MDS PREP
What is the significance of the intestinal phase of gastric acid secretion?
1) It is responsible for the majority of acid secretion
2) It is primarily responsible for the inhibition of acid secretion
3) It is only triggered by the thought of food
4) It is not a significant phase of gastric acid secretion
Physiology
Answer: 2
The intestinal phase plays a minor role in stimulating gastric secretion. However, it is crucial for inhibiting gastric secretion and motility once food enters the duodenum. Factors such as acidity, fatty acids, and osmolality of the duodenal contents trigger the release of hormones like secretin and cholecystokinin, which in turn inhibit gastric acid secretion.
Which of the following is NOT a primary bile acid synthesized in the liver from cholesterol?
1) Cholic acid
2) Chenodeoxycholic acid
3) Deoxycholic acid
4) Lithocholic acid
Physiology
Answer: 3
Deoxycholic acid is a secondary bile acid formed by bacterial conversion of cholic acid in the colon.
What is the function of the reticular formation in the regulation of sleep and wakefulness?
1) It initiates sleep
2) It maintains wakefulness
3) It is not involved in sleep-wake regulation
4) It initiates REM sleep
The reticular formation plays a crucial role in maintaining wakefulness by sending activating signals to the thalamus and cortex.
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 role of ghrelin in the control of food intake?
1) It stimulates the release of growth hormone
2) It suppresses the secretion of gastric acid
3) It inhibits food intake
4) It increases the sensation of hunger
Ghrelin increases the sensation of hunger, stimulating appetite and food intake, particularly before meals.
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 effect of oxytocin on the myoepithelial cells of the mammary gland?
1) Contraction to facilitate milk ejection
2) Relaxation to facilitate milk secretion
3) Increase in cellular metabolism
4) Growth and proliferation of myoepithelial cells
E. Inhibition of milk secretion
Oxytocin causes contraction of the myoepithelial cells surrounding the mammary alveoli, which presses milk into the larger ducts and leads to the milk let-down reflex. This is essential for milk ejection during lactation.
How does the skin color change in light-skinned patients with high serum bilirubin levels?
1) The skin turns yellow.
2) The skin turns green.
3) The skin turns blue.
4) The skin turns red.
In light-skinned patients with high serum bilirubin levels, the skin turns yellow due to the deposition of bilirubin.