2 structure and function of sensory, relay & motor neurons AO1 +3

what does information travels through?

• neurons in form of electrical impulses called action potentials

• when one neuron communicates with another, info changes into electrical form into chemical form (neurotransmitters) at a synapse

in order, how does the neuron cell collects info

1 dendrites

2 cell body - weighs up info recieved and makes binary decision to fire its act. pot. or not

3 axon

4 axon terminal - action potential will travel along the axon to axon term.

motor neuron

sends commands from the CNS to move muscles

sensory neuron

• in PNS

• sends signals towards CNS about sensory experience then carry signals away from the organs in th PNS to brain and spinal cord (CNS)

• collects info from sensory organs and sends it to the CNS.

its body is not amongst its dendrites but along its axon

relay neuron

• form connections between sensory and motor neurons

• found only in CNS

conveys info from one neuron to another.

has a short axon

relay neuron

• form connections between sensory and motor neurons

• found only in CNS

conveys info from one neuron to another.

has a short axon

explain synaptic transmission

action poetential towards the axon terminal in presynaptic neuron

triggers vesicles that contain neurotransmitters move to the cell membrane at the axon terminal and burst, releasing NT into the synapse ten diffuse across the synapse

NT binds to receptors on post synaptic neuron

they dont enter the post SN but bind to receptors which triggers a signal in post SN a new impulese can be set down of next post SN, process then restarts

what happens adter synaptic transmission

once the NT have bound to the receptors and a signal has been sent in the post synaptic neuron, the NT unbind from the receptors

they float back to the presynaptic neuron which recycles at reuptake port back into vesicles

any remaining NT in the synapse are broken down by enzymes and cleared away for the next signal

describe and explain excitation and inhibition

• NT either have EX or IN effect on post SN

• EX NT makes the post synaptic cell more +ively charged and more likely to fire a new electrical impulse

eg. acetylcholine, is a NT that involved with memory and movement. more impulses make mind more busy and active

• IN NT make post SN more negatively charged, therefore less likely to fire a new electrical impulse.

eg. serotonin, makes mind calmer and less busy

summation of cell body

• summation happens in cell body of the neuron, where the excitatory and inhibitatory signals are added together.

• if there is more EX NT, neurons fires an electrical impusle

• if inhibitory NT outweigh, then neuron doesnt fire

how do these neurons work together - pan and touch away

• the receptors on skin sense the stimulus

• sensory neurons sends an electrical impulse towards CNS from the dendrites along axon to axon terminal

• in CNS, the relay neurons carry this signal to motor neuron

• transmitted the signal away from CNS towards the muscle

• move hand away