2.85

describe the structure and functioning of a simple reflex arc illustrated by the withdraw of a finger from a hot object.

the different parts of the nervous system may be involved when your body responds to a stimulus- simplest response is reflexes.

reflexes are rapid, automatic responses to a specific stimulus that often acts to protect you in someway. eg. blinking if something gets in your eye or sneezing if you breathe in dust.

the pathway that signals travel along during a reflex is called a reflex arc:

stimulus -> receptor -> sensory neurone -> relay neurone in CNS -> motor neurone -> effector -> response.

simple reflexes are usually spinal reflexes- means that the signals are processed by the spinal cord not the brain. the spinal cord sends a signal back to the effector.

effectors are parts of the body that respond eg. muscles or glands.

example of spinal reflexes include touching a hot object: