Medical Physiology Paper I | MCQ Quiz | OmpathStudy Kenya

Question 1

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

Accepted Answer

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. ---

Question 2

Which of the following will not lead to a diuresis?

Accepted Answer

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). ---

Question 3

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

Accepted Answer

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. ---

Question 4

An increase in renin is caused by

Accepted Answer

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. ---

Question 5

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

Accepted Answer

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. ---

Question 6

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

Accepted Answer

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. ---

Question 7

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

Accepted Answer

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. ---

Question 8

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

Accepted Answer

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. ---

Question 9

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

Accepted Answer

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

Question 10

Which of the following is a cause of metabolic alkalosis?

Accepted Answer

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

Question 11

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

Accepted Answer

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. ---

Question 12

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

Accepted Answer

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. ---

Question 13

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

Accepted Answer

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. ---

Question 14

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

Accepted Answer

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. ---

Question 15

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

Accepted Answer

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. ---

Question 16

Which of these statements is INCORRECT?

Accepted Answer

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. ---

Question 17

Which of these statements is INCORRECT?

Accepted Answer

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. ---

Question 18

Thyroid Hormone

Accepted Answer

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. ---

Question 19

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

Accepted Answer

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. ---

Question 20

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

Accepted Answer

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

Question 21

Acidophils of the anterior pituitary includes

Accepted Answer

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

Question 22

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

Accepted Answer

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. ---

Question 23

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

Accepted Answer

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. ---

Question 24

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

Accepted Answer

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. ---

Question 25

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

Accepted Answer

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

Question 26

In males, testosterone (or DHT) stimulates all of the following except

Accepted Answer

Bone development in growth spurt — While testosterone contributes to bone growth, the primary driver of the pubertal growth spurt is growth hormone and IGF-1, not testosterone directly. ---

Question 27

Which of the following regarding thyroxine produced by the thyroid gland is correct?

Accepted Answer

Thyroxine has a longer half-life than T3 — T4 (thyroxine) has a half-life of about 7 days compared to T3's half-life of about 1 day. T4 serves as a prohormone for the more active T3. ---

Question 28

Which of the following is a characteristic of steroid hormones?

Accepted Answer

Their action largely involves the synthesis of mRNA encoding their target genes — Steroid hormones act through intracellular receptors that function as transcription factors, directly regulating gene expression and mRNA synthesis. ---

Question 29

Excessive secretion of growth hormone (GH) in pre-pubertal individuals likely causes

Accepted Answer

a and c — Excess GH in children causes gigantism (excessive linear growth) and hyperglycemia (due to GH's anti-insulin effects on glucose metabolism). ---

Question 30

The temperature & pain sense loss usually develops with disease in

Accepted Answer

posterior horns of spinal cord — The posterior horns contain neurons that process pain and temperature sensations. Damage here affects these sensory modalities. ---

Question 31

If you were studying mutant rabbits which seem unable to sense and move away from a harmful heat source, you would look for a gene coding for what kind of protein?

Accepted Answer

thermoreceptor — Thermoreceptors detect temperature changes. A defect in thermoreceptor proteins would prevent the animal from sensing harmful heat. ---

Question 32

A phenomenon in which sensations become less noticeable with prolonged exposure is called

Accepted Answer

sensory adaptation — Sensory adaptation is the decreased response to a constant stimulus over time, allowing the nervous system to focus on changes rather than constant stimuli. ---

Question 33

Sensory receptors in the skin have a different structure than sensory receptors in the eye. The most reasonable explanation for the difference in structure is that

Accepted Answer

receptors in the eye respond to a different type of input than receptors in the skin — Different sensory modalities require different receptor structures. Photoreceptors detect light waves, while skin receptors detect mechanical pressure, temperature, and chemicals. ---

Question 34

Which of these receptors detects both touch and heat?

Accepted Answer

free nerve endings — Free nerve endings are the most versatile sensory receptors, capable of detecting multiple stimuli including light touch, temperature, and pain. ---

Question 35

You would expect that your pupils would be smallest when you are

Accepted Answer

sitting on the beach on a very sunny day — Pupils constrict (miosis) in bright light to protect the retina and optimize vision. The brightest condition listed is the sunny beach. ---

Question 36

Vision and hearing are different

Accepted Answer

sensory modalities — Sensory modalities are the different types of sensations (vision, hearing, touch, etc.). Vision and hearing are distinct sensory modalities. ---

Question 37

The photoreceptors we need to appreciate a blue sky on a sunny day are the , whereas the photoreceptors we need to see the stars at night are the .

Accepted Answer

cones; rods — Cones function in bright light and detect color (including blue), while rods function in dim light and are responsible for night vision. ---

Question 38

Some of the many things that can cause an eardrum to rupture are an ear infection, SCUBA diving, and poking the ear with a sharp object. Which of the following might a ruptured eardrum cause?

Accepted Answer

Environmental bacteria will be more likely to get into the middle ear — A ruptured eardrum creates an opening between the external environment and the normally sterile middle ear, increasing infection risk. ---

Question 39

are collections of 50-150 cells and are located on the surface of your tongue, back of your mouth, and roof of your mouth.

Accepted Answer

Taste buds — Taste buds are the sensory organs containing 50-150 taste receptor cells, located on the tongue, soft palate, and other oral structures. ---

Question 40

An injury to the lateral portion of the postcentral gyrus in the right hemisphere would result in some loss of sensation in the?

Accepted Answer

left facial area — The lateral portion of the postcentral gyrus (primary somatosensory cortex) processes sensations from the face and upper body. Due to decussation, the right hemisphere processes left-sided sensations. ---

Question 41

What best describes medial lemniscus?

Accepted Answer

is a tract of nerve fibers that conveys sensory signals to the thalamus — The medial lemniscus is the ascending sensory pathway that carries fine touch, vibration, and proprioceptive information from the dorsal column nuclei to the ventral posterior lateral nucleus of the thalamus. ---

Question 42

Severing which part of the spinothalamic tract would result in pain impulses from the right side being blocked?

Accepted Answer

left lateral — Pain and temperature fibers cross in the spinal cord and ascend in the lateral spinothalamic tract. To block right-sided pain, you would need to sever the left lateral spinothalamic tract (due to decussation). ---

Question 43

A pen is placed in your left hand behind your back. Which of the following tracts would NOT be involved in your ability to state what is in your hand?

Accepted Answer

association

Question 44

Which of these events occur when a person steps on a tack with their right foot?

Accepted Answer

The flexor muscles of the thigh contract, and the extensor muscles relax because of reciprocal innervation

Question 45

Inhibitory interneurons are involved in the following reflexes?

Accepted Answer

Golgi tendon reflex — The Golgi tendon reflex uses inhibitory interneurons to relax the contracting muscle when excessive tension is detected, preventing muscle damage. This is the only reflex listed that requires inhibitory interneurons. ---

Medical Physiology Paper I | MCQ Quiz | OmpathStudy Kenya

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