MDS PREP
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).
What is the effect of increased parathyroid hormone during pregnancy?
1) Decreased calcium ion liberation from maternal bones
2) Increased calcium ion absorption in the gut
3) Increased calcium ion excretion in the urine
4) Increased calcium ion mobilization from maternal bones for fetal use
Answer: 4) Increased parathyroid hormone during pregnancy stimulates liberation of calcium ions from maternal bones for the fetus's calcium needs.
What is the primary mechanism responsible for the reclamation of bile acids in the enterohepatic circulation?
1) Active transport in the ileum
2) Facilitated diffusion in the colon
3) Passive diffusion in the small intestine
4) Bacterial synthesis in the liver
Physiology
Answer: 1
Bile acids are actively reabsorbed in the ileum, primarily by the sodium-dependent bile acid transporter (ASBT), and returned to the liver.
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.
Which of the following substances does NOT directly depolarize taste cells during the sensation of bitter taste?
1) Increased intracellular calcium (Ca+) concentration
2) Activation of amiloride-sensitive Na+ channels
3) Closure of K+ channels
4) Release of neuronal glutamic acid
Bitter taste is mediated by the activation of bitter receptors, which are G protein-coupled and result in an increase in intracellular Ca+2 and subsequent neurotransmitter release, not by the activation of sodium channels as seen in salty taste transduction.
What is the primary site of vitamin B12 absorption in the intestine?
1) Stomach
2) Duodenum
3) Jejunum
4) Ileum
Physiology
Answer: 4
The ileum is the primary site of vitamin B12 absorption, facilitated by intrinsic factor binding to specific receptors.
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.
What is the main function of the cephalic phase of gastric secretion?
1) To secrete digestive enzymes
2) To increase gastric motility
3) To increase gastric acidity
4) To initiate the secretion of gastrin
E) To prepare the stomach for food intake
The cephalic phase of gastric secretion is initiated by the sight, smell, thought, or taste of food and prepares the stomach for the arrival of food by increasing gastric secretion, gastric motility, and salivation. It does not directly increase gastric acidity but does contribute to the overall digestive process.