Digestion and Absorption Flashcards
Where does protein digestion begin?
The stomach (pepsinogen/pepsin)
What are the roles of HCl in the stomach?
Lowers pH (to 2 ish) in order to denature proteins and kill pathogens
Where does most chemical digestion occur?
The small intestine
Which bacteria causes stomach ulcers?
Helicobacter pylori
What does diffusion transport?
Fatty acids pass through the hydrophobic cell membranes of epithelial cells
Osmosis?
Water diffuses across epithelial cell membranes in response to movement of ions and other hydrophilic monomers (occurs in small intestine and large intestine)
What does active transport require?
ATP
Active transport
Glucose and amino acid pumped against their concentration gradient
Facilitated diffusion
Protein channels within epithelial cell membranes allow passage of hydrophilic food molecules
Endocytosis
Invagination of the cell membrane to form a vesicle around bulk fluids/ large molecules that must remain intact in the intestinal lumen and bring them into the cell (ex: absorption of antibodies)
What does BELCH stand for?
Bile pigments, Epithelial cells of the intestine, Lignin, Cellulose, Human microflora (bacteria)
Main function of the large intestine?
Absorb water (and minerals, vitamins, and ions)
Why are cellulose and lignin not digested?
Humans don’t have the enzyme (cellulase) or gut bacteria necessary to break them down
Role of fiber in the diet?
cleans out old digestional cells, absorbs water to keep stool soft, works out microflora, lowers rate of colon and rectal cancer
Causes of stomach ulcers
overuse of NSAIDS and Helicobacter pylori
What is a stomach ulcer?
inflamed areas of the stomach wall caused by exposure of stomach cells to stomach acids
Treatments of stomach ulcers?
medication to lower stomach acid production and antibiotics
What does mitochondria in villi do?
produce ATP for active transport of nutrients into the blood
What do pinocytotic vesicles do in villi?
Translocate digested food products in bulk
What enzymes does the pancreas secrete?
Amylase, Lipase, and Trypsin
Substrate and product of amylase
starch to maltose
Substrate and product of lipase
triglycerides to monoglycerides/fatty acids/glycerol
Substrate and product of trypsin
proteins/peptides to amino acids
The general function of villi?
Increase surface area of epithelium over which absorption is carried out and absorb monomers, mineral ions, and vitamins
