MDS PREP
Which of the following is the correct sequence of enzyme activation in the pancreatic juice?
1) Trypsinogen -> Chymotrypsinogen -> Procarboxypeptidase A -> Proelastase
2) Enterokinase -> Trypsinogen -> Trypsin -> Chymotrypsinogen -> Chymotrypsin
3) Procarboxypeptidase B -> Chymotrypsinogen -> Trypsin -> Procarboxypeptidase A
4) Proelastase -> Chymotrypsinogen -> Chymotrypsin -> Trypsinogen
E) Trypsin -> Chymotrypsinogen -> Chymotrypsin -> Procarboxypeptidase A
The activation of pancreatic enzymes involves a cascade. Enterokinase, an enzyme present in the brush border of the small intestinal epithelial cells, first cleaves trypsinogen into active trypsin. Trypsin then cleaves chymotrypsinogen into chymotrypsin. This process continues with chymotrypsin activating proelastase and procarboxypeptidase A and B into their respective active forms, which are essential for the complete breakdown of proteins in the small intestine.
Which part of the autonomic nervous system is responsible for the regulation of the visceral organs during rest and digestion?
1) Sympathetic nervous system
2) Parasympathetic nervous system
3) Enteric nervous system
4) Sensory nervous system
The parasympathetic nervous system is involved in the regulation of the body's rest and digest functions. It operates to conserve energy and restore the body to a state of equilibrium. It acts on various visceral organs, such as the heart, gastrointestinal tract, and bladder, to slow down the heart rate, increase glandular secretions, and promote peristalsis for food assimilation.
What is the primary function of the Adrenal Medulla in the fight-or-flight response?
1) Secretion of cortisol
2) Secretion of epinephrine and norepinephrine
3) Secretion of aldosterone
4) Secretion of thyroxine
Answer: 2) Secretion of epinephrine and norepinephrineExplanation: The Adrenal Medulla is part of the sympathetic nervous system and produces the hormones epinephrine (adrenaline) and norepinephrine (noradrenaline) in response to stress or danger. These hormones are crucial for the fight-or-flight response, which prepares the body for immediate action by increasing heart rate, blood pressure, and diverting blood flow to the muscles and brain.
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 role of the sodium-calcium exchanger (NCX) in calcium homeostasis?
1) It transports calcium into cells
2) It transports sodium into cells and calcium out of cells
3) It transports sodium out of cells and calcium into cells
4) It has no role in calcium homeostasis
The sodium-calcium exchanger (NCX) transports sodium into cells and calcium out of cells, playing a crucial role in calcium homeostasis.
Which of the following is NOT a direct component of the corticospinal tract's termination?
1) Alpha-motor neurons (anterior or ventral horn cells)
2) Interneurons in the intermediate gray matter
3) Delta-motor neurons in the ventral horn
4) Gamma-motor neurons in the ventral horn
The corticospinal tract primarily terminates on alpha-motor neurons and interneurons, not directly on delta-motor neurons, which are involved in the control of muscle spindles and not in direct motor control.
Which of the following statements is true about the regulation of the sympathetic nervous system?
1) The sympathetic nervous system is primarily regulated by the parasympathetic nervous system.
2) The sympathetic nervous system is mainly controlled by the hypothalamus.
3) The sympathetic nervous system is regulated by the spinal cord through the sympathetic chain ganglia.
4) The sympathetic nervous system is primarily regulated by the sympathetic chain ganglia.
Answer: 3) The sympathetic nervous system is regulated by the spinal cord through the sympathetic chain ganglia, which receive input from the hypothalamus and other higher centers.
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.