Protein, Carbohydrate & Fat Absorption Flashcards
What partially breaks down proteins in the stomach?
Pepsin
What further breaks down proteins in the small intestine?
Trypsin
Chymotrypsin
What are trypsin and Chymotrypsin?
Pancreatic proteases
What peptidase helps in protein breakdown?
Carboxypeptidass
What is located on the luminal membrane that aids protein breakdown?
Aminopeptidases
What do carboxypeptidases do?
Remove the amino acids from the carboxyl end
What do Aminopeptidases do?
Remove amino acids from the amino end
Why passes into the cell along with amino acids?
Na+
What two transporters are there for carbohydrate absorption?
Glucose transporter (GLUT) Sodium-glucose transporter (SGLT)
What is the name of the membrane on the luminal side?
Apical membrane
What is the name of the membrane on the blood side of the epithelium?
Baso lateral membrane
What is transported by the GLUT in the small intestine?
Fructose
It is a GLUT5
What is transported by the SGLT in the small intestines?
Glucose
Galactose
Na+
Where does the majority of carbohydrate absorption take place?
First 20%
What happens to cellulose?
It is transported to the large intestine where it is partially metabolised by bacteria
What is transported across the baso lateral membrane in protein absorption?
K+ out
K+ in & Na+ out (ATP transporter)
Amino acids
What crosses the baso lateral membrane in carbohydrate absorption?
K+ out
K+ in & Na+ out (ATP transporter)
Fructose, glucose & galactose out
Does breakdown of proteins to amino acids occur completely in the lumen before entering the enterocyte?
No - some small peptides pass into the enterocyte and break down to amino acids
What happens to the fat droplets in the first step of fat absorption?
They are emulsified
What is used to emulsify the fat droplets?
Bile salts
Why do bile salts emulsify fat droplets?
They have a hydrophobic part and a hydrophilic part. The hydrophobic part goes into the fat droplets and the hydrophilic part sticks out. This breaks up the fat droplet
What is the name of the emulsified fat droplets?
Micelles
What breaks down micelles into free fatty acids and monoglyceeides?
Pancreatic lipase
What happens to the free molecules of fatty acids and monoglycerides?
They diffuse into the enterocytes and into the endoplasmic reticulum
Here they combine to form triglycerides and combine with cholesterol and phospholipids
They collectively form a chylomicron
The chylomicron then passes out the cell into the lymphatics where it is transported to cells
What is the mechanism in which chylomicrons pass out of the enterocytes?
Exocytosis
