MDS PREP
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
Deoxycholic acid is NOT a primary bile acid synthesized in the liver from cholesterol; it is a secondary bile acid formed from the bacterial action on primary bile acids in the intestine.
What is the role of intrinsic factor in vitamin B12 absorption?
1) It protects vitamin B12 from gastric digestion
2) It facilitates binding of vitamin B12 to intestinal receptors
3) It synthesizes vitamin B12 in the gastrointestinal tract
4) It increases the production of gastric acid
Physiology
Answer: 2
Intrinsic factor binds to vitamin B12 and protects it from digestion, allowing it to be absorbed in the ileum.
Which of the following statements about the neuronal circuit of the cerebellum is true?
1) Climbing fibers originate from the cerebral cortex and terminate on purkinje cells.
2) Mossy fibers establish excitatory synapses with interneurons in the molecular layer.
3) Stellate and basket cells are stimulated by inhibitory inputs from purkinje cells.
4) Golgi cells are inhibited by mossy fiber inputs.
E. All of the above.
Mossy fibers originate from various sources in the brain and spinal cord and terminate on granule cells in the granular layer of the cerebellum. The axons of granule cells, called parallel fibers, stimulate the purkinje cells and also synapse with interneurons such as stellate and basket cells in the molecular layer and Golgi cells in the granular layer. Climbing fibers originate from the inferior olivary nuclei and synapse directly on purkinje cells. The statement that stellate and basket cells are stimulated by inhibitory inputs from purkinje cells is incorrect; they are stimulated by parallel fibers and inhibit purkinje cells. Golgi cells are also stimulated by mossy fibers and help in the regulation of the overall output of the cerebellum.
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 are the two major functions of GH?
1) Stimulation of growth hormone-dependent lipolysis and glycogenolysis
2) Stimulation of gluconeogenesis and growth of the skeletal system
3) Stimulation of cortisol synthesis and thyroid hormone release
4) Regulation of insulin secretion and cardiovascular function
Answer: 2) The two major functions of GH are the growth of the skeletal system and metabolic effects, including gluconeogenesis.
Which area of the brain is associated with the comprehension of speech?
1) Wernicke’s area
2) Broca’s area
3) Primary auditory cortex
4) Angular gyrus
E. Occipital lobe
Wernicke's area, located in the posterior part of the superior temporal gyrus, is involved in language comprehension. It receives input from the secondary somatic, auditory, and visual association areas and is critical for understanding spoken and written language.
What is the role of the corpus luteum in the second half of the menstrual cycle?
1) It secrets FSH
2) It secrets LH
3) It secrets estrogen and progesterone
4) It secrets inhibin
The corpus luteum secretes estrogen and progesterone during the second half of the menstrual cycle, which are essential for maintaining the uterine lining.
What is the role of calbindin in calcium absorption in the intestine?
1) It sequesters calcium in the intestinal lumen
2) It transports calcium across the brush border membrane
3) It binds calcium and prevents it from affecting epithelial signaling
4) It stimulates the release of calcium from the intestinal cells into the bloodstream
Physiology
Answer: 3
Calbindin sequesters calcium within the intestinal epithelial cells to prevent it from interfering with calcium-dependent signaling processes, thereby facilitating efficient calcium absorption without disrupting normal cellular function.