Anatomy and Physiology II (M8) Comprehensive Lecture Exam

Correct Answer: A. True

Explanation of the Correct Answer:

A. True

High levels of testosterone do indeed inhibit the release of gonadotropin-releasing hormone (GnRH) by the hypothalamus. This is part of a negative feedback mechanism that helps regulate testosterone production. When testosterone levels are high, the hypothalamus senses this and decreases the secretion of GnRH. In turn, lower GnRH levels reduce the secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the anterior pituitary gland. This ultimately reduces the stimulation of the Leydig cells in the testes, decreasing the production of testosterone. This feedback loop helps maintain a balance in testosterone levels.

Why the Other Option Is Incorrect:

B. False

This statement is false because, as mentioned, high levels of testosterone do inhibit GnRH secretion through negative feedback. Therefore, "False" is incorrect.

Correct Answer: A. Antagonists

Explanation of the Correct Answer:

Antagonists are hormones that act on the same target cells but produce opposite effects. A classic example is insulin and glucagon. Both target liver cells, but while insulin lowers blood glucose levels by promoting glucose uptake and storage, glucagon raises blood glucose levels by stimulating glycogen breakdown and glucose release into the bloodstream. These opposing actions help maintain homeostasis by balancing physiological responses.

Why the Other Options Are Incorrect:

B. Hydrophilic hormones

This is incorrect because hydrophilic hormones are classified based on their solubility in water, not their interaction effects. They bind to cell surface receptors and typically initiate signaling cascades. Examples include insulin and epinephrine, but this term does not describe the nature of their effects relative to each other.

C. Neurohormones

Neurohormones are hormones secreted by neurosecretory cells (such as in the hypothalamus) into the blood. Examples include oxytocin and ADH. While neurohormones can affect target tissues, the term doesn't indicate whether the hormones work in opposition or synergy.

D. Synergists

Synergists are hormones that work together to amplify a response. For instance, glucagon, epinephrine, and cortisol can all work together to increase blood glucose levels, producing a greater effect than any one hormone acting alone. This is the opposite of antagonistic action.

Correct Answer: D. Neutrophil

Explanation of the Correct Answer:

D. Neutrophil

Neutrophils are the most prevalent white blood cells (WBCs) in the bloodstream, making up approximately 60-70% of the total white blood cell count. They are part of the body’s innate immune system and play a crucial role in defending against bacterial infections. Neutrophils are phagocytes, meaning they can ingest and destroy bacteria and other pathogens. They are often the first immune cells to arrive at the site of an infection.

Why the Other Options Are Incorrect:

A. Monocyte

Monocytes make up about 2-8% of the white blood cell count. They are larger cells that differentiate into macrophages and dendritic cells when they enter tissues. While important in the immune response, they are not the most prevalent WBCs.

B. Basophil

Basophils make up a very small percentage of white blood cells, typically less than 1%. They are involved in inflammatory responses and release histamine during allergic reactions, but they are not the most common type of WBC.

C. Eosinophil

Eosinophils account for approximately 1-4% of the total WBC count. They are primarily involved in combating parasitic infections and play a role in allergic reactions. They are not as prevalent as neutrophils.

Correct Answer: B. Lungs

Explanation of the Correct Answer:

B. Lungs

After blood is pumped from the right ventricle of the heart, it enters the pulmonary arteries, which are unique because they carry deoxygenated blood. These arteries transport the blood away from the heart and toward the lungs. In the lungs, gas exchange occurs: carbon dioxide is released from the blood, and oxygen is absorbed. This oxygen-rich blood will then return to the heart through the pulmonary veins and enter the left atrium, ready to be pumped to the rest of the body.

Why the Other Options Are Incorrect:

A. Brain

Blood must first pass through the lungs to become oxygenated before it is sent to the brain via the systemic circulation. The brain is not the immediate next destination after the pulmonary arteries.

C. Right atrium

The right atrium receives deoxygenated blood from the body via the superior and inferior vena cava. It does not receive blood directly from the pulmonary arteries.

D. Body

The body receives oxygenated blood from the left ventricle via the aorta. Blood must first pass through the lungs for oxygenation before it can be sent to the body.

Correct Answer:

Cone

Explanation:

Cone cells are photoreceptors located in the retina of the eye, and they are responsible for detecting color and providing sharp, detailed central vision in bright light. There are three types of cones, each sensitive to different wavelengths corresponding to red, green, or blue light. Together, they allow us to perceive a full spectrum of colors.

Why Other Options are Wrong:

Pupil

The pupil is the opening in the center of the iris that controls the amount of light entering the eye. It does not detect color.

Iris

The iris is the colored part of the eye and controls the size of the pupil. While it gives the eye its color, it does not play a role in color vision.

Rod

Rod cells are also located in the retina but are responsible for black and white vision and function best in dim light. They do not detect color.

Correct Answer: D. Pancreas

Explanation of the Correct Answer:

D. Pancreas

The pancreas is a dual-function gland—it serves both endocrine and exocrine roles. As an endocrine gland, it contains clusters of cells called islets of Langerhans, which release hormones directly into the bloodstream. These hormones include insulin, glucagon, and somatostatin, all of which regulate blood glucose levels. As an exocrine gland, the pancreas produces digestive enzymes (such as amylase, lipase, and proteases) that are secreted into the small intestine via the pancreatic duct to help break down food. This unique dual function makes the pancreas essential for both hormonal regulation and digestion.

Why the Other Options Are Incorrect:

A. Liver

The liver performs many metabolic and detoxification functions and does secrete some hormones (like insulin-like growth factor-1), but it is not classified as an exocrine gland in the digestive sense, nor does it have the dual structure typical of endocrine/exocrine glands like the pancreas.

B. Adrenals

The adrenal glands are purely endocrine glands. They secrete hormones such as cortisol, aldosterone, and adrenaline but have no exocrine function.

C. Spleen

The spleen is part of the immune and lymphatic systems. It filters blood and helps fight infection. It does not have endocrine or exocrine functions.

Correct Answer: B. Hypersecretion of cortisol

Explanation of the Correct Answer:

B. Hypersecretion of cortisol

Cushing's disease is specifically caused by a pituitary adenoma (a benign tumor in the anterior pituitary) that leads to excess secretion of adrenocorticotropic hormone (ACTH). This elevated ACTH stimulates the adrenal cortex to produce excessive amounts of cortisol, a glucocorticoid hormone. Cortisol helps regulate metabolism, immune response, and stress. In Cushing's disease, chronically high cortisol levels lead to symptoms such as central obesity, a round "moon face," a fatty hump between the shoulders (buffalo hump), muscle weakness, thin skin that bruises easily, and high blood pressure. The condition is a specific form of Cushing’s syndrome, which refers more broadly to cortisol excess from any cause.

Why the Other Options Are Incorrect:

A. Hypersecretion of aldosterone

Excess aldosterone production is associated with Conn's syndrome, not Cushing’s disease. Aldosterone regulates sodium and potassium balance and blood pressure, but it does not lead to the classic symptoms seen in Cushing’s.

C. Hyposecretion of insulin

This describes type 1 diabetes mellitus, a condition in which insufficient insulin leads to high blood sugar. It has no direct connection to the ACTH-cortisol axis or Cushing’s disease.

D. Hyposecretion of epinephrine

Low levels of epinephrine, a hormone produced by the adrenal medulla, can affect the body’s stress response but are not responsible for the features seen in Cushing’s disease. Cushing’s involves the adrenal cortex, not the medulla.

Correct Answer:

B. Lucidum

Explanation:

The stratum lucidum is a clear, thin layer of dead skin cells found only in thick skin, such as the palms of the hands and soles of the feet. It lies between the stratum granulosum and stratum corneum.

Why Other Options are Wrong:

Corneum

This is the outermost layer present in both thin and thick skin.

Granulosum

Found in both types of skin, it helps with keratinization but is not exclusive to thick skin.

Basale

This deepest layer is involved in cell division and melanin production and is present in all skin types.

Correct Answer: B.  7, 8, 5, 2, 6, 1, 4, 3

Explanation of the Correct Answer:

Here is the correct flow order of blood into and through the kidney:

Renal artery (7): Blood enters the kidney through the renal artery, which branches off the abdominal aorta.

Segmental artery (8): The renal artery further branches into the segmental arteries, which supply different regions of the kidney.

Interlobar artery (5): The segmental arteries branch into the interlobar arteries, which run between the lobes of the kidney.

Arcuate artery (2): The interlobar arteries branch into arcuate arteries that curve around the top of the renal pyramids.

Interlobular (cortical radiate) artery (6): The arcuate arteries give rise to interlobular arteries that radiate outwards into the cortex of the kidney.

Afferent arteriole (1): The interlobular arteries give rise to the afferent arterioles, which lead into the glomerulus for filtration.

Glomerulus (4): The afferent arteriole brings blood into the glomerulus, a capillary bed where filtration of blood occurs to form urine.

Efferent arteriole (3): After filtration, blood exits the glomerulus via the efferent arteriole, which then leads to the peritubular capillaries or vasa recta.