6.1 - Digestive and Absorption Flashcards
Which enzyme is secreted by the salivary glands in the mouth, and what substrate does it act upon?
Salivary amylase, which breaks down starch into maltose
Where does protein digestion begin in the human digestive system?
Stomach. Proteases are enzymes which breakdown protein into smaller peptides.
What is the optimal pH for endopeptidases? (High or low?)
Low - the stomach is very acidic!
What is the role of the pancreas in digestion? (2 points needed)
Releases enzymes which aid in the breakdown of macromolecules into smaller monomers. These monomers can then be absorbed through the villi of the small intestine.
What enzymes (3) does the pancreas produce, what substrate does it act upon and where do these substrates end up?
Pancreatic amylase: Released into the small intestine, where it breaks down starch –> maltose. Maltose is then broken down into glucose, which is transported through the bloodstream.
Endopeptidases: Released into the small intestine, where it breaks down peptides –> amino acids. Amino acids are transported through the bloodstream.
Lipases: Released into the small intestine, where it breaks down triglycerides –> glycerol + fatty acids. Fatty acids are transported through the lacteal system.
What are the two types of muscle found in the small intestine, and what are their functions?
Circular and longitudinal muscle.
These two muscles rhythmically contract and relax, allowing the food to move down the alimentary canal in one direction.
Draw and label a transverse section of the small intestine.
Should have longitudinal and circular muscles, mucosa and epithelium labelled.
Explain the role of villi in absorption.
MR SLIM.
M: microvilli - increases surface area
R: rich blood supply - for the rapid absorption of nutrients
S: single layer of epithelium - decrease diffusion distance for nutrients
L: lacteals - for lipid absorption
I: intestinal glands - releases digestive juices
M: membrane proteins - facilitates the transport of digested materials into the epithelial cell
Where does active transport occur during absorption?
Glucose and amino acids are actively transported into intestinal epithelial cells. REQUIRES ENERGY!
Where does facilitated diffusion occur during absorption?
Vitamins and minerals, as well as SOME monosaccharides like fructose are transported into epithelial cells via facilitated diffusion. (BUT NOT GLUCOSE!!!!!!!!)
How is water transported into intestinal epithelial cells?
Via osmosis.
Where does simple diffusion occur during absorption?
Lipid products enter intestinal epithelial cells via simple diffusion.
Which polysaccharide remains UNDIGESTED? Hint: cows can digest this.
Cellulose! Humans do not have the enzyme cellulase to breakdown cellulose.
