Anatomy and Physiology II (M8) Comprehensive Lecture Exam

Correct Answer: C. T lymphocytes (T cells)

Explanation of the Correct Answer:

C. T lymphocytes (T cells)

The thymus is a primary lymphoid organ essential for the development of T lymphocytes (T cells). The thymus is responsible for the maturation and differentiation of T cells from their precursors, which originate in the bone marrow. When the thymus is not functioning properly, as in the case of it shrinking or stopping hormone production, T cells will be significantly affected. As a result, there would be a decrease in the number of mature T cells available for immune responses. T cells play a crucial role in the adaptive immune system, helping to identify and destroy infected or cancerous cells.

Why the Other Options Are Incorrect:

A. Neutrophils

Neutrophils are a type of white blood cell involved in the innate immune response and are primarily produced in the bone marrow. Their development is not directly influenced by the thymus. A decrease in thymus function would not directly affect the number of neutrophils in circulation.

B. Lymphocytes (B cells)

B lymphocytes (B cells) are involved in the humoral immune response and are primarily produced in the bone marrow. Although T cells assist in the activation of B cells, the production of B cells themselves is not directly affected by the thymus. Therefore, a decrease in thymus function would not cause a significant decrease in the number of B cells.

D. Eosinophils

Eosinophils are another type of white blood cell involved in allergic reactions and the defense against parasitic infections. Like neutrophils, eosinophils are produced in the bone marrow, and their development is not directly related to the thymus.

Correct Answer: C. Regulate red blood cell production by the bone marrow.

Explanation of the Correct Answer:

C. Regulate red blood cell production by the bone marrow

Erythropoietin (EPO) is a hormone primarily produced by the kidneys in response to low oxygen levels in the blood. It stimulates the bone marrow to produce more red blood cells (RBCs), a process known as erythropoiesis. This increase in RBC production helps to enhance the oxygen-carrying capacity of the blood, which is essential when the body is experiencing oxygen deprivation (such as at high altitudes or in certain diseases).

Why the Other Options Are Incorrect:

A. Conserve or eliminate hydrogen and bicarbonate ions

This function is related to the kidney's role in maintaining acid-base balance and regulating the pH of the blood. While the kidneys do help with the regulation of hydrogen and bicarbonate ions, this is not the primary function of erythropoietin.

B. Regulate blood solute concentration

Blood solute concentration (such as electrolytes and proteins) is regulated by the kidneys, but erythropoietin does not directly play a role in this process. Erythropoietin specifically targets the production of red blood cells in the bone marrow.

D. Regulate removal of metabolic waste

The removal of metabolic waste products like urea and creatinine is carried out by the kidneys, but again, this is not the role of erythropoietin. Erythropoietin is concerned with regulating red blood cell production in response to oxygen levels, not waste elimination.

Correct Answer: B. Duodenum

Explanation of the Correct Answer:

B. Duodenum

The main pancreatic duct carries pancreatic juices (which include digestive enzymes like amylase, lipase, and proteases and bicarbonate) from the pancreas into the duodenum. The duodenum is the first part of the small intestine, where pancreatic juices mix with chyme (partially digested food) from the stomach. These juices help neutralize the acidic chyme from the stomach and assist in further digestion by breaking down proteins, fats, and carbohydrates.

Why the Other Options Are Incorrect:

A. Stomach

The stomach is not the destination for pancreatic juices. The stomach produces gastric acid and digestive enzymes to break down food. Pancreatic juices are not secreted into the stomach, but into the duodenum.

C. Gallbladder

The gallbladder stores bile, which is released into the duodenum to aid in fat digestion. It does not receive pancreatic juices, which are transported to the duodenum via the main pancreatic duct.

D. Liver

The liver produces bile (which aids in fat digestion) and releases it into the duodenum via the bile ducts, but it does not receive pancreatic juices. The pancreatic juices are directed to the duodenum, not the liver.

Correct Answer: C. 25%

Explanation of the Correct Answer:

C. 25%

If both parents are heterozygous (meaning they carry one normal allele and one mutated allele, represented as "Ss" for sickle cell anemia), there is a possibility for their child to inherit two recessive alleles (one from each parent). In this case, the child would inherit the recessive disease, which in this case is sickle cell anemia.

Using a Punnett square for a cross between two heterozygous parents (Ss x Ss), the possible combinations for their offspring would be:

25% SS (normal, not affected)

50% Ss (carrier, not affected but carrying the sickle cell gene)

25% ss (affected with sickle cell anemia)

Therefore, there is a 25% chance that the child will inherit two recessive alleles (ss) and have the disease.

Why the Other Options Are Incorrect:

A. 75%

This would indicate a much higher likelihood of the child having sickle cell anemia, which is not correct in a heterozygous cross.

B. 50%

This would be the chance of the child being a carrier (Ss), but not having the disease itself. The correct chance of having the disease is 25%, not 50%.

D. 0%

This would mean that none of the children would inherit the disease, which is incorrect given that there is a 25% chance of the child inheriting two recessive alleles (ss) and having sickle cell anemia.

Correct Answer: A. True

Explanation of the Correct Answer:

A. True

Testosterone is indeed produced by the Leydig cells (also called interstitial cells) in the male testes. These cells are located in the interstitial spaces between the seminiferous tubules of the testes. Leydig cells respond to luteinizing hormone (LH) from the anterior pituitary, which stimulates them to produce and secrete testosterone. Testosterone is the primary male sex hormone and is responsible for the development of male secondary sexual characteristics, including increased muscle mass, deep voice, and facial hair.

Why the Other Option Is Incorrect:

B. False

This statement is false because testosterone is, in fact, produced by the Leydig cells in the male testes. Therefore, "False" is the incorrect answer.

Correct Answer:

Use deodorant regularly.

Explanation:

Apocrine glands are a type of sweat gland found in areas such as the armpits and groin. These glands produce a thicker sweat that, when broken down by bacteria on the skin’s surface, leads to body odor. Using deodorant helps to mask odor and may include antiperspirants that reduce sweating, making it a practical recommendation for someone with highly active apocrine glands.

Why Other Options are Wrong:

Clean the nails frequently.

This advice is related to hand hygiene but has no relevance to apocrine gland activity or body odor.

Keep the ears clean.

Ceruminous glands, not apocrine glands, are responsible for earwax production. This advice pertains to ear hygiene, not sweat or odor.

Obtain treatment for the rash.

This is appropriate if the issue involves skin irritation or infection, but not specifically for the normal activity of apocrine glands leading to body odor.

Correct Answer: C. Mammary glands

Explanation of the Correct Answer:

C. Mammary glands

Oxytocin is a hormone released by the posterior pituitary gland. One of its primary roles is to stimulate milk ejection (let-down reflex) in the mammary glands during breastfeeding. Oxytocin acts on target cells in the smooth muscle of the mammary glands, causing them to contract and expel milk through the ducts to the nipple. Additionally, oxytocin also promotes uterine contractions during labor, but with respect to this question, the mammary glands are the correct organ with oxytocin-responsive target cells.

Why the Other Options Are Incorrect:

A. Lungs

The lungs are not a target organ for oxytocin. They are not involved in oxytocin-regulated physiological processes such as milk ejection or uterine contractions.

B. Bones

Oxytocin does not act directly on bones. While some research explores its broader systemic roles, bones are not recognized as a primary or clinically significant target of oxytocin.

D. Kidneys

Oxytocin does not primarily influence kidney function. The hormone associated with water retention in the kidneys is antidiuretic hormone (ADH), not oxytocin.

Correct Answer: A. T lymphocytes

Explanation of the Correct Answer:

A. T lymphocytes

Thymosin and thymopoietin are hormones secreted by the thymus, an organ located in the upper chest behind the sternum. These hormones play a critical role in the maturation and differentiation of T lymphocytes (T cells), which are essential components of the adaptive immune system. Immature T cells originate in the bone marrow but migrate to the thymus, where thymic hormones help them develop the ability to recognize foreign antigens while avoiding attacks on the body's own tissues. This process is crucial for developing a functional and self-tolerant T-cell population.

Why the Other Options Are Incorrect:

B. B lymphocytes

B lymphocytes mature in the bone marrow, not the thymus, and their development is not regulated by thymosin or thymopoietin.

C. Alpha cells

Alpha cells are located in the pancreas and secrete glucagon. Their development is unrelated to thymic hormones.

D. Chief cells

Chief cells are found in the stomach and are responsible for secreting pepsinogen, a precursor to the digestive enzyme pepsin. They are not influenced by thymic hormones.

Correct Answer: D. Metabolism

Explanation of the Correct Answer:

D. Metabolism

Metabolism refers to the sum of all chemical reactions that occur within the body to maintain life. These reactions are involved in processes like energy production, growth, repair, and maintenance. Metabolism can be divided into two categories: catabolism, which breaks down molecules to release energy, and anabolism, which uses energy to build molecules.

Why the Other Options Are Incorrect:

A. Phosphorylation

Phosphorylation is a specific chemical process where a phosphate group is added to a molecule, typically a protein, to alter its activity. While important in regulating many metabolic pathways, it is just one of the many reactions that occur during metabolism, not the entire sum of reactions.

B. Oxidation

Oxidation is a chemical reaction where a molecule loses electrons, often associated with the release of energy. It is a part of many metabolic pathways, particularly in the production of ATP in the mitochondria, but it does not describe the entirety of the body's chemical processes.

C. Homeostasis

Homeostasis refers to the body’s ability to maintain a stable internal environment (e.g., temperature, pH, and electrolyte balance). It is a regulatory process that involves various physiological mechanisms but does not refer to the totality of chemical reactions occurring in the body.