Neurons & synaptic transmission

what is a neuron ?

the basic building blocks of the nervous system

neurons are nerves cells that process and transmit messages through electrical and chemical signals

what are sensory neurons

they carry out messages from the PNS to the CNS.

they have long dendrites and short axons

what are relay neurons ?

these connect the sensory neurons to the motor neurons or other relay neurons

they have short dendrites and long axons

what are motor neurons

these connect the CNS to effectors such as muscle glands

They have short dendrites and long axons

what are the main structures in neurons ?

cell body

nucleus

axon

dendrites

myelin sheath

nodes of ranvier

terminal button

what is the cell body ?

this contains the nucleus

what is the nucleus ?

this is where genetic material of the cell is

what are dendrites

these are branch like structures that protrude from the cell body.

they receive / carry nerve impulses from neighbouring neurons

axons

carries impulses away from the cell body down the length of the neuron

myelin sheath ?

this is a fatty layer that protects the axon and speed up electrical transmission of the impulse

nodes of ranvier

these are the gaps that segment the myelin sheath

these speed up the transmission of the impulse by forcing it to “jump” across the gaps along axon

terminal button

at the end of the axon

they communicate with the next neuron in the chain across a gap known as the synapse

where are sensory neurons located ?

located outside the CNS, in the PNS in clusters known as ganglia

where are relay neurons located ?

they make up 97% of all neurons and most are found within the brain and the visual system

where can motor neurons be found ?

the cell bodies of motor neurons may be located in the central nervus system but they have long axons which form part of the peripheral nervous system

action potential

occurs when a neuron is activated by a stimulus, the inside of the cell becomes positively charged for a split second causing action potential

what is the charge of a neuron at resting state compared to the outside of the neuron

it is negatively charged compare to the outside

what does action potential cause

his creates an electrical impulse that travels down the axon towards the end of the neuron known as electrical transmission

synaptic transmission

the process by which neighbouring neurons communicate with each other by sending chemical messages across the gap (synapse) that separates

neurotransmitter

Brain chemicals released from synaptic vesicles that relay signals across the synapse from one neuron to another

neurotransmitters can be broadly divided from excitatory function + those that perform an inhibitory function