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Biology Revision Year 2 > Nerves > Flashcards

Flashcards in Nerves Deck (47)
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1

describe the neurone at resting potential.

the outside is + the inside - , the membrane is polarised, the voltage is approx - 70mV,

2

describe how the Na/K pumps maintain the resting potential

Na is moved out using active transport, Na cannot diffuce back in = electrochemical gradient, pottasium is pumped in but can move out via facilitated diffusion - making the outside + compared to the inside

3

when is a neurone depolarised?

when it is stimulated

4

describe what happens when the neurone is stimulated

the stimulus excites the cell membrane, causing Na ion channels to open. Na diffuses down the electrochemical gradient, making the inside less negative

5

describe depolarisation

if the threshhold is reached (-55mV) more channels open and Na diffuses rapidly into the membrane

6

describe repolarisation

when +3mV is reached the sodium channels close up. K diffuses out through the opened channels, returning the membrane to resting potential

7

describe the nervous system in comparison to the endocrine system

nervous system is short lived, fast and localised (endocrine opposite)

8

what is included in the CNS?

brain and spinal cord

9

what is the peripheral system?

all other neurones

10

what do we dived the peripheral into?

sematic and autonomic

11

what is the sematic nervous system?

concious decision eg) muscle movement

12

what is the autonomic nervous system?

unconcious eg) heart rate

13

what 2 sections can we divide the autonomic system into?

parasympathetic and sympathetic

14

describe the parasympathetic

decreases/ slows things down eg) heart rate

15

what neurotransmitter controls the parasympathetic?

acetylcholine

16

describe the sympathetic

increases/ speeds things up eg) heart rate

17

what neurotransmitter controls the sympathetic?

noradrenaline

18

describe the route from stimulus to response

stimulus - receptor - sensory - intermediate (cns) - motor - effector - response

19

describe the receptor

specific, cell or protein, transforms stimulus into nerve impulse

20

describe the sensory neurone

Single long dendron, single short axon, (draw a diagram and check)

21

decribe the intermediate neurone

within cns, many short dendrites/ axons (draw a diagram)

22

describe the motor neurone

many short dendrites, single long axon, ends at neuromuscular junction

23

describe the effector

muscle/gland

24

describe the sodium pottassium pump

maintains the resting potential by active transport of Na+ out and K+ in. some K+ diffuse out by facilitated diffusion

25

what happens at generator potential?

a weak stimulus causes some voltage gated Na+ channels to open, some Na+ diffuses in, threshold isnt reached so returns to resting potential.

26

what happens at threshold?

many voltage gated Na+ channels open, Na+ diffuse into axon, positive feedback (rapid depolarisation)

27

describe repolarisation

K+ channels open, K+ diffuses out, sodium ion channels close

28

what is hyperpolarisation?

membrane potential is more negative than resting potential because K+ channels are slow to close

29

what is the refractory period?

another action potential cannot be started, ensuring action potentials are discrete, unidirectional nervous impulse

30

Describe how resting potential is established in an axon by the movement of ions across the membrane

Active transport of sodium out, diffusion of K in
making the inside more negative than the outside