Digestive System Flashcards
What is mechanical digestion?
Mechanical digestion is digestion involving the action of teeth
What is chemical digestion?
Chemical digestion is digestion involving the action of Enzymes
What is an Enzyme?
An Enzyme is a biological catalyst. There are hundreds of different enzymes working in the body. Each one acts on a different substance.
What is a catalyst?
A catalyst is a substance that speeds up the a rate of a reaction and is not used up in the reaction
What is digestion?
The breakdown of large insoluble food molecules into smaller soluble food molecules
What is soluble?
A soluble substance is one which dissolves in a solute e.g. Water
What is insoluble?
An insoluble substance is one that cant dissolve in a solvent
Why do we need to digest food?
The food we eat is too large to get into our cells for the body to use. It must first be broken down into smaller soluble pieces. This happens in the Digestive system.
What happens after the food is digested?
After the food is digested it is absorbed into the bloodstream. The bloodstream then carries the digested food to the cells where it is needed
What is amylase?
Amylase is an example of an enzyme( a biological catalyst). Amylase is found in silva in the mouth and in the small intestine.
What does amylase do?
Amylase breaks down starch into smaller units called maltose
What does Substrate mean?
The substance on which an enzyme acts on is called the substrate of the enzyme
What does product mean?
The substance that is formed as a result of the reaction is called the product
List and explain the four stages in Nutrition?
1) Eating: the food is taken into the mouth
2) Digestion: the food is broken down into smaller, soluble molecules
3) Absorption: the digested food is taken into the bloodstream and carried out in cells where it is used
4) getting rid of undigested waste as faeces
What does the digestive system or gut consist of?
The digestive system/ gut is a long tube stretching from the mouth to the anus that consists of;
1) mouth
2) oesophagus
3) stomach
4) small intestine
5) large intestine
Explain stage 1 of digestion(mouth)?
The mouth is where the digestion begins
- enzymes in saliva(amylase) begin to chemically break down into maltose sugar
- at the same time the teeth physically break down the food into smaller pieces
Explain stage 2 of digestion(oesophagus)?
The oesophagus is a muscular tube which leads to the stomach. The food is ‘shunted’ down the oesophagus by muscular contractions of the wall
Explain stage 3 of digestion( the stomach) ?
The stomach is a big muscular bag which holds the food for three hours
- it produces enzymes and other digestive juices to digest the food
- the stomach muscle churns and mixes the food
- hydrochloric acid kills bacteria and other germs
Explain stage 4 of the digestive system(Small intestine)
More enzymes are added to complete the breakdown of the food
- the digested food now passes from the small intestine to the bloodstream. This is known as absorption
- the leftovers are water and undigested food. This is passed into the large intestine
Explain stage 5 of digestion(the large intestine)?
The main function of the large intestine is to take water back into the bloodstream to prevent dehydration
- the remaining material is called faeces and is released from the body through the anus
What do teeth do?
The teeth crush and cut the food we eat so that it is easier for the enzymes to work on it
How many teeth are in an adult human mouth?
32
What are the four types of teeth and what do they do?
Incisor: cutting and biting food
Canine: tearing food
Premolar: crushing and grinding food
Molar: crushing and grinding food
Explain how the liver and pancreas are involved in digestion?
- the liver produces bile from the liver to the small intestine where it helps break up fat into smaller pieces making it easier for enzymes to digest fat
- the pancreas produces enzymes. These enzymes pass into the small intestine where they break down food
