MDS PREP
What is the role of the acrosome in sperm penetration of the egg during fertilization?
1) It produces energy for the sperm's movement
2) It contains enzymes that help dissolve the egg's outer layers
3) It transfers genetic material to the egg
4) It has no role in the penetration process
Physiology
Answer: 2
The acrosome contains enzymes such as hyaluronidase and acrosin that are essential for breaking down the zona pellucida, the egg's outermost layer, allowing the sperm to penetrate and fertilize the egg.
What is the primary function of the somatic sensory area of the parietal lobe?
1) Auditory perception
2) Visual perception
3) Somatic sensation interpretation
4) Olfactory perception
The somatic sensory area of the parietal lobe, particularly Brodmann's areas 3, 1, and 2, is involved in the interpretation of tactile, proprioceptive, and other sensory information from the body.
What is the significance of the ponto-genital occipital spikes seen in REM sleep?
1) They indicate deep sleep
2) They indicate the onset of dreaming
3) They are associated with eye movement
4) They are markers of REM sleep
Ponto-genital occipital spikes, or PGO waves, are characteristic of REM sleep and are thought to be associated with the onset of dreaming, as they often coincide with rapid eye movement and increased brain activity during this phase.
MCQ: The macula densa is found in:
1) The proximal convoluted tubule
2) The loop of Henle
3) The distal convoluted tubule
4) The collecting duct
The macula densa is found in the distal convoluted tubule, where it senses sodium chloride concentration and helps regulate glomerular filtration rate.
What is the primary function of the neck in a sperm cell?
1) It connects the head and tail of the sperm
2) It produces the sperm's energy for movement
3) It is responsible for the fertilization process
4) It contains the cell's genetic material
Physiology
Answer: 1
The neck of the sperm cell is a small structure that connects the head, which contains the nucleus with the chromosomes, to the tail, which is responsible for the sperm's movement.
What is the role of carbonic anhydrase in the reabsorption of bicarbonate in the renal tubules?
1) It facilitates the formation of carbonic acid in the tubular lumen.
2) It catalyzes the conversion of carbon dioxide and water to carbonic acid in the tubular cells.
3) It enhances the secretion of hydrogen ions into the tubular lumen.
4) It accelerates the dissociation of carbonic acid into carbon dioxide and water in the tubular cells.
E) It is not involved in the reabsorption of bicarbonate.
Carbonic anhydrase is present in the tubular cells and accelerates the reaction of carbon dioxide and water to form carbonic acid, which then dissociates into bicarbonate and hydrogen ions. This facilitates the reabsorption of bicarbonate into the blood and maintains the acid-base balance.
Which of the following statements is true about the regulation of the sympathetic nervous system?
1) The sympathetic nervous system is primarily regulated by the parasympathetic nervous system.
2) The sympathetic nervous system is mainly controlled by the hypothalamus.
3) The sympathetic nervous system is regulated by the spinal cord through the sympathetic chain ganglia.
4) The sympathetic nervous system is primarily regulated by the sympathetic chain ganglia.
Answer: 3) The sympathetic nervous system is regulated by the spinal cord through the sympathetic chain ganglia, which receive input from the hypothalamus and other higher centers.
What is the primary effect of acetylcholine on the cardiac muscles?
1) Decreased heart rate
2) Increased heart rate
3) No effect on heart rate
4) Increased force of contraction
Answer: 1) Decreased heart rateExplanation: In the heart, acetylcholine acts on muscarinic receptors, which are present on the sinoatrial (SA) and atrioventricular (AV) nodes. This leads to a decrease in heart rate by slowing the sinoatrial (SA) node's automaticity and increasing the time it takes for an electrical impulse to pass through the AV node.