Nervous co-ordination

Question 1

Cell body

Answer 1

Contains organelles

Makes proteins and neurotransmitters

Question 2

Dentrites

Answer 2

Carries P to surrounding cells

Increased SA

Question 3

Axon

Answer 3

Long conductive fibre

Carries impulse

Question 4

Schwann cells

Answer 4

Wrap around axon, forms myelin sheath, allows node hopping

Question 5

What is resting potential

Answer 5

No impulse being conducted
More Na+ and K+ outside
-70mv

Question 6

How is resting potential acheived

Answer 6

Sodium potassium pump
2k+ in and 3Na+ out via AT
Creates concentration gradient
so K+ diffuse out and Na+ diffuse in
Membrane more permeable to K+

Question 7

How does an AP move

Answer 7

Like a Mexican wave

Question 8

How is an AP produced

Answer 8

Stimulus causing influx of Na+
Reaches threshold
Depolarisation - voltage gated Na+ channels open
AP reached - 40mv
Repolarisation - voltage gated Na+ channels close, K+ channels open
Goes past resting potential and into refractory period
Another impulse can’t be generated as Na+ channels close

Question 9

Importance of refractory period

Answer 9

Ensures each impulse is separate
Ensures AP travels in one direction
Prevents over reaction to stimulation

Question 10

All or nothing law

Answer 10

Depolarisation must reach at least -55mv or no AP is generated
If threshold is met/exceeded, AP is always generated and always peaks at 40mv
Makes sure animals only respond to certain large stimuli

Question 11

Factors affecting conduction speed

Answer 11

Myelination and saltatory conduction/ node hopping
Axon diameter - wider = faster as it prevents ions from leaking out
Temperature, increases rate of movement and enzyme activity

Question 12

Synapse process

Answer 12

Knob depolarised, Ca2+ moves in
Causes vesicles to move and fuse to pre synaptic membrane
Neurotransmitter released, diffuses down synaptic cleft, binds to receptors on post synaptic membrane
Causes Na+ channels to open so Na+ diffuses in
If threshold is met, AP is generated
Neurotransmitter released and returns to knob, channels close

Question 13

What neurotransmitter is used in a cholinergic synapse

Answer 13

Acetylcholine

Question 14

What is summation

Answer 14

Build up of neurotransmitter

Question 15

Spatial summation

Answer 15

Many different neurones provide enough neurotransmitter

Question 16

Temporal summation

Answer 16

One neurone repeatedly releases neurotransmitter over a short period of time

Question 17

Inhibitory synapse

Answer 17

Cl- ions move into post synaptic neurone, K+ ions move out
Lowers voltage to around -80mv
AP unlikely

Question 18

Neuromuscular junction

Answer 18

Unidirectional
Only excitatory
Connects motor neurone to muscles
End point for AP
Acetylcholine binds to receptors on muscle fibers

Question 19

Cholinergic synapse

Answer 19

Unidirectional
Excitatory and inhibitory
Connects neurone to neurone
New AP can be generated in the following neurone
Acetyl choline binds to post synaptic neurone