Human anatomy is the branch of anatomy devoted to the structure of the human body. It cannot be totally divorced from physiology because structure and function go hand in hand. The study of anatomy proceeds along two different lines at the same time, regional anatomy and systemic anatomy. Regional anatomy looks at the body according to structure and location. The systemic approach divides the body according to function, e.g. the digestive system. The regional approach is of great importance, especially for the surgeon. At the same time a systemic knowledge of anatomy allows one to understand how the different parts of the body interrelate.
Generally, students of certain biological sciences, paramedics, prosthetists and orthotists, physiotherapists, occupational therapy, nurses, and medical students learn gross anatomy and microscopic anatomy from anatomical models, skeletons, textbooks, diagrams, photographs, lectures and tutorials. But how about you? You need to know the basics when it comes to certain organs and glands location and functions.
Urinary System Location
The urinary system (also called the excretory system) is the organ system that produces, stores, and eliminates urine. In humans it includes two kidneys, two ureters, the bladder, the urethra, and two sphincter muscles.
Appendix (or vermiform appendix; also cecal (or caecal) appendix; also vermix) is a blind-ended tube connected to the cecum (or caecum), from which it develops embryologically. The cecum is a pouchlike structure of the colon. The appendix is located near the junction of the small intestine and the large intestine. The term “vermiform” comes from Latin and means “worm-shaped”.
The most common explanation for the appendix’s existence in humans is that it’s a vestigial structure which has lost its original function. See the top 10 useless body parts.
The esophagus (or oesophagus), sometimes known as the gullet, is an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. During swallowing food passes from the mouth through the pharynx into the esophagus and travels via peristalsis to the stomach. It is usually about 25–30 cm long and connects the mouth to the stomach. It is divided into cervical, thoracic and abdominal parts. Due to the inferior pharyngeal constrictor muscle, the entry to the esophagus opens only when swallowing or vomiting.
The lung (adjectival form: pulmonary) is the essential respiration cell in many air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located near the backbone on either side of the heart. Their principal function is to transport oxygen from the atmosphere into the bloodstream, and to release carbon dioxide from the bloodstream into the atmosphere. This exchange of gases is accomplished in the mosaic of specialized cells that form millions of tiny, exceptionally thin-walled air sacs called alveoli.
The pleural cavity is the body cavity that surrounds the lungs. The pleura is a serous membrane which folds back onto itself to form a two-layered, membrane structure. The thin space between the two pleural layers is known as the pleural cavity. It normally contains a small amount of pleural fluid. The outer pleura (parietal pleura) is attached to the chest wall. The inner pleura (visceral pleura) covers the lungs and adjoining structures, viz. blood vessels, bronchi and nerves.
The parietal pleura is highly sensitive to pain, while the visceral pleura is not, due to its lack of sensory innervation.
The spleen is an organ found in virtually all vertebrate animals with important roles in regard to red blood cells and the immune system. In humans, it is located in the left upper quadrant of the abdomen. It removes old red blood cells and holds a reserve of blood in case of hemorrhagic shock while also recycling iron. It synthesizes antibodies in its white pulp and removes antibody-coated bacteria along with antibody-coated blood cells by way of blood and lymph node circulation. The spleen is purple and gray. Recently, it has been found to contain in its reserve half of the body’s monocytes within the red pulp. These monocytes, upon moving to injured tissue (such as the heart), turn into dendritic cells and macrophages while promoting tissue healing. It is one of the centers of activity of the reticuloendothelial system and can be considered analogous to a large lymph node, as its absence leads to a predisposition toward certain infections.
The stomach is a muscular, hollow, dilated part of the alimentary canal which functions as an important organ of the digestive tract. It is involved in the second phase of digestion, following mastication (chewing). The stomach is located between the oesophagus and the small intestine. It secretes protein-digesting enzymes and strong acids to aid in food digestion, through smooth muscular contortions (called segmentation) before sending partially-digested food (chyme) to the small intestines.
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion. The liver is necessary for survival; there is currently no way to compensate for the absence of liver function long term, although liver dialysis can be used short term.
This organ plays a major role in metabolism and has a number of functions in the body, including glycogen storage, decomposition of red blood cells, plasma protein synthesis, hormone production, and detoxification. It lies below the diaphragm in the abdominal-pelvic region of the abdomen. It produces bile, an alkaline compound which aids in digestion via the emulsification of lipids. The liver’s highly specialized tissues regulate a wide variety of high-volume biochemical reactions, including the synthesis and breakdown of small and complex molecules, many of which are necessary for normal vital functions.
The kidneys are organs with several functions. They are seen in many types of animals, including vertebrates and some invertebrates. They are an essential part of the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid-base balance, and regulation of blood pressure. They serve the body as a natural filter of the blood, and remove wastes which are diverted to the urinary bladder. In producing urine, the kidneys excrete wastes such as urea and ammonium; the kidneys also are responsible for the reabsorption of water, glucose, and amino acids. The kidneys also produce hormones including calcitriol, renin, and erythropoietin.
Located at the rear of the abdominal cavity in the retroperitoneum, the kidneys receive blood from the paired renal arteries, and drain into the paired renal veins. Each kidney excretes urine into a ureter, itself a paired structure that empties into the urinary bladder.
The pancreas is a gland organ in the digestive and endocrine system of vertebrates. It is both an endocrine gland producing several important hormones, including insulin, glucagon, and somatostatin, as well as an exocrine gland, secreting pancreatic juice containing digestive enzymes that pass to the small intestine. These enzymes help to further break down the carbohydrates, proteins, and lipids in the chyme.
The thyroid gland or simply, the thyroid, is one of the largest endocrine glands in the body, and is not to be confused with the parathyroid glands. The thyroid gland is found in the neck, inferior to (below) the thyroid cartilage (also known as the Adam’s Apple) and at approximately the same level as the cricoid cartilage. The thyroid controls how quickly the body uses energy, makes proteins, and controls how sensitive the body should be to other hormones.
The thyroid gland participates in these processes by producing thyroid hormones, the principal ones being triiodothyronine (T3) and thyroxine (T4). These hormones regulate the rate of metabolism and affect the growth and rate of function of many other systems in the body. T3 and T4 are synthesized utilizing both iodine and tyrosine. The thyroid gland also produces calcitonin, which plays a role in calcium homeostasis.
The parathyroid glands are small endocrine glands in the neck that produce parathyroid hormone. Humans usually have four parathyroid glands, which are usually located on the rear surface of the thyroid gland, or, in rare cases, within the thyroid gland itself or in the chest. Parathyroid glands control the amount of calcium in the blood and within the bones.
The parathyroid glands are four or more small glands, about the size of a grain of rice, located on the posterior surface (back side) of the thyroid gland. The parathyroid glands usually weigh between 25mg and 40mg in humans. There are typically two, one above the other, on the left lobe of the thyroid and similarly on the right.
Pituitary Gland Location
The pituitary gland is located at the base of the brain, behind the bridge of the nose. It is about one-half inch (1.25 cm) in diameter. The pituitary gland rests within a hollowed out area of the sphenoid bone called the sella turcica. The pituitary gland is referred to as the “master gland” because it monitors and regulates many bodily functions through the hormones that it produces: Growth and sexual/reproductive development and function; Glands (thyroid gland, adrenal glands, and gonads); Organs (kidneys, uterus, and breasts).
The pituitary gland is connected by a stalk to a part of the brain called the hypothalamus. Together, the brain and pituitary gland form the neuroendocrine system. This system constantly monitors glands and organs to determine whether to send or to stop the chemical messengers (hormones) that control their functions.
The thymus is a specialized organ of the immune system. The only known function of the thymus is the production and “education” of T-lymphocytes (T cells), which are critical cells of the adaptive immune system. The thymus is composed of two identical lobes and is located anatomically in the anterior superior mediastinum, in front of the heart and behind the sternum.
The prostate is a compound tubuloalveolar exocrine gland of the male reproductive system in most mammals. The function of the prostate is to store and secrete a slightly alkaline fluid, milky or white in appearance, that usually constitutes 20-30% of the volume of the semen along with spermatozoa and seminal vesicle fluid. The alkalinity of semen helps neutralize the acidity of the vaginal tract, prolonging the lifespan of sperm. The alkalinization of semen is primarily accomplished through secretion from the seminal vesicles. The prostatic fluid is expelled in the first ejaculate fractions, together with most of the spermatozoa. In comparison with the few spermatozoa expelled together with mainly seminal vesicular fluid, those expelled in prostatic fluid have better motility, longer survival and better protection of the genetic material (DNA).
The ovary is an ovum-producing reproductive organ, often found in pairs as part of the vertebrate female reproductive system. Ovaries in females are homologous to testes in males, in that they are both gonads and endocrine glands. Ovaries are oval shaped . The ovary (for a given side) is located in the lateral wall of the pelvis in a region called the ovarian fossa. The fossa usually lies beneath the external iliac artery and in front of the ureter and the internal iliac artery.
The ovaries aren’t attached to the fallopian tubes but to the outer layer of the uterus via the ovarian ligaments. Usually each ovary takes turns releasing eggs every month. However, if there was a case where one ovary was absent or dysfunctional then the other ovary would continue providing eggs to be released.
Adrenal Glands Location
The adrenal glands (also known as suprarenal glands) are endocrine glands that sit on top of the kidneys; in humans, the right suprarenal gland is triangular shaped while the left suprarenal gland is semilunar shaped. They are chiefly responsible for releasing hormones in conjunction with stress through the synthesis of corticosteroids such as cortisol and catecholamines, such as epinephrine. Adrenal glands affect kidney function through the secretion of aldosterone, a hormone involved in regulating plasma osmolarity.
Small Intestine Location
The small intestine is the part of the gastrointestinal tract (git) following the stomach and followed by the large intestine, and is where the vast majority of digestion and absorption of food takes place. The primary function of the small intestine is the absorption of nutrients and minerals found in food. The small intestine in an adult human measures on average 6 meters (about 19 feet). It can measure around 50% longer at autopsy because of loss of smooth muscle tone after death. It is approximately 2.5–3 cm in diameter.
Large Intestine Location
The large intestine (or “large bowel”) is the second-to-last part of the digestive system — the final stage of the alimentary canal is the anus. Its function is to absorb water from the remaining indigestible food matter, and then to pass useless waste material from the body. This article is primarily about the human gut, though the information about its processes are directly applicable to most mammals.
The large intestine consists of the cecum and colon. It starts in the right iliac region of the pelvis, just at or below the right waist, where it is joined to the bottom end of the small intestine. From here it continues up the abdomen, then across the width of the abdominal cavity, and then it turns down, continuing to its endpoint at the anus.
The large intestine is about 1.5 metres (4.9 ft) long, which is about one-fifth of the whole length of the intestinal canal.
Heart Valves, Aortas and Ventricles Location
A heart valve normally allows blood to flow through it in only one direction. There are four in a mammalian heart and they determine the pathway of blood flow through the heart. A heart valve opens or closes depending on the different pressures on each side of it.
The four valves in the heart are:
- The two atrioventricular (AV) valves, which are between the atria and the ventricles, are the mitral valve and the tricuspid valve.
- The two semilunar (SL) valves, which are in the arteries leaving the heart, are the aortic valve and the pulmonary valve.
A form of heart disease occurs when a valve malfunctions and allows some blood to flow in the wrong direction. This is called regurgitation.
Normal Heart Blood Circulation
The heart pumps oxygenated blood to the body and deoxygenated blood to the lungs. In the human heart there is one atrium and one ventricle for each circulation, and with both a systemic and a pulmonary circulation there are four chambers in total: left atrium, left ventricle, right atrium and right ventricle. The right atrium is the upper chamber of the right side of the heart. The blood that is returned to the right atrium is deoxygenated (poor in oxygen) and passed into the right ventricle to be pumped through the pulmonary artery to the lungs for re-oxygenation and removal of carbon dioxide. The left atrium receives newly oxygenated blood from the lungs as well as the pulmonary vein which is passed into the strong left ventricle to be pumped through the aorta to the different organs of the body.