GIT physiology 3

Question 1

What are the types of carbohydrates + what can/cant we digest and why

Answer 1

Polysaccharides + disacharides concumed
Startches - amylose + amylopectin
broken by amyalse - contains alpha glycoside bonds which can be broken
cellulose- fiber, contains beta bonds cannot be digested
Glycogen - storage molcule for glucose

Amylase breaks to disaccharides, Disacharides broken by disacharidases on brush boarder

Question 2

What is special about protein in relation to fuel molecule

Answer 2

No used as energy under normal circumstances’
8/20 amino acids must be injested where other metabolic made
1/2 amino acids injested 1/2 amino acids are metabolicly synthesised

Question 3

What fats must be eaten + How are lipids classified

Answer 3

Vitamins ADEK + omaga 3 and 5 - good energy source
Mostly triacylglycerol
short<6, med6-12, long 13-24
absorbed as MAGs+ FFA

Question 4

What are the luminal + contact enzymes for
- peptides
- carbohydrates

Answer 4

Proteins: HCl + proteases stomach + SI
- contact: peptidases
carbohydrates: Amylase mouth + SI
- Contact: disaccharidases

Question 5

What are the 4 stages of lipid digestion

Answer 5

1. emulsiphication mixing - mechanical digestion motility breaks appart large fat droplets throughout chyme
2. emulsiphication stabilisation - Droplets are stabilised to create emulsion droplets(ED), increase SA for digestion
   - Stomach =Simple emulsification
   - SI = bile salts + compounds emulsificaion
3. Hydrolysis - Colipiase attaches lipase to ED where it cleaves TAGs at R1 and R2 at the surface of the droplet
4. Micelles form = small droplets stbilised by bile salts until digestion - contain MAGs+ FFA + bile salts

Question 6

What strucutre are bile salts + how are the processed

Answer 6

Bile salts = ampiphillic substance
- 1 hydrophbic and 1 hydrophillic side

Metabolically exspensive -> 95% absorbed back via illeum