Digestive system (9) Flashcards
(22 cards)
Stomach: secretes six products
- HCl ( kills microbes, denatures protein, and convert pepsinogen to pepsin)
- Pepsinogen (cleaved in the stomach to pepsin; an enzyme that partially digests protein)
- Mucus (protect mucosa)
- Bicarbonate (protects mucosa)
- Water (dissolves and dilutes ingested material)
- Intrinsic factor (required for normal absorption of vitamin B 12)
Gastric Gland: contain three cell types
- Mucous
- Cheif cells
- Parietal cells
Mucous cells: produce bicarbonate rich mucus to protect stomach cells.
Chief cells: secrete pepsinogen
Parietal: secretes HCl –> cleaves pepsinogen to pepsin
Parietal is like Parental protects it
also secretes intrinsic factor, a glycoprotein involved in the proper absorption of vitamin B12.
Pepsin
digests protein by cleaving peptide bonds, resulting in short peptide segments.
Pyloric Gland: contains G cells
G-cells: secrete gastrin, a peptide hormone that increases HCl secretion and gastric motility.
Duodenum
involved in chemical digestion
Brush border Enzyme
Diasccharideses digests disaccharides
Brush border peptidases include aminopeptidase and dipeptidases.
Diasccharideses
maltase digests maltose
sucrase ———> sucrose
lactase————> lactose
Aminopeptidases (enzyme) (from brush border)
removes N-terminal amino acid from a peptide
Dipeptidases (enzyme) (from brush border)
cleaves peptide bonds of dipeptides to release free amino acids.
Enteropeptidase
the enzyme that is critical for activation of trypsinogen. Trypsinogen will then activate trypsin.
Trypsin will activate procarboxypeptidases A and B.
Deficiency of enteropeptidase will lead to trypsinogen deficiency and protein will not cleave and which results in amino acids deficiency.
Secretin (hormone)
secretin stimulates the release of pancreatic juice into the digestive tract and slows motality.
Cholecystokinin (CCK) (hormone)
stimulates bile release from the gallbladder, the release of pancreatic juice, and satiety from the brain.
Bile
emulsify fats and cholesterol into micelles.
produced in the liver and stored in the gallbladder.
Pancreatic juice
a complex mixture of several enzymes in a bicarbonate-rich alkaline solution.
Pancreatic juice contains an enzyme that can digest all three types of nutrients: carbohydrates, fat, proteins.
acinar cells: produces pancreatic juice
Pancreatic lipase
capable of breaking down fats into free fatty acids and glycerol.
Liver
takes up excess sugar to create glycogen, a storage form of glucose.
stores fats as triacylglycerols.
Bilirubin
The biproduct of the breakdown of hemoglobin. Bilirubin travels to the liver, where it is conjugated and secreted into the bile for excretion.
Unable to process or excrete bilirubin, will cause jaundice.
Amylase
alpha-amylase secreted in the mouth, initiates the digestion of carbohydrates by cleaving alpha-1,4 bonds but not alpha- 1,6 bonds.
secreted by the pancreas also, breaks down large polysaccharides into small disaccharides.
Absorption
Jejunum and ileum involve in absorption.
- Water-soluble such as monosaccharides, amino acids, water-soluble vitamins, and water enters the capillary bed.
- Fat-soluble, such as fats, cholesterol, and fat-soluble vitamins (A, D, E, K)
Chylomicrons
-Triglycerides and cholesterol molecules are packaged into chylomicrons.
enter the lymphatic system through lacteals. Lacetals converge and enter the venous circulation at the thoracic duct, which empties into the left subclavian duct.
Large Intestine
Absorbs water and salt, forming semisolid feces.
Liver failure
The high concentration of ammonia in the blood
Low concentration of clotting factors in the blood
