Neurons

Question 1

What defines the CNS?

Answer 1

Neurons in the brain and the spinal cord

Question 2

What are neurons and their function?

Answer 2

Neurons are specialised cells which gather signals; process them; depending on processing, send signals to other neurons

Question 3

Name parts of a neuron

Answer 3

Dendrites
Cell body
Nucleus 
Axon
Nodes of Ranvier
Myelin (sheath) 
Pre synaptic terminal

Question 4

Define what is meant by a myelin sheath

Answer 4

Fatty layer of insulation around the axon which speeds conduction.

Fact: loss of myelination causes disease states such as multiple sclerosis

Question 5

What is the simple process of neuron firing

Answer 5

1. Gathers signals from dendrites
2. Sums electrical signals
3. If it reaches threshold, cell fires and sends AP down axon causing pre synaptic terminals to release neurotransmitters into the synapse
4. Neurotransmitters cause next dendrite to be exited or inhibited

Question 6

What determines neuron function?

Answer 6

1. Shape (e.g. Dendrite density)
2. Size: axon length, width and myelin
3. Spacial arrangements: sensory; axon towards brain (afferent). Motor; dendrite from brain (efferent). Interneurons; neuron to neuron connection