Digestion and Absorption Flashcards
1
Q
What is digestion?
A
the hydrolysis of large biological molecules into smaller molecules which can be absorbed across cell membranes
2
Q
How are carbohydrates digested?
A
- amylase in saliva hydrolyses polysaccharides (like starch)
- maltase in the ileum break down maltose
- sucrase breaks down sucrose
- lactase breaks down lactose
3
Q
How are lipids digested?
A
- lipases hydrolyse the ester bond between the monoglycerides and fatty acid
- lipids are emulsified into micelles by bile salts released by the liver
4
Q
why does emulsification occur?
A
it increases the surface area and speeds up the chemical reaction
5
Q
How are proteins digested?
A
by enzymes called peptidases
6
Q
What are the types of peptidases?
A
- exo
- endo
- di
7
Q
what are the function of exopeptidase?
A
it hydrolyses bonds at ends of a polypeptides
8
Q
what are the function of endopeptidase?
A
it hydrolyses peptide bonds between specific amino acids in the middle of a polypeptide
9
Q
what are the function of dipeptidase?
A
break dipeptides into individual amino acids
10
Q
How are amino acids absorbed?
A
- co-transport
- sodium is actively transported into the capillaries through sodium-potassium pump
- concentration gradient established causing sodium to move into the epithelial cells with amino acids (sodium by faciliated diffusing and amino acids through active trabsport)
- amino acid then moves into the blood by facilitaed diffusion
11
Q
How are monoglycerides absorbed after digestion?
A
- Monoglycerides and fatty acids are polar so they can easily diffuse into the epithelial cells lining the epithelium.
- Once inside they are transported to the
endoplasmic reticulum (ER) where they are reformed into triglycerides again - After this they move out of the cells by exocytosis in vesicles into the lymph system
