31. Histamine a) Release is reduced by increased gastrin levels b) Stimulates se
ID: 3483200 • Letter: 3
Question
31. Histamine
a) Release is reduced by increased gastrin levels
b) Stimulates secretion of H+ into the stomach
c) Decreases the release of pepsinogen
d) Stimulates contraction of the gallbladder
32. Chylomicrons?
a) Enter the lymphatic system through lacteals in the GI tract
b) First enter the circulation through capillary beds in the GI tract
c) Are acted on by skeletal muscles lipoprotein lipase (LPL) to yield fatty acids
d)` a and c are correct
33. Which one of the following statements is true?
a) Gastric inhibitory peptide (GIP) is decresed when glucose is present in the small intestine
b) Secretin stimulates release of bicarbonate by the liver
c) Cholecystokinin (CCK) stimulates gastric motility and secretion.
d) Motilin stimulates the Migration motor pattern
34. Which one of the following statements is correct?
a) To be effective enterokinase must be converted from an inactive to an active form.
b) The pancreas secretes acid to neutralize chyme that enters the small intestine.
c) Mucous cells secrete mucous and bicarbonate to prevent HCL from
damaging the stomach
d) The primary exocrine function of the pancreas is to secrete gastrin
35. Which of the following statements is correct?
a) Activation of parasympathetic nerves increases the frequency and strength of of contraction of smooth muscle in the small intestine
b) Gastrin increase motility of the stomach and decreases motility of the small intestine
c) Nitric oxide (NO) causes contraction of contraction of smooth muscle in the small intestine
d) None of the above is correct
Explanation / Answer
Ans 31: b.
Histamine activates the parietal cells to release HCl. HCl is secreted by active transport into the stomach. Hydrochloric acid (HCl) forms in the lumen of the stomach by the union of H+ and Cl. H+ brought into lumen of the stomach by the potassium exchanger which brings H+ from parietal cell to lumen of the stomach (active transport). Cl- that was brought into parietal cell by the chloride shift, is passed out of the apical surface of the cell by passive transport (facilitated diffusion with help of a membrane protein).
Ans 32: d
Clusters of triglycerides that are coated with proteins inside epithelial cells of small intestine they are the water-soluble droplets and allows triglycerides to be released from cell by exocytosis as secretory vesicles. Enter permeable lacteals (enter lymph) to be transported to circulatory system. They are too large to enter capillaries directly. Lacteals are more permeable and they then travel in lymph vessels until lymph is returned to the venous blood vessels near the heart.
Ans 33: b
Secretin stimulates the pancreas to secrete bicarbonate-rich pancreatic juice into the duodenum. As acidic-rich chyme is released from the stomach into the duodenum, it causes cells in the wall of the duodenum to release the hormone secretin into the blood. When it reaches the pancreas, secretin then stimulates the pancreas to release bicarbonate-rich juice into the duodenum. This bicarbonates-rich juice neutralizes the acidic-chyme mixture. The higher pH leads to a reduction in the release of secretin. Only small amounts of acidic-rich chyme are released from the stomach at one time. So the release of secretin is adjusted frequently until all chyme for one meal is released from the stomach into the small intestines and neutralized. Neutral pH allows digestive enzymes to be active.
Ans 34: c
In the stomach several mucosal defence mechanisms protect the stomach against hydrochloric acid and other agents. The pre-epithelial protection is made up by the mucus bicarbonate barrier. Mucus and bicarbonate are secreted by mucus cells which creates a pH gradient maintaining the epithelial cell surface at near neutral pH.
Ans 35: c
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