Nerves

Question 1

Briefly describe the structure of a neuron

Answer 1

Projections called dendrites
Cell body w nucleus and organelles
Axon
Myelin sheath 
Nodes of ranvier 
Axon terminal W terminal buttons

Question 2

What is the function of sensory neurons

Answer 2

Info from PNS (sensory receptors) to CNS
Sensory receptors in eyes, skin, mouth etc
Sensory info = neural impulse decoded in brain making appropriate sensation and we react accordingly
Enable reflex actions

Question 3

What is the structure of sensory neurons

Answer 3

Long dendrites short axons

Question 4

What is the function of a relay neuron

Answer 4

Connect sensory and motor or other relay neurons inside CNS

Question 5

Describe the structure of a relay neuron

Answer 5

Short dendrite long axon

Question 6

What is the function of the motor neurons

Answer 6

Connect CNS to muscles and glands
Project axons out of CNS and directly or indirectly control muscles
Connect w muscle and control contraction
When axon is activated = contraction, inhibited = relaxation

Question 7

Describe the structure of motor neurons

Answer 7

Short dendrites long axons

Question 8

Describe transmission within the neuron

Answer 8

Electrical impulse travels through due to action potential. Inside is negatively charged compared to outside but when activated the inside becomes positively charged for small amount of time and the electrical impulse travels to the pre synaptic neuron.

Question 9

Describe transmission between neurons

Answer 9

Separated by a synapse. Electrical impulse triggers neurotransmitters to be released by chemicals into synapse, they diffuse and are picked up by post synaptic receptor sites. Chemical message converted to electrical impulse and starts again. Neurotransmitters have specialised receptor sites in a lock and key mechanism. Remaining neurotransmitters are reuptaken by pre synaptic neuron and stored for later use

Question 10

What is an excitatory neurotransmitter

Answer 10

Causes the neighbouring neuron to fire - EPSP released so more likely to fire

Question 11

What is an inhibitory neurotransmitter

Answer 11

Neighbouring neurone less likely to fire - releases IPSPs which make neuron less likely to fire

Question 12

What is summation

Answer 12

Neighbouring neuron receives EPSP and IPSP - whichever there is more of (net effect). Excitatory = fires, IPSP = doesn’t.