MDS PREP
Which sleep stage is associated with the lowest body temperature, decreased heart rate, and decreased muscle tone?
1) Stage 1 NREM
2) Stage 2 NREM
3) Stage 3 NREM
4) REM sleep
Stage 3 NREM, also known as slow-wave sleep, is characterized by delta waves on EEG and is associated with the lowest body temperature, decreased heart rate, and decreased muscle tone, indicating a deep restorative sleep state.
Which type of autonomic nerve fibers are primarily involved in the pupillary light reflex?
1) Muscarinic
2) Adrenergic
3) Nicotinic
4) GABAergic
The pupillary light reflex is mediated by the parasympathetic nervous system, which uses acetylcholine as its neurotransmitter and acts on muscarinic receptors. The contraction of the sphincter pupillae muscle, which is innervated by the parasympathetic system, results in pupil constriction (miosis) in response to light.
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 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.
What is the primary function of the macula densa?
1) Filtration of blood
2) Regulation of glomerular filtration rate
3) Secretion of renin
4) Reabsorption of glucose
The primary function of the macula densa is to regulate glomerular filtration rate by sensing sodium chloride concentration in the tubular fluid.
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).
All of the following promote activation of muscle contraction EXCEPT
1. Binding of myosin to actin.
2. Opening of the sarcoplasmic reticulum Ca channel.
3. Ca2+ binding to troponin C.
4. Opening of Na channels.
Physiology
Answer: 1
Activation of muscle contraction is promoted by :
Opening of the sarcoplasmic reticulum Ca channel.
Ca2+ binding to troponin C.
Opening of Na channels
Ca2+ binding to the Ca2+-ATPase
What is the primary neurotransmitter released by the parasympathetic nervous system?
1) Norepinephrine
2) Acetylcholine
3) Serotonin
4) Dopamine
The parasympathetic nervous system primarily uses acetylcholine as its neurotransmitter, which acts on muscarinic receptors to produce its characteristic effects on various organs.