Digestive System Flashcards
What is the enteric nervous system?
Collection of about 100 million neurons, independent of the brain and spine, govern the function of the digestive tract and trigger peristalsis. Highly regulated by the autonomous nervous system. (But can function independently of the brain and the spine).
Which glands are not innervated by the parasympathetic nervous system?
Sweat glands
What hormones trigger feeling of thirst?
ADH and aldosterone
Which hormones trigger a feeling of hunger?
ghrelin and glucagon
Which hormones promote a feeling of satiety?
Leptin and cholecystokinin
Mastication
Chewing
What are the digestive enzymes present in the saliva? What do they do?
Salivary amylase (ptyalin) —> starch —>maltose and dextrin Lipase—> hydrolysis of lipids
What are the different parts of the esophagus? What are they made of?
Upper third —> skeletal muscles
Bottom third —> smooth muscles
Middle third —> mixed
What are the sphincters involved in ingestion?
Upper esophageal sphincter
Lower esophageal sphincter (cardiac sphincter)
Four anatomical divisions of the stomach?
1- fundus
2- body
3- pylorus
4- antrum
What kind of glands exist in each of the four regions of the stomach?
1- gastric glands in fundus and body
2- pyloric glands in pylorus and antrum
What is the nerve input for the gastric glands?
Vagus nerve
What are the cell types in gastric glands, what do each do?
1-mucous cells , produce bicarbonate rich mucous
2-chief cells produce pepsinogen
3- parietal cells produce HCL and intrinsic factor
What is the gastric juice?
Secretions of the chief cells and parietal cells
What is the function of the intrinsic factor? What kind of a molecule is it?
Glycoproteins: involved in the proper absorption of vitamin B12
How is pepsinogen converted to pepsin and what does it cut?
H+ ion.
Cuts peptide bonds near aromatic amino acids.
What cell type do the pyloric glands contain? And what do they secrete? What is the function of the thing that they secrete?
G cells
Secrete Gastrin
1-Induces the secretion of HCL from the parietal cells
2- signals the stomach to contract
Name two compounds that are directly absorbed in the stomach
Alcohol and aspirin
What is the Zellinger-Ellison syndrome?
Rare disease from a gastrin secreting tumor (gastrinoma)
Excessive secretion of HCL—> ulcers
What are the three sections of the small intestine in order? Which ones are involved in digestion, and which ones are involved in absorption?
Duodenum, involved mostly in digestion
Jejunum and Ileum involved in absorption
What are the brush border enzymes and what triggers their release?
Disaccharidases and peptidases (including dipeptidase) They are present in the luminal surface of cells lining the duodenum
Presence of chyme induces their release
What structure secretes enteropeptidase and what is the function of enteropeptidas?
Duodenum
It turns trypsinogen to trypsin which turn chymotrypsinogen into chymotrypsin
And enteropeptidase also activates procarboxypeptidases A and B
What structure produces Aminopeptidases and what is their function?
Glands in the duodenum,
They remove the N-terminal amino-acid from a peptide.
What is secretin (is it a hormone or an enzyme) what does it do?
Hormone
1-causes pancreatic enzymes to be released into the duodenum
2- regulates PH by decreasing secretion of HCL from parietal cells and increasing bicarbonate secretion from the pancrease
3- is an entergastrone (slows motility through the digestive tract)
What structure releases cholecystokinin? What triggers its secretion, and what does it do?
Small intestine
presence of chyme in the duodenum (especially fat and proteins) triggers its secretion
Functions:
1- acts on the brain and promotes feeling of satiety
2- stimulates the release of bile and pancreatic juices.
What are the bile salts derived from and what do they do?
Derived from cholesterol and the they emulsify fat (mechanical digestion of fat) and they aid in chemical digestion
Celiac disease
Immune reaction against gluten. antibodies cross react with elements of the small intestine, causing damage to the mucosa. Is not an allergy. Can cause issues for absorption of fats and fat soluble vitamins.
What germ layer do the accessory organs of digestion originate from?
Endoderm
What are the pancreatic enzymes?
1- pancreatic amylase
2-trypsinogen, chymotrypsinogen, procarbxypeptidase A and B
2-pancreatic lipase
Functions of the liver
1- processing and synthesis of nutrients (glycogenesis, glycogenolysis, gluconeogenesis, storage and mobilization of fats
2- production of urea
3-detox of chemicals
4-production of bile
5-synthesis of albumin and clotting factors.
Bile ducts connect what to what?
Connect the liver to both the gallbladder and the small intestine.
Where does the blood that comes from the hepatic portal vein end up?
Inferior vena cava
What happens if liver can’t process and secrete bilirubin properly?
Jaundice.
Note that bilirubin TRAVELs to the liver and is PROCESSED (conjugated) there.
What are the functions of albumin ?
1-Maintains the blood oncotic pressure
2- serves as carrier for many drugs and hormones.
What is the effect of cholecystokinin on gallbladder?
Makes it contract and push out bile into the biliary tree.
What processes can lead to cirrhosis of the liver?
1-chronic alcohol consumption
2-hepatitis c
3-autoimmune hepatitis
4-fatty liver disease
What is cirrhosis?
Scarring of the liver, as the scar builds up, creates increased resistance within the portal vein, resulting in portal hypertension’s, backup of fluid within the portal system —> swollen veins in the digestive system (especially esophagus)
What are the complications of cirrhosis?
1-Vein in esophagus may rupture and be life threatening—> hematemesis
2-bleeding disorders (production of clotting factors is disrupted)
3- increased ammonia in the blood—> affects mentation
4-hepatocellular carcinoma
For absorption, what are each of these compounds broken down into:
Carbs, proteins, triacylglycerols
Carbs—> monosaccharides
Proteins—> amino acids, di or tripeptides
Triacylglycerols—> 2-monoacylglycerol, fatty acids
How are simple sugars (monosaccharides) and amino acids absorbed in the intestines?
They are absorbed using secondary active transport and facilitated diffusion into the epithelial cells lining the small intestine. Then, they diffuse from the cell into the capillaries.
How are fats absorbed in the small intestines (clarify how for short chain fatty acids compared to larger fats, glycerol and cholesterol)
Smaller fatty acids diffuse into the epithelial cells and there they are modified into triglycerides and esterified cholesterol. Then they are packaged into chylomicrons. Chylomicrons enter the lymphatic circulation by entering the lacteals.
How are the fat soluble vitamins absorbed?
They dissolve directly into the chylomicrons and enter the lymphatic circulation.
What are the three anatomical sections of the large intestine?
Cecum, colon, rectum
How (through what) does the fluid go from the small intestine to the large intestine? What part does it enter?
Through the ileocecal valve. Goes to cecum first
Where is the appendix attached?
near the ileocecal valve (?)
What are the four anatomical sections of the colon?
Ascending, transverse, descending, and sigmoid
Does large or small intestine absorb more water?
Small intestine
