BIOL 213
Human Anatomy & Physiology I
Proctored Midterm Exam
2026
(Questions & Solutions)
Multiple Choice Questions (10)
A patient presents with muscle weakness and fatigue. Laboratory results reveal decreased
acetylcholine receptors at the neuromuscular junction. Which condition is most likely?
a) Guillain-Barré syndrome
b) Myasthenia gravis
c) Multiple sclerosis
d) Amyotrophic lateral sclerosis
Answer: b) Myasthenia gravis
Rationale: Myasthenia gravis is an autoimmune disorder targeting acetylcholine receptors, leading to
muscle weakness.
During insulin release from pancreatic beta cells, which ion primarily triggers exocytosis of insulin
granules?
a) Sodium (Na⁺)
b) Chloride (Cl⁻)
c) Calcium (Ca²⁺)
d) Potassium (K⁺)
Answer: c) Calcium (Ca²⁺)
Rationale: Elevated intracellular calcium triggers insulin granule exocytosis in beta cells.
Which vessel layer contains smooth muscle responsible for vasoconstriction?
a) Tunica intima
b) Tunica media
c) Tunica adventitia
d) Endothelium
Answer: b) Tunica media
Rationale: The tunica media layer is made primarily of smooth muscle, controlling vessel diameter.
Which region of the nephron is primarily responsible for the countercurrent multiplier mechanism?
a) Proximal convoluted tubule
b) Distal convoluted tubule
c) Loop of Henle
d) Collecting duct
Answer: c) Loop of Henle
Rationale: The loop of Henle creates the medullary osmotic gradient via countercurrent
multiplication.
In cardiac conduction, which structure delays the impulse to allow ventricular filling?
a) SA node
,b) AV node
c) Bundle of His
d) Purkinje fibers
Answer: b) AV node
Rationale: The AV node delays electrical impulses briefly, coordinating atrial and ventricular
contraction.
Which component of blood acts as a primary buffer maintaining pH?
a) Sodium bicarbonate
b) Hemoglobin
c) Plasma proteins
d) Platelets
Answer: a) Sodium bicarbonate
Rationale: Bicarbonate ions buffer blood pH by neutralizing acids.
Which brain region regulates homeostasis of body temperature and hunger?
a) Cerebellum
b) Hypothalamus
c) Pons
d) Medulla oblongata
Answer: b) Hypothalamus
Rationale: The hypothalamus governs autonomic functions including temperature and appetite.
What type of epithelium lines the respiratory tract from the nasal cavity to the bronchi?
a) Simple squamous
b) Stratified squamous
c) Pseudostratified ciliated columnar
d) Transitional
Answer: c) Pseudostratified ciliated columnar
Rationale: This epithelium traps particles and moves mucus upward.
Which hormone directly increases osteoclast activity to elevate blood calcium levels?
a) Calcitonin
b) Parathyroid hormone (PTH)
c) Vitamin D
d) Growth hormone
Answer: b) Parathyroid hormone (PTH)
Rationale: PTH stimulates osteoclasts to resorb bone, releasing calcium.
Which neurotransmitter primarily inhibits postsynaptic neurons in the central nervous system?
a) Glutamate
b) Acetylcholine
c) Gamma-aminobutyric acid (GABA)
d) Dopamine
Answer: c) Gamma-aminobutyric acid (GABA)
Rationale: GABA is the major inhibitory neurotransmitter in the CNS.
True/False Questions (8)
The liver synthesizes most plasma proteins including clotting factors.
True
Rationale: The liver produces albumin and clotting factors essential for plasma function.
, Interstitial fluid surrounds cells and contributes to the extracellular fluid compartment.
True
Rationale: Interstitial fluid bathes cells and is a component of extracellular fluid.
The receptor potential in sensory neurons is always an all-or-none event.
False
Rationale: Receptor potentials are graded potentials, varying in magnitude.
Cardiac muscle cells rely mainly on anaerobic metabolism during prolonged activity.
False
Rationale: Cardiac muscle depends primarily on aerobic metabolism for ATP.
The blood-brain barrier allows free passage of most lipid-soluble molecules.
True
Rationale: Lipid solubility aids crossing of the blood-brain barrier.
Type 1 muscle fibers are fast-twitch and fatigue quickly.
False
Rationale: Type 1 fibers are slow-twitch and fatigue resistant.
The S1 heart sound is caused by the closing of the semilunar valves.
False
Rationale: S1 is due to closure of atrioventricular valves.
The sodium-potassium pump moves 3 sodium ions out and 2 potassium ions into the cell per cycle.
True
Rationale: This pump maintains cell resting potential and ionic gradients.
Short Answer Questions (10)
Explain the role of the sarcoplasmic reticulum in muscle contraction.
Answer: The sarcoplasmic reticulum stores and releases calcium ions, which bind to troponin,
triggering cross-bridge formation and muscle contraction.
Rationale: Calcium release is essential for actin-myosin interaction during contraction.
Describe the mechanism of gas exchange in the alveoli.
Answer: Oxygen diffuses from alveolar air (high concentration) into pulmonary capillaries (low O₂),
while carbon dioxide diffuses from blood to alveoli following partial pressure gradients.
Rationale: Passive diffusion based on partial pressure differences enables gas exchange.
List three functions of the liver beyond metabolism and detoxification.
Answer: Bile production, plasma protein synthesis, and storage of vitamins/minerals.
Rationale: These contribute to digestion, blood maintenance, and nutrient homeostasis.
How does aldosterone affect the kidney’s distal tubule?
Answer: Aldosterone increases sodium reabsorption and potassium secretion, promoting water
retention and blood pressure maintenance.
Rationale: It acts on principal cells enhancing sodium channels and pumps.
What is the significance of the isoelectric point in a protein?
Answer: It is the pH at which the protein has no net charge, influencing solubility and function.
Rationale: Protein behavior changes with pH and net charge affecting interactions.
Human Anatomy & Physiology I
Proctored Midterm Exam
2026
(Questions & Solutions)
Multiple Choice Questions (10)
A patient presents with muscle weakness and fatigue. Laboratory results reveal decreased
acetylcholine receptors at the neuromuscular junction. Which condition is most likely?
a) Guillain-Barré syndrome
b) Myasthenia gravis
c) Multiple sclerosis
d) Amyotrophic lateral sclerosis
Answer: b) Myasthenia gravis
Rationale: Myasthenia gravis is an autoimmune disorder targeting acetylcholine receptors, leading to
muscle weakness.
During insulin release from pancreatic beta cells, which ion primarily triggers exocytosis of insulin
granules?
a) Sodium (Na⁺)
b) Chloride (Cl⁻)
c) Calcium (Ca²⁺)
d) Potassium (K⁺)
Answer: c) Calcium (Ca²⁺)
Rationale: Elevated intracellular calcium triggers insulin granule exocytosis in beta cells.
Which vessel layer contains smooth muscle responsible for vasoconstriction?
a) Tunica intima
b) Tunica media
c) Tunica adventitia
d) Endothelium
Answer: b) Tunica media
Rationale: The tunica media layer is made primarily of smooth muscle, controlling vessel diameter.
Which region of the nephron is primarily responsible for the countercurrent multiplier mechanism?
a) Proximal convoluted tubule
b) Distal convoluted tubule
c) Loop of Henle
d) Collecting duct
Answer: c) Loop of Henle
Rationale: The loop of Henle creates the medullary osmotic gradient via countercurrent
multiplication.
In cardiac conduction, which structure delays the impulse to allow ventricular filling?
a) SA node
,b) AV node
c) Bundle of His
d) Purkinje fibers
Answer: b) AV node
Rationale: The AV node delays electrical impulses briefly, coordinating atrial and ventricular
contraction.
Which component of blood acts as a primary buffer maintaining pH?
a) Sodium bicarbonate
b) Hemoglobin
c) Plasma proteins
d) Platelets
Answer: a) Sodium bicarbonate
Rationale: Bicarbonate ions buffer blood pH by neutralizing acids.
Which brain region regulates homeostasis of body temperature and hunger?
a) Cerebellum
b) Hypothalamus
c) Pons
d) Medulla oblongata
Answer: b) Hypothalamus
Rationale: The hypothalamus governs autonomic functions including temperature and appetite.
What type of epithelium lines the respiratory tract from the nasal cavity to the bronchi?
a) Simple squamous
b) Stratified squamous
c) Pseudostratified ciliated columnar
d) Transitional
Answer: c) Pseudostratified ciliated columnar
Rationale: This epithelium traps particles and moves mucus upward.
Which hormone directly increases osteoclast activity to elevate blood calcium levels?
a) Calcitonin
b) Parathyroid hormone (PTH)
c) Vitamin D
d) Growth hormone
Answer: b) Parathyroid hormone (PTH)
Rationale: PTH stimulates osteoclasts to resorb bone, releasing calcium.
Which neurotransmitter primarily inhibits postsynaptic neurons in the central nervous system?
a) Glutamate
b) Acetylcholine
c) Gamma-aminobutyric acid (GABA)
d) Dopamine
Answer: c) Gamma-aminobutyric acid (GABA)
Rationale: GABA is the major inhibitory neurotransmitter in the CNS.
True/False Questions (8)
The liver synthesizes most plasma proteins including clotting factors.
True
Rationale: The liver produces albumin and clotting factors essential for plasma function.
, Interstitial fluid surrounds cells and contributes to the extracellular fluid compartment.
True
Rationale: Interstitial fluid bathes cells and is a component of extracellular fluid.
The receptor potential in sensory neurons is always an all-or-none event.
False
Rationale: Receptor potentials are graded potentials, varying in magnitude.
Cardiac muscle cells rely mainly on anaerobic metabolism during prolonged activity.
False
Rationale: Cardiac muscle depends primarily on aerobic metabolism for ATP.
The blood-brain barrier allows free passage of most lipid-soluble molecules.
True
Rationale: Lipid solubility aids crossing of the blood-brain barrier.
Type 1 muscle fibers are fast-twitch and fatigue quickly.
False
Rationale: Type 1 fibers are slow-twitch and fatigue resistant.
The S1 heart sound is caused by the closing of the semilunar valves.
False
Rationale: S1 is due to closure of atrioventricular valves.
The sodium-potassium pump moves 3 sodium ions out and 2 potassium ions into the cell per cycle.
True
Rationale: This pump maintains cell resting potential and ionic gradients.
Short Answer Questions (10)
Explain the role of the sarcoplasmic reticulum in muscle contraction.
Answer: The sarcoplasmic reticulum stores and releases calcium ions, which bind to troponin,
triggering cross-bridge formation and muscle contraction.
Rationale: Calcium release is essential for actin-myosin interaction during contraction.
Describe the mechanism of gas exchange in the alveoli.
Answer: Oxygen diffuses from alveolar air (high concentration) into pulmonary capillaries (low O₂),
while carbon dioxide diffuses from blood to alveoli following partial pressure gradients.
Rationale: Passive diffusion based on partial pressure differences enables gas exchange.
List three functions of the liver beyond metabolism and detoxification.
Answer: Bile production, plasma protein synthesis, and storage of vitamins/minerals.
Rationale: These contribute to digestion, blood maintenance, and nutrient homeostasis.
How does aldosterone affect the kidney’s distal tubule?
Answer: Aldosterone increases sodium reabsorption and potassium secretion, promoting water
retention and blood pressure maintenance.
Rationale: It acts on principal cells enhancing sodium channels and pumps.
What is the significance of the isoelectric point in a protein?
Answer: It is the pH at which the protein has no net charge, influencing solubility and function.
Rationale: Protein behavior changes with pH and net charge affecting interactions.
