MDS PREP
What is the primary function of the rubrospinal tract?
1) Control of distal muscle movement
2) Control of posture and balance
3) Control of autonomic functions
4) Control of respiration
The rubrospinal tract is a lateral pathway that originates in the red nucleus and is involved in the control of distal muscle movement, particularly in the control of fine motor movements of the limbs.
What is the primary function of the myenteric plexus in the gastrointestinal tract?
1) Control of gastrointestinal motility
2) Regulation of intestinal secretion
3) Blood flow regulation in the gut wall
4) Nutrient absorption from the intestinal lumen
E) Maintenance of the mucosal barrier function
The myenteric plexus, or Auerbach's plexus, is located between the longitudinal and circular muscle layers of the gut wall. Its primary function is to regulate the motility of the gastrointestinal tract. It does so by coordinating the contractions of the smooth muscles, which are responsible for peristalsis and the propulsion of food through the digestive system. The myenteric plexus works in conjunction with the submucosal plexus and can be influenced by both the sympathetic and parasympathetic nervous systems.
What is the significance of the transport maximum for substances like glucose and phosphate?
1) It indicates the maximum amount that can be filtered by the glomerulus
2) It represents the maximum amount that can be actively reabsorbed by the tubules
3) It is the point at which the substance begins to be excreted in the urine
4) It is the point at which the substance becomes toxic to the body
The transport maximum for substances like glucose and phosphate represents the maximum amount that can be actively reabsorbed by the tubules before reaching saturation and being excreted in urine.
The primary regulators of gastric emptying are:
1) Vagal reflexes
2) Intestinal hormones
3) Local neural reflexes
4) All of the above
Gastric emptying is regulated by a combination of vagal reflexes, intestinal hormones such as secretin and cholecystokinin, and local neural reflexes known as the enterogastric reflex. These mechanisms work in concert to modulate the rate of emptying based on the needs of the body.
What is the function of the enteric nervous system?
1) Controls the heart rate and rhythm
2) Regulates the contraction of skeletal muscles
3) Regulates the function of the gastrointestinal tract
4) Controls the pupillary response to light
The enteric nervous system is the intrinsic nervous system of the gastrointestinal tract and is responsible for the regulation of digestion and other gastrointestinal functions. It can operate independently of the central nervous system and consists of a network of neurons and glial cells that are embedded within the wall of the gut, coordinating local reflexes and influencing the muscle and secretory activities of the digestive system.
What are the main stimuli that increase the secretion of growth hormone (GH)?
1) High blood glucose levels and physical inactivity
2) Hypoglycemia, exercise, protein meals, and stress
3) REM sleep and increased IGF-1 levels
4) High cortisol and fatty acid levels
Answer: 2) Main stimuli that increase GH secretion include hypoglycemia, exercise, protein meals, and stress.
What is the main function of the sodium-potassium-chloride cotransporter in the thick ascending limb of the loop of Henle?
1) To reabsorb sodium and chloride
2) To reabsorb sodium and potassium
3) To reabsorb sodium and secrete hydrogen
4) To reabsorb sodium, potassium, and chloride
E) To reabsorb sodium and hydrogen carbonate
The sodium-potassium-2-chloride (Na+-K+-2Cl-) cotransporter in the thick ascending limb of the loop of Henle is responsible for reabsorbing sodium and chloride ions from the tubular fluid into the blood. This process helps in the maintenance of osmotic balance and the generation of the medullary interstitial gradient.
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
Physiology
Answer: 3
Deoxycholic acid is a secondary bile acid formed by bacterial conversion of cholic acid in the colon.