Physiology: Absorption & Digestion

Question 1

What is the 4 classification & function of CHO

Answer 1

1. Simple CHO: energy & increase in blood glucose
2. Complex CHO: gradual increase in blood glucose & digested slowly
3. Starch: complex CHO & large number of glucose
4. Fibre: non-digestible complex CHO that promote gut flora growth

Question 2

What is the main source of energy

Answer 2

CHO

Question 3

What is the pathway of CHO digestion

Answer 3

1. Mouth: food chewed & mixed w/ salivary amylase & starched hydrolysed to smaller dextrins
2. Stomach:amylase is inactivated by HCl
3. Small intestine: pancreatic amylase digest & disaccharides are exposed to intestinal enzymes from brush border
4. Colon: dietary fibres & resistant starch fermented by flor & produces SCFA & gas

Question 4

What is the absorption of CHO

Answer 4

SGLT 1 make use of secondary active transport of glucose galactose w/ 2Na+ & water due to electrochemical gradient created by Na/K ATPase at the basolateral membrane
GLUT 5 affiliated diffusion of fructose
GLUT 2 on basolateral membrane & transports glucose, galactose & fructose into blood to hepatic portal vein

Question 5

What hold the amino acids together

Answer 5

Peptide bond

Question 6

What is protein sensitive towards

Answer 6

pH & temperature changes

Question 7

What is 4 endogenous sources of protein

Answer 7

1. Shed epithelial cells
2. Mucoproteins
3. Digestive enzymes
4. Leaked plasma protein

Question 8

What is the process of protein digestion

Answer 8

Mouth: mechanical digestion
Stomach protein denaturation by HCl, enzymes & proteases & breaks down protein bonds to form peptide chains. Pepsin also responsible for digestion
Small intestine majority of digestion in duodenum & upper jejenum by pancreatic proteases & pancreatic brush border enzymes

Question 9

What is the 3 process of protein absorption

Answer 9

AA use Na/K transporter
Tri-/dipeptides used H co transporter (peptide transporter)
Large peptides also absorbed like Ab
All absorbed into blood & hepatic portal vein

Question 10

What is the 3 forms of lipids

Answer 10

TG, Ch & phospholipid

Question 11

What is the process of fat digestion

Answer 11

Mouth food chewed & mixed w/ lingual lipase
Stomach gastric lipase partially digest SCFA & MCT to FA & glycerol
Small intestine bile emulsification to increase surface area & FA + Ch + bile salts form micelle that is soluble in chyme
Colon in stool <10% unabsorbed FA

Question 12

What is the process of fat absorption

Answer 12

Apical surface of enterocyte, FFA & monoglyceride diffuse from micelle & form TG
TG + phospholipid + Ch + protein form chylomicron & gets absorbed into lacteal
Transported to systemic circulation via thoracic duct

Question 13

What is the function of apoproteins

Answer 13

Aids in absorption of fats & makes it more stabile

Question 14

Where does most absorption of vitamins & minerals occur

Answer 14

Small intestine as it is released from digestion of macronutrients

Question 15

Where is the different types of vitamin & minerals absorbed (fat-, water soluble, B12 & calcium)

Answer 15

Fat soluble vitamins at small intestine as micelle
Water soluble vitamins at ileum w/ Na cotransporter
B12 w/ intrinsic factor at stomach
Calcium dependant on vitamin D, blood calcium levels & PTH levels

Question 16

What is 6 factors that influence absorption efficacy

Answer 16

1. Binding of nutrients to another substance that prevent absorption, enhance absorption or is required for absorption
2. pH (iron, Ca & B12)
3. Competition around active transported w/ another nutrient
4. Nutritional need, deficiency, excess supply or hormonal control
5. The form of vitamin/mineral ingestion
6. Part of phosphate that is indigestible