Final Exam - Chapter 21

Cholecystokinin is a hormone released by the small intestine in response to the presence of fats and proteins. It stimulates the release of bile from the gallbladder into the duodenum, which aids in the digestion and absorption of fats. Therefore, the statement that cholecystokinin stimulates the release of bile into the duodenum is true.

The white pulp of the spleen gets its color mainly from lymphocytes and macrophages. This is because the white pulp is composed of lymphoid tissue, which contains a high concentration of lymphocytes and macrophages. Lymphocytes are a type of white blood cell that play a key role in the immune response, while macrophages are large phagocytic cells that help to engulf and eliminate pathogens. The presence of these cells in the white pulp gives it a distinct white coloration. Therefore, the statement is true.

Perforins are proteins that are used by the immune system to destroy infected or cancerous cells. They are a key component of both the nonspecific resistance and cellular immunity responses. Nonspecific resistance refers to the general defense mechanisms that the body has against pathogens, while cellular immunity involves the activation of specific immune cells to target and eliminate infected or abnormal cells. Since perforins play a role in both of these processes, the statement is true.

Constriction of the afferent arteriole reduces the glomerular filtration rate because it decreases the blood flow into the glomerulus. The afferent arteriole is responsible for supplying blood to the glomerulus, where filtration occurs. When it constricts, it narrows the opening and restricts the amount of blood that can enter the glomerulus. As a result, less blood is filtered and the glomerular filtration rate decreases.

Peristalsis is the process of wave-like muscle contractions that propel food through the digestive system. The myenteric nerve plexus, also known as the Auerbach's plexus, is a network of nerves located between the circular and longitudinal muscle layers of the gastrointestinal tract. It plays a crucial role in regulating the contractions and movements of the digestive system, including peristalsis. Therefore, the statement that peristalsis is controlled by the myenteric nerve plexus is true.

Urine can be as dilute as 50 mOsm/L

The cardinal signs of inflammation are redness, swelling, heat, and pain. Fever, on the other hand, is not considered one of the cardinal signs of inflammation. Fever is a systemic response of the body to an infection or inflammation, characterized by an elevated body temperature. While fever can be associated with inflammation, it is not considered one of the primary signs.

Pepsinogen, trypsinogen, and procarboxypeptidase are enzymatically inactive zymogens. Zymogens are inactive forms of enzymes that are converted into their active forms through specific cleavage reactions. Pepsinogen is converted into pepsin, trypsinogen is converted into trypsin, and procarboxypeptidase is converted into carboxypeptidase. These conversions occur in the stomach and small intestine, where the acidic environment and specific enzymes facilitate the activation process. Therefore, it is true that pepsinogen, trypsinogen, and procarboxypeptidase are enzymatically inactive zymogens.

Angiotensin II is a hormone that constricts blood vessels and stimulates the release of aldosterone, which promotes water and sodium reabsorption in the kidneys. This results in reduced urine output, as less water and sodium are excreted in the urine. Therefore, the statement that angiotensin II reduces urine output is true.

A lymph node is the only lymphatic organ that has both afferent and efferent lymphatic vessels. Afferent lymphatic vessels bring lymph fluid containing pathogens, toxins, and waste products into the lymph node, while efferent lymphatic vessels carry filtered lymph fluid away from the node. This allows the lymph node to act as a filtering station, where immune cells can encounter and eliminate harmful substances before the lymph fluid is returned to the bloodstream. The spleen, tonsils, Peyer's patches, and thymus are all lymphatic organs, but they do not have both afferent and efferent lymphatic vessels.

Basophils and mast cells are types of white blood cells that play a role in the immune response. They release histamine and heparin, which are important molecules involved in inflammation and allergic reactions. Histamine causes blood vessels to dilate and become more permeable, while heparin prevents blood clotting. Therefore, it is true that histamine and heparin are secreted by basophils and mast cells.

A person who is HIV-positive and has a TH (CD4) count of 1,000 cells/mL does not have AIDS. This is because AIDS is diagnosed when the CD4 count drops below 200 cells/mL or when certain opportunistic infections occur in HIV-positive individuals. With a CD4 count of 1,000 cells/mL, the person's immune system is still relatively strong, indicating that they have not progressed to AIDS. Therefore, the statement "True" is correct.

Glyosuria does not occur in diabetes insipidus.

Chief cells are a type of exocrine cell found in the stomach lining that secrete digestive enzymes, specifically pepsinogen. Pepsinogen is converted into pepsin, an enzyme that helps break down proteins into smaller peptides. These enzymes are essential for the digestion and absorption of nutrients in the stomach. Parietal cells, on the other hand, secrete hydrochloric acid, which helps activate pepsinogen into pepsin. Mucous neck cells secrete mucus to protect the stomach lining, goblet cells secrete mucus in the respiratory and digestive tracts, and enteroendocrine cells secrete hormones that regulate various digestive processes.

Micturition refers to the process of emptying the bladder. The detrusor muscle is responsible for contracting and relaxing to control the flow of urine. When the detrusor muscle contracts, it creates pressure on the bladder, causing urine to be expelled. Therefore, it is correct to say that micturition depends on the contraction of the detrusor muscle.

T lymphocytes undergo clonal deletion and anergy in the thymus. Clonal deletion refers to the process of eliminating T lymphocytes that recognize self-antigens, preventing the development of autoimmune diseases. Anergy refers to the state of functional inactivation of T lymphocytes that do not encounter antigens during their maturation process. Both clonal deletion and anergy are important mechanisms for ensuring the proper functioning of the immune system and maintaining self-tolerance. Therefore, the statement that T lymphocytes undergo clonal deletion and anergy in the thymus is true.

A sodium deficiency, also known as hyponatremia, can cause glycosuria. This is because when sodium levels are low, it can disrupt the balance of fluids and electrolytes in the body, leading to increased glucose levels in the urine. This condition, known as glycosuria, occurs when the kidneys are unable to reabsorb all the glucose filtered from the blood, resulting in its excretion in the urine. Therefore, it is true that a sodium deficiency can cause glycosuria.

The kidney has more distal convoluted tubules than collecting ducts. This statement is true because the distal convoluted tubules are responsible for reabsorbing water and electrolytes from the filtrate, while the collecting ducts are responsible for further concentrating the urine and reabsorbing water. Therefore, there are multiple distal convoluted tubules in the kidney to ensure efficient reabsorption, whereas there is only one collecting duct for each nephron.

Helper T cells are also necessary to humoral immunity

When the stomach is filled with food, it sends signals to the colon to start contracting. This is because the stomach needs to empty its contents into the small intestine for further digestion and absorption. The contractions of the colon help to push the food along the digestive tract and eventually eliminate waste from the body. Therefore, it is true that filling of the stomach stimulates contractions of the colon.

Anergy is a loss of lymphocyte activity, where as auto immune diseases result from mis directed activity.

Lysozyme is a bacteria-killing enzyme

The correct answer is gastric pits, intestinal crypts. Gastric pits are invaginations in the lining of the stomach that contain gastric glands, which secrete gastric juices. Intestinal crypts, on the other hand, are invaginations in the lining of the small intestine that contain intestinal glands, which secrete digestive enzymes and mucus. Both gastric pits and intestinal crypts are similar in structure and function as they both play a role in the secretion of digestive juices and the absorption of nutrients.

Amino acids are essential molecules for various biological processes and are actively reabsorbed by the kidneys. Therefore, under normal circumstances, the renal clearance of amino acids is zero, meaning that they are not excreted in the urine. This is because the kidneys efficiently reabsorb amino acids back into the bloodstream to maintain their balance in the body.

The correct answer is the glomerulus. The glomerulus is a compact ball of capillaries located in the renal corpuscle of the nephron. It is responsible for the initial filtration of blood in the kidney, where waste products and excess fluid are filtered out to form urine. The glomerulus plays a crucial role in the process of urine formation and is an essential component of the nephron.

The duodenum secretes a hormone called cholecystokinin (CCK) which inhibits contractions of the stomach. CCK is released in response to the presence of food in the duodenum and acts to slow down the emptying of the stomach, allowing for proper digestion and absorption of nutrients. This hormone also stimulates the release of bile from the gallbladder and pancreatic enzymes, further aiding in the digestion process. Therefore, the statement is true.

Perforin is a protein released by cytotoxic T cells and natural killer cells that forms pores in the target cell's membrane, leading to cell lysis. This is similar to the cytolytic action of the complement system, which also forms pores in the target cell's membrane, causing cell death. Interleukin-1 is a pro-inflammatory cytokine, platelet-derived growth factor stimulates cell growth and division, granzymes are enzymes released by cytotoxic T cells to induce apoptosis in target cells, and IgE is an antibody involved in allergic reactions.

Most of the tooth is dentin

ADH (antidiuretic hormone) is responsible for regulating the concentration of urine by increasing water reabsorption in the kidneys. When ADH secretion is increased, the kidneys reabsorb more water, resulting in a smaller volume of more concentrated urine. The specific gravity of urine is a measure of its concentration, with a higher specific gravity indicating a higher concentration of solutes. Therefore, increased ADH secretion would cause the urine to have a higher specific gravity.

Interferons inhibit viral replication; perforins lyse bacteria.

A glomerulus and glomerular capsule make up the renal corpuscle. The renal corpuscle is a structure within the kidney that is responsible for the initial filtration of blood to form urine. The glomerulus is a network of capillaries that filters blood, while the glomerular capsule surrounds the glomerulus and collects the filtrate. Together, they form the renal corpuscle, which is an important component of the nephron, the functional unit of the kidney. The other options, renal capsule, kidney lobule, kidney lobe, and nephron, do not accurately describe the specific structure formed by the glomerulus and glomerular capsule.

Calcium and sodium reabsorption by the PCT are influenced by parathyroid hormone and angiotensin II.

Interferons promote inflammation

Urea is the most abundant nitrogenous waste in the blood. It is produced in the liver during the breakdown of proteins and amino acids. Urea is then transported to the kidneys through the bloodstream, where it is filtered out and excreted in urine. Compared to other nitrogenous wastes like uric acid, ammonia, and creatinine, urea is present in higher concentrations in the blood, making it the most abundant nitrogenous waste. Albumin, on the other hand, is a protein and not a nitrogenous waste.

Urine contains more urea and chloride than sodium

Hepatocytes secrete bile into the bile canaliculi

Natural killer cells are involved in nonspecific resistance because they are able to recognize and kill infected or cancerous cells without the need for prior exposure or activation. They do not participate in specific defense because they do not have the ability to recognize specific antigens or produce antibodies like B cells and plasma cells. Helper T cells and cytotoxic T cells are involved in specific defense as they play a role in coordinating and executing specific immune responses against pathogens.

Intrinsic factor is involved in the absorption of vitamin B12.

Neutrophils are a type of white blood cell that play a crucial role in the immune response against bacterial infections. They are equipped with a process called respiratory burst, which involves the production of reactive oxygen species (ROS) to kill bacteria. This burst of ROS helps neutrophils to neutralize and eliminate the invading bacteria effectively. Therefore, neutrophils utilize the respiratory burst to kill bacteria.

The fibrous capsule lies closest to the renal cortex. The renal cortex is the outer region of the kidney, and the fibrous capsule is a layer of connective tissue that surrounds the kidney. It provides support and protection to the kidney, and is in direct contact with the renal cortex. The other options listed, such as the parietal peritoneum, renal fascia, perirenal fat capsule, and renal pelvis, are all located outside or inside the kidney, but not directly adjacent to the renal cortex.

The proximal convoluted tubule is responsible for reabsorbing most of the sodium from the glomerular filtrate. This tubule is located in the kidney and is the first part of the renal tubule system. It plays a crucial role in the reabsorption of water, electrolytes, and other solutes from the filtrate back into the bloodstream. The proximal convoluted tubule has a high density of transport proteins on its epithelial cells, which actively transport sodium ions out of the tubule and into the surrounding capillaries. This reabsorption process helps maintain the body's sodium balance and regulate blood pressure.

The kidney has more afferent arterioles than any of the other structures listed. Afferent arterioles are responsible for bringing blood into the glomerulus, where filtration occurs. They are numerous and play a crucial role in maintaining proper blood flow and filtration in the kidney. The other structures listed, such as arcuate arteries, minor calyces, medullary pyramids, and collecting ducts, are important components of the kidney but do not have as many as afferent arterioles.

Beavers have relatively little need to conserve water because they live in aquatic environments and have easy access to water. Therefore, they could be expected to have shorter nephron loops compared to humans. Nephron loops play a crucial role in reabsorbing water from the filtrate, so shorter loops would result in less water being reabsorbed, allowing beavers to excrete more water and maintain a higher water intake.

Haustra are pouches that form in the large intestine, not the small intestine. The absorptive surface area of the small intestine is increased by its length, the presence of the brush border, circular folds, and villi. These structures increase the surface area available for absorption of nutrients from digested food.

Fat digestion begins in the stomach.

The correct answer is the intestinal phase. During this phase, the enterogastric reflex is activated to inhibit gastric activity. This reflex is triggered by the presence of chyme in the small intestine, which sends signals to the stomach to slow down gastric emptying and reduce gastric secretion. This helps to ensure that the small intestine has enough time to digest and absorb nutrients properly.

When micturition occurs, the detrusor muscle contracts. The detrusor muscle is a smooth muscle layer found in the wall of the urinary bladder. It is responsible for contracting and emptying the bladder during urination. The other options listed, such as the internal urethral sphincter, external urethral sphincter, and muscularis of the ureter, are not directly involved in the contraction of the bladder during micturition. Therefore, the correct answer is the detrusor muscle.

A microglial cell is a type of macrophage found in the central nervous system. It is responsible for immune defense and scavenging debris and pathogens in the brain and spinal cord. Unlike other macrophages, microglial cells are derived from the same lineage as white blood cells and are specifically adapted to the unique environment of the central nervous system. They play a crucial role in maintaining brain health and regulating inflammation.

The correct order of events in humoral immunity is as follows: first, endocytosis of an antigen occurs (5), then antigen display takes place (1), followed by secretion of interleukin (3), clonal selection (4), and finally, antibody secretion (2).

Among the given options, a hormone is the only substance that is not an enzyme. Hormones are chemical messengers that are produced by glands in the body and are responsible for regulating various bodily functions. Enzymes, on the other hand, are proteins that catalyze biochemical reactions in the body. Nutrients can refer to a variety of substances required for growth and metabolism, while emulsifiers are compounds that help mix oil and water. Neurotransmitters are chemicals that transmit signals between nerve cells. Therefore, the correct answer is a hormone.