MDS PREP
What is the primary function of bile acids in the intestine?
1) Emulsification of dietary fat
2) Neutralization of intestinal pH
3) Digestion of proteins
4) Absorption of water and electrolytes
Physiology
Answer: 1
Bile acids, through the formation of micelles, aid in the emulsification of fat, facilitating its digestion and absorption.
In the somatosensory area-I of the cerebral cortex, which of the following statements is true?
1) The body is represented in a distorted manner, with the face and hands having a disproportionately larger representation than the rest of the body.
2) The body is represented in a manner proportional to its size, with no distortion in the representation of different body parts.
3) The body is represented in a reversed order, with the feet at the top and the face at the bottom of the postcentral gyrus.
4) Each side of the cortex receives sensory information from the same side of the body.
Answer: 1) The body is represented in a distorted manner in the somatosensory area-I, with the face and hands having a disproportionately larger representation due to their higher innervation density.
What is the primary effect of epinephrine on the gastrointestinal tract during the fight-or-flight response?
1) Increases motility and secretions
2) Decreases motility and secretions
3) Relaxes the gastrointestinal muscles
4) Dilates blood vessels in the GI tract
Answer: 2) Decreases motility and secretionsExplanation: Epinephrine decreases gastrointestinal motility and secretions as part of the fight-or-flight response. This is because the body's priority shifts from digestion to the preparation for immediate action, diverting blood away from the GI tract and reducing its activity to focus on more critical bodily functions.
Which vitamin is the most important antioxidant in the body, acting in the lipid phase of membranes?
1) Vitamin C
2) Vitamin A
3) Vitamin E (tocopherol)
4) Vitamin B
Physiology
Answer: 3
Vitamin E is the most important antioxidant in the body, acting in the lipid phase of membranes and protecting against the effects of free radicals. It is crucial for maintaining the integrity and function of cellular organelles and the cell membrane by preventing the oxidation of unsaturated fats.
What is the primary effect of insulin on the skeletal muscles?
1) Stimulation of protein synthesis
2) Increased glycolysis
3) Increased glucose uptake and glycogen synthesis
4) Stimulation of muscle contraction
Answer: 3) Increased glucose uptake and glycogen synthesisExplanation: Insulin stimulates glucose uptake by muscle cells and promotes glycogen synthesis. It does so by increasing the number of glucose transporters on the muscle cell membrane and facilitating the transport of glucose into the cells.
What is the primary role of sleep spindles during sleep?
1 ) To facilitate memory consolidation
2) To maintain muscle tone
3) To regulate body temperature
4) To initiate REM sleep
Sleep spindles are associated with the transition from stage 1 to stage 2 NREM sleep and are thought to play a role in memory consolidation and the integration of new information.
What is the primary mechanism by which insulin stimulates glucose uptake in the liver?
1) Induction of glucokinase
2) Increase in glycolysis rate
3) Inhibition of gluconeogenesis
4) Stimulation of glycogenolysis
Answer: 1) Induction of glucokinaseExplanation: Insulin enhances glucose uptake in the liver by inducing the synthesis of glucokinase, an enzyme that converts glucose into glucose-6-phosphate. This "glucose trapping" mechanism keeps intracellular glucose levels low and promotes further glucose entry into the cell.
What is the threshold for phosphate excretion in the urine?
1) 0.10 mM
2) 0.50 mM
3) 1.00 mM
4) 2.00 mM
Physiology
Answer: 2
The threshold for phosphate excretion is when the plasma phosphate concentration reaches approximately 0.50 mM, causing some to be filtered into the urine.