the intestines Flashcards
What is chyme like in the intestines?
Isotonic
Neutral
Digestion nearly complete
What is the role of the intestines?
Absorb nutrients
Absorb water/electrolytes
What is absorption in the intestines?
Movement of electrolytes, water and nutrients from the gut lumen into the blood
What is needed for maximum absorption?
Large surface area, slow movement of content
How often is mucosa shed?
3-6days
What are carbohydrates?
Chains of sugars e.g. polysaccharides, disaccharides and monosaccharides
What do you need to do to carbohydrates to be absorbed?
Break them down into monosaccharides
Where does final breakdown of carbohydrates occur?
Brush border
What does glucose need to enter?
Na+
What are the end products of carbohydrate digestion?
Fructose
Galactose
Glucose
What does maltose break?
alpha 1-4 bonds
What does isomaltase break?
alpha 1-6 bonds
What does starch break down into?
Glucose, Maltose (two glucose) and alpha dextrin (glucose)
What is lactose broken down into?
Glucose and galactose
What is sucrose broken down into?
Glucose and fructose
How is glucose and galactose absorbed?
SGLT 1 with Na into enterocyte
then GLUT 2 into blood
How is fructose absorbed?
GLUT 5 into enterocyte
then GLUT 2 into blood
Why does water follow glucose?
Glucose uptake stimulates Na uptake which helps move water due to osmotic gradient- oral rehydration
What types of proteins are absorbed?
Amino acids
Dipeptides
Tripeptides
What does pepsinogen released from chief cells get converted into and how?
Pepsin by HCl
What does pepsin do?
Acts on protein
and move to small intestine
What does the pancreas release proteases as?
Zymogens
why is trysinogen important?
Converted to trypsin by enteropeptidase which then activated other proteases (chymotrysinogen to chymotrypsin)
What do exopeptidases do?
break bonds at ends of polypeptides to produce dipeptised or individual amino acids (carboxypeptidase)
