MDS PREP
What happens when the estrogen level crosses a certain threshold during the menstrual cycle?
1) It inhibits the release of LH and FSH
2) It stimulates the release of LH and FSH
3) It has no effect on pituitary hormone secretion
4) It triggers ovulation
When estrogen levels cross a certain threshold during the menstrual cycle, it triggers ovulation by stimulating the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH).
What is the primary function of the descending limb of the Loop of Henle?
1) Reabsorption of sodium and chloride
2) Reabsorption of water
3) Secretion of potassium
4) Active transport of glucose
The primary function of the descending limb of the Loop of Henle is the reabsorption of water, which concentrates the tubular fluid as it descends.
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.
The regulation of sodium reabsorption in the kidney tubules involves which of the following?
1) Tubulo-glomerular feedback
2) Glomerulo-tubular feedback
3) Both A and B
4) Neither A nor B
Tubulo-glomerular feedback (TGF) and glomerulo-tubular feedback (GTF) are both important in regulating sodium reabsorption in the kidney tubules. TGF involves the macula densa sensing the sodium chloride concentration in the tubular fluid and adjusting the glomerular filtration rate accordingly, while GTF is the adjustment of tubular sodium reabsorption in response to changes in glomerular filtration rate.
What is the primary site of bilirubin deposition in tissues during jaundice?
1) The liver
2) The spleen
3) The skin and sclera
4) The pancreas
The primary site of bilirubin deposition in tissues during jaundice is the skin and sclera, leading to yellowing.
Which hormone is primarily responsible for the conversion of 7-dehydrocholesterol to cholecalciferol in the skin?
1) Parathyroid hormone (PTH)
2) Vitamin D
3) Ultraviolet B (UV2) light
4) 25-hydroxyvitamin D3
Ultraviolet B (UVB) light is primarily responsible for the conversion of 7-dehydrocholesterol to cholecalciferol (vitamin D3) in the skin.
What is the primary mechanism of bicarbonate reabsorption in the proximal convoluted tubule?
1) Passive diffusion
2) Active transport
3) Combination with hydrogen ions
4) Co-transport with sodium
The primary mechanism of bicarbonate reabsorption in the proximal convoluted tubule involves combination with hydrogen ions, forming carbonic acid, which is then converted to water and carbon dioxide.
What is the typical osmolality of intestinal chyme?
1) Isotonic with blood (~300 mOsm/L)
2) Hypotonic (<300 mOsm/L)
3) Hypertonic (>300 mOsm/L)
4) Varies greatly depending on the composition of ingested food
E) Is not relevant for nutrient absorption
The osmolality of intestinal chyme can vary widely depending on the type and quantity of food consumed. It can range from isotonic to hypertonic or hypotonic relative to blood. The intestinal mucosa plays a critical role in adjusting water and ion transport to maintain the osmolality of the blood and facilitate the absorption of nutrients.