Proteins that speed up chemical reactions in the body
The chemical produced by an endocrine gland
The junction where one neuron can transfer an impulse to another neuron
Organs that produce and release chemicals either through tiny tubes called ducts or directly into the bloodstream
Transports oxygen, nutrients, and wastes; fights infection; helps regulate body temperature
The two passages that direct air into the lungs
The process of removing wastes
The complete removal or destruction of something
Includes the brain and the spinal cord
The substances in food that provide raw materials the body’s cells need to carry out all their essential processes
Tiny thin-walled sacs of lung tissue where gases can move between air and blood
A group of organs that work together, performing major functions
An organ that produces and releases chemicals through ducts or into the bloodstream
Brings in oxygen needed by cells; removes carbon dioxide from body
Fluid that travels through the lymphatic system consisting of water, white blood cells, and dissolved materials
A thick column of nervous tissue that links the brain to most of the nerves that branch out through the body
The transfer of energy from a wave to a material that it encounters
An action or change in behavior that occurs as a result of a stimulus
The involuntary reaction of jumping when you hear a loud noise