The Nervous System

The nervous system is made up of the central Medical RF.Com/Science Photo Library The nervous system is made up of the central nervous system (CNS) and the peripheral nervous system.

Nervous system- sense organs

The Nervous System We have 5 sense organs that help us detect our surroundings Ears- Sound and balance Nose- Chemicals (smell) Tongue- Chemicals (taste) Skin- Touch, heat, pressure Eyes- Light

Stimulus Receptor Coordinator Effector Response The Nervous System The NERVOUS SYSTEM consists mainly of the brain, the spinal cord, nerve cells (“neurones”) and receptors. CNS Central Nervous System is made up of the brain and spinal cord. Types of receptor: Light receptors in the eyes Sound receptors in the ears Chemical receptors on the tongue and in the nose Touch, pressure and temperature receptors in the skin Changes of position receptors in the ears (balance) Stimulus Receptor Coordinator Effector Response

Examples of reactions Bright light Sour taste Losing balance Stimulus Receptor (i.e. the thing that detects the stimulus) Effector (i.e. the thing that will do the reaction) Response (i.e. action taken) Bright light Eye Pupil Pupil constrict Sour taste Taste bud Salivary Gland Produce saliva Losing balance Ear Muscles Movement (stop you falling down) Sit on a drawing pin Touch receptors Movement

Structure of a motor neurone. The nerve impulse is carried along the nerve fibre.

Extension

A reflex arc

The impulse goes from receptor to CNS and then to effector to bring about the response. The relay neurone (purple) inside the spinal cord coordinates the response by connecting the sensory neurone to an appropriate motor neurone (green). The information travels from one neurone to another across a small gap called a synapse.