Digestion Flashcards
Which enzyme digests carbohydrates and where is it found?
Amylase hydrolyses starch into disaccharides
*Saliva
*Pancreas
What are the 3 membrane-bound disaccharidases?
- Maltase
- Sucrase
- Lactase
What digests lipids and how?
Bile salts emulsify lipids to form micelles
What does pancreatic lipase do?
Triglyceride –> monoglyceride + 2 fatty acids
What do endopeptidase, exopeptidase and dipeptidase do?
Endo - hydrolyses peptide bonds WITHIN a protein molecule
Exo - hydrolyses peptide bonds at the ENDS of a protein molecule
Di - hydrolyses a dipeptide into 2 amino acids
How are small intestines adapted for absorption?
- Increased SA
- Thin-walled
- Contain muscle so can move (maintains conc. gradient)
- Well supplied with blood and lymph vessels (transports nutrients away + maintains conc. gradient)
- Epithelial cells have microvilli
Explain co-transport in 4 steps
- Na+ actively transported into capillary
- Creates Na+ gradient
- Na+ and monosaccharide/amino acid co-transported into epithelial cell by facilitated diffusion
- Monosaccharide/amino acid transported into capillary by facilitated diffusion
Explain how monoglycerides and fatty acids are absorbed in 6 steps
- At cell surface membrane micelles break down
- Monoglycerides and fatty acids diffuse into epithelial cell
- Forms ester bonds in smooth endoplasmic reticulum
- Formation of chylomicrons inside Golgi apparatus
- Exocytosis from epithelial cell
- Chylomicrons transported in lymph system
What do chylomicrons do?
Release proteins and triglycerides into lymph system
Where are maltase enzymes located in the ileum (part of small intestine where absorption occurs)?
Embedded in cell surface membrane of epithelial (lining) cells
Define lactose-intolerant
Don’t produce lactase enzyme so no absorption of alpha glucose or galactose into epithelial cells
