MDS PREP
What is the primary function of the theophylline?
1) It acts as a muscle relaxant
2) It increases intracellular cAMP levels
3) It inhibits acetylcholine receptors
4) It stimulates the release of insulin
Theophylline is a methylxanthine derivative that acts as a phosphodiesterase inhibitor, leading to increased intracellular cyclic AMP (cAMP) levels. This can stimulate various cellular processes, including smooth muscle relaxation and bronchodilation in the respiratory system. It also enhances insulin secretion.
Which of the following statements about glomerular filtrate is true?
1) It contains high levels of proteins.
2) It is isotonic to plasma.
3) It is essentially protein-free.
4) It has a higher concentration of glucose than plasma.
Glomerular filtrate is essentially protein-free, allowing for the passage of water, electrolytes, and small molecules while retaining larger proteins in the bloodstream.
What is the primary function of the pharyngeal stage of deglutition?
1) Voluntary contraction of the pharyngeal muscles to move food into the esophagus
2) Relaxation of the upper esophageal sphincter
3) Closure of the epiglottis to prevent aspiration of food into the trachea
4) Involuntary contraction of the pharyngeal muscles to propel the food bolus into the esophagus
E) Stimulation of salivary glands to secrete saliva
The pharyngeal stage of deglutition involves involuntary contraction of the pharyngeal muscles and is responsible for the rapid passage of the food bolus from the oral cavity to the upper esophagus. It is primarily a reflex act triggered by the voluntary movement of food into the back of the mouth.
What is the role of ghrelin in the control of food intake?
1) It stimulates the release of growth hormone
2) It suppresses the secretion of gastric acid
3) It inhibits food intake
4) It increases the sensation of hunger
Ghrelin increases the sensation of hunger, stimulating appetite and food intake, particularly before meals.
What hormone is secreted by the kidneys that stimulates red blood cell production?
1) Renin
2) Erythropoietin
3) Aldosterone
4) Cortisol
Erythropoietin is the hormone secreted by the kidneys that stimulates red blood cell production in response to low oxygen levels in the blood.
What happens when the estrogen level crosses a certain threshold during the menstrual cycle?
1) It inhibits the release of LH and FSH
2) It stimulates the release of LH and FSH
3) It has no effect on pituitary hormone secretion
4) It triggers ovulation
Physiology
Answer: 4
Around day 11 of the menstrual cycle, the rising estrogen level reaches a threshold that has a positive feedback effect on LH secretion, leading to the LH surge. This LH surge is essential for ovulation to occur.
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 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.