digestion Flashcards
1
Q
Describe the process of starch digestion
A
- (salivary/pancreatic amylase hydrolyses starch into maltose;
- By hydrolysing glycosidic bonds;
- Maltose is hydrolysed into glucose;
- By Maltase;
2
Q
Describe the processes involved in the absorption and transport of digested lipid molecules from the ileum into lymph vessels.
A
- Micelles contain bile salts and fatty acids/monoglycerides;
- Make fatty acids/monoglycerides (more) soluble (in water) OR Bring/release/carry fatty acids/monoglycerides to cell/lining (of the iluem) OR Maintain high(er) concentration of fatty acids/monoglycerides to cell/lining (of the ileum);
- Fatty acids/monoglycerides absorbed by simple diffusion into epithelial cell;
- Triglycerides (re)formed (in cells);
- Vesicles move to cell membrane;
3
Q
Describe the role of micelles in the absorption of fats into the cells of the ileum.
A
- Micelles include bile salts and fatty acids;
- Make the fatty acids (more) soluble in water;
- Bring/release/carry fatty acids to cell/lining (of the ileum);
- Maintain high(er) concentration of fatty acids to cell/lining (of the ileum);
- Fatty acids (absorbed) by diffusion;
4
Q
Describe the role of enzymes in the digestion of proteins in a mammal.
A
- (Reference to) hydrolysis of peptide bonds;
- Endopeptidase act in the middle of protein/polypeptide OR Endopeptidase produces short(er) polypeptides/ increase number of ends;
- Exopeptidases act at end of protein/polypeptide OR Exopeptidase produces dipeptides/amino acids;
- Dipeptidase acts on dipeptide/between two amino acids OR Dipeptidase produces (single) amino acids;
5
Q
Describe the absorption of glucose (Cotransport)
A
- Sodium ions actively transported from ileum/epithelial cell to blood;
- Maintains / forms diffusion gradient for sodium to enter cells from gut (and with it, glucose);
- Glucose enters by facilitated diffusion with sodium ions;
6
Q
Describe how amino acids are absorbed from the ileum into the blood (5)
A
- Sodium ions actively transported out of epithelial cell into the blood (by sodium potassium pump);
- This creates a concentration gradient for Na+(between lumen of ileum and the epithelial cell);
- Na+ and amino acid enter by facilitated diffusion;
- Na+ diffuse into the cell down its concentration gradient;
- Amino acids move into the cell against their concentration gradient;
- Amino acids move into the blood by facilitated diffusion;