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What organs in GI is HCO3 secreted?
Salivary glands and pancreas
What are the products when H and HCO3 combine? What is the enzyme responsible?
H2O and C02. Carbonic Anhydrase.
What are the 4 salivary glands in a dog? Why do they produce a lot of saliva?
zygomatic gland, parotid gland, Mandrular gland, sublingual gland. Need to moisten the food because they dont chew their food very well.
What is the composition of saliva?
- buffer (HCO3, H2PO4)
- Na, Cl
What is the function of saliva?
- moisten food to facilitate chewing and swallowing
- neutralize fermentation acids (ruminants)
Who is saliva controlled?
- flow rate increased by cholinergic stimulation
- salivary center (medulla)
- reflex stimulation from mechanoreceptors in mouth and stomach
What does amylase do?
breaks down complex carbs into simple sugars (E.g Starch to glucose)
Describe the type of epithelial cells in the esophagus, stomach, small intestine, and large intestine?
- esophagus - squamous
- stomach - cubodial
- small intestine - columnar
- large intestine - cubodial. Have krypts not villi
What do the chief cells secrete?
pepsinogen which is eventually cleaved to pepsin that degrades proteins at low PH
What do the parietal cells secrete?
- intrinsic factors (that facilitate B12 absorption thru ilieum)
What stimulate gastrin, GIP, CCK, and secretin?
- Gastrin - peptides, AA
- GIP - glucose, AA, FA
- CCK - FA, AA
- secretin - Acid
What are the 2 sections of the pancreas? And what do these sections secrete?
- Exocrine - Proenzyme, Enzyme, Bicarbonate
- Endocrine - insulin, and glucagon
What do the acinar cells in the pancreas secretion?
Release of enzymes (lipase - fats, amylase - carbs, nuclease - DNA), and proenzyme (trypsiogen - proteins. Which is activated by enterokinase in SI which converts to trypsin the active form.
What do the ductular cells do in pancreatic secretion?
release bicarbonate ions.
What is the function of pancreas secretion?
- facilitate digestion
- neutralize digesta to avoid tissue damage
How do fat and AA control pancreatic secretion?
CCK influences acinar cells which release enzymes.
How does H plus control pancreatic secretion?
secretin acts on ductular cells which release bicarbonate ions
What is bile composed of?
- bile acids - synthesized from cholesterol, and conjugated with taurine and glycine
- water and electrolytes
What is the function of bile?
- facilitate digestion and absorption of fat and fat soluble vitamins
- provide excretory route for metabolites and drugs
- provide an additional buffer for neutralization
Where are bile salts stored and are they reabsorbed?
Stored in the gall bladder, are recycled via ilium 6-8 times a day.
How does entry of fat cause bile secretion?
fat causes CCK secretion, which stimulates relaxation of sphincter of oddi and contraction of the gall bladder.