The Human Body

Question: What is the largest salivary gland in the human body?

Answer: Human beings have three pairs of majorsalivary glands that open into the mouth through ducts. The parotid glands, the largest of the three, are located between the ear and the ascending branch of the lower jaw.

Question: Which region of the brain produces oxytocin in humans?

Answer: Oxytocin is produced by the hypothalamus. It is stored and secreted into the bloodstream from the posterior pituitary gland.

Question: The inner surface of every blood vessel is lined by a thin layer of cells known as the:

Answer: The inner surface of every blood vessel is lined by a thin layer of cells known as the endothelium. The endothelium is separated from the tough external layers of the vessel by the basal lamina, an extracellular matrix produced by surrounding epithelial cells.

Question: Which part of the human eye can be transplanted from a dead donor to a living person?

Answer: When a person’s cornea is damaged it can be removed and replaced by a healthy one, using a corneal transplant, usually taken from a deceased donor.

Question: Which of these is the principal muscle of respiration?

Answer: The diaphragm is a dome-shaped, muscular, and membranous structure that separates the thoracic (chest) and abdominal cavities in mammals. The diaphragm is the principal muscle of respiration.

Question: Which of these is a neurological disorder?

Answer: Alzheimer disease is a disorder involving the disruption of electrical signals in the brain. It is named for Alois Alzheimer, a Bavarian neurologist.

Question: Which of these glands function as both an endocrine and exocrine gland?

Answer: The pancreas is a compound gland that functions as both an endocrine and exocrine gland. The pancreas weighs approximately 80 grams (about 3 ounces) and is shaped like a pear.

Question: An eyeball that is longer than typical from front to back causes what condition?

Answer: Myopia is a visual abnormality in which the resting eye focuses the image of a distant object at a point in front of the retina, resulting in a blurred image. Myopic eyes are usually longer than normal from front to back.

Question: What moves food down the esophagus?

Answer: Peristalsis is the involuntary movement of longitudinal and circular muscles, primarily in the digestive tract but occasionally in other hollow tubes of the body; it takes the form of progressive wavelike contractions. Peristaltic waves occur in the esophagus, where they move food to the stomach; peristalsis also occurs in the stomach and intestines.

Question: The permanent cessation of menstruation is known as:

Answer: Menopause is the permanent cessation of menstruation that results from the loss of ovarian function and therefore represents the end of a woman’s reproductive life. Menopause occurs in most women between ages 45 and 55.

Question: Which of these glands produces tears?

Answer: The lachrymal gland secretes tears. It is located near the eye.

Question: What is the flat muscle of the calf located beneath the gastrocnemius muscle called?

Answer: The soleus muscle is a flat, broad muscle of the calf of the leg lying just beneath the gastrocnemius muscle. It arises from the upper portions of the tibia and fibula.

Question: What are the three bones that, together, transmit sound to the inner ear?

Answer: The middle ear is spanned by a chain of three tiny bones: the malleus (hammer), incus (anvil), and stapes (stirrup). These bones, which are also called the auditory ossicles, transmit vibrations caused by sound waves from the eardrum membrane to the liquid of the inner ear.

Question: What is the longest segment of the small intestine?

Answer: The ileum is the longest (and final) segment of the small intestine. It is specifically responsible for the absorption of vitamin B₁₂ and the reabsorption of conjugated bile salts.

Question: Which enzyme was discovered by William Maddock Bayliss and Ernest Henry Starling in the year 1902?

Answer: Secretin is a digestive hormone that is secreted by the wall of the upper part of the small intestine (the duodenum); it regulates gastric acid secretion and pH levels in the duodenum. It was discovered in 1902 by British physiologists William Maddock Bayliss and Ernest Henry Starling.

Question: Where are the adrenal glands located in the human body?

Answer: The adrenal glands are located at the top of each kidney. They are two small and virtually identical triangular endocrine glands.

Question: What is the transparent gel-like material in the eyeball?

Answer: Much of the eyeball is filled with a transparent gel-like material, called the vitreous humour, that helps to maintain the spheroidal shape of the eyeball. (The vitreous humour is not the same as the aqueous humour.)

Question: Which of the following is connective tissue made of fat cells?

Answer: Adipose tissue is a type of connective tissue consisting mainly of fat cells (adipose cells, or adipocytes), specialized to synthesize and contain large globules of fat, within a structural network of fibers.

Question: In a human, the left lung has two of these, but the right lung has three. What are they?

Answer: A person’s lungs are divided into lobes, which are separated from one another by tissue fissures. The right lung has three major lobes; the left lung, which is slightly smaller because of the asymmetrical position of the heart, has two lobes.

Question: What is the largest nerve in the human body?

Answer: The sciatic nerve is the largest and thickest nerve of the human body; it is the principal continuation of all the roots of the sacral plexus. It emerges from the spinal cord in the lumbar portion of the spine and runs down through the buttocks and the back of the thighs.

Question: Which is the largest gland in the human body?

Answer: The liver is the largest gland in the human body. It is a spongy mass of wedge-shaped lobes that has many metabolic and secretory functions.

Question: How many pairs of spinal nerves are there in the human body?

Answer: In humans there are 31 pairs of spinal nerves: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal.

Question: The undigested food material from the small intestine is received by the:

Answer: The cecum is a pouch or large tubelike structure in the lower abdominal cavity that receives undigested food material from the small intestine. It is considered the first region of the large intestine.

Question: Which of these is the largest hollow space in a human body?

Answer: The abdominal cavity is the largest hollow space of the body. It contains the greater part of the digestive tract, the liver and pancreas, the spleen, the kidneys, and the adrenal glands.

Question: Which of the following is the narrowest portion of the stomach?

Answer: The pylorus is the narrowest portion of the stomach. It forms the outlet from the stomach into the duodenum. It is approximately 2 cm (almost 1 inch) in diameter and is surrounded by thick loops of smooth muscle.

Question: Which of the following is the most important to speech function and the creation of articulate speech?

Answer: The Broca area is the region of the brain that contains neurons closely involved in speech function. This area, located in the frontal part of the left hemisphere of the brain, was discovered in 1861 by French surgeon Paul Broca, who found that it serves a vital role in the generation of articulate speech.

Question: What hormone, produced in the pancreas, regulates blood sugar levels?

Answer: Insulin is the hormone that regulates the level of sugar (glucose) in the blood. It is produced in the pancreas.

Question: Which enzyme is responsible for the regulation of blood pressure?

Answer: Renin is the enzyme secreted by the kidney that is part of a physiological system that regulates blood pressure.

Question: Which of these act as a storehouse for fats?

Answer: Bone marrow is either red or yellow, depending upon the preponderance of hematopoietic or fatty tissue. Yellow bone marrow serves primarily as a storehouse for fats, but itmay be converted to red marrow under certain conditions, such as severe blood loss or fever.

Question: Which of these hormones is produced by the testes?

Answer: Testosterone is produced by the male testis and is responsible for the development of the male sex organs and masculine characteristics, including facial hair and deepening of the voice.

Question: What is the average temperature of a healthy human?

Answer: The average temperature of a healthy human is 36.9° C (98.6° F).

Question: Which of these glands is present as a pair in the human body?

Answer: The adrenal glands (also called suprarenal glands) are a pair of small triangular endocrine glands, one of each is located above each kidney. In humans, each adrenal gland weighs about 5 grams (0.18 ounce) and measures about 30 mm (1.2 inches) wide, 50 mm (2 inches) long, and 10 mm (0.4 inches) thick.

Question: What is the most common type of gallstone?

Answer: Gallstones are crystalline substances embedded in a small amount of protein material formed most often in the gallbladder. The most common type of gallstone consists principally of cholesterol.

Question: Which muscle group covers the front and sides of the thigh?

Answer: The quadriceps femoris muscle is the large fleshy muscle group covering the front and sides of the thigh. It has four parts: rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius.

Question: How many bones are present in a human wrist?

Answer: A human’s wrist consists of eight small carpal bones, which are arranged in two rows of four each.

Question: What is the name of the system in the human body that transports blood?

Answer: The cardiovascular system is the organ system that conveys blood through vessels to and from all parts of the human body, carrying nutrients and oxygen to tissues and removing carbon dioxide and other wastes.

Question: How many types of cells are there in a bone?

Answer: There are four types of cells in a bone. They are osteoblasts, osteocytes, osteoclasts, and mesenchymal stem cells.

Question: The period of contraction of the ventricles of the heart is known as:

Answer: Systole is a period of contraction of the ventricles of the heart that occurs between the first and second heart sounds of the cardiac cycle. It causes the ejection of blood into the aorta and pulmonary trunk.

Question: What is the name of the tissue that connects muscle to bone?

Answer: Tendon tissue connects muscles to bones. The tendon is firmly connected to muscle fibers at one end and to components of the bone at its other end. Tendons are strong and are capable of withstanding the stresses generated by muscular contraction.

Question: Which of these transports urine from the kidneys to the bladder?

Answer: The ureter is a narrow, thick-walled duct that transports urine from a kidney to the bladder. A person typically has one ureter for each kidney. Each ureter is a narrow tube that is about 12 inches (30 cm) long.

Question: What is the largest joint in a human body?

Answer: The knee is the largest joint in the body. It has to sustain the greatest stresses because it supports the entire weight of the body above it.

Question: Which of the following is also known as voluntary muscle?

Answer: Skeletal muscle is also known as voluntary muscle. Skeletal muscles are attached to bones by tendons.

Question: Where is the pharynx located?

Answer: The pharynx, or throat, is a part of the body that helps with eating and with breathing. It is a passage that leads from the mouth and nose to the esophagus and the larynx.

Question: Where is the esophagus located?

Answer: The esophagus is a tube through which food passes from the pharynx to the stomach. The walls of the esophagus move in waves to push the food down the tube to the stomach.

Question: Which membranes cover and protect the brain and spinal cord?

Answer: The meninges are the three membranous envelopes—pia mater, arachnoid, and dura mater—that surround the brain and spinal cord. The meninges, together with the cerebrospinal fluid, protect the central nervous system.

Question: Where are red blood cells formed?

Answer: Red cells, formed in bone marrow, are the most numerous kind of blood cells. Each drop of blood contains about 300 million of them.

Question: Which part of the skull contains the brain?

Answer: The cranium is the part of the skull that contains the brain, is globular, and is relatively large in comparison with the face. In most other animals the facial portion of the skull, including the upper teeth and the nose, is larger than the cranium.

Question: Which of these organs will, if it is healthy, float in water?

Answer: The lungs are soft, light, spongy, elastic organs that normally, after birth, always contain some air. If healthy, they will float in water; diseased lungs sink.

Question: What is the hardest tissue in the human body?

Answer: In mammals, the outer layer of enamel, which is wholly inorganic, is the hardest tissue in the body. It covers part or all of the crown of the tooth. Enamel, when mature, consists predominantly of apatite crystals containing calcium and phosphate.

Question: In humans, the highest vertebra that supports the skull is known as the:

Answer: In humans, the skull is supported by the atlas, which is the highest vertebra. The atlas permits nodding motion. The atlas turns on the next-lower vertebra, the axis, to allow for side-to-side movement of the skull.

Question: The inner surface of the stomach is lined by a mucous membrane known as the:

Answer: The inner surface of the stomach is lined by a mucous membrane known as the gastric mucosa. It is a glycoprotein that serves two purposes: (1) the lubrication of food masses to facilitate movement within the stomach and (2) the formation of a protective layer over the lining epithelium of the stomach cavity.

Question: What is the formation of new blood vessels called?

Answer: Angiogenesis is the formation of new blood vessels. It is a normal process during the growth of the body and in the body’s replacement of damaged tissue.

Question: Which of these parts of the eye has no blood vessels?

Answer: The cornea contains no blood vessels (except at its margins). That means it is transparent. It does, however, contain many nerves and is very sensitive to pain or touch. The cornea gets nutrients and oxygen from tears and through the aqueous humour.

Question: What is the appendix attached to in the human body?

Answer: The appendix is closed at one end and is attached at the other end to the cecum, the pouchlike beginning of the large intestine into which the small intestine empties its contents.

Question: Name the blood vessel that carries unfiltered blood from the aorta to the kidney.

Answer: The renal artery is one of the pair of large blood vessels that branch off from the abdominal aorta and enter into each kidney. At the inner concavity of each kidney, there is an opening, known as the hilum, through which the renal artery passes. After passing through the hilum, the renal artery divides ordinarily into two large branches, and each branch divides into many smaller arteries, which bring blood to the nephrons, the functioning units of the kidney.

Question: How many tarsal bones do human ankles have?

Answer: There are seven tarsal bones in a human body. The talus articulates above with the bones of the lower leg to form the ankle joint. The other six tarsals, tightly bound together by ligaments below the talus, function as a strong weight-bearing platform.

Question: Which part of the human body prevents food from entering the respiratory tract?

Answer: The epiglottis, at the upper part of the larynx, is a flaplike projection into the throat that prevents food from entering the respiratory tract. As food is swallowed, the whole larynx structure rises to the epiglottis so that the passageway to the respiratory tract is blocked.

Question: What hormone stimulates the secretion of milk by the mammary glands?

Answer: Prolactin is a protein hormone produced by the pituitary gland of mammals that acts with other hormones to initiate secretion of milk by the mammary glands.

Question: Which of these carries air from a person’s larynx to their lungs?

Answer: A person’s trachea, or windpipe, carries air from a person’s larynx to the main bronchi and thus to the person’s lungs. The trachea serves as a passage for air, moistens and warms it while it passes into the lungs, and protects the respiratory surface from an accumulation of foreign particles.

Question: What fraction of the human body is made up of blood?

Answer: Blood is the life fluid of the human body and the liquid that transports nutrients and removes waste. It makes up about 1/13 of the total weight of the human body.