Diegestive System II Flashcards
Function of the mucus surface cells
- Physical barrier between the lumen and the epithelium
What stimulates the mucus surface layer?
- Tonic secret tonic secretion when the mucosa is irritated
Mucous neck layer secretion and function
- Secrete bicarbonate which acts as a buffer to the gastric acid to prevent damage to the epithelium
What stimulates the release of bicarbonate from mucous cells?
- Both the mucous and bicarbonate at decreased together
The function of parietal cells secreting gastric acid?
- Activation of pepsin which kills bacteria
Function of parietal cells secreting intrinsic factors
- Complexes with vitamin B12 to permit absorption
What stimulates the release of gastric acid and intrinsic factors?
- Gastrin, acetylcholine and histamines
What does the mucous neck and surface layer do for protection
- They protect the epithelial surface
- The NSAIDS and alcohol destroy the mucosal barrier which leads to gastric irritation
Function of the secretaries of histamines from Enterochroffmaffin like cells
- Stimulates gastric acid secretion
What stimulates the release of histamine?
Acetylcholine and gastrin
Function of chief cells secreting pepsin
- For the digestion of proteins
Function of chief cells secreting gastric lipase
- Initiates the digestion of fats
What stimulates the release of pepsin and gastric lipase
- Acetylcholine for acid secretion
Process of protein breakdown in the stomach
- Proteins initially breakdown in the stomach into pepsinogens
-This causes the inactive enzyme to be secreted from chief cells - The gastric acid then activates the inactive pepsin which digests the collagen in the meat
Fat breakdown in the stomach
- Triglycerides are broken down by gastric lipase which is secreted by the chief cells
- This forms diglycerides and a free fatty acid
Function of somatostatin secretion from D cells
- Inhibits the gastric acid secreation
Function of gastrin secretion from G cells
- Stimulates gastric acid secretion
What stimulates the D cells to secrete somatostatin
- Acid in the stomach
What stimulates the G cells to secrete gastrin
- Acetylcholine, peptides and amino acids
Paracrine effect
- ## Histamine stimulates G cells to secrete gastrin to stimulate the gastric acid secretion
Somatostatin inhibition of paracrine effect
- Hormone that is a global inhibitor
- Inhibits secreation of histamines, gastrin and gastric acid secreation
Histamine receptor antagonist
- Prevent histamine activation of gastrin-gastric acid secreation
- Drugs used to treat dyspepsia
How does the bacteria Helicobacter pylori effect the stomach?
- Requires treatment with antibiotic
- Creates the inflammation of gastric mucosa
Intrinsic factor
- Responsible for binding to vitamin B12
- Without binding B12 cannot be absorbed
- Required for erythropoeisis and DNA formation
Intestinal secreations
- Mucus is secreted by the duodenal glands and goblet cells
- Protection of of duodeum from gastric acids and digestive juices
- Sucrase, lactase, maltase and amylase digest carbs via glucose transporters
Cholecytokinn
- Stimulates the gall bladder contractions, pancreatic enzyme secreation and inhibition of gastric emptying and secretion
Secretin
- Stimulates the bicarbonate secretion
- Inhibition of gastric emptying and secretion
Gastric inhibitory peptide
- Inhibition of gastric emptying and secreations
Glucagon like peptide
- Inhibition of gastric emptying and secreation
- Decrease in appetiete
Liver
- Recieves 30% cardiac output
- Contains heptocytes for metabolism
- Glucose, fat metabolism and protien synthesis
- Hormone synthesis, detoxification, urea production and storage
Gallbladder
- Small pouch like organ under liver
- Storage of bile and bile is passed from gall to liver via bile ducts
Bile
- Non-enzymatic solution secreated from heptocytes
- Contains bile acids, biliburin and cholesterol
- Bile salts act as detergents to solublise fat and move them forward in small intestine
Process of fat absorption
- Bile salts coat fat droplet forming an emulsion
- Pancreatic lipase break them into monoglycerides
- Monoglycerides broken into free fatty acids and cholesterol which diffuse through entrocytes
- Absorbed fat cholesterol and protiens form chylomicron
- Chylomicrons are removed through lymphatic system
Metabolisation in Pancreas
Exocrine glands
- Mostly exocrine tissue
- Pancreatic enzymes to aid digestion
- Alkaline clear milky liquid containing amylase lipase and trypsin
Metabolisation in Pancreas
Endocrine glands
- Small percentage in pancreas lots of endocrines
- Ilets of langahan insulin glucose regulation occours
Pancreas secretions
Ancinar cells
- Exocrine cells that release digestive juices send via duct which creates bicarbonate mucus which neutralises the acidic chyme also activates enzymes
