PSC1002/L29 Stomach Flashcards
Give 3 functions of the small intestine.
Digestion
Nutrient absorption
Electrolyte absorption
Water absorption
Secretion
Which enzyme is involved in luminal digestion of starch-type polysaccharides?
Amylases
Which enzymes are involved in membrane digestion by disaccharidases? (3)
Maltase
Sucrase-isomaltase
Lactase
Why is amylase described as an endo-enzyme?
It can only break internal bonds so cannot produce monosaccharides
Give 2 transporters of the apical membrane.
SGLT1
Glucose, galactose
Na+ coupled, secondary active transport
Give a transporter of the basolateral membrane.
GLUT2
Facilitated diffusion
Give 3 types of protein digestion and their related enzymes.
Luminal digestion by gastric and pancreatic proteases
Membrane digestion by brush-border peptidases
Cytosolic digestion within epithelium of small peptides
Give 2 substances absorbed in the small intestine.
Amino acids
Peptides
Intact protein absorbed in antigenic quantities
Describe digestion by gastric pepsin. (2)
10-20% digestion
Endopeptidases
Describe digestion by pancreatic peptidases. (3)
E.g., trypsin
Endopeptidases and exopeptidases
Short peptides (2-6AA) and free amino acids
Describe protein digestion by membrane and cytosolic peptidases. (3)
Endo, exo or dipeptidases
Many different types
Free amino acids
What is acid microclimate used for?
Peptide absorption
H+ coupled di/tripeptide transport
What follows peptide absorption?
Cytosolic peptide digestion or export by unknown basolateral transporter
Give 3 drugs which utilise peptide carriers.
Angiotensin-converting enzyme (ACE) inhibitors
B-lactam antibiotics
Prodrugs (Val-acyclovir)
Give 3 types of amino acid transporters.
Neutral
Cationic
Anionic