MDS PREP
What is the primary neurotransmitter involved in the sympathetic nervous system's response at the neuromuscular junction?
1) Acetylcholine
2) Norepinephrine
3) Epinephrine
4) Dopamine
Answer: 2) The primary neurotransmitter involved in the sympathetic nervous system's response at the neuromuscular junction is norepinephrine, which acts on alpha and beta-adrenergic receptors.
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
The primary function of bile acids in the intestine is the emulsification of dietary fat, which aids in fat digestion and absorption.
What is the primary function of the pyloric sphincter?
1) To regulate the flow of chyme into the small intestine
2) To mix and churn food in the stomach
3) To secrete intrinsic factor for vitamin B12 absorption
4) To secrete mucus for the protection of the gastric mucosa
E) To produce hydrochloric acid
The pyloric sphincter, also known as the pylorus, is a ring of smooth muscle that connects the stomach to the duodenum. It relaxes to allow small, controlled amounts of chyme to pass from the stomach into the duodenum. This regulation is important to prevent the rapid emptying of the stomach and the potential overwhelming of the small intestine with food and acid.
The regulation of sodium reabsorption in the kidney tubules involves which of the following?
1) Tubulo-glomerular feedback
2) Glomerulo-tubular feedback
3) Both A and B
4) Neither A nor B
Tubulo-glomerular feedback (TGF) and glomerulo-tubular feedback (GTF) are both important in regulating sodium reabsorption in the kidney tubules. TGF involves the macula densa sensing the sodium chloride concentration in the tubular fluid and adjusting the glomerular filtration rate accordingly, while GTF is the adjustment of tubular sodium reabsorption in response to changes in glomerular filtration rate.
What is the mechanism by which glucose is reabsorbed in the proximal tubules of the kidney?
1) Passive diffusion
2) Facilitated diffusion
3) Active transport
4) Osmosis
Physiology
Answer: 3
Glucose is reabsorbed via active transport mechanisms that involve sodium-glucose co-transporters (SGLTs) and glucose transporters (GLUTs).
What is the primary mechanism of vibration detection in the musculoskeletal system?
1) Meissner's corpuscles
2) Pacinian corpuscles
3) Merkel's discs
4) Ruffini's endings
Pacinian corpuscles are rapidly adapting mechanoreceptors that are highly sensitive to high-frequency vibrations and are responsible for detecting rapid changes in pressure.
What is the primary role of estrogen during the follicular phase of the menstrual cycle?
1) Suppression of FSH secretion
2) Stimulation of follicular development
3) Preparation of the endometrium for implantation
4) Induction of the LH surge
During the follicular phase of the menstrual cycle, estrogen stimulates follicular development, promoting the maturation of ovarian follicles.
What happens when the corpus luteum regresses during the menstrual cycle?
1) It secrets more estrogen and progesterone
2) It stops secreting estrogen and progesterone
3) It starts secreting FSH and LH
4) It causes an increase in the thickness of the endometrium
When the corpus luteum regresses during the menstrual cycle, it stops secreting estrogen and progesterone, leading to the shedding of the uterine lining.