Animal Organs
Large multicellular organisms develop organ systems to perform certain functions. During development, cells differentiate so that they are able to perform their specific function.
A tissue is a group of cells whose structure and function is the same or similar.
Examples of tissues are:
Muscular tissue -- these contract so that the organism can move
Glandular tissue -- these produce (secrete) substances such as hormones and enzymes
Epithelial tissue -- some parts of the body are covered in this.
Tissues make up organs. One organ can be made up of several different tissues.
An example of an organ is the stomach. The stomach is made up of:
Muscular tissue -- this churns up the contents
Glandular tissue -- this produces digestive juices
Epithelial tissue -- this covers the outside and inside of the stomach.
Organ systems are groups of organs that work together to perform a specific function.
An example of an organ system is the digestive system. This contains:
Glands -- these produce digestive juices (examples of glands in the digestive system include the pancreas and the salivary glands)
The stomach and small intenstine -- this is where digestion occurs
The liver -- this produces bile
The small intestine -- this is where soluble food is absorbed
The large intestine -- this is where water is absorbed from undigested food, producing excretion (poop).