Physio Questions Flashcards
Differentiate the action of the CCK1 and 2 receptors?
• what hormone works on these receptors?
• what determines which one it favors?
CCK1 receptor:
• Contracts the gallbladder
• Acted on ONLY by CCK that has been SULFATED at the 7th position
CCK2 receptor:
• Releases gastrin
• Receptors for NON-sulfated CCK and acts to stimulated parietal cells
T or F: GI hormones must pass through the liver AND the heart before reaching there target
True, they are released on the basolateral side and must travel through the portal vein and into systemic circulation before it gets to the arterial supply for the given cells
T or F: patients with ZE often present with a gastric ulcer?
False
Which Neurotransmitter(s) is/are released from sympathetic neurons?
NE
Which Neurotransmitter(s) is/are released from parasympathetic neurons?
Ach
Which Neurotransmitter(s) is/are released from enteric neurons?
Ach
VIP
NO
GRP
What structure do afferent signals get integrated at to create efferent peristalsis in the esophagus?
Nucleus Ambiguus of the Vagus
note the secondary peristaltic wave is not affected significantly
What happens to pressure in different parts of the esophagus as we breath?
Above Diaphragm:
• Pressure drops in the esophagus with inhalation and increases with exhalation
Below Diaphragm:
• the opposite would likely be true
What nerve and/or mediators are responsible for receptive relaxation of the stomach?
Vagus N is responsible for receptive relaxation
What does increased fat content in a meal do to the segmental contractions in the small intestine?
Increased Fat increases the NUMBER of duodenal SEGMENTING contractions
This is because fat stimulates CCK release which mediates the effect
Does amplitude or frequency of slow waves change during MMCs in the stomach?
Amplitude INCREASES in the atrum, frequency is unchanged
What type of response is receptive relaxation?
• what is the mediator?
Receptive relaxation is a VASOVAGAL response
• VIP is the mediator
**Note: cutting the vagus just above the diaphragm would ruin this response
What is the effect of CCK on gastric emptying ?
• what stimulates its release?
• what else does it do?
CCK slows down gastric emptying and increases gallbladder contraction to increase fat absorption
Fat in the duodenum stimulates its release
If a region of the intestine can contract at all then the slow waves are happening and the enteric NS is likely in tack. So what does it mean if there is only weak contractions in somewhere like the small intestine ?
Suggests that its likely a muscle disorder causing weakness
What type of contractions in the intestine occur at intervals allowed by slow waves, but have contractions occur seemly at random when monitored at 3 different loci?
This is indicative of segmental contractions
Remember that when the colon is distended the ileocecal valve contracts
Remember that when the colon is distended the ileocecal valve contracts
T or F: segemental contractions of the colon occur more often than do peristaltic contractions
True
T or F: all of the following cause relaxation of the ileocecal sphincter: •Eating a meal • Distention of the Ileum • Injection of Gastrin • Injection of CCK
True
How does the concentration of water in saliva change at high flow rate and low flow rate?
High Flow Rate:
• More Na+, Cl-, slightly less K+, and slightly more HCO3-
• This means at high flow rate the concentration of water is lower
What part of response to a meal would be completely prevented by vagotomy?
Cephalic
Why does the amount of H+ in gastric secretions increase with the rate of secretion according to the two component model of gastric acid secretion?
There is an increase in VOLUME of parietal cell secretions (NOT an increase in the concentration of H+ secreted by these cells)
What nutrients stimulate gastrin?
Peptides only
In a patient that is born without pepsin, how much would there digestion of protein be affected?
Protein digestion would only be affected minimally by the lack of pepsin
What is the only GASTRIC phase in which acetylcholine mediates the release of gastrin?
In the GASTRIC phase - via the vasovagal reflex
In the cephalic phase GRP stimulates the release of gastrin
T or F: vagal stimulation directly stimulates pancreatic enzyme release
True
Which phase of digestion is the pancreatic response most prominent?
The INTESTINAL phase
T or F: Pancreatic bicarbonate is secreted primarily in the gastric phase of digestion.
False, it occurs mostly in the intestinal phase and **IS SECRETED IN AMOUNTS APPROXIMATELY EQUAL TO GASTRIC ACID
Are pancreatic enzymes secreted in response to sham feeding?
Yes, but the DUCTAL CELLS ARE NOT so there is no major increase in HCO3 or the volume of pancreatic fluid
Does the osmolality of the bile change in the gallbladder?
• why or why not?
NO, only Na and Cl are absorbed and water follows so the solution stays at the same concentration overall, but there is an increase in the proportion of bile salts and of K+
What absorption of what sugar would not be affected by hypoxia in enterocytes?
Fructose, it is absorbed by GLUT5 in a passive mech
Where is enterokinase located?
Brush Border
What is the function of Co-lipase?
Prevents inactivation by bile salts
Why are most medium chain fatty acids not found in chylomicrons?
They are absorbed directly into the blood.
Note: Cholesterol does NOT act as a good emulsifying agent, Bile salts, fatty acids, lecithin, and dietary protein do
Note: Cholesterol does NOT act as a good emulsifying agent, Bile salts, fatty acids, lecithin, and dietary protein do
How is chloride absorbed in the distal ileum and colon?
Absorbed mostly through Cl- being exchanged for HCO3-
Remember Na and Cl are CO-transported in the small intestine
Remember Na and Cl are CO-transported in the small intestine
T or F: ouabain can inhibit Cl- secretion in the small intestine.
True, for the cAMP activated Cl- secretion channel to work, the NaK2Cl channel must be influxing ions, for this channel to work Na must be traveling down its concentration gradient
Somatostatin inhibits both gastrin secretion and parietal cell acid secretion when the antrum is acidified
Somatostatin inhibits both gastrin secretion and parietal cell acid secretion when the antrum is acidified
