MDS PREP
What is the primary neurotransmitter involved in the sympathetic nervous system's response at the neuromuscular junction?
1) Acetylcholine
2) Norepinephrine
3) Epinephrine
4) Dopamine
Answer: 2) The primary neurotransmitter involved in the sympathetic nervous system's response at the neuromuscular junction is norepinephrine, which acts on alpha and beta-adrenergic receptors.
What is the role of the corpus luteum in the second half of the menstrual cycle?
1) It secrets FSH
2) It secrets LH
3) It secrets estrogen and progesterone
4) It secrets inhibin
The corpus luteum secretes estrogen and progesterone during the second half of the menstrual cycle, which are essential for maintaining the uterine lining.
In the somatosensory area-I of the cerebral cortex, which of the following statements is true?
1) The body is represented in a distorted manner, with the face and hands having a disproportionately larger representation than the rest of the body.
2) The body is represented in a manner proportional to its size, with no distortion in the representation of different body parts.
3) The body is represented in a reversed order, with the feet at the top and the face at the bottom of the postcentral gyrus.
4) Each side of the cortex receives sensory information from the same side of the body.
Answer: 1) The body is represented in a distorted manner in the somatosensory area-I, with the face and hands having a disproportionately larger representation due to their higher innervation density.
What is the function of the hypothalamus in the regulation of spermatogenesis?
1) It produces gonadotropin-releasing hormone (GnRH) which stimulates the release of LH and FSH from the pituitary
2) It produces androgens such as testosterone
3) It directly controls the maturation of spermatids
4) It has no role in spermatogenesis
Physiology
Answer: 1
The hypothalamus produces GnRH, which stimulates the anterior pituitary to release follicle-stimulating hormone (FSH) and luteinizing hormone (LH). FSH is essential for the maturation of spermatogonia into primary spermatocytes, while LH acts on Leydig cells to produce testosterone, which is critical for the later stages of spermatogenesis and sperm maturation.
The release of which hormone is triggered by the macula densa cells during tubulo-glomerular feedback?
1) Renin
2) Angiotensin II
3) Atrial Natriuretic Peptide (ANP)
4) Aldosterone
The macula densa cells respond to decreases in sodium chloride concentration in the tubular fluid by releasing renin, which initiates the renin-angiotensin-aldosterone system (RAAS). This leads to increased sodium reabsorption and water retention, thereby restoring the sodium chloride balance and blood volume.
What is the role of leptin in the regulation of food intake?
1) It stimulates food intake
2) It inhibits food intake
3) It has no effect on food intake
4) It increases the absorption of nutrients in the intestine
Physiology
Answer: 2
Leptin is a hormone secreted by adipose tissue that acts on the hypothalamus to inhibit food intake and increase energy expenditure. It plays a key role in regulating body weight and metabolism by signaling satiety and modulating the sensation of hunger and fullness.
What is the primary action of endorphins on the body?
1) Inhibition of pain
2) Stimulation of growth
3) Regulation of mood and emotions
4) Increased blood pressure
E. Regulation of sleep-wake cycle
Endorphins, particularly ?-endorphin, are opioid peptides that act as natural painkillers. They are released during stress and pain and bind to opioid receptors in the brain and spinal cord to inhibit the transmission of pain signals. While they do have secondary effects on mood and stress response, their primary function is pain inhibition.
What is the mechanism by which glucose is reabsorbed in the proximal tubules of the kidney?
1) Passive diffusion
2) Facilitated diffusion
3) Active transport
4) Osmosis
Glucose is reabsorbed in the proximal tubules of the kidney primarily through active transport mechanisms, utilizing sodium-glucose transporters.