D3

Question 1

Small intestine absorption ( CHO)

Answer 1

digestion : polysaccharides to maltose

disaccharides broken down to monosaccharides by brush border enzymes )
Sucrose by sucrase
Lactose by lactase
Maltose by maltase

To across apical membrane into epithelia cell, need to do diffusion

glucose transporter or GLUT (fructose )
Secondary active trasporter ( glucose or galactose) co transport with NA

basolateral membrane using GLUT

Question 2

Small intestine absorption ( Protein)

Answer 2

digestion: peptides (2-3 AA) and individual
Small peptide to individual AA by brush border enzymes
small peptide + secondary active tranporter (H+) co transport
Individual AA + secondary active transporter ( NA+) Co transport
Peptide in cell broken into aa by peptidase
cross basolateral by facilitate diffusion amiono acid transporter

Question 3

Small intestine absorption ( Fat)

Answer 3

fat not very soluable
Emulsification : triglycerides goated in bile salt + phospolipids
fat globules into smaller emulsifcation droplet

bile salt + phospholipids have polar ( water like ) non polar ( not water like ) side
repel other emulsification droplet and become more water soluble
more SA

Pancreatic lipase : triglyceride to monoglyceride + 2 free fatty acid chain

across apical membraine by simple difuffsion :
if too much they will go back to bulk , so must maintain balance

Question 4

Micelle

Answer 4

Bile salt + monoglycerides and fatty acid
stop reforming of triglyceride
smaller than emulficiation
temporary to control amount of fat
help migrate to apical membrane before breaking down

Question 5

Fat pt 2

Answer 5

after crossing apical membrane
inside cell:
monoglycerides and fatty acid reform triglyceride + phopholipids + cholesterol
form chylomicron in a vesicle
exocytosis:
vesicle fuse with basolateral membrane
membrane opens up and relase chylomicron in to intertitial fluid

Question 6

Absoprtion ( small intestine )

Answer 6

Carbs + protein
Interstitial fluid to blood capilaries
join to form portal vein :
circulate to liver for usage storage or processing

fat ( Chylomicrons) : too large to go blood capillaries
Moves from interstital fluid to lacteal ( has large pore )
flow with lymphatic vessel and enter blood by subclavian vein
go to liver and adipose where lipoprotein breaks down into monoglyceride and fatty acid

Question 7

Large intestine

Answer 7

12-24 hours
microbiome :
undigested carbs : gases
Undigested fat to short chain fatty acid
small amount of vitatmin produced

Haustral churning : filling till stretch to some point
smooth muscle contract push contents forward

Question 8

Mass movement

Answer 8

3-4 times a day
wave of intese peristalsis from transverse colon
Gastrocolic reflex

Question 9

Defecation reflex

Answer 9

Rectal wall distension by mechanorecepter
signal sent to medulla
contracty rectum
relax internal anal shpincter
initial contraction of external anal sphincter
Once pressure is reached, relax external anal sphincter and expel

voluntary can overide external anal sphincter relaxation :
move back to sigmoid colon and reduc the stretch
goes away temporary