A & P 2 - Gi Tract Hormones

Front 1

What are the functions of all the cells in the Stomach?

Back 1

Chief cells:
-secrete pepsinogen which converts to pepsin and breaks down proteins into peptides
-secrete gastric lipase which splits triglycerides into FA and monoglycerides

Parietal Cells:
-secrete HCl which kill microbes, denature proteins, and convert pepsinogen to pepsin
-screte Intrinsic Factor which absorb B12

Surface Mucosal Cells and Neck cells:
-secrete mucus which forms a protective barrier that prevents digestion of stomach wall
-absorb small quantity of water, ions, and short chain FA

G cells:
-secrete gastrin to stimulate parietal cells to secrete HCl and cheif cells to secrete pepsinogen; contracts LES, increases motility in stomach, and relaxes pyloric sphincter

Muscularis:
-mixing waves to macerate food and mix it with gastric juice to form chyme
-peristalsis to force chyme through pyloric sphincter

Pyloric Sphincter:
-opens to permit chyme into duodenum and prevents backflow of chyme into duodenum

Front 2

What are the enzymes in the Saliva?

Back 2

salivary amylase:
-breaks starch into maltose, and alpha dextrins

lingual lipase:
-breaks triglycerides into FA and diglycerides

Front 3

What are the enzymes in the gastric juice?

Back 3

Pepsin:
-break proteins into peptides

Gastric lipase:
-break triglycerides into FA and monoglycerides

Front 4

What are the enzymes releases in the pancreas?

Back 4

all from Pancreatic acinar cells

Pancreatic amylase:
-breaks starches into maltose, and alpha dextrins

Trypsin:
-breaks proteins into peptides

Chymotrypsin:
-breaks proteins into peptides

Elastase:
-breaks proteins into peptides

Carboxypeptidase:
-breaks AA at carboxyl end

Pancreatic lipase:
-breaks triglycerides that have been emulsified by bile salts into FA and monoglycerides

Nucleases:
Ribonuclease and deoxyribnuclease

Front 5

What are the enzymes released in the Small intestine?

Back 5

released in the brush border

Alpha dextrinase:
-breaks alpha dextrins into glucose

lactase
maltase
sucrase

enterokinase:
-converts trypsinogen into trypsin

aminopeptidase:
-breaks off AA at amino end

Front 6

What are the major hormones that control digestion?

Back 6

Gastrin:
stimulated by:
-distension of stomach, partially digested proteins and caffeine in stomach
-high pH of stomach chyme stimulates gastrin secretion by G cells
-located mainly in pyloric antrum of stomach
Actions:
-promotes secretion of gastric juice; increases gastric motlity and promotes growth of gastric mucosa
-constricts LES, relaxes pyloric sphincter

Secretin:
responds to:
-acidic chyme that enters SI stimulates secretion of secretin by S cells in mucosa of duodenum
Actions:
-stimulates secretion of pancreatic juice and bile rich in HCO3
-inhibits secretion of gastric juice, promotes maintenance of pancreas, enhances effects of CCK

CCK:
responds to:
-partially digested proteins, triglycerides, and FA that enter SI
-released in mucosa of SI or in brain
actions:
-stimulate pancreatic juice rich in digestive enzymes, causes ejectino of bile from galbladder and opening of sphincter of Oddi
-induces satiety
-inhibits gastric emptying, enhances effect of secretin