the force that pulls objects towards the Earth
gravity
a special muscle that pumps blood around the body
heart
cannot be changed back to what it was before
irreversible
the organ which breaks down food into tiny particles that can move into the blood; undigested food is pushed out at the end of it
intestines
bean-shaped organs that filter blood to remove wast products
kidneys
the organs we use for breathing
lungs
the brain and nerves
nervous system
a part inside the body that carries out a specific function to keep us alive
organ
different organs that work together to carry out a certain function in the body
(organ) system
making the environment dirty with waste products
pollution
a consumer that eats other animals (which are their prey)
predador
an animal that is eaten by another animal (a predador)
prey
to re-process something and make into a new product
recycling
a store of something necessary for life, such as water, energy and minerals
resource
can be changed back to what it was before
reversible
liquid produced in the mouth
saliva
