Case 3 - The pancreas Flashcards
Where are proteins digested and what are they digested to?
stomach, pancreas, brush border,
amino acids, dipeptides and tripeptides
Where are polysaccharides digested and what are they digested to?
saliva, pancreas, brush border
monosaccharides
Where are triglycerides digested and what are they digested to?
free fatty acids and monoglycerides
stomach, pancreas, bile salts
What are the different methods of absorption across the SI
simple diffusion - lipids
carrier mediated - amino acids and sugars e.g. facilitated diffusion and secondary active transport
receptor mediated - B12 and intrinsic factor, cholesterol e.g. endocytosis
What is the main site of absorption
small intestine - duodenum and jejunum
What is absorbed in the ileum?
vitamin B12, bile salts and potassium
What causes the surface area of the SI to decrease and what are the consequences?
Crohns or coeliac disease
Leads to malabsorption
What mechanism is used for carbohydrate absorption
carrier mediated - secondary active transport
Describe the process of carbohydrate absorption from the lumen into isf
absorbed as monosaccharides, glucose/fructose via a sodium coupled transporter
SGLT1
glucose and sodium bind to the carrier, sodium binds first x2 and opens the binding site for glucose, transport channel undergoes a conformational change and empties the glucose into the cell.
accumulation of glucose moves glucose out of the cell via GLUT2 carrier facilitated diffusion
What is the function of an SGLT1 transporter
sodium and glucose transporter
How are peptides absorbed?
Absorbed via pep T1 co transporter with Hydrogen ions, the peptides are hydrolysed to amino acids in the enterocytes
How is alanine absorbed
Via Bo contrasporter sodium
How is glutamate absorbed?
Via Xag: a co-transporter of alanine, sodium x2 and others e.g. glutamate.
What is Hartnup disease
rare genetic disease,c causes appearance of amino acids in urine
Why is fat digestion dependent on bile salts?
Bile salt emulsify the fat droplets to increase surface area for digestion by lipase
formation of mixed micelles will stabilise the products of tg hydrolysis (mg +fa) while they are transported to apical membrane
absence of bile leads to steatorrhoea