B2 Digestive System
What Are Protiens Broken Down By
Proteins are broken down by a group of enzymes called proteases into individual monomers called amino acids.
What Is Starch A Polymer Of
glucose, produced by plants.
What Is Starch Broken Down By
by the enzyme amylase into maltose molecules. These are then broken down further by maltase into glucose
two examples of protease enzymes
Pepsin
Trypsin
What Are Lipids Broken Down By
broken down by lipase enzymes, and converted into glycerol and fatty acids
How does bile help with the digestion of lipids
! It emulsifies the lipids / fats
- it breaks the fats into tiny droplets
! which increases the surface area for lipase enzymes to break them down
! Which makes digestion faster
What Is Bile
! Bile is produced in the liver
! It is stored in the gall bladder before it is released into the small intestine
How Does Bile Help Hydrachloric Acid
! Hydrochloric acid in the stomach makes the ph too acidic for enzymes in the small intestine to work properly
! Bile is an alkaline - it neautralises the acid
! makes conditons alkaline
! The enzymes in the stomach work best in alkaline conditions
Salivary Glands
These produce amylase enzyme in the saliva
Gullet
Oesophagus
Liver
Where bile is produced
Bile neautralises stomach acid and emulsifies fats
Gall Bladder
Where bile is stored before it is released into the small intestine
Large Intestine
Where excess water is absorbed from the food
Stomach
! It pummels the food with it s muscular walls
! It produces the protease enzyme pepsin
! It produces hydrochloric acid for two reasons
1 ) To kil bacteria
2 ) To give the right ph for the protease enzyme to work
Pancreas
Produces protease , amylase and lipase enzymes
It releases these into the small intestine
Small Intestine
1 ) Produces protease , amylase and lipase enzymes to complete digestion
2 ) This is also where the digested food is absorbed out of the digestive system into the blood
Rectum
Where the faeces ( made up of indigestible food ) are stored before they are released through the anus
Name Three Parts Of The Digestive System That Produces Protease Enzymes
Pancreas
Stomach
Small Intestine
The digestive system has two main roles. Briefly describe each of them
Digestion - process of breaking down large food molecules into smaller molecules
Absorption - process of absorbing these small food molecules into the body
Three roles of the stomach
1 ) The stomach contracts its muscular walls to churn and mix the food.
2 ) It produces pepsin, which is a type of protease enzyme, and breaks proteins down into amino acids.
3 ) It produces hydrochloric acid, which a) provides the right pH for pepsin to function, and b) kills microorganisms.
Two roles of bile
Bile is made by the liver, but it is stored in the gallbladder
After we have meal, it is released into the small intestine where it helps in two ways:
1 ) One is to emulsify lipids, which means separate large droplets of lipid into smaller droplets.
2 ) The other is to neutralise the acid from the stomach, which bile can do because it is alkaline
Villi are finger-like protrusions of the small intestine that are responsible for absorbing nutrients into the body.
Give three ways in which villi are adapted for this role.
! There are many villi, which gives them a large total surface area over which to absorb nutrients
! They have a single layer of cells on their surface, which means nutrients only have to diffuse a short distance.
! They have a good blood supply which maintains a strong concentration gradient between the lumen and the blood
! The cells lining the villi have microvilli on their surface, which further increases the surface area