Stomach

The stomach is a storage tank for digesting food. Its walls have a lot of muscle in them so it can stretch if you eat a lot of food. It can hold up to a gallon of food. When it is empty, it shrinks back down and its walls fold up into wrinkles called rugae.

The lining of the stomach has lots of goblet cells that make a slimy mucous that protects the stomach from the powerful acids it uses to digest food. There are also gastric pits that make the gastric juice. Gastric juice is a mixture of chemicals that digest food.
It includes; hydrochloric acid (HCL) that kills bacteria on the foods you eat and helps the other chemicals work. Another chemical in gastric juice is pepsin, the chemical that digests proteins.

The stomach is where protein digestion begins. The stomach does both mechanical and chemical digestion. It churns the food and mixes it with the gastric juices. By the time it leaves the stomach, the food is broken down into a creamy paste called chyme.

Now it is ready to move on to the small intestine.

NGSS Life Science Progression K-12


LS1.A Structure and Function


K-2 All organisms have external parts that they use to perform daily functions.
3-5 Organisms have both internal and external macroscopic structures that allow for growth, survival, behavior, and reproduction.
6-8 All living things are made up of cells. In organisms, cells work together to form
tissues and organs that are specialized for particular body functions.
9-12 Systems of specialized cells within organisms help perform essential functions of life. Any one system in an organism is made up of numerous parts. Feedback mechanisms maintain an organism’s internal conditions within certain limits and mediate behaviors.