1: Physiology - Neurons, excitation and inhibition in the CNS Flashcards Preview

Neurology Week 2 2018/19 > 1: Physiology - Neurons, excitation and inhibition in the CNS > Flashcards

Flashcards in 1: Physiology - Neurons, excitation and inhibition in the CNS Deck (40)
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1

What is the start of an axon called?

Hillock

2

How are materials like mitochondria, proteins etc. transported along a nerve axon?

Axonal transport

3

What are the names of axonal transport which move materials

a) towards the presynaptic terminal

b) towards the cell body?

a) Anterograde axonal transport

b) Retrograde axonal transport

4

How do viruses travel within nerves?

(Retrograde) axonal transport

5

What is a synapse?

Point of chemical/electrical communication between nerve cells

6

What is a neurite?

A structure which projects from a nerve cell body

so an axon or a dendrite

7

unipolar, multipolar neurons

8

What is meant when describing an axon by its Golgi type?

Golgi type I axons are long

Golgi type II axons are short

9

What is the membrane potential of

a) sodium

b) potassium?

a) +60 mV

b) -90mV

10

In general, what is the threshold potential of a neuron?

The membrane potential required for Nachannels to open

11

Which channels open to cause the upstroke of an action potential in neurons?

Na+

12

What channels open to cause the downstroke of an action potential?

K+ channels

13

What overcompensations are caused by the opening of

a) sodium

b) potassium?

a) Overshoot

b) Undershoot

i.e the membrane hyperpolarises before returning to normal

14

What is the difference between the conduction of action potentials and passive signals through nerve axons?

Action potentials have a fixed amplitude all the way along so they can travel long distances

Passive signals decay in amplitude and can therefore only travel short distances

15

How far can action potentials travel in the body compared to passive signals?

Much further than passive signals

16

Revise ohm's law (V=IR)

Resistance of axon is constant

Current leaks as you go along the axon

So the further along the axon you go, the greater the decrease in action potential

17

from what I can tell...

decreasing resistance INCREASES length constant because the action potential can travel further before decaying to 37% (specific number because it matches to exponential function)

look at ratio specifically

 

18

rm/ri

19

How does conduction velocity change with an increasing length constant?

The greater the length constant, the greater the distance the current can spread without decaying

So the greater the conduction velocity

20

How does insulating a nerve axon with myelin increase the conduction velocity?

Insulation INCREASES membrane resistance while internal resistance remains unchanged

So the ratio rm/ri INCREASES

So length constant INCREASES

So conduction velocity increases

21

Which glial cells insulate nerve axons in the

a) CNS

b) PNS?

a) Oligodendrocytes

b) Schwann cells

22

What is a Node of Ranvier?

Gap between Schwann cells (found only in the PNS)

23

What is saltatory conduction?

The jumping of an action potential between Nodes of Ranvier

24

Saltatory conduction occurs only in (myelinated / unmyelinated) neurons.

myelinated PNS neurons only

because they have Nodes of Ranvier

25

How does myelination change the conduction velocity?

Myelination increases conduction velocity

26

Which type of disease slows down or stops nerve conduction?

Demyelinating disorders

27

Which demyelinating disorders affect the

a) CNS

b) PNS?

a) MS

b) Guilain-Barre syndrome

28

What is the name of the space between pre-synaptic and post-synaptic neurons?

Synaptic cleft

29

In terms of a synapse, what is a vesicle?

Structure which contains neurotransmitter

30

What is a membrane differentiation?

Area between a vesicle and neurotransmitter receptor

small as possible to make neurotransmission quick