BIOS 256 Exam 1 Questions and Answers Verified
Solutions Latest Update
Anatomy & Physiology IV With Lab
BIOS 256 Exam 1 — 50 Multiple-Choice Questions
Domain 1: Endocrine System Structure & Function (Q1–Q10)
1. Which of the following hormones is classified as a peptide hormone?
A) Cortisol
B) Insulin
C) Aldosterone
D) Testosterone
Rationale: Insulin is a peptide hormone composed of 51 amino acids arranged in two chains (A
and B) connected by disulfide bonds. Peptide hormones are synthesized as larger precursor
molecules (preproinsulin) that undergo post-translational modification, are stored in secretory
vesicles, and bind to cell-surface receptors to initiate intracellular second-messenger cascades.
In contrast, cortisol, aldosterone, and testosterone are steroid hormones derived from
cholesterol that cross the plasma membrane and bind intracellular receptors to directly
modulate gene transcription.
2. The hypothalamic-hypophyseal portal system carries releasing and inhibiting
hormones from the hypothalamus directly to which structure?
A) Posterior pituitary
B) Anterior pituitary
C) Thyroid gland
D) Adrenal cortex
Rationale: The hypothalamic-hypophyseal portal system is a specialized capillary network that
transports hypothalamic releasing and inhibiting hormones (e.g., GHRH, TRH, CRH, GnRH,
somatostatin, dopamine) directly from the median eminence of the hypothalamus to the
anterior pituitary (adenohypophysis) without first entering the systemic circulation. This portal
arrangement ensures that these hormones reach their target cells in the anterior pituitary at
high concentrations. The posterior pituitary (neurohypophysis) receives direct neuronal
projections from the supraoptic and paraventricular nuclei rather than blood-borne signals via
this portal system.
3. Which anterior pituitary hormone stimulates the adrenal cortex to secrete
glucocorticoids?
A) Thyroid-stimulating hormone (TSH)
B) Growth hormone (GH)
C) Adrenocorticotropic hormone (ACTH)
D) Follicle-stimulating hormone (FSH)
Rationale: Adrenocorticotropic hormone (ACTH), also known as corticotropin, is produced by
corticotroph cells of the anterior pituitary under the stimulatory control of hypothalamic
corticotropin-releasing hormone (CRH). ACTH acts on the adrenal cortex—specifically the zona
fasciculata—to stimulate the synthesis and secretion of glucocorticoids, principally cortisol. TSH
,targets the thyroid gland, GH targets the liver and other tissues to produce IGFs, and FSH
targets the gonads to promote gametogenesis.
4. Antidiuretic hormone (ADH) is synthesized in the hypothalamus but released
from the posterior pituitary. Which hypothalamic nuclei produce ADH?
A) Arcuate nucleus and ventromedial nucleus
B) Supraoptic nucleus and paraventricular nucleus
C) Dorsomedial nucleus and preoptic area
D) Suprachiasmatic nucleus and mammillary body
Rationale: Antidiuretic hormone (ADH, vasopressin) is synthesized by neurosecretory cells in
the supraoptic and paraventricular nuclei of the hypothalamus. These neurons extend their
axons down the hypothalamo-hypophyseal tract to terminate in the posterior pituitary
(neurohypophysis), where ADH is stored in Herring bodies and released into the bloodstream in
response to increased plasma osmolarity (detected by osmoreceptors) or decreased blood
volume (detected by baroreceptors). The posterior pituitary does not synthesize ADH; it merely
stores and releases it.
5. Which of the following best describes the mechanism of thyroid hormone
synthesis involving thyroglobulin?
A) Thyroglobulin is synthesized in the rough ER of parafollicular cells and secreted into the
bloodstream
B) Iodide is transported into follicular cells by the Na+/I− symporter and
oxidized by thyroid peroxidase on the colloid surface
C) T3 and T4 are directly synthesized in the cytoplasm of follicular cells without iodination
D) Thyroglobulin is stored in the nucleus of follicular cells until TSH stimulates its
conversion to T3
Rationale: Thyroid hormone synthesis is a multi-step process: (1) Iodide is actively transported
into follicular cells via the Na+/I− symporter (NIS) on the basolateral membrane; (2) Iodide is
transported to the colloid (lumen) and oxidized to iodine by thyroid peroxidase (TPO) at the
apical surface; (3) Iodine organifies tyrosine residues on thyroglobulin (Tg) forming MIT and
DIT; (4) TPO catalyzes coupling of MIT + DIT → T3 and DIT + DIT → T4 within the Tg
molecule; (5) TSH stimulates pinocytosis of colloid, lysosomal digestion of Tg, and release of T3
and T4 into the bloodstream. Parafollicular (C) cells produce calcitonin, not thyroid hormones.
6. Parathyroid hormone (PTH) increases blood calcium levels through which of
the following mechanisms?
A) Inhibiting osteoclast activity and promoting calcium deposition in bone
B) Stimulating osteoclast activity, enhancing renal calcium reabsorption, and
promoting activation of vitamin D
C) Decreasing intestinal calcium absorption and increasing urinary calcium excretion
D) Directly stimulating calcitonin secretion from the thyroid gland
Rationale: Parathyroid hormone (PTH), secreted by chief cells of the parathyroid glands in
response to decreased plasma Ca2+, raises blood calcium through three coordinated
mechanisms: (1) it stimulates osteoclast bone resorption, releasing calcium and phosphate from
bone matrix into the blood; (2) it enhances renal tubular reabsorption of calcium in the distal
convoluted tubule while inhibiting phosphate reabsorption in the proximal tubule (phosphaturic
effect); and (3) it promotes the renal conversion of 25-hydroxyvitamin D to its active form,
1,25dihydroxyvitamin D (calcitriol), which increases intestinal absorption of dietary calcium.
PTH and calcitonin have opposing effects on blood calcium.
, 7. The zona glomerulosa of the adrenal cortex primarily produces which class of
hormones?
A) Glucocorticoids
B) Androgens
C) Mineralocorticoids
D) Catecholamines
Rationale: The adrenal cortex is organized into three distinct zones, each producing a different
class of steroid hormones: the outermost zona glomerulosa produces mineralocorticoids
(primarily aldosterone, which regulates sodium reabsorption and potassium excretion in the
kidneys); the middle zona fasciculata produces glucocorticoids (primarily cortisol, which
regulates metabolism and the stress response); and the innermost zona reticularis produces
adrenal androgens (primarily dehydroepiandrosterone/DHEA and androstenedione).
Catecholamines (epinephrine and norepinephrine) are produced by the adrenal medulla, which
is functionally and embryologically distinct from the cortex.
8. The adrenal medulla secretes catecholamines in response to sympathetic
preganglionic stimulation. What percentage of the medullary catecholamine
output is epinephrine?
A) Approximately 20%
B) Approximately 50%
C) Approximately 80%
D) Approximately 100%
Rationale: The adrenal medulla is essentially a modified sympathetic ganglion where
chromaffin cells, innervated by sympathetic preganglionic fibers (T5–L2), secrete
catecholamines into the bloodstream. Approximately 80% of the medullary output is
epinephrine (adrenaline) and 20% is norepinephrine (noradrenaline). This ratio reflects the fact
that most chromaffin cells express phenylethanolamine N-methyltransferase (PNMT), the
enzyme that converts norepinephrine to epinephrine, and PNMT expression is maintained by
the high local concentration of cortisol from the adjacent adrenal cortex via the intra-adrenal
portal system.
9. In the pancreatic islets, which cell type secretes glucagon, and what is its
primary metabolic effect?
A) Beta cells; decreased blood glucose
B) Alpha cells; increased blood glucose
C) Delta cells; inhibition of both insulin and glucagon
D) PP cells; stimulation of pancreatic enzyme secretion
Rationale: Alpha cells (α-cells) constitute approximately 15–20% of pancreatic islet cells and
secrete glucagon in response to decreased blood glucose, increased amino acids, and
sympathetic stimulation. Glucagon’s primary metabolic effect is to raise blood glucose by
stimulating hepatic glycogenolysis (breakdown of glycogen to glucose), gluconeogenesis
(synthesis of glucose from non-carbohydrate precursors), and ketogenesis. Beta cells secrete
insulin (lowering blood glucose), delta cells secrete somatostatin (inhibiting both insulin and
glucagon locally), and PP cells secrete pancreatic polypeptide (regulating exocrine pancreatic
secretions).
Solutions Latest Update
Anatomy & Physiology IV With Lab
BIOS 256 Exam 1 — 50 Multiple-Choice Questions
Domain 1: Endocrine System Structure & Function (Q1–Q10)
1. Which of the following hormones is classified as a peptide hormone?
A) Cortisol
B) Insulin
C) Aldosterone
D) Testosterone
Rationale: Insulin is a peptide hormone composed of 51 amino acids arranged in two chains (A
and B) connected by disulfide bonds. Peptide hormones are synthesized as larger precursor
molecules (preproinsulin) that undergo post-translational modification, are stored in secretory
vesicles, and bind to cell-surface receptors to initiate intracellular second-messenger cascades.
In contrast, cortisol, aldosterone, and testosterone are steroid hormones derived from
cholesterol that cross the plasma membrane and bind intracellular receptors to directly
modulate gene transcription.
2. The hypothalamic-hypophyseal portal system carries releasing and inhibiting
hormones from the hypothalamus directly to which structure?
A) Posterior pituitary
B) Anterior pituitary
C) Thyroid gland
D) Adrenal cortex
Rationale: The hypothalamic-hypophyseal portal system is a specialized capillary network that
transports hypothalamic releasing and inhibiting hormones (e.g., GHRH, TRH, CRH, GnRH,
somatostatin, dopamine) directly from the median eminence of the hypothalamus to the
anterior pituitary (adenohypophysis) without first entering the systemic circulation. This portal
arrangement ensures that these hormones reach their target cells in the anterior pituitary at
high concentrations. The posterior pituitary (neurohypophysis) receives direct neuronal
projections from the supraoptic and paraventricular nuclei rather than blood-borne signals via
this portal system.
3. Which anterior pituitary hormone stimulates the adrenal cortex to secrete
glucocorticoids?
A) Thyroid-stimulating hormone (TSH)
B) Growth hormone (GH)
C) Adrenocorticotropic hormone (ACTH)
D) Follicle-stimulating hormone (FSH)
Rationale: Adrenocorticotropic hormone (ACTH), also known as corticotropin, is produced by
corticotroph cells of the anterior pituitary under the stimulatory control of hypothalamic
corticotropin-releasing hormone (CRH). ACTH acts on the adrenal cortex—specifically the zona
fasciculata—to stimulate the synthesis and secretion of glucocorticoids, principally cortisol. TSH
,targets the thyroid gland, GH targets the liver and other tissues to produce IGFs, and FSH
targets the gonads to promote gametogenesis.
4. Antidiuretic hormone (ADH) is synthesized in the hypothalamus but released
from the posterior pituitary. Which hypothalamic nuclei produce ADH?
A) Arcuate nucleus and ventromedial nucleus
B) Supraoptic nucleus and paraventricular nucleus
C) Dorsomedial nucleus and preoptic area
D) Suprachiasmatic nucleus and mammillary body
Rationale: Antidiuretic hormone (ADH, vasopressin) is synthesized by neurosecretory cells in
the supraoptic and paraventricular nuclei of the hypothalamus. These neurons extend their
axons down the hypothalamo-hypophyseal tract to terminate in the posterior pituitary
(neurohypophysis), where ADH is stored in Herring bodies and released into the bloodstream in
response to increased plasma osmolarity (detected by osmoreceptors) or decreased blood
volume (detected by baroreceptors). The posterior pituitary does not synthesize ADH; it merely
stores and releases it.
5. Which of the following best describes the mechanism of thyroid hormone
synthesis involving thyroglobulin?
A) Thyroglobulin is synthesized in the rough ER of parafollicular cells and secreted into the
bloodstream
B) Iodide is transported into follicular cells by the Na+/I− symporter and
oxidized by thyroid peroxidase on the colloid surface
C) T3 and T4 are directly synthesized in the cytoplasm of follicular cells without iodination
D) Thyroglobulin is stored in the nucleus of follicular cells until TSH stimulates its
conversion to T3
Rationale: Thyroid hormone synthesis is a multi-step process: (1) Iodide is actively transported
into follicular cells via the Na+/I− symporter (NIS) on the basolateral membrane; (2) Iodide is
transported to the colloid (lumen) and oxidized to iodine by thyroid peroxidase (TPO) at the
apical surface; (3) Iodine organifies tyrosine residues on thyroglobulin (Tg) forming MIT and
DIT; (4) TPO catalyzes coupling of MIT + DIT → T3 and DIT + DIT → T4 within the Tg
molecule; (5) TSH stimulates pinocytosis of colloid, lysosomal digestion of Tg, and release of T3
and T4 into the bloodstream. Parafollicular (C) cells produce calcitonin, not thyroid hormones.
6. Parathyroid hormone (PTH) increases blood calcium levels through which of
the following mechanisms?
A) Inhibiting osteoclast activity and promoting calcium deposition in bone
B) Stimulating osteoclast activity, enhancing renal calcium reabsorption, and
promoting activation of vitamin D
C) Decreasing intestinal calcium absorption and increasing urinary calcium excretion
D) Directly stimulating calcitonin secretion from the thyroid gland
Rationale: Parathyroid hormone (PTH), secreted by chief cells of the parathyroid glands in
response to decreased plasma Ca2+, raises blood calcium through three coordinated
mechanisms: (1) it stimulates osteoclast bone resorption, releasing calcium and phosphate from
bone matrix into the blood; (2) it enhances renal tubular reabsorption of calcium in the distal
convoluted tubule while inhibiting phosphate reabsorption in the proximal tubule (phosphaturic
effect); and (3) it promotes the renal conversion of 25-hydroxyvitamin D to its active form,
1,25dihydroxyvitamin D (calcitriol), which increases intestinal absorption of dietary calcium.
PTH and calcitonin have opposing effects on blood calcium.
, 7. The zona glomerulosa of the adrenal cortex primarily produces which class of
hormones?
A) Glucocorticoids
B) Androgens
C) Mineralocorticoids
D) Catecholamines
Rationale: The adrenal cortex is organized into three distinct zones, each producing a different
class of steroid hormones: the outermost zona glomerulosa produces mineralocorticoids
(primarily aldosterone, which regulates sodium reabsorption and potassium excretion in the
kidneys); the middle zona fasciculata produces glucocorticoids (primarily cortisol, which
regulates metabolism and the stress response); and the innermost zona reticularis produces
adrenal androgens (primarily dehydroepiandrosterone/DHEA and androstenedione).
Catecholamines (epinephrine and norepinephrine) are produced by the adrenal medulla, which
is functionally and embryologically distinct from the cortex.
8. The adrenal medulla secretes catecholamines in response to sympathetic
preganglionic stimulation. What percentage of the medullary catecholamine
output is epinephrine?
A) Approximately 20%
B) Approximately 50%
C) Approximately 80%
D) Approximately 100%
Rationale: The adrenal medulla is essentially a modified sympathetic ganglion where
chromaffin cells, innervated by sympathetic preganglionic fibers (T5–L2), secrete
catecholamines into the bloodstream. Approximately 80% of the medullary output is
epinephrine (adrenaline) and 20% is norepinephrine (noradrenaline). This ratio reflects the fact
that most chromaffin cells express phenylethanolamine N-methyltransferase (PNMT), the
enzyme that converts norepinephrine to epinephrine, and PNMT expression is maintained by
the high local concentration of cortisol from the adjacent adrenal cortex via the intra-adrenal
portal system.
9. In the pancreatic islets, which cell type secretes glucagon, and what is its
primary metabolic effect?
A) Beta cells; decreased blood glucose
B) Alpha cells; increased blood glucose
C) Delta cells; inhibition of both insulin and glucagon
D) PP cells; stimulation of pancreatic enzyme secretion
Rationale: Alpha cells (α-cells) constitute approximately 15–20% of pancreatic islet cells and
secrete glucagon in response to decreased blood glucose, increased amino acids, and
sympathetic stimulation. Glucagon’s primary metabolic effect is to raise blood glucose by
stimulating hepatic glycogenolysis (breakdown of glycogen to glucose), gluconeogenesis
(synthesis of glucose from non-carbohydrate precursors), and ketogenesis. Beta cells secrete
insulin (lowering blood glucose), delta cells secrete somatostatin (inhibiting both insulin and
glucagon locally), and PP cells secrete pancreatic polypeptide (regulating exocrine pancreatic
secretions).
