MDS PREP
What happens to the skin color in dark-skinned patients with high serum bilirubin levels?
1) It turns yellow.
2) It turns green.
3) It remains unaffected.
4) It turns blue.
In dark-skinned patients with high serum bilirubin levels, the skin turns yellow due to the accumulation of bilirubin.
Which of the following is the primary active transport mechanism for calcium absorption in the intestine?
1) Vitamin D dependent calcium binding protein (calbindin)
2) Sodium-calcium exchanger (NCX)
3) Calcium-dependent ATPase
4) All of the above
The primary active transport mechanism for calcium absorption in the intestine involves all of the above: vitamin D dependent calcium binding protein (calbindin), sodium-calcium exchanger (NCX), and calcium-dependent ATPase.
What is the primary mechanism by which acid secretion is regulated in the stomach?
1) By the pH of the stomach content
2) By the amount of food present
3) By the time of day
4) By the type of food consumed
Physiology
Answer: 1
The primary mechanism by which gastric acid secretion is regulated is through the feedback loop involving the pH of the stomach content. Low pH inhibits further acid secretion by decreasing the release of gastrin and the responsiveness of parietal cells to gastrin.
What is the transport maximum for phosphate reabsorption in the kidneys?
1) 0.10 mM/min
2) 0.50 mM/min
3) 1.00 mM/min
4) 2.00 mM/min
The transport maximum for phosphate reabsorption in the kidneys is approximately 0.50 mM/min, indicating the maximum amount that can be reabsorbed before excretion occurs.
What is the function of the middle piece in a sperm cell?
1) It produces the enzymes needed for sperm maturation
2) It contains the mitochondria for energy production
3) It is responsible for the sperm's ability to penetrate the egg
4) It is involved in the process of fertilization
The middle piece of a sperm cell contains mitochondria, which provide the energy needed for sperm motility and movement towards the egg.
What is the primary effect of thyroid hormones on the peripheral vascular resistance during the fight-or-flight response?
1) Increases peripheral vascular resistance
2) Decreases peripheral vascular resistance
3) No effect on peripheral vascular resistance
4) Variable effect on peripheral vascular resistance
Answer: 2) Decreases peripheral vascular resistanceExplanation: Thyroid hormones cause vasodilatation in several vascular beds, which decreases peripheral vascular resistance. This, along with increased cardiac output, leads to an overall increase in systolic blood pressure despite the diastolic BP possibly decreasing due to reduced resistance.
What is the threshold for glucose excretion in the urine in a healthy individual?
1) 100 mg/100 ml
2) 180 mg/100 ml
3) 200 mg/100 ml
4) 250 mg/100 ml
The threshold for glucose excretion in the urine in a healthy individual is approximately 180 mg/100 ml, above which glucose appears in the urine.
What is the primary function of chymotrypsin in the digestive process?
1) Converting chymotrypsinogen into chymotrypsin
2) Breaking down proteins into peptides
3) Catalyzing the hydrolysis of disulfide bonds in proteins
4) Activating pepsinogen into pepsin
E) Releasing gastrin from gastric mucosa
Chymotrypsin is an endopeptidase enzyme that plays a crucial role in the digestive system by breaking down proteins into smaller peptides. It is activated from its precursor chymotrypsinogen by the enzyme trypsin. Once active, chymotrypsin hydrolyzes the peptide bonds at the carboxyl side of aromatic and bulky amino acids, such as phenylalanine, tryptophan, and tyrosine. This process is essential for the further digestion and absorption of dietary proteins.