ch 8 Flashcards
define ingestion
it is the intake of food into the body
define digestion
it is the breakdown of foood from large to small, insolube to solube food particles
define absorption
it is passage of digested food from small intestine to blood across the wall of the small intestine
define assimilation
it is making use of food by cells where they become part of the cell
define egestion
it is the removal of undigested food out of the body
describe mechanical digestion in mouth
chewing by teeth jaw and cheek muscles
describe chemical digestion in mouth
salivary amylase enzyme turn the starch to maltose sugar at ph 7.5
describe physical digestion in oesophagus
wall of oesophagus does peristalsis , which is a wave of contractions and relaxations of muscle to push down the food
define sphincter
ring of muscles
describe mechanical digestion in the stomach
churning action, the muscle walls of the stomach contract and relax to mix the food with the gastric juice
describe chemical digestion in stomach
gastric juice, contains pepsin and HCL.
pepsin turns proteins to amino acids when ph is 2
function of HCL in stomach? [3]
-activates pepsin enzyme
-provides optimum PH 2 for pepsin enzyme
-kills bacteria in food by denaturing the bacterial enzyme
where is bile juice produced?
where is it stored?
where does it work?
liver
gall bladder
duodenum
bile juice carries out which type of digestion in stomach?
mechanical
describe and explain function of bile juice? [2]
- emulsification of fats: large fat particles (globules) are turned into small fat particles ( droplets) to incraese surface area to make it easier for chemical digestion by lipase
-neutrilization of hcl from stomach to avoid denaturing of the intestinal enzyme as they only work in ph8
describe chemical digestion in the small intestine
3 enzymes + NAHCO3 to provide optimum ph8 for the enzymes
enzymes:
-pancreatic amylase turns the starch to maltose sugar then to glucose
-pancreatic lipase turns lipids into fatty acids + glycerol
-pancreatic protease (trypsin) turns proteins into amino acids
2 similarities between pepsin and trypsin enzyme ?
-both proteases
-both digest proteins
4 diffrences between pepsin and trypsin enzyme
- pepsin works in stomach but trypsin work in the small intestine
-pepsin works in PH2 but trypsin PH8
-pepsin need HCL but trypsin need NAHCO3
-pepsin secreted in gastric juice but trypsin secreted in pancreatic juice
adaptation of the small intestine for absorbing food [7]
(explain each one)
-small intestine is very long 5m, to give enough time for food to be absorbed
-it has villi, to increase surface area for absorbtion
-villi have smaller projection on the surface called microvilli, for more increase in surface area
-villi contain blood capillaries, to absorb digested food as it passes through small pores in the blood vessels
-villi contatin lacteals (lymph vessels) , to absorb fatty acids and glycerol
-villi has thin wall (1 epithelial cell thickness), for easy passage of digested food to blood capillaries
-the epithelial cells contain much mitochondria to produce energy for active uptake
function of muscle layer in the small intestine
peristalsis
what is the disease that damages the villi in small intestine?
coeliac disease
main effect of coeliac disease?
- less absorption of nutrients
function of colon? [3]
- absorption of water
-egestion of faeces
-production of vitamin K, which is used in blood clotting
state for incisors :
no in each jaw?
shape?
function?
-4
-chisel shape with sharp edge
-cutting and biting food
