Small intestine

Question 1

Peristalsis

Answer 1

circular muscle behind bolus contract, relax in front

Longitudinal muscles ahead contract –> shorten adjacent segments

Question 2

Migrating Motor Complex

Answer 2

when gut is empty ~every 90 mins, stimulated by motilin (from M cells and erythromycin), supressed by feeding, pyloric sphincter= relaxed

Question 3

CCK

Answer 3

I-cells

Question 4

HCO3-

Answer 4

Pancreatic duct cells

Question 5

Glucose and galactose

Answer 5

actively absorbed by SGLT1

2Na and glucose

Question 6

Fructose

Answer 6

passively absorbed by GLUT5 transporter

Question 7

enterokinase

Answer 7

crypt cells

changes trypsinogen –> trypsin

Question 8

endopeptidases

Answer 8

cut within chain: trypsin, chymotrypsin, elastase

Question 9

exopeptidases

Answer 9

cut last peptide bond: carboxypeptidase

Question 10

Pancreatic lipase

Answer 10

cleaves outer FA–> monoglyceride + “ free Fa –> complex bile salts –> mixed micelles (fats and hydrophilic elements) –> brush border –> triglyceride resynthesised by ER –> chlyomicra (fat & protein) –> lymphatic lacteals

Question 11

Glycerol

Answer 11

can go straight into capillaries

Question 12

Dcytb

Answer 12

reduces Fe3+ –> Fe2+

Question 13

DMT

Answer 13

Cotransports Fe2+ with H+

Question 14

Haeme oxygeriase

Answer 14

oxidisesFe2+ in haem –> release Fe3+

Question 15

Absorption Ca

Answer 15

Regulated by VitB: increases number open Ca channels

Calbindin picks up Ca–. basement membrane –> swaps for H+ and also Na+ - transporter uses 3 Na+

Question 16

Na+ and K+ secretion are regulated in the colon by

Answer 16

aldosterone