Nervous system

Question 1

PNS

Answer 1

somatic nervous, autonomic, parasympathetic, sympathetic

Question 2

Somatic

Answer 2

Conscious control, bicep curl

Question 3

Autonomic

Answer 3

unconscious body activity; heart and breathing rate

Question 4

parasympathetic

Answer 4

slows things down, acetycholine neurotransmitter, decreasing heart reate

Question 5

sympathetic

Answer 5

speeds things up; noradrenaline neurotransmitter,increasing heart rate

Question 6

nerve pathway

Answer 6

sitmulus, receptor, seconsry neurone, relay neurone, motor neurone, effector, response

Question 7

sensory neurone

Answer 7

1) single long dendron

2) single short axon

Question 8

relay neurone

Answer 8

1) within CNS
2) many short dendrites
3) many short axons

Question 9

motor neurones

Answer 9

1) many short dendrites
2) single long axon
3) ends with neuromuscular junction

Question 10

Resting potential

Answer 10

1) na+/K+ pump uses active transport (atp), 3 NA+ out and 2K+ in
2) voltage gated sodium ion channel: closed, membrane is not permeable to Na+ ions
3) K+ ion channels: open, some K+ diffuse down the electochemical gradient, doesnt reach eq due to the postiive charge outside the axon

Question 11

7 stages of action potential

Answer 11

1) resting potential
2) generator potential
3) threshold
4) depolarisation
5) repolarisation
6) hyperpolarisation
7) Refractory period

Question 12

Generator potential

Answer 12

1) weak stimulus
2) some Na+ voltage gated channels open
3) some Na+ diffuses in
4) does not reach threshold
5) Na+K+ pump restores resting potential

Question 13

Threshold

Answer 13

1) Generator potential reaches threshold
2) many voltage gated Na+ channels open
3) Na+ diffused into axon
4) positive feedback; rapid change–> depolarisation

Question 14

Depolarisation

Answer 14

1) Na+ channels are open

2) Na+ diffuses in

Question 15

Repolarisation

Answer 15

1) K+ voltage gated channels are open
2) K + diffuses out
3) voltage gated Na+ close

Question 16

Hyperpolarisation

Answer 16

1) when membrane potential is more neagitve than the resting potential
2) K+ channels are slow to close

Question 17

Refractory period

Answer 17

1) another action potential cannot be started
2) ensures action potentials are discrete ( don’t overlap) and are unidirectional ( one way)
3) behind the depolarisation phase of an action potential

Question 18

myelin sheath

Answer 18

1) schwann cells produce myelin
2) electrical insulator prevents depolarisation of membrane
3) prevents movement of ions in or out of neurone

Question 19

Nodes of Ranvier

Answer 19

1) gaps in myelin sheath
2) lots of Na+K+ ion channels
3) depolarisation can only happen at the nodes
4) saltatory conduction

Question 20

Saltatory conduction

Answer 20

1) when an action potential jumps between nodes of ranvier
2) speeds up transmission of nerve impulses
3) cytoplasm conducts enough charge to depolarise next node

Question 21

temperature

Answer 21

higher temp causes faster speeds of action potentials (up to 40 degrees)
molecules diffuses faster at higher temps due to more KE

Question 22

Diameter of axon

Answer 22

1) greater the diameter, the faster the speed of the action potential
2) less resistance
3) more surface area for ion movement

Question 23

synapse

Answer 23

junction between neurones; chemical transmission by neurotransmitters, ACh

Question 24

Cholinergic synapse stages

Answer 24

1) Action potential arrives at presynaptic knob
2) voltage gated Ca2+ channels open , Ca2+ diffuse in
3) vesicles full of ACh fuse with the presynaptic membrane by exocytosis
4) ACh diffuses across the synaptic cleft
5) ACh binds with receptor on post synaptic membrane ( complementary to ACh shape)
6) Some Na+ channels open, Na+ diffuses in, if threshold is reached…
7) change in potential difference across a mebrane: excitatory post synaptic potential set up as voltage gated Na+ channels are open
8) action potential triggered in the post synaptic membrane
9) enzyme acetylcholinesterase breaks down ACh and stops the response
10) Products are reabsorbed into the preysnaptic knob and recycled

Question 25

inhibitory ion channel synapse

Answer 25

1) have neuroreceptors that are Cl- channels 2) when channels are open, negative cl- ions diffuse in causing a local hyperpolarisation called an inhibitory post synaptic potential (IPSP), therefore makes an action potential less likely 3) impulse in one neurone can inhibit an impulse in the next 4) neurotransmitters such as glycine or GABA

Question 26

Synapses are uni directional

Answer 26

1) only receptors on post synaptic membrane 2) neurotransmittere are released from presynaptic knob 3) diffuses from hig to low conc across synaptic cleft

Question 27

synaptic divergence

Answer 27

when one neurone joins many neurones: spreads the action potnetial to other parts of the body

Question 28

synaptic convergence

Answer 28

many neurones join a single neurone which amplifies the signal

Question 29

spatial summation

Answer 29

weak stimulus may only create a few action potentials, doesnt always trigger an action potnetial on post synaptic neurone therefore, when neurotransmitters from multiple neurone combine to trigger an action potnetial in a post syantpic neurone

Question 30

temporal summation

Answer 30

a single action potential doesn't always trigger an action potential in the post synaptic membrane therefore a strong stimulus will cause more frequent action potentials which will release more neurotransmitter and adds up to tirgger an action potential in post synaptic membrane

Question 31

neuromuscular junctions

Answer 31

synapse between a motor neurone and a muscle fibre

Question 32

difference between cholinerigc synapse and neuromusucular junction

Answer 32

1) more receptors on post synaptic membrane 2) an action potential is always generated in the post synaptic membrane 3) acetylcholineesterase is found in pits in the post synaptic membreane 4) receptors are called nicotinic cholinerigc receptors

Question 33

agonist

Answer 33

drugs that sitmulate a synapse

Question 34

antagonist

Answer 34

drugs that inhibit a synapse

Question 35

nictotine

Answer 35

mimcs affect of ACh, agonist 1) binds to cholinergic receptors 2) triggers action potential in post synaptic neurone 3) receptor remains unrepsonsive to more stimulation for some time 4) affected neurorecpetors release other trnasmitters in CNS: adrenaline: triggers fight or flight repsonse of sympathetic nervous system and heart rate and blood pressure increases dopamine: stimualtes reward system in brain; feelings of pleasure endorphins: cause feelings of well being; lead to withdrawal symptoms causing addiction

Question 36

lidocaine

Answer 36

quick acting, short lasting local anesthetic 1) blocks voltage gated Na+ channels preventing production of action potnetials, therefore no pain felt 2) can also prevent heart arrhythmias; blocks sodium channels, rasing depolarisation thresholds, reduces prevents early action portential from pacemaker region that could lead to arrythmias 3) local anaesthetic; inhiboits sensory neurones 4) muscle relaxant; inhibiting motor neurones

Question 37

cobra venom; alpha neurotoxin

Answer 37

1) binds tightly and irrevirsibly to acetylcholine receptors in neuromuscular junctions 2) stops the receptors from openign 3) therefore prvents transmission of impulses across synapses 4) skeletal muscles stop contracting leading to paralysis 5) fatal if the toxin reaches the breathing muscles 6) in very low conc, relaxes muscles of trachea and bronchi in severe asthma attacks, saves lives