Secretions of the GI System Flashcards
Salivary secretions are regulated by cranial nerves ___ and ____
7 + 9
What are the three salivary glands?
Parotid + Submandibular + Sublingual
What initiates carb. digestion?
Alpha amylase
What initiates fat digestion?
Lingual lipase
What is found in saliva that acts as a major lubricant?
Mucous
What chelates iron and is needed for bacterial replication?
Lactoferrin
What does alpha amylase initiate?
Carb. digestion
What does lingual lipase initiate?
Fat digestion
What does lactoferrin do?
Chelates iron; iron is needed for bacterial replication
Which of following is not associated with salivary secretion? A. Salivatory nucleus B. Lingual lipase C. Vagus nerves D. Parotid gland
C. Vagus nerves
What secretes HCl?
Parietal cells
What does pepsin do?
Contributes to protein digestion
What is the function of HCl?
To denature dietary proteins + kill ingested microorganisms
What does gastric lipase do?
Contributes to fat digestion
What are intrinsic factors in gastric juice?
A glycoprotein necessary for Vit. B12 absorption
What kind of pump does the gastric acid secretion use?
Proton pump; pumps H+ from cytoplasm into stomach lumen for K+
How does Cl- get into parietal cells?
Via the Cl/HCO3 exchange
Parietal cells contain receptors for what that stimulate acid secretion?
- ACh
- Gastrin
- Histamine
There are several pathways to stimulate gastric acid secretion. What are they?
- Vagus nerve via ACh
- Endocrine stimulation for gastrin from G cells
- Paracrine stimulation from histamines
What happens to gastric acid secretion if the vagus nerve via ACh is stimulated?
Calcium increases
What happens to gastric acid secretion if gastrin is stimulated?
Endocrine stimulation, Calcium increases
What happens to gastric acid secretion if histamines are released?
Paracrine stimulation, increases cAMP
What does secretin do?
Stimulates production of bicarbonate
Where is secretin produced?
Duodenum
What cells produce secretin?
S cells
When gastric pH is low, H+ (promotes/inhibits) G cells
inhibits
When gastric pH is low, Somatostatin levels are (increased/decreased) and (promote/inhibit) G cells
increased + inhibit
When gastric pH is low, secretin is (produced/inhibited)
produced
Why is prostaglandin important?
Part of the secretion of mucus
Where is prostaglandin E2 produced?
Stomach
Prostaglandin E2 is an antagonist to what in the parietal cells?
Histamine
Prostaglandin E2 is an (agonist/antagonist) to histamine in the parietal cells?
antagonist
Prostaglandin E2 (promote/inhibit) production of cAMP
inhibit
Because NSAIDS inhibit prostaglandins , what do they do to gastric acid secretion?
Increases it
What can occur as a result of chronic use of NSAIDS?
Erosive gastritis
Mucus glands are (stimulated/inhibited) by sympathetic stimulation
inhibited
The enterocytes in the crypts do what?
Secrete large amounts of water/electrolytes
The enterocytes over the surfaces of the villi do what?
Reabsorb the water/electrolytes along the end products of digestion
The mucus glands are inhibited by (sympathetic/parasympathetic) stimulation
Sympathetic
The enterocytes that cover the villi, contain digestive enzymes that digest specific food substances while they are being absorbed through the epithelium and one of which is peptidase. What does it do?
Splits small peptides into AA
The enterocytes that cover the villi, contain digestive enzymes that digest specific food substances while they are being absorbed through the epithelium and some are sucrase, maltase, isomaltase, and lactase. What does it do?
Splits disaccharides into monosaccharides
The enterocytes that cover the villi, contain digestive enzymes that digest specific food substances while they are being absorbed through the epithelium and one of which is intestinal lipase. What does it do?
Splits neutral fats into glycerol and FA
Which of the following statements is False?
A. NSAIDs inhibit prostaglandin formation and increase gastric acid secretion.
B. The production of alkaline mucus in small intestines, in part, is stimulated by the vagus nerves
C. Enterocytes in the intestinal villi secrete peptidases for breaking down carbohydrates
D. Enterocytes in the intestinal crypts secrete water.
C. Enterocytes in the intestinal villi secrete peptidases for breaking down carbohydrates
As chyme goes from stomach to small intestine, what must be neutralized quick?
Acid; this is done via pancreas which secretes alkaline fluid
What must be broken down further after it passes the stomach?
Macromolecules; fats + proteins + starch; pancreas will produce enzymes that break this down
What enzyme hydrolyzes starches, glycogen, and most other carbs (except cellulose)?
Pancreatic amylase
When there is a presence of acid, ______ stimulation potentiate the effects of secretin
Cholinergic
When there is a presence of acid, ______ stimulates ductal bicarbonate production
Secretin
When there is a presence of acid, ____-______ stimulates acinar enzyme secretion
CCK-cholecystokinin
Cholinergic, secretin, CCK-cholecytokinin secretion are triggered by the presence of _____
acid
Secretion of bile is through the _____ tract
biliary
Biles facilitates digestion of fats by emulsification and solubilization of fats. This is known as the _____ action
Detergent
What does the bile salts do to the surface area of fats?
Increase SA
Bile salts form mixed micelles and enhance the absorption of lipids by epithelial cells in the _____
ileum
Bile is actively secreted by what cell?
Hepatocytes from cholesterol
50% cholesterol eliminations is due to what?
Synthesizing bile salts
The recirculation of bile is known as what?
Enterohepatic circulation
(T/F) Bile amount is typically big enough to assimilate the lipid content of a typical meal
False, not enough. Entire bile pool is recirculated 2+ times
A. ACh,
B. gastrin,
C. histamine,
D. secretin
Vagus nerves_____
G cells_____
CCK receptor_____
H2 receptor ______
asd
A. ACh,
B. gastrin,
C. histamine,
D. secretin
Bicarbonate production______
cAMP activation _______
ECl cells _______
Endocrine ______
adf
A. ACh,
B. gastrin,
C. histamine,
D. secretin
Paracrine_______
Calcium-dependent-pathway________
Parietal cells______
Increases gastric secretion_______
adsf
What do trypsin and chymotrypsin do?
Splits Proteins
