BHS Anatomy and Physiology 5 — Questions and Answers
Question 1: The countercurrent multiplier system in the kidney is located in the:
- Proximal convoluted tubule
- Glomerulus
- Loop of Henle (Correct answer)
- Bowman's capsule
Correct answer: Loop of Henle
The loop of Henle creates a hyperosmotic medullary gradient through the countercurrent multiplier mechanism, enabling urine concentration.
Question 2: Which type of cell junction prevents molecules from passing between adjacent epithelial cells?
- Desmosomes
- Gap junctions
- Tight junctions (Correct answer)
- Hemidesmosomes
Correct answer: Tight junctions
Tight junctions (zonula occludens) seal adjacent epithelial cells together, preventing paracellular movement of substances.
Question 3: The Frank-Starling law of the heart states that:
- Heart rate increases with sympathetic stimulation
- Stroke volume increases as ventricular end-diastolic volume increases (Correct answer)
- Cardiac output decreases with increased afterload
- Contractility is inversely proportional to preload
Correct answer: Stroke volume increases as ventricular end-diastolic volume increases
The Frank-Starling law states that the greater the stretch of the ventricular myocardium (preload), the greater the force of contraction and stroke volume.
Question 4: Which structure in the inner ear is responsible for detecting linear acceleration and gravity?
- Semicircular canals
- Organ of Corti
- Otolithic organs (utricle and saccule) (Correct answer)
- Cochlear duct
Correct answer: Otolithic organs (utricle and saccule)
The utricle and saccule contain otolithic membranes with calcium carbonate crystals (otoliths) that detect linear acceleration and head tilt.
Question 5: The primary function of the large intestine is:
- Protein digestion
- Fat emulsification
- Water and electrolyte absorption (Correct answer)
- Enzyme secretion
Correct answer: Water and electrolyte absorption
The large intestine primarily absorbs water and electrolytes from indigestible food matter and compacts feces for elimination.
Question 6: During an action potential, repolarization occurs when:
- Sodium channels open rapidly
- Potassium channels open and K⁺ flows out of the cell (Correct answer)
- The membrane reaches threshold potential
- Calcium ions enter the cell
Correct answer: Potassium channels open and K⁺ flows out of the cell
Repolarization occurs when voltage-gated K⁺ channels open, allowing potassium to flow out of the cell and restoring the negative resting membrane potential.
Question 7: The reticulospinal tract is classified as part of the:
- Dorsal column–medial lemniscal system
- Lateral corticospinal tract
- Medial motor system (Correct answer)
- Spinothalamic tract
Correct answer: Medial motor system
The reticulospinal tract is part of the medial motor system, which controls axial and proximal limb muscles for posture and locomotion.
BHS Anatomy and Physiology 5
The countercurrent multiplier system in the kidney is located in the: