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Organ Systems |
Animals have organs that make up the organ system. The heart is the main organ that makes up the circulatory system. It moves blood through the body. All vertebrates have a closed circulatory system. Blood travels through blood vessels. Mammals have hearts with four chambers.
The respiratory system brings oxygen to the blood and removes the waste gas carbon dioxide. For humans, air travels between the mouth and lungs. Lungs take oxygen out of the air and release gases into the air.
The excretory system removes liquid wastes. Humans have kidneys, which are waste removal organs, and a bladder which stores liquid waste that then leaves the body.
The digestive system breaks down food into nutrients that can be absorbed and the circulatory system carries the nutrients to body cells. The teeth, saliva, esophagus, stomach, intestines, liver, and glands are the parts of the body used for breaking down foods. Vertebrates and most invertebrates have a digestive system.
The nervous system helps animals sense changes in the world and controls their organ systems. Vertebrates and almost all invertebrates have a nervous system. Humans have a larger region of vision than region of smell. There is a large developed area for thinking and memory.
The skeletal system forms a vertebrate’s bones. This supports the body and protects the organs. It works with the muscular system to allow a vertebrate to move. The muscular system is made up of the body’s muscles. Vertebrates must use bones and muscles together to move in different ways.
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