Neurons and Synaptic Transmission

Outline neurons

• work as communication pathways from the brain to and from the body

• they communicate by transmitting signals both electrically and chemically

Describe motor neurons

• control muscle movement

• when stimulated release neurotransmitters which bind to receptors on muscles to trigger response

Describe sensory neurons

• found in receptors: eyes, ears, tounge

• carry nerve impulses to spinal cord and brain, which is translated into sensations

Describe relay neurons

• found in brain and spinal cord

• between sensory input and motor output

• allow neurons to communicate

What are neurotransmitters?

• influence our behaviour by effecting neighbouring neurons

• excitatory - increase the positive charge of the neurone it attaches to. This often leads to action potential by opening Na+ pathways e.g. adrenaline and dopamine.

• inhibitory- increase the negative charge of the neuron attaches to. This reduces the chance of action potential by opening e.g. serotonin and melatonin.

what is action potential

occurs when an electrical impulse is sent from the cell body, down the axon to the terminal buttons

What is synaptic transmission?

The process of an axon terminal connecting the neuron to other neurons

Describe excitatory and inhibitory neurotransmitters in synaptic transmission

• if neurotransmitter is excitatory then postsynaptic neuron is more likely to fire an impulse

• If neurotransmitter is inhibitory, then postsynaptic neuron is less likely to fire in pulse

• Excitatory and inhibitory influences are summed if net effect on postsynaptic is inhibitory neuron will be less likely to fire and if net effect is excitatory neuron will be more likely to fire

Describe the first 2 steps of synaptic transmission

• The action potential travels down the axon and reaches the terminal button

• The electric impulse opens the calcium gates and calcium floods the terminal button

Describe the next 2 steps of synaptic transmission

• vesicles containing neurotransmitters moved towards the end of the terminal button

• Neurotransmitters are released into the sign up and travel across

3 Describe the next 2 steps of synaptic transmission

• neurotransmitters bind to the receptors on the postsynaptic neuron

• message is converted back into an electrical impulse/action potential

Describe the last 2 steps of synaptic transmission

• some leftover neurotransmitter to go through a process of reuptake

• Some leftover neurotransmitters are destroyed by enzymes