Medical Physiology Paper I – 58 MCQs | Kenya MBChB

58 Year 2: Physiology exam questions on Medical Physiology Paper I for medical students. Includes MCQs, answers, explanations and written questions. Sample: Whi

This MCQ set contains 58 questions on Medical Physiology Paper I in the Year 2: Physiology unit. Each question includes the correct answer and a detailed explanation for active recall and exam preparation.

Q1: Which of the following will lead to an increase in glomerular fluid filtration in the kidneys?

  1. A. a decrease in the fluid pressure in Bowman's space
  2. B. an increase in the fluid pressure in Bowman's space
  3. C. an increase in the glomerular capillary blood pressure
  4. D. a decrease in the glomerular capillary blood pressure
  5. E. constriction of the afferent arteriole

Correct answer: C – an increase in the glomerular capillary blood pressure

Glomerular filtration rate (GFR) is determined by the net filtration pressure, which equals glomerular capillary pressure minus (Bowman's capsule pressure + colloid osmotic pressure). Increasing glomerular capillary blood pressure directly increases the driving force for filtration. ---

Q2: Which of the following is a component of the renal response to metabolic acidosis?

  1. A. reabsorption of H+
  2. B. secretion of HCO3- into the tubular lumen
  3. C. secretion of ammonium into the tubular lumen
  4. D. secretion of glutamine into the interstitial fluid

Correct answer: C – secretion of ammonium into the tubular lumen

During metabolic acidosis, the kidneys compensate by increasing acid excretion and bicarbonate regeneration. Ammonium (NH4+) secretion into the tubular lumen is a major mechanism for eliminating excess acid from the body. ---

Q3: Which of the following will not lead to a diuresis?

  1. A. excessive sweating
  2. B. central diabetes insipidus
  3. C. nephrogenic diabetes insipidus
  4. D. excessive water intake

Correct answer: A – excessive sweating

Excessive sweating causes fluid loss through the skin, leading to dehydration and concentrated urine (antidiuresis). The other options all cause increased urine production (diuresis). ---

Q4: Which of the following contributes directly to the generation of a hypertonic medullary interstitium in the kidney?

  1. A. secretion of urea into Henle's loop
  2. B. active water reabsorption in the ascending limb of Henle's loop
  3. C. Na+ reabsorption in the distal convoluted tubule
  4. D. water reabsorption in the cortical collecting duct

Correct answer: A – secretion of urea into Henle's loop

The hypertonic medullary interstitium is created by the countercurrent multiplier system. Urea recycling and accumulation in the medulla is crucial for maintaining the high osmolarity needed for urine concentration. ---

Q5: An increase in renin is caused by

  1. A. a decrease in sodium intake
  2. B. a decrease in renal sympathetic nerve activity
  3. C. an increase in blood pressure in the renal artery
  4. D. an injection of aldosterone

Correct answer: A – a decrease in sodium intake

Renin release is stimulated by decreased sodium delivery to the macula densa, decreased blood pressure, and increased sympathetic activity. Low sodium intake triggers renin release to activate the renin-angiotensin-aldosterone system. ---

Q6: What happens at plasma concentrations of glucose higher than transport maximum (TM)?

  1. A. renal vein glucose concentration equals the renal artery glucose concentration
  2. B. excretion rate of glucose equals the filtration rate of glucose
  3. C. reabsorption rate of glucose equals the filtration rate of glucose
  4. D. excretion rate of glucose increases with increasing plasma glucose concentrations
  5. E. Additional glucose cannot be reabsorbed and is excreted in urine, with excretion rate increasing proportionally to plasma glucose concentration.

Correct answer: D – excretion rate of glucose increases with increasing plasma glucose concentrations

When glucose concentration exceeds the transport maximum, the reabsorption transporters become saturated. Additional glucose cannot be reabsorbed and is excreted in urine, with excretion rate increasing proportionally to plasma glucose concentration. ---

Q7: Which of the following would produce an increase in the reabsorption of isosmotic fluid in the proximal tubule?

  1. A. extracellular fluid volume expansion
  2. B. decreased peritubular capillary protein concentration
  3. C. increased peritubular capillary hydrostatic pressure
  4. D. increased glomerular filtration fraction

Correct answer: D – increased glomerular filtration fraction

Increased filtration fraction leads to increased protein concentration in peritubular capillaries, which increases colloid osmotic pressure and promotes fluid reabsorption from the proximal tubule. ---

Q8: Which of the following would cause an increase in both glomerular filtration rate (GFR) and renal plasma flow (RPF)?

  1. A. constriction of the efferent arteriole
  2. B. dilation of the afferent arteriole
  3. C. constriction of the afferent arteriole
  4. D. dilation of the efferent arteriole

Correct answer: B – dilation of the afferent arteriole

Afferent arteriole dilation increases both blood flow into the glomerulus (increasing RPF) and glomerular capillary pressure (increasing GFR). This is the only option that increases both parameters. ---

Q9: Which of the following is true about reabsorption of filtered HCO3-?

  1. A. can proceed normally in the presence of a renal carbonic anhydrase inhibitor
  2. B. acidifies tubular fluid to a pH of 4.4
  3. C. is directly linked to excretion of H+ as NH4+
  4. D. is inhibited by decreases in arterial PCO2

Correct answer: D – is inhibited by decreases in arterial PCO2

Bicarbonate reabsorption depends on H+ secretion, which is driven by carbonic anhydrase activity. Decreased arterial PCO2 (respiratory alkalosis) reduces H+ secretion and thus inhibits bicarbonate reabsorption. ---

Q10: Kipchoge runs a marathon in 90°F weather and replaces all volume lost in sweat by drinking distilled water. After the marathon, she will have

  1. A. decreased total body water
  2. B. increased intracellular osmolarity
  3. C. decreased intracellular fluid volume
  4. D. decreased plasma osmolarity
  5. E. . Replacing sweat losses with pure water dilutes body fluids, leading to decreased plasma osmolarity (hyponatremia).

Correct answer: D – decreased plasma osmolarity

Sweat contains electrolytes (hypotonic to plasma). Replacing sweat losses with pure water dilutes body fluids, leading to decreased plasma osmolarity (hyponatremia). ---

Q11: Which of the following causes hyperkalemia?

  1. A. exercise
  2. B. alkalosis
  3. C. insulin injection
  4. D. treatment with β-agonists
  5. E. The other options typically cause hypokalemia by promoting cellular potassium uptak

Correct answer: A – exercise

Exercise releases potassium from muscle cells into the extracellular fluid, causing hyperkalemia. The other options typically cause hypokalemia by promoting cellular potassium uptake. ---

Q12: Which of the following is a cause of metabolic alkalosis?

  1. A. diarrhea
  2. B. chronic renal failure
  3. C. ethylene glycol ingestion
  4. D. hyperaldosteronism

Correct answer: D – hyperaldosteronism

Hyperaldosteronism causes excessive sodium retention and potassium/hydrogen loss, leading to metabolic alkalosis. The other options typically cause metabolic acidosis. ---

Q13: The decision to delay extraction of the oocyte until 7 hours after a rise in LH levels is because the midcycle LH surge causes

  1. A. capacitation during sperm entry
  2. B. formation of antrum in the mature/Graafian follicle
  3. C. cortical reaction in the oocyte
  4. D. meiotic progression of an oocyte from prophase I to metaphase II

Correct answer: D – meiotic progression of an oocyte from prophase I to metaphase II

The LH surge triggers completion of meiosis I in the oocyte, progressing from prophase I arrest to metaphase II. This maturation process takes several hours and is essential for successful fertilization. ---

Q14: Regarding a healthy 30-year-old woman with regular 28-day menstrual cycles, which statement is correct?

  1. A. At day 5, her endometrium is in the secretory phase
  2. B. At day 15, her blood estrogen levels peak
  3. C. At day 22, her blastocyst would be implanted (if she is pregnant)
  4. D. At day 7, her ovary releases a secondary oocyte
  5. E. At day 27, her blood progesterone levels peak

Correct answer: C – At day 22, her blastocyst would be implanted (if she is pregnant)

Ovulation occurs around day 14, fertilization within 24 hours, and implantation occurs 6-7 days after fertilization (around day 21-22 of the cycle). ---

Q15: The Leydig cell is primarily characterized by

  1. A. aromatization of testosterone
  2. B. secretion of inhibin
  3. C. secretion of testosterone
  4. D. expression of receptors only to FSH
  5. E. transformation into the corpus luteum

Correct answer: C – secretion of testosterone

Leydig cells are the primary testosterone-producing cells in the testes, responding to LH stimulation to synthesize and secrete testosterone. ---

Q16: Loss-of-function mutations of which enzyme would be responsible for the presence of labia in an XY subject at birth?

  1. A. 5α-reductase
  2. B. 21α-hydroxylase
  3. C. Aromatase
  4. D. Tyrosine hydroxylase

Correct answer: A – 5α-reductase

5α-reductase converts testosterone to dihydrotestosterone (DHT), which is essential for external male genital development. Its absence leads to ambiguous genitalia with female-appearing external structures. ---

Q17: Which is NOT characteristic of a normal post-pubertal male?

  1. A. Inhibin from the Sertoli cells decreases FSH secretion
  2. B. Testosterone has paracrine effects on the Sertoli cells
  3. C. Testosterone stimulates GnRH from the hypothalamus
  4. D. Testosterone inhibits LH secretion
  5. E. GnRH from the hypothalamus is released in pulses

Correct answer: C – Testosterone stimulates GnRH from the hypothalamus

Testosterone provides negative feedback to the hypothalamus, inhibiting (not stimulating) GnRH release. This is a key component of the hormonal regulation of male reproduction. ---

Q18: An XY human embryo with androgen insensitivity has which of the following at the age of 3-4 weeks?

  1. A. Testes
  2. B. Mullerian ducts
  3. C. Uterus
  4. D. Labia
  5. E. Scrotum

Correct answer: B – Mullerian ducts

At 3-4 weeks, both Mullerian and Wolffian ducts are present. In androgen insensitivity syndrome, testes develop and produce anti-Mullerian hormone, but Mullerian ducts are initially present before regression. ---

Q19: A patient with premature ovarian failure is associated with which of the following?

  1. A. A detectable level of plasma hCG
  2. B. An above-normal level of plasma LH
  3. C. An above-normal level of plasma progesterone
  4. D. An above-normal level of plasma inhibin
  5. E. An above-normal level of plasma prolactin

Correct answer: B – An above-normal level of plasma LH

Premature ovarian failure results in loss of negative feedback from ovarian hormones, leading to elevated FSH and LH levels due to lack of inhibition from estrogen and inhibin. ---

Q20: How many days after fertilization would a woman with normal menstrual cycles BEGIN to have an elevated plasma hCG?

  1. A. 2 days
  2. B. 7 days
  3. C. 12 days
  4. D. 17 days

Correct answer: B – 7 days

hCG is produced by the trophoblast after implantation, which occurs approximately 6-7 days after fertilization. Detectable levels appear shortly after implantation begins. ---

Q21: Which of these statements is INCORRECT?

  1. A. Anti-diuretic hormone is released from the posterior pituitary
  2. B. The anterior pituitary lobe is a collection of axon terminals
  3. C. The median eminence is a swelling that contains a capillary bed
  4. D. A portal vessel carries hypophysiotropic hormones from the hypothalamus to the anterior pituitary gland
  5. E. The infundibulum is a structure that sits between the hypothalamus and the pituitary lobes

Correct answer: B – The anterior pituitary lobe is a collection of axon terminals

The anterior pituitary is composed of endocrine cells (adenohypophysis), not axon terminals. The posterior pituitary consists of axon terminals from hypothalamic neurons. ---

Q22: Which of these statements is INCORRECT?

  1. A. Anti-diuretic hormone is released from the posterior pituitary
  2. B. The anterior pituitary lobe is a collection of axon terminals
  3. C. The median eminence is a swelling that contains a capillary bed
  4. D. A portal vessel carries hypophysiotropic hormones from the hypothalamus to the anterior pituitary gland
  5. E. The infundibulum is a structure that sits between the hypothalamus and the pituitary lobes

Correct answer: B – The anterior pituitary lobe is a collection of axon terminals

Same as Question 21 - The anterior pituitary consists of endocrine cells, not axon terminals. This is a characteristic of the posterior pituitary. ---

Q23: Thyroid Hormone

  1. A. Is a hydrophilic amine synthesized and secreted by thyrotroph cells
  2. B. Release from the thyroid gland requires exocytosis of the colloid contents
  3. C. Is an important regulator of the body's basal metabolic rate (BMR)
  4. D. Inhibits growth and development
  5. E. Synthesis requires primary active counter-transport of iodide/iodine into the cytosol

Correct answer: C – Is an important regulator of the body's basal metabolic rate (BMR)

Thyroid hormones (T3 and T4) are the primary regulators of basal metabolic rate, affecting oxygen consumption and heat production in most body tissues. ---

Q24: Which of the following statements is INCORRECT?

  1. A. Growth Hormone (GH) has plasma membrane receptors on cells of the Liver, Bone, and Muscle
  2. B. Insulin-like Growth Factor (IGF-1) exhibits short-loop negative feedback on Growth Hormone (GH)
  3. C. Somatotroph cells in the anterior pituitary respond to Growth Hormone-Releasing Hormone (GHRH) and increase their release of Growth Hormone into the g
  4. D. Growth Hormone-Releasing Hormone (GHRH) and Somatostatin are both hypophysiotropic hormones that travel through the portal vessel to the anterior pitu
  5. E. Growth Hormone-Releasing Hormone (GHRH) and Somatostatin are both released from the hypothalamus nuclei

Correct answer: B – Insulin-like Growth Factor (IGF-1) exhibits short-loop negative feedback on Growth Hormone (GH)

IGF-1 provides long-loop negative feedback on GH, not short-loop feedback. Short-loop feedback refers to the hormone itself inhibiting its own release. ---

Q25: Dopamine from the hypothalamus nuclei

  1. A. Is a hydrophobic catecholamine
  2. B. Has receptors on lactotroph cells of the anterior pituitary
  3. C. Has receptors in breast tissue
  4. D. Has a positive tropic action on Thyrotropin-releasing hormone (TRH)
  5. E. Has a positive tropic action on prolactin secretion

Correct answer: B – Has receptors on lactotroph cells of the anterior pituitary

Dopamine acts as prolactin-inhibiting hormone (PIH), binding to receptors on lactotroph cells to inhibit prolactin release. ---

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