Pain-killing drugs bear a remarkable resemblance to

Endorphins

Endorphins are known to be body natural painkiller; they are produced by the central nervous system and the pituitary gland. Endorphins interact with receptors (opiate) in the brain to other to reduce the perception of pain and they act similarly to drug s such as codeine and morphine.

structure is maintained and sustained by:

-cytoskeleton: gives cells coherence

-cell wall: support

-cytoplasm: shape

hope this .

stimulus is a change in the environment that causes an organism to react. the response is the reaction to the stimulus. some examples of stimuli for zebras are drought, to many predators, and bad feeding grounds such as dead grass or plants. zebras respond to stimuli just like all other living organisms