Nerve impulses: Transmission

?
  • Created by: Esme.B
  • Created on: 07-10-17 12:07
What causes sodium channels to open?
They are voltage-gated so slight changes in the potential across the membrane.
1 of 20
What term is given to the sideways movements of sodium ions along a neuronal away from the region of high concentration?
Local current
2 of 20
In a myelinated neurone where does diffusion of sodium and potassium ions occur?
only at Nodes of Ranvier
3 of 20
What is saltatory conduction?
Where an action potential appears to jump from one node to the next
4 of 20
What speed can myelinated neurones conduct action potentials up to?
120ms-1
5 of 20
What is meant by the 'all-or-nothing' rule?
As long as the threshold potential has been reached all action potentials reach a depolarisation of +40mV
6 of 20
What do more frequent action potentials indicate?
A higher intensity stimulus
7 of 20
What is 'Local Currents'?
The movement of ions along the neurone.
8 of 20
What does unmyelinated neurones use to allow sodium ions into the neurone?
Voltage-gated Sodium ion channels.Na+ ions diffuse from an area of high concentration along the neurone. Na+ gated channels open when the potential difference across the membrane is reduced.
9 of 20
What speed can unmyelinated neurones conduct action potentials up to?
20ms-1
10 of 20
what % of unmyelinated neurones are in the CNS (central nervous system) and PNS (peripheral nervous system)
100%- CNS / 67%-PNS
11 of 20
what does Myelin speed up?
The rate of conduction. Speed up the transmission of the impulse.
12 of 20
Whats the Myelin Sheath formed from?
Schwann Cells. Wrapped around the neurones.
13 of 20
what are the gaps between the Myelin Sheath's called?
The Node of Ranvier.
14 of 20
How does Na+ ions move into the myelinated neurone?
Ionic exchanges only occur at Nodes of Ranvier which creates elongated local currents.
15 of 20
what is Saltatory conduction?
Action potential seems to jumps from one node to the next
16 of 20
what % of myelinated neurones are in the CNS (central nervous system) and PNS (peripheral nervous system)
0%- CNS / 33% - PNS
17 of 20
suggest why Saltatory conduction makes conduction more rapid.
only a few ions needs to move along the neurone to alter the charge at the next node. The ions can move along very quickly.
18 of 20
what type of disease is Multiple Sclerosis (MS)?
Auto-immune disease.- own immune system attacks itself. Immune system attacks the myelin Sheath.- impulses not sent efficiently around the body.
19 of 20
what do the symptoms of MS depend on?
depends on where the neurone are effected. Symptoms are very diverse. Actuate or chronic. build up of scar tissue. no true cause known.
20 of 20

Other cards in this set

Card 2

Front

What term is given to the sideways movements of sodium ions along a neuronal away from the region of high concentration?

Back

Local current

Card 3

Front

In a myelinated neurone where does diffusion of sodium and potassium ions occur?

Back

Preview of the front of card 3

Card 4

Front

What is saltatory conduction?

Back

Preview of the front of card 4

Card 5

Front

What speed can myelinated neurones conduct action potentials up to?

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Neuronal and Hormonal communication resources »