BIOL 252 Final Exam | Human Anatomy & Physiology II
w/Lab Q&A | Portage Learning
1. Which of the following best describes the primary function of the sodium-
potassium pump in maintaining the resting membrane potential of a neuron?
A) It actively transports three sodium ions out of the cell and two potassium ions into the
cell, contributing to a negative interior.
B) It passively diffuses sodium and potassium ions down their concentration gradients
to equalize charge across the membrane.
C) It pumps two sodium ions into the cell and three potassium ions out, creating a
positive interior relative to the exterior.
D) It facilitates the movement of chloride ions into the cell to counteract the positive
charge of potassium.
Correct Answer: It actively transports three sodium ions out of the cell and two
potassium ions into the cell, contributing to a negative interior.
Rationale: The sodium-potassium pump (Na⁺/K⁺ ATPase) hydrolyzes ATP to move three
Na⁺ out and two K⁺ in against their gradients. This electrogenic action removes more
positive charge than it brings in, helping establish the negative resting membrane
potential. Passive diffusion would not maintain the concentration gradients necessary
for neuronal excitability.
2. What is the primary role of the axon hillock in a neuron?
A) It serves as the main receptive area for synaptic inputs from other neurons.
B) It integrates graded potentials and initiates action potentials if the threshold is
reached.
C) It stores neurotransmitters in vesicles for release at the synaptic cleft.
D) It provides structural support and insulation for the axon through myelin production.
Correct Answer: It integrates graded potentials and initiates action potentials if the
threshold is reached.
Rationale: The axon hillock is the region where the axon emerges from the soma and
contains a high density of voltage-gated sodium channels. It sums excitatory and
inhibitory postsynaptic potentials; if the net depolarization reaches threshold, an action
potential is generated. Dendrites receive inputs, while the hillock is the trigger zone for
output.
, 3. A researcher is studying the endocrine system and observes a gland that
secretes hormones directly into the bloodstream without using ducts. Which
term best classifies this gland?
A) Exocrine gland
B) Apocrine gland
C) Endocrine gland
D) Holocrine gland
Correct Answer: Endocrine gland
Rationale: Endocrine glands are ductless and release hormones into the interstitial fluid
and then the bloodstream for transport to target cells. Exocrine glands secrete through
ducts onto epithelial surfaces. Apocrine and holocrine are subtypes of exocrine
secretion mechanisms, not classifications of ductless glands.
4. According to the principles of hormonal regulation, which of the following
describes a negative feedback loop in the endocrine system?
A) The hypothalamus increases releasing hormone secretion when thyroid hormone
levels rise.
B) The anterior pituitary increases TSH secretion when thyroid hormone levels are high.
C) Rising cortisol levels inhibit CRH and ACTH secretion from the hypothalamus and
pituitary.
D) The posterior pituitary releases more ADH as blood osmolarity decreases.
Correct Answer: Rising cortisol levels inhibit CRH and ACTH secretion from the
hypothalamus and pituitary.
Rationale: Negative feedback occurs when the end product of a hormonal axis
suppresses earlier steps in the pathway. Cortisol from the adrenal cortex inhibits
hypothalamic CRH and anterior pituitary ACTH, preventing overproduction. Options A,
B, and D describe positive feedback or incorrect relationships that would amplify
hormonal imbalances.
5. Which of the following best explains why the heart's left ventricular wall is
significantly thicker than the right ventricular wall?
A) The left ventricle must pump blood through the pulmonary circuit at lower pressure.
B) The left ventricle must generate higher pressure to overcome systemic vascular
resistance.
,C) The right ventricle receives oxygenated blood directly from the lungs and requires less
force.
D) The left ventricle contains more automaticity than the right ventricle.
Correct Answer: The left ventricle must generate higher pressure to overcome systemic
vascular resistance.
Rationale: The left ventricle pumps blood into the systemic circulation, which has much
higher resistance than the pulmonary circuit. This requires greater contractile force,
leading to a thicker myocardial wall. The right ventricle pumps to the lungs at lower
pressure, so its wall is thinner. Automaticity is a property of nodal tissue, not ventricular
muscle mass.
6. In the context of the cardiac cycle, what event does the QRS complex of a normal
electrocardiogram represent?
A) Atrial depolarization
B) Ventricular depolarization
C) Ventricular repolarization
D) Atrial repolarization
Correct Answer: Ventricular depolarization
Rationale: The QRS complex reflects the rapid depolarization of the ventricles, which
precedes ventricular contraction (systole). The P wave represents atrial depolarization,
and the T wave represents ventricular repolarization. Atrial repolarization is typically
obscured by the QRS complex due to its small amplitude.
7. Which of the following is a primary function of the lymphatic system?
A) Transporting oxygenated blood from the lungs to peripheral tissues.
B) Filtering lymph and initiating adaptive immune responses against pathogens.
C) Secreting digestive enzymes into the small intestine for nutrient breakdown.
D) Producing red blood cells within the bone marrow of long bones.
Correct Answer: Filtering lymph and initiating adaptive immune responses against
pathogens.
Rationale: The lymphatic system returns excess interstitial fluid to the blood, filters
lymph through lymph nodes, and provides sites for immune surveillance and activation.
It does not transport oxygenated blood (cardiovascular system), secrete digestive
enzymes (pancreas), or produce red blood cells (bone marrow).
, 8. What is the primary mechanism by which carbon dioxide is transported in the
blood?
A) Dissolved directly in plasma as CO₂ gas
B) Bound to hemoglobin at the heme iron site
C) As bicarbonate ions formed through the carbonic anhydrase reaction
D) As carbaminohemoglobin bound to the globin portion of hemoglobin
Correct Answer: As bicarbonate ions formed through the carbonic anhydrase reaction
Rationale: About 70% of CO₂ is transported as bicarbonate (HCO₃⁻). Inside red blood
cells, carbonic anhydrase catalyzes CO₂ + H₂O ⇌ H₂CO₃ ⇌ H⁺ + HCO₃⁻. Bicarbonate
then moves into plasma in exchange for chloride. A smaller percentage binds to globin
(carbaminohemoglobin), and a minor fraction dissolves in plasma.
9. Which of the following accurately describes the function of the muscularis
externa in the gastrointestinal tract?
A) It secretes mucus to lubricate the luminal surface and protect the epithelium.
B) It contains two layers of smooth muscle that produce peristalsis and segmentation.
C) It absorbs the majority of nutrients through villi and microvilli.
D) It houses the enteric nervous system responsible for hormone release.
Correct Answer: It contains two layers of smooth muscle that produce peristalsis and
segmentation.
Rationale: The muscularis externa consists of an inner circular layer and an outer
longitudinal layer of smooth muscle. Coordinated contractions of these layers generate
peristalsis (propulsive movement) and segmentation (mixing). Mucus secretion occurs
in the mucosa, nutrient absorption occurs through mucosal villi, and the enteric nervous
system is distributed in submucosal and myenteric plexuses.
10. A patient is undergoing a renal function test, and the clinician explains that the
glomerular filtration rate is primarily determined by which of the following
factors?
A) The colloid osmotic pressure of the blood in the glomerular capillaries.
B) The net filtration pressure across the glomerular membrane and the surface area
available for filtration.
C) The rate of active transport of sodium in the proximal convoluted tubule.
D) The concentration of antidiuretic hormone in the collecting duct.
w/Lab Q&A | Portage Learning
1. Which of the following best describes the primary function of the sodium-
potassium pump in maintaining the resting membrane potential of a neuron?
A) It actively transports three sodium ions out of the cell and two potassium ions into the
cell, contributing to a negative interior.
B) It passively diffuses sodium and potassium ions down their concentration gradients
to equalize charge across the membrane.
C) It pumps two sodium ions into the cell and three potassium ions out, creating a
positive interior relative to the exterior.
D) It facilitates the movement of chloride ions into the cell to counteract the positive
charge of potassium.
Correct Answer: It actively transports three sodium ions out of the cell and two
potassium ions into the cell, contributing to a negative interior.
Rationale: The sodium-potassium pump (Na⁺/K⁺ ATPase) hydrolyzes ATP to move three
Na⁺ out and two K⁺ in against their gradients. This electrogenic action removes more
positive charge than it brings in, helping establish the negative resting membrane
potential. Passive diffusion would not maintain the concentration gradients necessary
for neuronal excitability.
2. What is the primary role of the axon hillock in a neuron?
A) It serves as the main receptive area for synaptic inputs from other neurons.
B) It integrates graded potentials and initiates action potentials if the threshold is
reached.
C) It stores neurotransmitters in vesicles for release at the synaptic cleft.
D) It provides structural support and insulation for the axon through myelin production.
Correct Answer: It integrates graded potentials and initiates action potentials if the
threshold is reached.
Rationale: The axon hillock is the region where the axon emerges from the soma and
contains a high density of voltage-gated sodium channels. It sums excitatory and
inhibitory postsynaptic potentials; if the net depolarization reaches threshold, an action
potential is generated. Dendrites receive inputs, while the hillock is the trigger zone for
output.
, 3. A researcher is studying the endocrine system and observes a gland that
secretes hormones directly into the bloodstream without using ducts. Which
term best classifies this gland?
A) Exocrine gland
B) Apocrine gland
C) Endocrine gland
D) Holocrine gland
Correct Answer: Endocrine gland
Rationale: Endocrine glands are ductless and release hormones into the interstitial fluid
and then the bloodstream for transport to target cells. Exocrine glands secrete through
ducts onto epithelial surfaces. Apocrine and holocrine are subtypes of exocrine
secretion mechanisms, not classifications of ductless glands.
4. According to the principles of hormonal regulation, which of the following
describes a negative feedback loop in the endocrine system?
A) The hypothalamus increases releasing hormone secretion when thyroid hormone
levels rise.
B) The anterior pituitary increases TSH secretion when thyroid hormone levels are high.
C) Rising cortisol levels inhibit CRH and ACTH secretion from the hypothalamus and
pituitary.
D) The posterior pituitary releases more ADH as blood osmolarity decreases.
Correct Answer: Rising cortisol levels inhibit CRH and ACTH secretion from the
hypothalamus and pituitary.
Rationale: Negative feedback occurs when the end product of a hormonal axis
suppresses earlier steps in the pathway. Cortisol from the adrenal cortex inhibits
hypothalamic CRH and anterior pituitary ACTH, preventing overproduction. Options A,
B, and D describe positive feedback or incorrect relationships that would amplify
hormonal imbalances.
5. Which of the following best explains why the heart's left ventricular wall is
significantly thicker than the right ventricular wall?
A) The left ventricle must pump blood through the pulmonary circuit at lower pressure.
B) The left ventricle must generate higher pressure to overcome systemic vascular
resistance.
,C) The right ventricle receives oxygenated blood directly from the lungs and requires less
force.
D) The left ventricle contains more automaticity than the right ventricle.
Correct Answer: The left ventricle must generate higher pressure to overcome systemic
vascular resistance.
Rationale: The left ventricle pumps blood into the systemic circulation, which has much
higher resistance than the pulmonary circuit. This requires greater contractile force,
leading to a thicker myocardial wall. The right ventricle pumps to the lungs at lower
pressure, so its wall is thinner. Automaticity is a property of nodal tissue, not ventricular
muscle mass.
6. In the context of the cardiac cycle, what event does the QRS complex of a normal
electrocardiogram represent?
A) Atrial depolarization
B) Ventricular depolarization
C) Ventricular repolarization
D) Atrial repolarization
Correct Answer: Ventricular depolarization
Rationale: The QRS complex reflects the rapid depolarization of the ventricles, which
precedes ventricular contraction (systole). The P wave represents atrial depolarization,
and the T wave represents ventricular repolarization. Atrial repolarization is typically
obscured by the QRS complex due to its small amplitude.
7. Which of the following is a primary function of the lymphatic system?
A) Transporting oxygenated blood from the lungs to peripheral tissues.
B) Filtering lymph and initiating adaptive immune responses against pathogens.
C) Secreting digestive enzymes into the small intestine for nutrient breakdown.
D) Producing red blood cells within the bone marrow of long bones.
Correct Answer: Filtering lymph and initiating adaptive immune responses against
pathogens.
Rationale: The lymphatic system returns excess interstitial fluid to the blood, filters
lymph through lymph nodes, and provides sites for immune surveillance and activation.
It does not transport oxygenated blood (cardiovascular system), secrete digestive
enzymes (pancreas), or produce red blood cells (bone marrow).
, 8. What is the primary mechanism by which carbon dioxide is transported in the
blood?
A) Dissolved directly in plasma as CO₂ gas
B) Bound to hemoglobin at the heme iron site
C) As bicarbonate ions formed through the carbonic anhydrase reaction
D) As carbaminohemoglobin bound to the globin portion of hemoglobin
Correct Answer: As bicarbonate ions formed through the carbonic anhydrase reaction
Rationale: About 70% of CO₂ is transported as bicarbonate (HCO₃⁻). Inside red blood
cells, carbonic anhydrase catalyzes CO₂ + H₂O ⇌ H₂CO₃ ⇌ H⁺ + HCO₃⁻. Bicarbonate
then moves into plasma in exchange for chloride. A smaller percentage binds to globin
(carbaminohemoglobin), and a minor fraction dissolves in plasma.
9. Which of the following accurately describes the function of the muscularis
externa in the gastrointestinal tract?
A) It secretes mucus to lubricate the luminal surface and protect the epithelium.
B) It contains two layers of smooth muscle that produce peristalsis and segmentation.
C) It absorbs the majority of nutrients through villi and microvilli.
D) It houses the enteric nervous system responsible for hormone release.
Correct Answer: It contains two layers of smooth muscle that produce peristalsis and
segmentation.
Rationale: The muscularis externa consists of an inner circular layer and an outer
longitudinal layer of smooth muscle. Coordinated contractions of these layers generate
peristalsis (propulsive movement) and segmentation (mixing). Mucus secretion occurs
in the mucosa, nutrient absorption occurs through mucosal villi, and the enteric nervous
system is distributed in submucosal and myenteric plexuses.
10. A patient is undergoing a renal function test, and the clinician explains that the
glomerular filtration rate is primarily determined by which of the following
factors?
A) The colloid osmotic pressure of the blood in the glomerular capillaries.
B) The net filtration pressure across the glomerular membrane and the surface area
available for filtration.
C) The rate of active transport of sodium in the proximal convoluted tubule.
D) The concentration of antidiuretic hormone in the collecting duct.
