biology unit 3 (digestion) new

why do we digest food

Digestion breaks food down into smaller, soluble particles, so they can be absorbed and carried by the blood and enter cells

what is mechanical digestion

Pieces of food are physically broken down by teeth and mushed by the tounge and stomach chruning, this allows food to be swallowed and mixed with enzymes and digestive juice.

what is made when proteins react with protease

Amino acids

what is made when carbohydrates react with carbohydase such as amylase

Simple sugars

what is made when lipids react with lipase

Glycerol and fatty acids

what is peristalsis

The 2 muscles lining the gut contracting in diffrent directions to move food through the digestive system

what dose the mouth do in digestion

Teeth Cut and grid food to make it easier to swallow

Salvia lubricates the food and contains charbohdrase enzymes like amylase to start digesting carbohydrates like startch

what dose the oesophagus do in digestion

Delivers food from the mouth to the stomach by peristalsis

what happens in the stomach during digestion

The stomach muscles churn the food giving it a larger surgace area and mix it with stomach acid and enzymes, the stomach acid destroys bacteria and provides optimum pH(2) for poretase enzymes, the protease enzymes digest the proteins in the food into amino acids

what happens in the small intestine during digestion

Bile from the liver neutralise the stomach acid, providing a new optimum pH for the next enzyme

Carbohydase and lipase enzymes made by the pancrease are poured onto the food

Protease and more charbohdrase enzymes made by the small intestine are also ported onto the food

Digestion si completed

where is digested food absorbed

Through the lining of the small intestine and into the blood

how is the small intestine adapted for absorption

Is very long to allow a longer time for digestion and absoprtion

Has a good blood supply to maintain diffusion

Has villi

role of the villi

To ncreases the surface area where digested food is absorbed

properties of the villi

Very thin walls for shorter diffusion distance

Excellent blood supply to takewayw the abosred digested food-this helps to maintain concentration gradient

what happens in the large intestine

The bacteria finish digested some of the material we can’t

The water is now absorbed and soild stool is formed

where is bile amde

The liver

what are the functions of bile

Neutralise stomach acid-produces new optimum pH for enzyme in the small intestine

Emulsifis lipids, the splits it into smaller bubbles with a larger overall surface area, for enzymes to act on

what is used to test for startch

Iodine

what colour change happens when startch is present

Brown to blue black

what is used to test for protien

Birtue solution

what colour change happens when protien is present

Blue to violet

how do we find out the energy in food

By burning it as chemical energy can be transformed to heat energy

what are the beinfit of using a calorimeter

It all so for fair tests and more accurate results as heat can not escape into the enviroment because it is well insulate, and the oxygen pumped in allows all food to be burned

what is used to test for glucose

Bendicts solution and heat

what colour change happens when glucose is present

Blue to brick red