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organisation of the digestion system - Coggle Diagram
organisation of the digestion system
tissues and organs
cells-tissue-organ-organ system-organism
a tissue is a group of cells with a similar function
an organ is a group of tissue
human digestive system
1) food is broken down in mouth using mechanical break down and saliva containing amylase
2) food gets taken to the to the stomach down the oesophagus using peristalsis which is where it contracts to push the food down
3) stomach contains hydrochloric acid which kills bacteria and creates the optimum pH for pepsin (a protease enzyme)
muscular walls mechanically break down food in stomach
4) food gets taken to the small intestine where the enzymes amylase, protease and lipase break the food down
small intestine also absorbs the nutrients
5) goes to the large intestine where excess water is removed to create stool
rectum poos out the stool
enzymes
protease
produced in stomach, small intestine and pancreas
breaks down proteins into amino acids
amylase
produced in the salivary glands, stomach small intestine
breaks down starch (carbohydrates) into simple sugars such as glucose
lipase
produced in the small intestine and the pancreas
breaks down lipids into glycerol and fatty acids
lock and key diagram
every enzyme has to have a specific active sight to fit the molecules substrate when they bind the enzyme substrate complex is formed
if the temperature is too high the enzyme will become denatured meaning it cant lock onto the substrate
if the pH is too high or low the enzyme will become denatured
what is an enzyme?
it is a biological catalyst that speeds up the rate of reaction without being used up
e.g:breaking food down
liver
gull bladder
the liver produces bile
which is stored in the gull bladder
bile is alkaline and is released into the small intestine to neutralise the hydrochloric acid and create slightly alkaline conditions for the optimum pH
bile breaks down fat into tiny droplets to increase the rate of breakdown as the surface area increases (emulsification)
small intestine
contains villi which increases surface area
round the edge it has a single layer of cells for a short diffusion pathway
good blood supply means nutrients can be quickly absorbed through the one cell thick membrane
food tests
1) lipids - add ethanol to see if lipids are present a white foamy layer is formed if present
2) proteins- add biuret solution, goes purple if present
3) glucose- add benedict solution and heat up, if present it can turn either green, yellow or brick red
4) starch- add iodine if it turns black or blue black starch is present