Digestion Flashcards
What helps chemical digestion take place more quickly and how is it achieved
Increase in surface area
Physical digestion breaks food into smaller pieces
Describe peristalsis
The process of food passing through the gut
Starts at oesophagus and continues through alimentary canal
Food moves along by contraction of circular muscles in gut wall
What is produced in the liver
Bile
What is function of gall bladder
Bile stored here before it is released into the small intestine
What does large intestine do
Absorb water into bloodstream
By this stage the material in large intestine has had most/all of useful food molecules removed
What does small intestine do
Digestion and absorption of useful food molecules into blood
Chemical digestion
Uses enzymes to break down large insoluble molecules (carbohydrates,fats and proteins) into smaller molecules
These can then diffuse through walls of small intestine and into blood or lymph
How are large insoluble molecules digested in the body
Digested by specific enzymes found in mouth,stomach and small intestine
Describe how insoluble carbohydrate digestion starts in the mouth
Carbohydrase enzymes break down large insoluble carbohydrates (long chains of sugar molecules eg. starch)
into small soluble sugars, individual sugar molecules
Describe the two-step process of breaking starch down into glucose
Starch (amylase) > maltose
Maltose (maltase) > glucose
Starch breaks to maltose by amylase
Maltose breaks to glucose by maltase
In the stomach how are insoluble proteins broken down
Protease enzymes break down large insoluble proteins into smaller peptides
These are ultimately broken down to soluble amino acids
Describe purpose of hydrochloric acid in stomach
Released by cells in the wall of stomach
Kills most bacteria in food and creates conditions that help enzymes to work effectively
Give example of bacteria that can survive in acidic conditions
Proteus bacterium
What does the pancreas produce to digest carbohydrates and proteins
Pancreas produces carbohydrases and proteases for digestion of carbohydrates and proteins
How does the pancreas break down fats
The pancreas produces lipase enzymes to break down fats into fatty acids and glycerol
Why do protease enzymes work so well in the stomach
Stomach acid provides optimum pH for protease ezymes to work
Other enzymes in the mouth and small intestine require more alkaline pH for optimal acivity
Describe how soluble molecules absorbed into blood
Small soluble molecules (produced by digestion) are absorbed into the blood through wall of small intestine
Done mainly through diffusion (some active transport)
After soluble molecules enter blood how do they then enter body tissues
Molecules enter blood in small intestine and enters body tissues after being processed by the liver
How is the small intestine adapted for efficient absorption of food
Being very long
Possessing thousands of villi and microvilli (on epithelial cell) which increases surface area
Thin lining reduces diffusion distance for dissolved food molecules
Good blood supply from extensive capillary network
Why is fat hard to digest
Does not mix easily with water in the intestine
Why is bile produced in the body
Emulsifies fat droplets
(breaks big droplets into smaller drops, increase surface area) Enables lipase enzymes to work faster (break down fats into fatty acids and glycerol)
Physical digestion
Includes chewing and squeezing food in the stomach to break it into smaller pieces to pass through gut easily
