Medical Physiology Paper I – 45 MCQs | Kenya MBChB

45 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 45 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 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. ---

Q2: 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). ---

Q3: 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. ---

Q4: 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. ---

Q5: 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. ---

Q6: 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. ---

Q7: 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. ---

Q8: 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. ---

Q9: 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). ---

Q10: 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. ---

Q11: 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. ---

Q12: 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. ---

Q13: 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. ---

Q14: 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. ---

Q15: 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. ---

Q16: 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. ---

Q17: 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. ---

Q18: 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. ---

Q19: Which of the following options is NOT a basal level (unstressed) function of cortisol?

  1. A. Promote fetal development of brain, intestines, and lungs
  2. B. Promote an adequate amount of glucose in the plasma between meals
  3. C. Promote bone resorption
  4. D. Maintain adequate mean arterial blood pressure
  5. E. Provide an anti-inflammatory function that prevents hyper-immune responses

Correct answer: E – Provide an anti-inflammatory function that prevents hyper-immune responses

While cortisol has anti-inflammatory effects, preventing hyper-immune responses is primarily a stress response function, not a basal function. ---

Q20: Which of the following is a function of adrenal catecholamine epinephrine during stress?

  1. A. Increases digestive activity
  2. B. Constricts pupils
  3. C. Decreases central nervous system alertness
  4. D. Dilates respiratory airways
  5. E. Mobilizes glucose from the long bones

Correct answer: D – Dilates respiratory airways

Epinephrine causes bronchodilation during the fight-or-flight response, increasing airflow to support increased oxygen demands during stress. ---

Q21: Acidophils of the anterior pituitary includes

  1. A. Somatotrophs and Lactotrophs
  2. B. Lactotrophs and gonadotrophs
  3. C. Corticotrophs and thyrotrophs
  4. D. Somatotrophs and thyrotrophs

Correct answer: A – Somatotrophs and Lactotrophs

Acidophils are cells that stain with acidic dyes and include somatotrophs (GH-producing) and lactotrophs (prolactin-producing) cells. ---

Q22: A polypeptide that is secreted from the posterior pituitary in response to suckling

  1. A. binds a receptor protein that is in the nucleus
  2. B. probably has the longest half-life amongst all known hormones
  3. C. is made and released primarily by a neuron
  4. D. is transported to the hypothalamus via the hypothalamic-pituitary portal vessel
  5. E. is made through enzymatic reactions

Correct answer: C – is made and released primarily by a neuron

Oxytocin is the hormone released during suckling. It is synthesized by hypothalamic neurons and released from their axon terminals in the posterior pituitary. ---

Q23: Which of the following are found in the hypothalamic-pituitary portal vessel?

  1. A. Thyroid-stimulating hormone and antidiuretic hormone
  2. B. Thyroid-stimulating hormone and ACTH
  3. C. Dopamine and Corticotrophin-releasing hormone
  4. D. Growth hormone and thyrotropin-releasing hormone

Correct answer: C – Dopamine and Corticotrophin-releasing hormone

The portal vessel carries hypothalamic releasing/inhibiting hormones to the anterior pituitary. Dopamine (PIH) and CRH are both hypothalamic hormones. ---

Q24: During the second day of fasting, which of the following can be used for energy production by non-CNS cells, except

  1. A. ketones
  2. B. FFA
  3. C. glucose
  4. D. amino acids

Correct answer: C – glucose

During prolonged fasting, glucose is spared for the CNS. Non-CNS cells primarily use fatty acids and ketones for energy, preserving glucose for brain metabolism. ---

Q25: A patient with a fruity odor breath complains of constant thirst, constant hunger, and frequent urination. Which of the following would be likely associated with this patient EXCEPT

  1. A. obesity
  2. B. undetectable levels of plasma C-peptide
  3. C. ketoacidosis
  4. D. dehydration

Correct answer: A – obesity

These symptoms suggest Type 1 diabetes with ketoacidosis. Type 1 diabetics are typically not obese, unlike Type 2 diabetics who often are overweight. ---

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