4&gs_lcp=Cgxnd3Mtd2l6LXNlcnAQDDIHCCMQigUQJzIECCMQJzIECCMQJzIHCAAQigUQQzIFCAAQgAQyBQgAEIAEMgUIABCABDIFCAAQgAQyBQguEIAEMgUIABCABEoECEEYAFAAWABgqhNoAHABeACAAZcBiAGXAZIBAzAuMZgBAKABAqABAcABAQ&sclient=gws-wiz-serp
===========================
"Anatomy of the human body" redirects here. For the textbook, see Gray's Anatomy.
Female (left) and male (right) adult human bodies photographed in ventral (above) and dorsal (below) perspectives. Naturally-occurring pubic, body, and facial hair has been deliberately removed to show anatomy.
The human body is the entire structure of a human being. It is composed of many different types of cells that together create tissues and subsequently organs and then organ systems. They ensure homeostasis and the viability of the human body.
It comprises a head, hair, neck, torso (which includes the thorax and abdomen), arms and hands, legs and feet.
The study of the human body includes anatomy, physiology, histology and embryology. The body varies anatomically in known ways. Physiology focuses on the systems and organs of the human body and their functions. Many systems and mechanisms interact in order to maintain homeostasis, with safe levels of substances such as sugar and oxygen in the blood.
The body is studied by health professionals, physiologists, anatomists, and artists to assist them in their work.
Composition
Main article: Composition of the human body
Elements of the human body by mass. Trace elements are less than 1% combined (and each less than 0.1%).
Element Symbol Percent mass Percent atoms
Oxygen O 65.0 24.0
Carbon C 18.5 12.0
Hydrogen H 9.5 62.0
Nitrogen N 3.2 1.1
Calcium Ca 1.5 0.22
Phosphorus P 1.0 0.22
Potassium K 0.4 0.03
Sulfur S 0.3 0.038
Sodium Na 0.2 0.037
Chlorine Cl 0.2 0.024
Magnesium Mg 0.1 0.015
Trace elements < 0.1 < 0.3
The human body is composed of elements including hydrogen, oxygen, carbon, calcium and phosphorus. These elements reside in trillions of cells and non-cellular components of the body.
The adult male body is about 60% water for a total water content of some 42 litres (9.2 imp gal; 11 US gal). This is made up of about 19 litres (4.2 imp gal; 5.0 US gal) of extracellular fluid including about 3.2 litres (0.70 imp gal; 0.85 US gal) of blood plasma and about 8.4 litres (1.8 imp gal; 2.2 US gal) of interstitial fluid, and about 23 litres (5.1 imp gal; 6.1 US gal) of fluid inside cells.[1] The content, acidity and composition of the water inside and outside cells is carefully maintained. The main electrolytes in body water outside cells are sodium and chloride, whereas within cells it is potassium and other phosphates.[2]
Cells
See also: List of distinct cell types in the adult human body
The body contains trillions of cells, the fundamental unit of life.[3] At maturity, there are roughly 30[4]–37[5][6] trillion cells in the body, an estimate arrived at by totaling the cell numbers of all the organs of the body and cell types. The body is also host to about the same number of non-human cells[4] as well as multicellular organisms which reside in the gastrointestinal tract and on the skin.[7] Not all parts of the body are made from cells. Cells sit in an extracellular matrix that consists of proteins such as collagen, surrounded by extracellular fluids. Of the 70 kg (150 lb) weight of an average human body, nearly 25 kg (55 lb) is non-human cells or non-cellular material such as bone and connective tissue.
Genome
Main article: Genome
See also: Genetics
Cells in the body function because of DNA. DNA sits within the nucleus of a cell. Here, parts of DNA are copied and sent to the body of the cell via RNA.[8] The RNA is then used to create proteins which form the basis for cells, their activity, and their products. Proteins dictate cell function and gene expression, a cell is able to self-regulate by the amount of proteins produced.[9] However, not all cells have DNA; some cells such as mature red blood cells lose their nucleus as they mature.
Tissues
The body consists of many different types of tissue, defined as cells that act with a specialised function.[10] The study of tissues is called histology and often occurs with a microscope. The body consists of four main types of tissues. These are lining cells (epithelia), connective tissue, nerve tissue and muscle tissue.[11]
Cells that lie on surfaces exposed to the outside world or gastrointestinal tract (epithelia) or internal cavities (endothelium) come in numerous shapes and forms – from single layers of flat cells, to cells with small beating hair-like cilia in the lungs, to column-like cells that line the stomach. Endothelial cells are cells that line internal cavities including blood vessels and glands. Lining cells regulate what can and can not pass through them, protect internal structures, and function as sensory surfaces.[11]
Organs
See also: List of organs of the human body
Organs, structured collections of cells with a specific function,[12] mostly sit within the body, with the exception of skin. Examples include the heart, lungs and liver. Many organs reside within cavities within the body. These cavities include the abdomen (which contains the stomach, for example) and pleura, which contains the lungs.
Heart
Main article: Heart
The heart is an organ located in the thoracic cavity between the lungs and slightly to the left. It is surrounded by the pericardium which holds it in place in the mediastinum and serves to protect it from blunt trauma, infection and help lubricate the movement of the heart via pericardial fluid.[13] The heart works by pumping blood around the body allowing oxygen, nutrients, waste, hormones and white blood cells to be transported.
Diagram of the human heart
The heart is composed of two atria and two ventricles. The primary purpose of the atria is to allow uninterrupted venous blood flow to the heart during ventricular systole. This allows enough blood to get into the ventricles during atrial systole. Consequently, the atria allow a cardiac output roughly 75% greater than would be possible without them.[14] The purpose of the ventricles is to pump blood to the lungs through the right ventricle and to the rest of the body through the left ventricle.[15]
The heart has an electrical conduction system to control the contractions and relaxation of the muscle. It starts in the sinoatrial node traveling through the atria causing them to pump blood into the ventricles. It then travels to the atrioventricular node which makes the signal slow down slightly allowing the ventricles to fill with blood before pumping it out and starting the cycle over again.[16]
Coronary artery disease is the leading cause of death worldwide, making up 16% of all deaths.[17] It is caused by the buildup of plaque in the coronary arteries supplying the heart, eventually the arteries may become so narrow that not enough blood is able to reach the myocardium,[18] a condition known as myocardial infarction or heart attack, this can cause heart failure or cardiac arrest and eventually death.[19] Risk factors for coronary artery disease include obesity, smoking, high cholesterol, high blood pressure, lack of exercise and diabetes.[20] Cancer can affect the heart, though it is exceedingly rare and has usually metastasized from another part of the body such as the lungs or breasts. This is because the heart cells quickly stop dividing and all growth occurs through size increase rather than cell division.[21]
Gallbladder
Main article: Gallbladder
The gallbladder is a hollow pear shaped organ located posterior to the inferior middle part of the right lobe of the liver. It is variable in shape and size. It stores bile before it is released into the small intestine via the common bile duct to help with digestion of fats. It receives bile from the liver via the cystic duct which connects to the common hepatic duct to form the common bile duct.[22]
The gallbladder gets its blood supply from the cystic artery which in most people emerges from the right hepatic artery.[22]
Gallstones is a common disease in which one or more stones form in the gallbladder or biliary tract. Most people are asymptomatic but if a stone blocks the biliary tract it causes a gallbladder attack, symptoms may include sudden pain in the upper right abdomen and or center of the abdomen. Nausea and vomiting may also occur. Typical treatment is removal of the gallbladder through a procedure called a cholecystectomy.[23][24] Having gallstones is a risk factor for gallbladder cancer which although quite uncommon is rapidly fatal if not diagnosed early.[25]
Systems
See also: List of systems of the human body
Circulatory system
Main article: Circulatory system
The circulatory system consists of the heart and blood vessels (arteries, veins and capillaries). The heart propels the circulation of the blood, which serves as a "transportation system" to transfer oxygen, fuel, nutrients, waste products, immune cells and signalling molecules (i.e. hormones) from one part of the body to another. Paths of blood circulation within the human body can be divided into two circuits: the pulmonary circuit, which pumps blood to the lungs to receive oxygen and leave carbon dioxide, and the systemic circuit, which carries blood from the heart off to the rest of the body. The blood consists of fluid that carries cells in the circulation, including some that move from tissue to blood vessels and back, as well as the spleen and bone marrow.[26][27][28]
Digestive system
Main article: Digestive system
Digestive system
The digestive system consists of the mouth including the tongue and teeth, esophagus, stomach, (gastrointestinal tract, small and large intestines, and rectum), as well as the liver, pancreas, gallbladder, and salivary glands. It converts food into small, nutritional, non-toxic molecules for distribution and absorption into the body. These molecules take the form of proteins (which are broken down into amino acids), fats, vitamins and minerals (the last of which are mainly ionic rather than molecular). After being swallowed, food moves through the gastrointestinal tract by means of peristalsis: the systematic expansion and contraction of muscles to push food from one area to the next.[29][30]
Digestion begins in the mouth, which chews food into smaller pieces for easier digestion. Then it is swallowed, and moves through the esophagus to the stomach. In the stomach, food is mixed with gastric acids to allow the extraction of nutrients. What is left is called chyme; this then moves into the small intestine, which absorbs the nutrients and water from the chyme. What remains passes on to the large intestine, where it is dried to form feces; these are then stored in the rectum until they are expelled through the anus.[30]
Endocrine system
Main article: Endocrine system
The endocrine system consists of the principal endocrine glands: the pituitary, thyroid, adrenals, pancreas, parathyroids, and gonads, but nearly all organs and tissues produce specific endocrine hormones as well. The endocrine hormones serve as signals from one body system to another regarding an enormous array of conditions, and resulting in variety of changes of function.[31]
Immune system
Main article: Immune system
The immune system consists of the white blood cells, the thymus, lymph nodes and lymph channels, which are also part of the lymphatic system. The immune system provides a mechanism for the body to distinguish its own cells and tissues from outside cells and substances and to neutralize or destroy the latter by using specialized proteins such as antibodies, cytokines, and toll-like receptors, among many others.[32]
Skin
Integumentary system
Main article: Integumentary system
The integumentary system consists of the covering of the body (the skin), including hair and nails as well as other functionally important structures such as the sweat glands and sebaceous glands. The skin provides containment, structure, and protection for other organs, and serves as a major sensory interface with the outside world.[33][34]
Lymphatic system
Main article: Lymphatic system
The lymphatic system extracts, transports and metabolizes lymph, the fluid found in between cells. The lymphatic system is similar to the circulatory system in terms of both its structure and its most basic function, to carry a body fluid.[35]
Musculoskeletal system
Main article: Musculoskeletal system
The musculoskeletal system consists of the human skeleton (which includes bones, ligaments, tendons, joints and cartilage) and attached muscles. It gives the body basic structure and the ability for movement. In addition to their structural role, the larger bones in the body contain bone marrow, the site of production of blood cells. Also, all bones are major storage sites for calcium and phosphate. This system can be split up into the muscular system and the skeletal system.[36]
Nervous system
Main article: Nervous system
Nervous system
The nervous system consists of the body's neurons and glial cells, which together form the nerves, ganglia and gray matter which in turn form the brain and related structures. The brain is the organ of thought, emotion, memory, and sensory processing; it serves many aspects of communication and controls various systems and functions. The special senses consist of vision, hearing, taste, and smell. The eyes, ears, tongue, and nose gather information about the body's environment.[37]
From a structural perspective, the nervous system is typically subdivided into two component parts: the central nervous system (CNS), composed of the brain and the spinal cord; and the peripheral nervous system (PNS), composed of the nerves and ganglia outside the brain and spinal cord. The CNS is mostly responsible for organizing motion, processing sensory information, thought, memory, cognition and other such functions.[38] It remains a matter of some debate whether the CNS directly gives rise to consciousness.[citation needed] The peripheral nervous system (PNS) is mostly responsible for gathering information with sensory neurons and directing body movements with motor neurons.[38]
From a functional perspective, the nervous system is again typically divided into two component parts: the somatic nervous system (SNS) and the autonomic nervous system (ANS). The SNS is involved in voluntary functions like speaking and sensory processes. The ANS is involved in involuntary processes, such as digestion and regulating blood pressure.[39]
The nervous system is subject to many different diseases. In epilepsy, abnormal electrical activity in the brain can cause seizures. In multiple sclerosis, the immune system attacks the nerve linings, damaging the nerves' ability to transmit signals. Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease, is a motor neuron disease which gradually reduces movement in patients. There are also many other diseases of the nervous system.[38]
Reproductive system
Main article: Human reproductive system
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The primary purpose of the reproductive system is to produce new humans in the form of children and ensure their sexual development so that they can produce new humans too. It is composed of the gonads (testicles and ovaries) which produce eggs and sperm cells (gametes) and produce hormones necessary for proper sexual development. The rest of the glands and ducts of the reproductive system are responsible for the transportation and sustaining of the gametes and to nurture the offspring.[40]
The reproductive system is first stimulated by the hypothalamus during puberty which causes the ovaries and testicles to produce testosterone (male) and estrogen and progesterone (female). Male puberty generally occurs between the ages of 13 and 15 and is characterized by beginning of sperm production and the development of secondary sex characteristics such as increased height and weight, broadened shoulders, pubic and facial hair, voice deepening and muscle development. Female puberty generally occurs between the ages of 9 and 13 and is characterized by ovulation and menstruation. The growth of secondary sex characteristics, such as growth of pubic and underarm hair, breast, uterine and vaginal growth, widening hips and increased height and weight, also occur during the female puberty process.[41]
The external male reproductive system is made up of the penis and the scrotum which is a sac containing the testicles. The penis consists of the glans, and contains the urethra and urinary meatus – the point where urine exits the penis. The rest of the penis is called the shaft and contains most of the urethra. The glans is covered by a fold of skin called the foreskin, although this can be removed through circumcision.[41]
Internal gross anatomy of the male reproductive system
Internally, the male reproductive system starts in the testes where hundreds of seminiferous tubules produce sperm which is then stored and matured into spermatozoon in the epididymis. They are then brought through the vas deferens which leads away from the testes to the seminal vesicles where the sperm cells are mixed with a fructose-rich fluid from the seminal vesicles allowing the sperm to stay alive and remain healthy. It is then brought by the ejaculatory duct through the prostate and bulbourethral gland, and mixed with fluids from said glands. The fluid from the prostate helps to neutralize the acidity of the vagina and keep the sperm alive. This mixture of sperm and accessory gland fluids is called semen and is released through the urethra during ejaculation. Almost the entire internal male reproductive system works in pairs with two testes, two epididymis, two vas deferens, two seminal vesicles, two ejaculatory ducts, two bulbourethral glands, but only one prostate and urethra.[41][42]
External female reproductive system with mons pubis highlighted
The external female reproductive system, also called the vulva, consists of the mons pubis, a fatty mass that covers the pubis, the labia majora (outer lips), the labia minora (inner lips), the vaginal opening which opens into the vagina and is where the penis is inserted during sexual intercourse and children are born. The urethral opening is for the urethra that carries urine from the bladder and the clitoris which contains the most sensitive nerve endings and in humans has no use other than sexual pleasure. Located between the anus and vulva is the perineum.[43][41]
Internal gross anatomy of the female reproductive system
Internally, the female reproductive system contains two ovaries, the uterus, two fallopian tubes and the cervix. At birth, a female has about 700,000 oocytes (the immature version of the egg cell) in both ovaries combined, although this degenerates to about 400,000 by the time puberty is reached. This is a lifetime supply, as after birth, no more oocytes are produced, compared to males where sperm cells are produced during their entire lifetime. During puberty, the menstrual cycle begins for the first time, in response to low estrogen and progesterone levels the hypothalamus releases gonadotropin releasing hormone (GnRH). This causes the anterior pituitary gland to release follicle-stimulating hormone (FSH) and luteinizing hormone (LH). FSH stimulates ovarian follicles to grow and one dominant follicle will eventually take over.
As the ovarian follicle continues to grow, it releases more estradiol which stimulates LH secretion and suppresses FSH secretion, preventing further follicular growth. When LH levels are highest, the follicle ruptures releasing the ovum in a process called ovulation where it is then moved to one of the fallopian tubes. After ovulation, the portion of the follicle that remains in the ovary is transformed into a corpus luteum which continues to produce estrogen and high levels of progesterone. The progesterone causes the endometrium to grow thick, preparing it for implantation of a fertilized egg. If fertilization occurs, the corpus luteum continues to secrete hormones until the placenta develops enough to secrete the necessary hormones for maintaining pregnancy. Eventually, the corpus luteum will turn into a corpus albicans which is essentially scar tissue. If fertilization fails, the corpus luteum will degrade into the corpus albicans and stop secreting enough progesterone and estrogen, causing the endometrial lining to break resulting in menstruation.[41][44]
Many diseases affect the reproductive system such as polycystic ovary syndrome (PCOS) which is characterized by elevated androgen levels, menstrual irregularities and/or small cysts on one or both of the ovaries. It is a common disease affecting at least 7% of adult women. Symptoms may include excess body hair, infertility, or weight gain, male pattern baldness.[45][46]
Another reproductive disease is testicular torsion, it occurs when the spermatic cord which holds up the testicle wraps around itself cutting off blood flow to the testicle. Testicular torsion is a medical emergency and can result in testicular death or infertility if not treated immediately by physically unwrapping the spermatic cord. If the testicle has suffered severe damage, it may need to be surgically removed in a lateral orchiectomy. The primary symptom of testicular torsion is severe testicular pain at rest, nausea and vomiting may also occur. Testicular torsion can occur at any age, although it is most common in 12-18 year olds.[47][48]
Sexually transmitted infections such as syphilis, HIV, chlamydia, HPV and genital warts are spread through sexual intercourse, including oral, vaginal, anal, and manual sex. Many of these infections can be lethal if left untreated though others are mostly harmless.[49][50]
Cancer can affect many parts of the reproductive system including the penis, testicles, prostate, ovaries, cervix, vagina, fallopian, uterus and vulva.[51]
Respiratory system
Main article: Respiratory system
The respiratory system consists of the nose, nasopharynx, trachea, and lungs. It brings oxygen from the air and excretes carbon dioxide and water back into the air. First, air is pulled through the trachea into the lungs by the diaphragm pushing down, which creates a vacuum. Air is briefly stored inside small sacs known as alveoli (sing.: alveolus) before being expelled from the lungs when the diaphragm contracts again. Each alveolus is surrounded by capillaries carrying deoxygenated blood, which absorbs oxygen out of the air and into the bloodstream.[52][53]
For the respiratory system to function properly, there need to be as few impediments as possible to the movement of air within the lungs. Inflammation of the lungs and excess mucus are common sources of breathing difficulties.[53] In asthma, the respiratory system is persistently inflamed, causing wheezing and/or shortness of breath. Pneumonia occurs through infection of the alveoli, and may be caused by tuberculosis. Emphysema, commonly a result of smoking, is caused by damage to connections between the alveoli.[54]
Urinary system
Main article: Urinary system
Female urinary system
The urinary system consists of the two kidneys, two ureters, bladder, and urethra. It removes waste materials from the blood through urine, which carries a variety of waste molecules and excess ions and water out of the body.
First, the kidneys filter the blood through their respective nephrons, removing waste products like urea, creatinine and maintaining the proper balance of electrolytes and turning the waste products into urine by combining them with water from the blood.[55] The kidneys filter about 150 quarts (170 liters) of blood daily, but most of it is returned to the blood stream with only 1-2 quarts (1-2 liters) ending up as urine.[56] The urine is brought by the ureters from the kidneys down to the bladder.
The smooth muscle lining the ureter walls continuously tighten and relax through a process called peristalsis to force urine away from the kidneys and down into the bladder. Small amounts of urine are released into the bladder every 10–15 seconds.
The bladder is a hollow balloon shaped organ located in the pelvis. It stores urine until the brain signals it to relax the urinary sphincter and release the urine into the urethra starting urination.[57] A normal bladder can hold up to 16 ounces (half a liter) for 3–5 hours comfortably.
Numerous diseases affect the urinary system including kidney stones which are formed when materials in the urine concentrate enough to form a solid mass, urinary tract infections which are infections of the urinary tract and can cause pain when urinating, frequent urination and even death if left untreated. Renal failure occurs when the kidneys fail to adequately filter waste from the blood and can lead to death if not treated with dialysis or kidney transplantation.[58] Cancer can affect the bladder, kidneys, urethra and ureters with the latter two being far more rare.[59]
Anatomy
Main articles: Outline of human anatomy and Anatomy
Cavities of human body
Human anatomy is the study of the shape and form of the human body. The human body has four limbs (two arms and two legs), a head and a neck which connect to the torso. The body's shape is determined by a strong skeleton made of bone and cartilage, surrounded by fat (adipose tissue), muscle, connective tissue, organs, and other structures. The spine at the back of the skeleton contains the flexible vertebral column which surrounds the spinal cord, which is a collection of nerve fibres connecting the brain to the rest of the body. Nerves connect the spinal cord and brain to the rest of the body. All major bones, muscles, and nerves in the body are named, with the exception of anatomical variations such as sesamoid bones and accessory muscles.
Blood vessels carry blood throughout the body, which moves because of the beating of the heart. Venules and veins collect blood low in oxygen from tissues throughout the body. These collect in progressively larger veins until they reach the body's two largest veins, the superior and inferior vena cava, which drain blood into the right side of the heart. From here, the blood is pumped into the lungs where it receives oxygen and drains back into the left side of the heart. From here, it is pumped into the body's largest artery, the aorta, and then progressively smaller arteries and arterioles until it reaches tissue. Here blood passes from small arteries into capillaries, then small veins and the process begins again. Blood carries oxygen, waste products, and hormones from one place in the body to another. Blood is filtered at the kidneys and liver.
The body consists of a number of body cavities, separated areas which house different organ systems. The brain and central nervous system reside in an area protected from the rest of the body by the blood brain barrier. The lungs sit in the pleural cavity. The intestines, liver, and spleen sit in the abdominal cavity.
Height, weight, shape and other body proportions vary individually and with age and sex. Body shape is influenced by the distribution of bones, muscle and fat tissue.[60]
Physiology
Main articles: Outline of physiology and Physiology
Human physiology is the study of how the human body functions. This includes the mechanical, physical, bioelectrical, and biochemical functions of humans in good health, from organs to the cells of which they are composed. The human body consists of many interacting systems of organs. These interact to maintain homeostasis, keeping the body in a stable state with safe levels of substances such as sugar and oxygen in the blood.[61]
Each system contributes to homeostasis, of itself, other systems, and the entire body. Some combined systems are referred to by joint names. For example, the nervous system and the endocrine system operate together as the neuroendocrine system. The nervous system receives information from the body, and transmits this to the brain via nerve impulses and neurotransmitters. At the same time, the endocrine system releases hormones, such as to help regulate blood pressure and volume. Together, these systems regulate the internal environment of the body, maintaining blood flow, posture, energy supply, temperature, and acid balance (pH).[61]
Development
Main article: Development of the human body
Baby being carried
Development of the human body is the process of growth to maturity. The process begins with fertilisation, where an egg released from the ovary of a female is penetrated by sperm. The egg then lodges in the uterus, where an embryo and later fetus develop until birth. Growth and development occur after birth, and include both physical and psychological development, influenced by genetic, hormonal, environmental and other factors. Development and growth continue throughout life, through childhood, adolescence, and through adulthood to old age, and are referred to as the process of aging.
Society and culture
Professional study
Further information: History of anatomy, History of medicine, and History of physiology
Anatomical study by Leonardo da Vinci
Health professionals learn about the human body from illustrations, models, and demonstrations. Medical and dental students in addition gain practical experience, for example by dissection of cadavers. Human anatomy, physiology, and biochemistry are basic medical sciences, generally taught to medical students in their first year at medical school.[62][63][64]
Depiction
Main article: Depictions of nudity
Figure drawing by Lovis Corinth (before 1925)
In Western societies, the contexts for depictions of the human body include information, art and pornography. Information includes both science and education, such as anatomical drawings. Any ambiguous image not easily fitting into one of these categories may be misinterpreted, leading to disputes.[65] The most contentious disputes are between fine art and erotic images, which define the legal distinction of which images are permitted or prohibited.
History of anatomy
Main article: History of anatomy
Two facing pages of text with woodcuts of naked male and female figures, in the Epitome by Andreas Vesalius, 1543
In Ancient Greece, the Hippocratic Corpus described the anatomy of the skeleton and muscles.[66] The 2nd century physician Galen of Pergamum compiled classical knowledge of anatomy into a text that was used throughout the Middle Ages.[67] In the Renaissance, Andreas Vesalius (1514–1564) pioneered the modern study of human anatomy by dissection, writing the influential book De humani corporis fabrica.[68][69] Anatomy advanced further with the invention of the microscope and the study of the cellular structure of tissues and organs.[70] Modern anatomy uses techniques such as magnetic resonance imaging, computed tomography, fluoroscopy and ultrasound imaging to study the body in unprecedented detail.[71]
History of physiology
Main article: History of physiology
The study of human physiology began with Hippocrates in Ancient Greece, around 420 BCE, and with Aristotle (384–322 BCE) who applied critical thinking and emphasis on the relationship between structure and function. Galen (c. 126 – c. 199) was the first to use experiments to probe the body's functions.[72] The term physiology was introduced by the French physician Jean Fernel (1497–1558). In the 17th century, William Harvey (1578–1657) described the circulatory system, pioneering the combination of close observation with careful experiment.[73] In the 19th century, physiological knowledge began to accumulate at a rapid rate with the cell theory of Matthias Schleiden and Theodor Schwann in 1838, that organisms are made up of cells. Claude Bernard (1813–1878) created the concept of the milieu interieur (internal environment), which Walter Cannon (1871–1945) later said was regulated to a steady state in homeostasis. In the 20th century, the physiologists Knut Schmidt-Nielsen and George Bartholomew extended their studies to comparative physiology and ecophysiology.[74] Most recently, evolutionary physiology has become a distinct subdiscipline.[75]
See also
- 이전글Muscle인체의 근육 .골격근, 심장근, 내장근-- 이런 근육들은 신경을 통해 뇌의 명령을 받아서 수축한단다. 22.08.13
- 다음글신체의 정상적인 주파수는 62∼68헤르츠인데 52헤르츠 이하에서 질병이 22.08.13
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