CNS Introduction

Question 1

What are the extensions from neurones called?

Answer 1

Dendrites.

Question 2

What is an action potential?

Answer 2

A short-lived depolarisation that moves down the axon and results in a chemical transmitter being released.

Question 3

What are neurotransmitters contained in?

Answer 3

Small pockets called vesicles.

Question 4

What is the movement of potassium and sodium across a normal membrane?

Answer 4

Potassium goes out of the cell and sodium goes into the cell.

Question 5

What is an excitatory synapse?

Answer 5

A synapse where depolarisation occurs - excitatory post synaptic potential (EPSP)

Question 6

What is the most important excitatory transmitter the brain uses?

Answer 6

Glutamate.

Question 7

What excitatory neurotransmitter is used in some areas of the brain?

Answer 7

Aspartate.

Question 8

What is an inhibitory synapse?

Answer 8

The transmitter hyperpolarizes and causes an inward negative current. An inhibitory post synaptic potential is created (IPSP).

Question 9

What is a common inhibitory neurotransmitter?

Answer 9

GABA.

Question 10

What is an alternative inhibitory neurotransmitter?

Answer 10

Glycine.

Question 11

What are the two types of synaptic summation?

Answer 11

Temporal summation and spatial summation.

Question 12

What are the differences between the two types of summation?

Answer 12

Temporal summation is when two EPSPs occur in a short time frame and add up to generate a large signal, whereas spatial summation is when two different potentials from different neurones combine to create an action potential.

Question 13

What is EPSP-IPSP cancellation?

Answer 13

When an excitatory and inhibitory potential cancel out each others effect to result in no change in membrane potential.

Question 14

Why is the CNS so complex?

Answer 14

Neurones are highly complex structures, there are multiple synapses on each neurone, there are several types of synapse, multiple transmitters, multiple receptors, multiple messenger systems and the neurones are interconnected in complex networks.

Question 15

How does a motor neurone compare to a pyramidal neurone?

Answer 15

A motor neurone has a relatively larger cell body in comparison to dendrites.

Question 16

Where are pyramidal neurones found?

Answer 16

In the cortex.

Question 17

Where are purkinje neurones found?

Answer 17

In the cerebellum.

Question 18

What is the defining feature of purkinje neurones?

Answer 18

They have lots of dendrites.

Question 19

What are the four different types of synapses?

Answer 19

Axo-somatic, axo-axonic, axo-dendritic and dendro-dendritic.

Question 20

What are the different types of CNA neurotransmitters?

Answer 20

Amines, amino acids, peptides and purines.

Question 21

What are G-protein Coupled receptors?

Answer 21

They are receptors that are linked to ion channels. When a transmitter binds, a g protein opens/closes an ion channel. They can also be linked to enzymes to release second messengers.

Question 22

What is the implication of having the CNS so complex?

Answer 22

There are multiple sites for dysfunction, resulting in subtle variations in the phenotype of disorders resulting in diagnosis problems.

Question 23

What is the implication of the CNS being so complex on drug action?

Answer 23

The drugs are rarely selective, but there are multiple possible drug targets even for a single neurotransmitter.