MDS PREP
Which of the following is NOT a clinical consequence of defective bile acid absorption?
1) Fat malabsorption
2) Steatorrhea
3) Hemolytic anemia
4) Vitamin K deficiency
Hemolytic anemia is NOT a clinical consequence of defective bile acid absorption; rather, it is associated with the destruction of red blood cells, while fat malabsorption, steatorrhea, and vitamin K deficiency can occur due to bile salt deficiency.
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
Calbindin binds calcium and prevents it from affecting epithelial signaling, facilitating calcium absorption in the intestine.
What is the primary function of the reticular activating system during wakefulness?
1) It initiates REM sleep
2) It suppresses sensory input
3) It filters and modulates sensory information
4) It maintains the overall level of arousal and alertness
The reticular activating system (RAS) is involved in the regulation of wakefulness and arousal by modulating the transmission of sensory information to the thalamus and cortex and by influencing the release of neurotransmitters that promote alertness.
In which part of the nephron does the reabsorption of glucose and amino acids primarily occur?
1) Proximal Convoluted Tubule (PCT)
2) Loop of Henle
3) Distal Convoluted Tubule (DCT)
4) Collecting Duct
The reabsorption of glucose and amino acids primarily occurs in the Proximal Convoluted Tubule (PCT), where these nutrients are actively transported back into the bloodstream.
What is the function of cholecystokinin (CCK) in the digestive system?
1) Stimulates the release of bile from the liver
2) Increases the secretion of water in the collecting tubules of the kidney
3) Relaxes the lower esophageal sphincter
4) Decreases the motility of the small intestine
Cholecystokinin (CCK) stimulates the release of bile from the liver and pancreatic enzymes, aiding in digestion.
The reticular formation gives rise to which of the following extrapyramidal tracts?
1) Corticospinal tract
2) Reticulospinal tract
3) Vestibulospinal tract
4) Rubrospinal tract
E. Tectospinal tract
The reticulospinal tract arises from neurons in the reticular formation of the brainstem and projects to the spinal cord. It influences both voluntary and involuntary motor activities, modulating the excitability of motor neurons. The corticospinal tract arises from the cerebral cortex, the vestibulospinal tract from the vestibular nuclei, the rubrospinal tract from the red nucleus, and the tectospinal tract from the superior colliculus.
Which cranial nerve is NOT involved in the parasympathetic control of the eye?
1) Oculomotor nerve (CN III)
2) Facial nerve (CN VII)
3) Trigeminal nerve (CN V)
4) Vagus nerve (CN X)
The vagus nerve is involved in the parasympathetic control of various visceral organs, but not the eye. The oculomotor nerve (CN III) innervates the pupillary sphincter and ciliary muscle for pupil constriction and accommodation, which are parasympathetic functions.
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.