Co-transport Of Glucose

Question 1

Increasing rate across mems

Answer 1

• epithelial cells possess microvilli which are finger-like projections
• provide more surface area for insertion of carrier proteins
• increase density (no) of CP&PC

Question 2

How is diffusion a part of absorption)

Answer 2

• carbs& proteins always digested so great conc of glucose&amino acids within ileum.
• there is conc gradient down where glucose moves by FD from inside ileum- blood
• blood constant circulated by heart so glucose absorbed into it is removed by cells as they use it during resp
• this helps maintain conc gradient btw inside ileum and blood
• so rate of movement is increased

Question 3

Why ‘co-transport?’

Answer 3

Either glucose/amino acids are drawn into the cells w sodium ions that have been ATd from NA-K PUMP

Question 4

Process of co-transport

Answer 4

1. Na+ ions aTd out of epith cells by NA-K pump to blood so higher conc of NA+ ions in lumen of intestine than epith
2. Na+ ions diffuse into epith cells down conc gradient thru co-transport protein In cell surf m.
3. They carry glucose/amino w them and pass into blood plasma by FD using another type of carrier

Question 5

Causes of diarrhoea

Answer 5

• loss of microvilli due to toxins
• excessive secretion of water due to toxins e.g cholera
• damage to epithelial cells lining the intestine

Question 6

Drinking water doesnt help diarrhoea?

Answer 6

• water is not being absorbed from intestine but is being lost from cells
• does not replace electrolytes (ions) that are being lost from intestinal cells

Question 7

Rehydration solution contains… for diarrhoea

Answer 7

Water to rehydrate tissues

• K IONS = to replace lost K IONS & stimulate appetite
• Na ions = to replace lost 1’s & optimise use
• glucose = energy, stim uptake of Na ions from intestine
• other ions = prevent imbalance& metabolic acidosis