4.2.2.1 the human digestive system Flashcards
What is the digestive system
It is an example of an organ system in which several organs work together to digest and absorb food.
State the order of the digestive system
Mouth, oesophagus, stomach, small intestine, large intestine, rectum, anus.
What is metabolism
The chemical processes (requiring energy) that occur within a living organism in order to maintain life.
What is a metabolic rate
Speed at which the chemical reactions occur within an organism
What happens during digestion
Large food molecules are broken down into small molecules by enzymes. The smalls molecules can then be absorbed into the circulating blood stream, travelling to tissue that needs repairing.
What is the function of the mouth
To chew food, enzymes in saliva break down starch into smaller sugar molecules
What does the oesophagus do
(Food pipe) this joins mouth and the stomach, food is squeezed to stomach.
What does the stomach do
HCl and enzymes digests proteins. Food is churned for hours here.
What does the small intestine do?
Small food molecules are absorbed into blood. The small intestine has small walls and villi to increase surface area.
What are villi
They help increase the surface area within the small intestine
What does the large intestine do
Water absorption and absorption of salts from undigested materials takes place here. The large intestine is the source of excretion, separating waste from wanted nutrients.
What does the rectum do
Stores waste until faeces is released into the toilet.
What does the liver do
Releases chemicals into small intestine. Bile is released here
What is bile
Bile is made in the liver and is stored in the gall bladder. It is alkaline to neutralise hydrochloric acid from the stomach. It also emulsifies fat to form small droplets which increases the surface area.
What increases the rate of fat breakdown by lipase
The alkaline conditions and large surface area
The products of digestion are used to build new carbohydrates..
Lipids and proteins.
Carbohydrases break down … into..
Carbohydrates into simple sugars
What does amylase break down and what is it broken down into
Carbohydrates and starches are broken down into glucose
Where is amylase found
In saliva and in the pancreas
What does protease break down and what is it broken into
Proteins are broken down, into amino acids
Where is protease found
In the stomach, small intestine and pancreas
What does lipase break down and what is it broken down into
Lipids are broken, broken down into glycerol and fatty acids
Where is lipase found
Pancreas and small intestine
What are enzymes
They catalyse (speed up) chemical reactions
_______ and ____ both emulsify fats, (speeding the reaction up)
Lipase and bile
What is an enzymes active site
The groove on their surface
What attaches to active sites
Substrates
What is a substrate
The surface on which an organism lives on which an enzyme can act.
Why are enzymes important during digestion
Enzymes are important as they break down food into certain acids and sugars. The three main enzymes are lipase, protease and amylase. For example, protease breaks down proteins into amino acids which then can be absorbed by the bloodstream. Food needs to be broken down as the molecules are too large to enter the bloodstream, therefore enzymes ensure that they are broken down so that the blood can absorb the useful product and the body can excrete the waste product.
What happens to enzymes if they are too cold
They become inactive, meaning, the collisions are decreased with substrates, reducing chance of attachment.
What happens to enzymes if they are too hot
They become denatured, meaning the active site changes shape and substrates de-attach
Enzymes work best at the ________ Ph
Optimum
What happens if the Ph of an enzyme is too high
The enzymes active site changes shape, becoming denatured
Depending of the enzyme the ________ pH changes
Optimum
What happens if the pH of an enzyme is too low
The active site changes shape and therefore the substrate can no longer fit within it. The enzyme has become denatured
