Product Code Database
The human body is the entire structure of a Human. It is composed of many different types of cells that together create tissues and subsequently organs and then Organ system.
The external human body consists of a human head, hair, neck, torso (which includes the thorax and abdomen), Sex organ, , Hand, human leg, and Foot. The internal human body includes organs, Human tooth, , muscle, , , and blood, and lymph.
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, iron, and oxygen in the blood.
The body is studied by health professionals, physiologists, anatomists, and artists to assist them in their work.
| Elements of the human body by mass. Trace element 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 chemical element 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% Body water content of some . This is made up of about of extracellular fluid including about of blood plasma and about of interstitial fluid, and about of fluid inside cells. The content, acidity and composition of the water inside and outside cells is carefully maintained. The main in body water outside cells are sodium and chloride, whereas within cells it is potassium and other .
Each of the cells of the human body experiences, on average, tens of thousands of DNA damages per day. These damages can block human genome replication or genome transcription, and if they are not DNA repair or are repaired incorrectly, they may lead to , or other genome alterations that threaten cell viability.
The heart has an electrical conduction system to control the contraction and relaxation of the muscles. It starts in the sinoatrial node traveling through the atria causing them to Cardiac cycle. 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.
Coronary artery disease is the leading cause of death worldwide, making up 16% of all deaths. It is caused by the buildup of Atherosclerosis in the coronary arteries supplying the heart, eventually the arteries may become so narrow that Ischemia is able to reach the Cardiac muscle, a condition known as myocardial infarction or heart attack, this can cause heart failure or cardiac arrest and eventually death. Risk factors for coronary artery disease include obesity, smoking, high cholesterol, Hypertension, lack of exercise and diabetes. Heart cancer, though it is exceedingly rare and has usually Metastasis from another part of the body such as the Lung cancer or Breast cancer. This is because the Cardiac muscle quickly stop dividing and all growth occurs through Hypertrophy rather than Mitosis.
The gallbladder gets its blood supply from the cystic artery, which in most people, emerges from the right hepatic artery.
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 Biliary colic; symptoms may include sudden pain in the upper right abdomen or center of the abdomen. Nausea and vomiting may also occur. Typical treatment is removal of the gallbladder through a procedure called a cholecystectomy. Having gallstones is a risk factor for gallbladder cancer, which, although quite uncommon, is rapidly fatal if not diagnosed early.
Digestion begins in the Human mouth, which Chewing food into smaller pieces for easier digestion. Then it is Swallowing, and moves through the esophagus to the stomach. In the stomach, food is mixed with to allow the extraction of . 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 Human feces; these are then stored in the rectum until they are expelled through the Human anus.
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 Ganglion outside the brain and spinal cord. The CNS is mostly responsible for organizing motion, processing Sense, thought, memory, cognition and other such functions. It remains a matter of some debate whether the CNS directly gives rise to consciousness. The peripheral nervous system (PNS) is mostly responsible for gathering information with and directing body movements with .
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 Speech and sense. The ANS is involved in involuntary processes, such as digestion and regulating blood pressure.
The nervous system is subject to many different diseases. In epilepsy, abnormal electrical activity in the brain can cause Seizure. In multiple sclerosis, the immune system attacks the myelin, damaging the nerves' ability to transmit signals. ALS (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.
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 hair and underarm hair, breast, Uterus and growth, widening hips and increased height and weight, also occur during puberty. Male puberty sees the further development of the Human penis and .
The female inner sex organs are the two ovaries, their , the uterus, and the cervix. At birth there are about 70,000 oocyte that degenerate until at puberty there are around 40,000. No more egg cells are produced. Hormones stimulate the beginning of menstruation, and the ongoing . The female external sex organs are the vulva (labia, clitoris, and vulval vestibule).
The male external genitalia include the penis and scrotum that contains the Testicle. The testicles are that produce the Sperm which are ejaculation in semen through the penis. Unlike the egg cells in the female, sperm cells are produced throughout life. Other internal sex organs are the Epididymis, Vas deferens, and some accessory glands.
Diseases that affect the reproductive system include polycystic ovary syndrome, a number of disorders of the testicles including testicular torsion, and a number of sexually transmitted infections including syphilis, HIV, chlamydia, HPV and . Cancer can affect most parts of the reproductive system including Penile cancer, testicles, Prostate cancer, Ovarian cancer, Cervical cancer, Vaginal cancer, fallopian, Uterine cancer and Vulvar cancer.
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. In asthma, the respiratory system is persistently inflamed, causing Wheeze 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.
First, the filter the blood through their respective , removing Metabolic waste like urea, creatinine and maintaining the proper balance of and turning the waste products into urine by combining them with water from the blood. 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, which passes from the kidneys through the into the bladder.
The lining the ureter walls continuously tighten and relax through a process called peristalsis, forcing small amounts of urine 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. A normal bladder can hold up to 16 ounces (half a liter) for 3–5 hours comfortably.
Numerous Urologic disease 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. Kidney failure occurs when the kidneys fail to adequately filter waste from the blood and can lead to death if not treated with Kidney dialysis or kidney transplantation. Cancer can affect the Bladder cancer, Kidney cancer, Urethral cancer and Ureteral cancer, with the latter two being far more rare.
Blood vessels carry blood throughout the body, which moves because of the beating of the heart. and 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 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 until it reaches tissue. Here, blood passes from small arteries into Capillary, then small veins and the process begins again. Blood carries oxygen, waste products, and from one place in the body to another. Blood is filtered at the and liver.
The body consists of a number of Body cavity, 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, Body shape and other body proportions vary individually and with age and sex. Body shape is influenced by the distribution of bones, muscle and Adipose tissue.
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 Action potential and . 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).
Genome
Cells in the body function because of DNA. DNA sits within the Cell nucleus. Here, parts of DNA are copied and sent to the body of the cell via RNA. The RNA is then used to create , 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. 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. The study of tissues is called histology and is often done with a microscope. The body consists of four main types of tissues. These are lining cells (Epithelium), connective tissue, Nervous tissue and Muscle.
Cells
Cells that line surfaces exposed to the outside world or gastrointestinal tract (Epithelium) or internal cavities (endothelium) come in numerous shapes and forms – from Epithelium, to cells with small beating hair-like Cilium 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 cannot pass through them, protect internal structures, and function as sensory surfaces.
Organs
Organs, structured collections of cells with a specific function, mostly sit within the body, with the exception of Human skin. Examples include the heart, and liver. Many organs reside within Body cavity within the body. These cavities include the abdomen (which contains the stomach, for example) and pleural cavity, which contains the lungs.
Heart
The heart is an organ located in the thoracic cavity between the 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. The heart works by pumping blood around the body allowing oxygen, , Metabolic waste, and white blood cells to be transported.
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 Systole. This allows enough blood to get into the ventricles during Systole. Consequently, the atria allows a cardiac output roughly 75% greater than would be possible without them. 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.
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 Lipid metabolism. It receives bile from the liver via the cystic duct, which connects to the common hepatic duct to form the common bile duct.
Systems
Circulatory system
The circulatory system consists of the heart and (Artery, and Capillary). The heart propels the circulation of the blood, which serves as a "transportation system" to transfer oxygen, fuel, nutrients, waste products, immune cells and signaling molecules (i.e. Hormone) 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.
Digestive system
The digestive system consists of the mouth including the tongue and Human tooth, esophagus, stomach, (gastrointestinal tract, small intestine and , and rectum), as well as the liver, pancreas, gallbladder, and . It converts food into small, nutritional, non-toxic for distribution and absorption into the body. These molecules take the form of (which are broken down into ), , and minerals (the last of which are mainly ionic rather than molecular). After being Swallowing, 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.
Endocrine system
The endocrine system consists of the principal : the Pituitary gland, thyroid, Adrenal gland, pancreas, parathyroids, and , but nearly all organs and tissues produce specific endocrine as well. The endocrine hormones serve as signals from one body system to another regarding an enormous array of conditions, resulting in variety of changes of function.
Immune system
The immune system consists of the white blood cells, the thymus, 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 Antibody, Cytokine, and toll-like receptors, among many others.
Integumentary system
The integumentary system consists of the covering of the body (the human skin), including hair and nails as well as other functionally important structures such as the and . The skin provides containment, structure, and protection for other organs, and serves as a major sensory interface with the outside world.
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.
Musculoskeletal system
The musculoskeletal system consists of the human skeleton (which includes , , , Joint and cartilage) and attached . 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 Human skeleton. (2025). 9781605476520, Lippincott Williams & Wilkins. ISBN 9781605476520
Nervous system
The nervous system consists of the body's and cells, which together form the Nerve, Ganglion and Grey matter, which in turn form the human 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 human eye, , tongue, and human nose gather information about the body's environment.
Reproductive system
The purpose of the reproductive system is to reproduce and nurture the growth of offspring. The functions include the production of germ cells and hormones. The Sex organ of the male reproductive system and the female reproductive system develops and mature at puberty. These systems include the internal and external Sex organ.
Respiratory system
The respiratory system consists of the nose, Pharynx, trachea, and Lung. 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 Capillary carrying deoxygenated blood, which absorbs oxygen out of the air and into the bloodstream.
Urinary system
The urinary system consists of the two , two , bladder, and urethra. It removes waste materials from the blood through urine, which carries a variety of waste molecules and excess and water out of the body.
Anatomy
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 human skeleton made of bone and cartilage, surrounded by fat (adipose tissue), muscle, connective tissue, organs, and other structures. The Spinal column at the back of the skeleton contains the flexible Spinal column, which surrounds the spinal cord, which is a collection of nerve fibres connecting the human brain to the rest of the body. 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 and .
Physiology
Human physiology is the study of how the human body functions. This includes the mechanical, physical, bioelectrical, and Biochemistry 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.
Development
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 childbirth. 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 Child, adolescence, and through Adult to old age, and are referred to as the process of Ageing.
Society and culture
Professional study
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.
Depiction
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. 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
In Ancient Greece, the Hippocratic Corpus described the anatomy of the skeleton and muscles. The 2nd century physician Galen compiled classical knowledge of anatomy into a text that was used throughout the Middle Ages. In the Renaissance, Andreas Vesalius (1514–1564) pioneered the modern study of human anatomy by dissection, writing the influential book De humani corporis fabrica. Anatomy advanced further with the invention of the microscope and the study of the cellular structure of tissues and organs. Modern anatomy uses techniques such as magnetic resonance imaging, CT scan, fluoroscopy and ultrasound imaging to study the body in unprecedented detail.
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 () was the first to use experiments to probe the body's functions. 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. 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. Most recently, evolutionary physiology has become a distinct subdiscipline.
See also
Human body lists
Books
(2025). 9780071825108, McGraw-Hill Education. ISBN 9780071825108
(2025). 9780808923718, Churchill Livingstone. ISBN 9780808923718
External links
|
|
