GI Flashcards
Regulating gastric acid secretion: What stimuli are involved in the intestinal phase?
Low pH in duodenal lumen, duodenal distension, presence of amino acids and fatty acids in the duodenum.
What cells secrete histamine?
Enterochromaffin like cells.
What are the consequences of vitamin A deficiency?
Night blindness, growth retardation, increased susceptibility to infection.
Name 2 ions that striated ducts reabsorb.
Na+ and Cl-
What enzyme is needed for fat digestion?
Pancreatic lipase.
What is the function of micelles?
They are lipid transport systems. They move to the epithelial brush border and release the fatty acids and monoglycerides for absorption.
What is the anterior layer of rectus sheath formed from?
External oblique aponeurosis and the anterior lamina of the internal oblique aponeurosis.
Is stage 3 of swallowing voluntary or involuntary?
Involuntary.
How do amino acids get absorbed into the blood?
Passive diffusion.
What is the mechanism for Cl- and HCO3- reabsorption?
Cl- is actively reabsorbed in exchage for HCO3-. The intestinal contents therefore become more alkaline.
Define malnutrition.
A lack of nutrition due to not eating enough, being unable to absorb nutrients, eating the wrong things.
Is vitamin A fat or water soluble?
Fat soluble.
What is the function of the muscles of the soft palate in swallowing?
They act to tense and elevate the soft palate.
If water input is 9L, how much is reabsorbed and how much is excreted in the faeces?
8.8L is reabsorbed and 0.2L is excreted in the faeces.
What molecule is produced that aids absorption?
Micelles.
How many pharyngeal arches are there?
5 (4 pharyngeal clefts and pouches).
Name the 4 main defence mechanisms against gastric acid secretion.
- Alkaline mucous.
- Tight junctions between epithelial cells.
- Replacing damaged cells.
- Feedback loops.
What is the recommended daily intake of vitamin A for men and women?
Women - 600µg. Men - 700µg.
What is the function of the muscles of the floor of the mouth in swallowing?
They raise the hyoid bone and larynx.
What are the end products of starch digestion?
Maltose!
Also maltotriose, glucose polymers and alpha-dextrins.
What happens in stage 2 of swallowing?
The nasopharynx closes off due to soft palate elevation. The trachea is closed off by the epiglottis. Elevation of the hyoid bone shortens and widens the pharynx.
How does Na+ move across the small intestine?
Na+ is actively transported from the lumen by pumps located in the cell membranes in the ileum and jejunum.
At what vertebral level is the intertubercular plane?
L4.
Where are the stem cells that replace the epithelium located?
The base of crypts.