3. Digestion Flashcards
What is the difference between absorption and assimilation?
Absorption=taking soluble molecules into the body. This occurs when molecules cross the cell surface membranes
Assimilation=Incorporating absorbed molecules into body tissue
PHYSICAL digestion
Large pieces of food are broken into smaller pieces
This is done by the teeth and the stomach muscles which churn the food up
Provides a large surface area for chemical digestion
CHEMICAL digestion
Large insoluble molecules broken down into smaller ones
Brought about by enzymes
All digestive enzymes function by hydrolysis
This is the splitting of molecules by adding water
Enzymes are specific
Hydrolysis
OESOPHAGUS
Carries food from mouth to stomach.
It is adapted to transport rather than digestion/absorption.
It is made up of a thick muscular wall
STOMACH
Stores and digests food, especially proteins
Muscular bag
Inner layer is glandular tissue. Produces proteases and mucus
SMALLINTESTINE
A long muscular tube. Inner walls are folded into VILLI. Epithelial cells of villi have microvilli
Produces enzymes to digest the food
Absorption takes place here
LARGEINTESTINE
A muscular tube
Water is reabsorbed here to produce faeces
RECTUM
Final section of intestines
Faeces are stored here prior to egestion through the anus
SALIVARYGLANDS
Situated near mouth
Secretions contain amylase which breaks starch into maltose
PANCREAS
A large gland below the stomach
Produces proteases, lipases and carbohydrases
MUCUS
Produced by glandular tissue
Prevents stomach wall been digested by its own enzymes
Major parts of the digestive system
The major parts of the digestive system are:
Oesophagus
Stomach
Small intestine
Large intestine
Rectum
And the glands associated with this system:
Salivary glands
pancreas
