Absorption

Question 1

products of digestion

Answer 1

amino acids, glucose, monoglycerides and fatty acids

Question 2

assimilation

Answer 2

use of products of digestion (for protein synthesis, respiration and formation of phospholipid bilayer)

Question 3

structure of the ileum in terms of absorption

Answer 3

mucosal layer contains folds, with contain further folds in the epithelial cell membrane

Question 4

how do villi and microvilli increase efficiency of absorption?

Answer 4

increase SA available for insertion of carier proteins to increase rate of absorption

Question 5

how does circulating blood increase absorption efficiency?

Answer 5

maintains concentration gradient by transporting products of digestion away

Question 6

how does a thin ileum wall increase absorption efficiency?

Answer 6

decreases distance for diffusion so increases rate of absorption

Question 7

how does a muscle layer increase absorption effiency?

Answer 7

maintain diffusion gradient by “pushing” molecules agains the villi

Question 8

where does absorption take place from and to?

Answer 8

From ileum lumen into:
capillary network
lacteal

Question 9

function of the Golgi body in absorption

Answer 9

• modifies/processes triglycerides
• combines them with proteins to form chylomicrons
• packages chylomicrons/triglycerides for release by exocytosis

Question 10

3 mechanisms for absorption

Answer 10

diffusion, active transport ad osmosis

Question 11

deamination

Answer 11

process of removing an amino group from an amino acid

Question 12

assimilation of glucose

Answer 12

glucose taken up for aerobic respiration to produce ATP

Question 13

what happens to excess glucose?

Answer 13

converted to glycogen or fat stores and stored in the liver

Question 14

assimilation of fats

Answer 14

used to form the phospholipid bilayer of cells

Question 15

what happens to excess fats?

Answer 15

stored as adipose tissue

Question 16

why can’t we store excess amino acids?

Answer 16

they are toxic in high concentrations due to the nitrogen they contain

Question 17

5 steps of absorption of lipids

Answer 17

1. monoglycerides ad fatty acids are released from micelles and enter the epithelial cells of mucosal tissue by simple diffusion
2. mooglycerides and fatty acids reform triglycerides
3. in golgi body, triglycerides are combined with proteins to form chylomicrons
4. chylomicrons released from epithelial cells by exocytosis and enter the lacteal
5. transported in lymph away from ileum and enter blood at thoracic duct

Question 18

why from chylomicrons?

Answer 18

surround trigycerides with a protein so soluble n water so can be transported in blood plasma

Question 19

4 steps of absorption of glucose/a.a.

Answer 19

1. Na+/K+ntiporter actively transported NA+out epithelial cellinto tissue fluid and K+ into epithelial cell
2. Na+ ion concentration loered inside cell, below that of gut lumen, creating a concentration gradient
3. Na+ ions passively transported into cell by facilitated diffusion via a symporter, which prvides energy to pull glucose/a.a. with them actively
4. Glucose/a.a. concentration increases above that of capillary so they’re transforted by facilitated diffusion into TF, via carrier proteins, down a concentration gradient