SCI 221 Exam 2 V1 | SCI 221 Human
Physiology with Intervention Skill-Based
(ISB) Experiential Learning | Q&A with
Rationale (SCI221 Exam 2) | Nightingale
College
1. What is the primary ionic movement responsible for the depolarization phase of an action
potential in a neuron?
A. Efflux of potassium ions out of the cell
B. Influx of calcium ions into the cell
C. Influx of sodium ions into the cell
D. Efflux of chloride ions out of the cell
Correct Answer: C
Rationale: Depolarization occurs when voltage-gated sodium channels open in response to
a threshold stimulus. This allows sodium ions to rush into the cell following their
electrochemical gradient, making the interior more positive. This rapid change in
membrane potential is the fundamental mechanism for signal propagation in the nervous
system.
2. Which neurotransmitter is primarily released at the neuromuscular junction to initiate
skeletal muscle contraction?
A. Acetylcholine
,B. Dopamine
C. Norepinephrine
D. Serotonin
Correct Answer: A
Rationale: Acetylcholine (ACh) is the specific neurotransmitter used at the neuromuscular
junction between motor neurons and skeletal muscle fibers. Upon release from the
synaptic vesicles, ACh binds to nicotinic receptors on the motor end plate. This binding
triggers an end-plate potential that leads to muscle fiber contraction.
3. In the autonomic nervous system, which receptor type is found on the target organs of the
parasympathetic nervous system?
A. Muscarinic receptors
B. Beta-2 adrenergic receptors
C. Nicotinic receptors only
D. Alpha-1 adrenergic receptors
Correct Answer: A
Rationale: Postganglionic parasympathetic neurons release acetylcholine, which acts upon
muscarinic receptors located on the effector organs. These receptors are G-protein coupled
and can produce either excitatory or inhibitory effects depending on the tissue. In contrast,
adrenergic receptors are associated with the sympathetic nervous system responses.
,4. A patient is diagnosed with Hyperthyroidism. Which of the following lab results would the
nurse expect to find if the pathology is primary?
A. High TSH and High T3/T4
B. Low TSH and High T3/T4
C. Low TSH and Low T3/T4
D. High TSH and Low T3/T4
Correct Answer: B
Rationale: In primary hyperthyroidism, the thyroid gland itself is overactive and produces
excessive amounts of T3 and T4. This high concentration of thyroid hormones provides
negative feedback to the anterior pituitary and hypothalamus. Consequently, the
production of Thyroid Stimulating Hormone (TSH) is suppressed, leading to low serum
TSH levels.
5. Which hormone is synthesized by the hypothalamus but stored and released by the
posterior pituitary (neurohypophysis)?
A. Growth Hormone (GH)
B. Prolactin
C. Adrenocorticotropic Hormone (ACTH)
D. Antidiuretic Hormone (ADH)
Correct Answer: D
, Rationale: Antidiuretic Hormone (ADH), also known as vasopressin, is produced by the
supraoptic nuclei of the hypothalamus. It travels down the axons of the hypothalamic-
hypophyseal tract to be stored in the posterior pituitary. Upon stimulation by high plasma
osmolarity, it is released into the bloodstream to act on the kidneys.
6. What is the function of the myelin sheath in the peripheral nervous system?
A. To decrease the speed of nerve impulse transmission
B. To increase the velocity of action potential through saltatory conduction
C. To provide a physical barrier against neurotransmitters
D. To generate ATP for the axon terminal
Correct Answer: B
Rationale: The myelin sheath, formed by Schwann cells in the PNS, acts as an insulator for
the axon. It allows action potentials to ‘jump’ from one Node of Ranvier to the next, a
process called saltatory conduction. This significantly increases the speed of electrical
transmission compared to unmyelinated fibers.
7. During a stress response, the adrenal medulla releases which of the following substances
into the blood?
A. Epinephrine and Norepinephrine
B. Aldosterone
C. Cortisol
Physiology with Intervention Skill-Based
(ISB) Experiential Learning | Q&A with
Rationale (SCI221 Exam 2) | Nightingale
College
1. What is the primary ionic movement responsible for the depolarization phase of an action
potential in a neuron?
A. Efflux of potassium ions out of the cell
B. Influx of calcium ions into the cell
C. Influx of sodium ions into the cell
D. Efflux of chloride ions out of the cell
Correct Answer: C
Rationale: Depolarization occurs when voltage-gated sodium channels open in response to
a threshold stimulus. This allows sodium ions to rush into the cell following their
electrochemical gradient, making the interior more positive. This rapid change in
membrane potential is the fundamental mechanism for signal propagation in the nervous
system.
2. Which neurotransmitter is primarily released at the neuromuscular junction to initiate
skeletal muscle contraction?
A. Acetylcholine
,B. Dopamine
C. Norepinephrine
D. Serotonin
Correct Answer: A
Rationale: Acetylcholine (ACh) is the specific neurotransmitter used at the neuromuscular
junction between motor neurons and skeletal muscle fibers. Upon release from the
synaptic vesicles, ACh binds to nicotinic receptors on the motor end plate. This binding
triggers an end-plate potential that leads to muscle fiber contraction.
3. In the autonomic nervous system, which receptor type is found on the target organs of the
parasympathetic nervous system?
A. Muscarinic receptors
B. Beta-2 adrenergic receptors
C. Nicotinic receptors only
D. Alpha-1 adrenergic receptors
Correct Answer: A
Rationale: Postganglionic parasympathetic neurons release acetylcholine, which acts upon
muscarinic receptors located on the effector organs. These receptors are G-protein coupled
and can produce either excitatory or inhibitory effects depending on the tissue. In contrast,
adrenergic receptors are associated with the sympathetic nervous system responses.
,4. A patient is diagnosed with Hyperthyroidism. Which of the following lab results would the
nurse expect to find if the pathology is primary?
A. High TSH and High T3/T4
B. Low TSH and High T3/T4
C. Low TSH and Low T3/T4
D. High TSH and Low T3/T4
Correct Answer: B
Rationale: In primary hyperthyroidism, the thyroid gland itself is overactive and produces
excessive amounts of T3 and T4. This high concentration of thyroid hormones provides
negative feedback to the anterior pituitary and hypothalamus. Consequently, the
production of Thyroid Stimulating Hormone (TSH) is suppressed, leading to low serum
TSH levels.
5. Which hormone is synthesized by the hypothalamus but stored and released by the
posterior pituitary (neurohypophysis)?
A. Growth Hormone (GH)
B. Prolactin
C. Adrenocorticotropic Hormone (ACTH)
D. Antidiuretic Hormone (ADH)
Correct Answer: D
, Rationale: Antidiuretic Hormone (ADH), also known as vasopressin, is produced by the
supraoptic nuclei of the hypothalamus. It travels down the axons of the hypothalamic-
hypophyseal tract to be stored in the posterior pituitary. Upon stimulation by high plasma
osmolarity, it is released into the bloodstream to act on the kidneys.
6. What is the function of the myelin sheath in the peripheral nervous system?
A. To decrease the speed of nerve impulse transmission
B. To increase the velocity of action potential through saltatory conduction
C. To provide a physical barrier against neurotransmitters
D. To generate ATP for the axon terminal
Correct Answer: B
Rationale: The myelin sheath, formed by Schwann cells in the PNS, acts as an insulator for
the axon. It allows action potentials to ‘jump’ from one Node of Ranvier to the next, a
process called saltatory conduction. This significantly increases the speed of electrical
transmission compared to unmyelinated fibers.
7. During a stress response, the adrenal medulla releases which of the following substances
into the blood?
A. Epinephrine and Norepinephrine
B. Aldosterone
C. Cortisol
