PCB 3703 Exam 3 V1 | PCB 3703 Human
Physiology | Actual Q&A with Rationale (PCB3703
Exam 3) | University of Central Florida
1. Which of the following is a characteristic of steroid hormones?
A. They are stored in secretory vesicles.
B. They bind to cell surface receptors.
C. They are primarily water-soluble.
D. They are derived from cholesterol and diffuse through the cell membrane.
Correct Answer: D
Explanation: Steroid hormones are lipophilic molecules that are synthesized on demand
from cholesterol. Because of their lipid nature, they cannot be stored in vesicles and instead
diffuse directly through the plasma membrane. Once inside the target cell, they typically
bind to intracellular receptors to influence gene transcription.
2. The secretion of growth hormone (GH) is inhibited by which of the following substances?
A. Growth hormone-releasing hormone (GHRH)
B. Ghrelin
C. Somatostatin
D. Dopamine
Correct Answer: C
,Explanation: Somatostatin, also known as growth hormone-inhibiting hormone (GHIH), is
produced by the hypothalamus to inhibit the release of GH from the anterior pituitary. This
creates a negative feedback loop to maintain homeostatic levels of growth hormone in the
blood. Conversely, GHRH stimulates the release of growth hormone during periods of
growth or stress.
3. In the hypothalamic-pituitary-adrenal (HPA) axis, which hormone is released from the
hypothalamus to stimulate the release of ACTH?
A. Corticotropin-releasing hormone (CRH)
B. Cortisol
C. Vasopressin
D. Thyrotropin-releasing hormone (TRH)
Correct Answer: A
Explanation: CRH is the primary hypothalamic regulator that triggers the secretion of
Adrenocorticotropic hormone (ACTH) from the anterior pituitary. ACTH then travels
through the systemic circulation to the adrenal cortex to induce the synthesis of cortisol.
This axis is vital for the body’s physiological response to prolonged stress.
4. Which cell type in the pancreas is responsible for the secretion of glucagon?
A. Beta cells
B. Delta cells
C. Alpha cells
, D. F cells
Correct Answer: C
Explanation: Alpha cells are located in the Islets of Langerhans and specialize in producing
glucagon during hypoglycemic states. Glucagon works to increase blood glucose levels by
stimulating glycogenolysis and gluconeogenesis in the liver. This action is antagonistic to
insulin, which is secreted by beta cells.
5. What is the primary physiological effect of parathyroid hormone (PTH)?
A. To decrease plasma calcium levels by stimulating bone deposition.
B. To increase plasma calcium levels by stimulating osteoclast activity.
C. To promote the excretion of calcium by the kidneys.
D. To inhibit the activation of Vitamin D.
Correct Answer: B
Explanation: PTH is released by the parathyroid glands in response to low serum calcium
levels. It acts on the bones to increase resorption, on the kidneys to reabsorb calcium, and
stimulates the production of calcitriol to increase intestinal absorption. Together, these
mechanisms restore calcium homeostasis in the extracellular fluid.
6. Which hormone is responsible for the ‘milk let-down’ reflex during lactation?
A. Prolactin
B. Oxytocin
Physiology | Actual Q&A with Rationale (PCB3703
Exam 3) | University of Central Florida
1. Which of the following is a characteristic of steroid hormones?
A. They are stored in secretory vesicles.
B. They bind to cell surface receptors.
C. They are primarily water-soluble.
D. They are derived from cholesterol and diffuse through the cell membrane.
Correct Answer: D
Explanation: Steroid hormones are lipophilic molecules that are synthesized on demand
from cholesterol. Because of their lipid nature, they cannot be stored in vesicles and instead
diffuse directly through the plasma membrane. Once inside the target cell, they typically
bind to intracellular receptors to influence gene transcription.
2. The secretion of growth hormone (GH) is inhibited by which of the following substances?
A. Growth hormone-releasing hormone (GHRH)
B. Ghrelin
C. Somatostatin
D. Dopamine
Correct Answer: C
,Explanation: Somatostatin, also known as growth hormone-inhibiting hormone (GHIH), is
produced by the hypothalamus to inhibit the release of GH from the anterior pituitary. This
creates a negative feedback loop to maintain homeostatic levels of growth hormone in the
blood. Conversely, GHRH stimulates the release of growth hormone during periods of
growth or stress.
3. In the hypothalamic-pituitary-adrenal (HPA) axis, which hormone is released from the
hypothalamus to stimulate the release of ACTH?
A. Corticotropin-releasing hormone (CRH)
B. Cortisol
C. Vasopressin
D. Thyrotropin-releasing hormone (TRH)
Correct Answer: A
Explanation: CRH is the primary hypothalamic regulator that triggers the secretion of
Adrenocorticotropic hormone (ACTH) from the anterior pituitary. ACTH then travels
through the systemic circulation to the adrenal cortex to induce the synthesis of cortisol.
This axis is vital for the body’s physiological response to prolonged stress.
4. Which cell type in the pancreas is responsible for the secretion of glucagon?
A. Beta cells
B. Delta cells
C. Alpha cells
, D. F cells
Correct Answer: C
Explanation: Alpha cells are located in the Islets of Langerhans and specialize in producing
glucagon during hypoglycemic states. Glucagon works to increase blood glucose levels by
stimulating glycogenolysis and gluconeogenesis in the liver. This action is antagonistic to
insulin, which is secreted by beta cells.
5. What is the primary physiological effect of parathyroid hormone (PTH)?
A. To decrease plasma calcium levels by stimulating bone deposition.
B. To increase plasma calcium levels by stimulating osteoclast activity.
C. To promote the excretion of calcium by the kidneys.
D. To inhibit the activation of Vitamin D.
Correct Answer: B
Explanation: PTH is released by the parathyroid glands in response to low serum calcium
levels. It acts on the bones to increase resorption, on the kidneys to reabsorb calcium, and
stimulates the production of calcitriol to increase intestinal absorption. Together, these
mechanisms restore calcium homeostasis in the extracellular fluid.
6. Which hormone is responsible for the ‘milk let-down’ reflex during lactation?
A. Prolactin
B. Oxytocin
