The system in the body that exchanges substances with the environment, breaking down large insoluble food molecules into smaller, soluble molecules that can be absorbed and used by cells
Main organs of the human digestive system
Mouth (containing teeth, tongue and salivary glands)
Gullet
Stomach
Liver
Gall bladder
Duodenum
Bile duct
Small intestine
Pancreas
Large intestine
Rectum
Anus
Digestive system
A muscular tube that squeezes food through it, starting at the mouth and ending at the anus
Contains glands like the pancreas and salivary glands that make and release digestive juices containing enzymes to break down food
Stomach and small intestine
Main organs where food is digested
Enzymes
Break down large insoluble food molecules into smaller, soluble ones
Small intestine
Adapted to have a very large surface area as it is covered in villi
Has a good blood supply and short diffusion distances to the blood vessels, greatly increasing diffusion and active transport from the small intestine to the blood
Digestion in the digestive system
1. Food is squeezed through the digestive system
2. Enzymes break down large insoluble food molecules into smaller, soluble ones
3. Soluble food molecules are absorbed into the blood in the small intestine
4. Undigested material passes into the large intestine where water is absorbed
5. Remaining material forms faeces which are stored and then passed out through the rectum and anus
Liver
Produces bile which helps in the digestion of lipids
Organs in a digestive system
Rely on each other to function properly
Organ
A structure in the body that carries out a specific function
Organ system
A group of organs that perform specific functions in the body
