Digestive system Flashcards
Function of carbohydrates
Source of energy, glucose is the main respiratory substrate
Function of protein
Growth and repair
Function of lipids
Energy, make up part of cell membranes so essential fro growth
What are carbohydrates ?
Starch - a polymer of glucose. Must be broken down into glucose molecules to pass through the gut
Cellulose - made up of glucose molecules. Cannot be broken down by the digestive system so is egested from the gut
What are carbohydrates used for in humans ?
Converted into glucose for respiration, or reassembles into glycogen for storage
What is glucose used for in plants ?
Converted into starch for storage, or cellulose for cell wall synthesis
What are proteins ?
Made up of amino acids. Too large to pass through the gut wall so must be broken down into amino acids. Once inside the body they are reassembled into the needed proteins for the individual. Excess amino acids are broken down in the liver
What are lipids ?
Esters of fatty acids and glycerol. They are too large to pass through the gut wall so must be digested first.
Once in the body cells, they are reassembled into the lipids the cell needs, eg for the cell membrane
Function of the mouth
Begins the digestion of carbohydrates
Function of the stomach
Begins the digestion of protein; small molecules such as alcohol are absorbed
Function of the small intestine - duodenum
Continues the digestion of carbohydrate and protein; begins the digestion of lipids
Function of the small intestine - ileum
Completes the digestion of carbohydrates and proteins into single sugars and amino acids; absorption of single sugars, amino acids and fatty acids and glycerol
Function of large intestine
Absorption of water; egestion of undigested food
What are catalysts ?
Increase rhetoric rate of chemical reactions. Enzymes are biological catalysts.
What are enzymes ?
Proteins that are responsible for various metabolic reactions in the body.
Where is amylase produced ?
In the salivary glands, the pancreas and the small intestine
What does amylase break down ?
Starch into sugars in the mouth and the small intestine
Where is protease produced ?
The stomach, the pancreas and the small intestine.
What does protease break down ?
Proteins into amino acids in the stomach and the small intestine
Where is lipase produced ?
The pancreas and the small intestine.
What does lipase break down ?
Lipids into fatty acids and glycerol in the small intestine
Where is bile made ?
The liver
Where is bile stored ?
The gall bladder
Where is bile released into
The small intestine
What does bile do ?
Neutralises the acid that was added to food in the stomach. It also increases the rate of breakdown of fat by lipase by emulsifying fats, which increases surface area.
Why does the stomach produce hydrochloric acid ?
The enzymes in the stomach work most effectively in these conditions
pH of bile
7-8
