MDS PREP
What is the osmolarity of the tubular fluid leaving the early distal tubule?
1) Isotonic to plasma
2) Hypertonic
3) Hypotonic
4) Variable
The osmolarity of the tubular fluid leaving the early distal tubule is hypotonic, as it has lost solutes while retaining water.
What is the function of the macula densa in the regulation of the nephron's function?
1) It secretes ADH to regulate water reabsorption.
2) It monitors sodium chloride concentration in the tubular fluid.
3) It produces erythropoietin to stimulate RBC production.
4) It is involved in the conversion of vitamin D to its active form.
The macula densa monitors sodium chloride concentration in the tubular fluid, playing a crucial role in regulating kidney function.
What is the main function of the cephalic phase of gastric secretion?
1) To secrete digestive enzymes
2) To increase gastric motility
3) To increase gastric acidity
4) To initiate the secretion of gastrin
E) To prepare the stomach for food intake
The cephalic phase of gastric secretion is initiated by the sight, smell, thought, or taste of food and prepares the stomach for the arrival of food by increasing gastric secretion, gastric motility, and salivation. It does not directly increase gastric acidity but does contribute to the overall digestive process.
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.
Elevation of aldosterone, in blood results in
1 Low 'Na' and low 'K' in urine
2 High 'Na' and high 'K' in urine
3 High 'Na' and low 'K' in urine
4 Low 'Na' and high 'K' in urine
Physiology
Answer: 2
Elevation of aldosterone, in blood results in High 'Na' and high 'K' in urine resulting in acidic urine and body alkalosis
What is the primary mechanism of the fight-or-flight response mediated by cortisol?
1) Increases heart rate and blood pressure
2) Facilitates gluconeogenesis and lipolysis
3) Relaxes smooth muscles of the gastrointestinal tract
4) Increases the sensitivity of the heart to catecholamines
Answer: 2) Facilitates gluconeogenesis and lipolysisExplanation: Cortisol, a glucocorticoid hormone, plays a key role in the fight-or-flight response by mobilizing energy stores. It stimulates gluconeogenesis in the liver and promotes lipolysis in adipose tissue, increasing the availability of glucose and fatty acids for energy production during stressful situations.
What is the primary mechanism by which the stomach protects itself from self-digestion by its own enzymes?
1) Mucus secretion by gastric mucosal cells
2) Presence of intrinsic factor in the gastric juice
3) High concentration of bicarbonate in gastric juice
4) Low pH of gastric juice inhibiting its own enzymes
E) The mucosal lining is impermeable to H+ ions
The stomach protects itself from the harsh acidic environment and its own digestive enzymes through the secretion of a thick layer of mucus by mucosal cells. This mucus barrier forms a physical and chemical barrier that shields the underlying tissue from the acid and pepsin. Additionally, the stomach lining has a high turnover rate and is continuously regenerated, and the enzymes in the gastric juice are inactive until they come into contact with food.
What is the effect of epinephrine on the bronchial smooth muscles during the fight-or-flight response?
1) Constriction (bronchoconstriction)
2) Dilatation (bronchodilatation)
3) No effect
4) Spasm
Answer: 2) Dilatation (bronchodilatation)Explanation: Epinephrine acts on beta-2 adrenergic receptors in the bronchial smooth muscles, leading to their relaxation and dilatation of the bronchioles. This allows for increased airflow and oxygenation of the lungs, which is essential during the fight-or-flight response.