The Nervous System The NERVOUS SYSTEM consists mainly

The Nervous System The NERVOUS SYSTEM consists mainly of the brain, the spinal chord, nerve cells (“neurones”) and receptors. Types of receptor: 1) Light receptors in the eyes 2) Sound receptors in the ears 3) Taste receptors on the tongue 4) Smell receptors in the nose 5) Touch, pressure and temperature receptors in the skin 6) Changes of position receptors in the ears (balance) 11/02/2022 Stimulus Receptor Coordinator Effector Response

Examples of reactions Stimulus Receptor (i. e. the thing that detects the stimulus) Bright light Sour taste Losing balance Sit on a drawing pin 11/02/2022 Effector (i. e. the thing that will do the reaction) Response (i. e. action taken)

Types of nerve cell Nucleus Cell body Muscle strands (effector) Nerve cells (neurones) are elongated with branched endings to connect to many muscles fibres. 1) Motor neurone 11/02/2022 Impulse 2) Sensory neurone Impulse 3) Relay neurone

Conscious actions A conscious action is one where the brain makes a considered response. Here’s what happens: 4) The brain decides to move away the 3) Here another sensory neurone hand carries the signal to the brain 5) This impulse is sent by MOTOR NEURONES to the hand muscles (the effectors) via the spinal chord… 2) The impulse is carried by SENSORY NEURONES to the spinal chord 1) Receptors in your skin detect a stimulus 6) Which then moves the hand away Stimulus 11/02/2022 Receptor Motor Neurone Sensory Neurone Effector Coordinator Response

Reflex actions Sometimes conscious action is too slow to prevent harm, e. g… In situations like this the body bypasses the brain to produce a quicker response. Here’s how it works… 11/02/2022

Reflex actions 11/02/2022

Synapses Neurones never touch each other – there is a small gap between them called a SYNAPSE. A signal is sent from one neurone to the next by a chemical transmitter across the synapse. These transmitters are then destroyed. 11/02/2022