Organisation and the digestive system (The chemistry of food (Reaction ,…
Organisation and the digestive system
Tissues and organs
A tissue is a group of cells with a similar structure and function
Organs are collections of tissues performing specific functions
The stomach contains muscular tissue to churn the food and digest juices, glandular tissue to produce digestive juices that break down the food, and epithelial tissue which covers the inside and outside of the organ.
The pancreas (glandular organ) makes hormones that control the blood sugar level as well as some of the enzymes that digest food.
Organs are organised into organ systems, which work together to form organisms
Organ systems in the body include the circularity system and the digestive system.
Cells create tissues, which create organs, which create organ systems, which create organisms (humans)
The human digestive system
Organ systems are groups of organs that perform specific functions in the body
The digestive system in a mammal is an organ system where several organs work together to digested and absorb food
It is between 6 and 9 metres long
The digestive system turns large insoluble molecules into small soluble molecules that can be absorbed by cells.
The digestive system contains many different organs and glands. Glands such as the pancreas release enzymes to break down food.
The small intestine is where molecules are absorbed into your blood. From there it is transported around your body.
The small intestine has adapted to have a very large surface area (covered in villae). This increases the diffusion and active transport rates.
The chemistry of food
Carbohydrates are made up of units of sugar
Simple sugars are carbohydrates that contain only one or two inits
Complex carbohydrates contain long chains of simple sugars bonded together
Lipids consists of three molecules of fatty acids bonded to a molecule of glycerol
Starch turns yellow
Iodine turns purple
Ethanol tests indicates the presence of lipids
Proteins turn biuret from blue purple
Protein molecules are made of chains of amino acids
Catalysts and enzymes
Enzymes are biological catalysts. They catalyse specific organisms using their shape
Enzymes are proteins. The amino acid chains are folded to form active sites which match the shape needed to fit the enzyme
Enzymes can join molecules together as well as break large molecules up.
Enzymes control metabolism. Enzymes build up starch, glycogen or cellulose from glucose; lipids from fatty acids; or proteins from amino acids.
They also break down large molecules such carbohydrates, lipids and proteins.
Factors affecting enzyme reaction
It is affected by pH and temperature
High temperature denature enzymes which means they cant react.
pH effected the shape of the active site and either stops is working or makes it work efficiently
How the digestive system works
Digestion involves the break down of large insoluble molecules into small soluble molecules
Digestive enzymes are produced by the glands in the lining of the digestive system
Proteases breaks down the amino acids
Amylase breaks down carbohydrates into simple sugars
Lipases breakdown lipid into fatty acids and glycogen
Making digestion efficient
Proteases works best in acid condition
This is why it is effective in the stomach because it produces hydrochloric acid
Bile neutralises acid
Bile also breaks up large drops of fat into smaller droplets. This provides a bigger surface area for the lipases to act upon. This therefore increase the speed of the chemical break down.
Your stomach produces a thick layer of mucus which prevents the stomach digesting itself. Because enzymes work better at different pH levels, bile (produced in the liver) is introduced into the stomach to increase the work rate of the relevant enzyme.