MDS PREP
Which of the following is NOT an action of bile salts?
1) Emulsification of fat
2) Facilitation of fat absorption
3) Neutralization of stomach acid
4) Conjugation of bile acids
Neutralization of stomach acid is NOT an action of bile salts; bile salts primarily emulsify fats and facilitate fat absorption.
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
Physiology
Answer: 1
The transport maximum for phosphate is 0.10 mM/min, indicating the maximum rate at which it can be reabsorbed by the renal tubules.
What is the role of gastrin in the gastric phase of acid secretion?
1) It is released by the pancreas and stimulates acid secretion in the stomach
2) It is released by the duodenum and inhibits acid secretion
3) It is released by the stomach and stimulates acid secretion in response to food
4) It has no role in gastric acid secretion
Gastrin is released by the stomach and stimulates acid secretion in response to food, playing a key role in the gastric phase of digestion.
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 happens when the corpus luteum regresses during the menstrual cycle?
1) It secrets more estrogen and progesterone
2) It stops secreting estrogen and progesterone
3) It starts secreting FSH and LH
4) It causes an increase in the thickness of the endometrium
Physiology
Answer: 2
The regression of the corpus luteum leads to a sharp decline in estrogen and progesterone levels, which in turn causes the endometrium to shed and results in menstrual bleeding.
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 significance of the latch effect in smooth muscle contraction?
1) It allows for rapid contraction and relaxation
2) It prevents the muscle from fully relaxing between contractions
3) It is responsible for the generation of the resting membrane potential
4) It is not relevant to the function of smooth muscles
Answer: 2) It prevents the muscle from fully relaxing between contractionsExplanation: The latch effect in smooth muscles refers to the ability of phosphorylated myosin heads to maintain their attachment to actin filaments even after calcium levels decrease, thus preventing full relaxation without further calcium influx. This sustained contraction with minimal energy expenditure is a characteristic feature of smooth muscles.
MCQ: The pancreas has which of the following cell types?
1) Alpha cells
2) Beta cells
3) Delta cells
4) All of the above
The pancreas has all of the following cell types: alpha cells (which produce glucagon), beta cells (which produce insulin), and delta cells (which produce somatostatin).