nervous transmission

Question 1

(Nerve Action Potentials)
action potentials

Answer 1

nerve impulses

Question 2

(Nerve Action Potentials)
what requires a membrane potential

Answer 2

electrical charge differences across cell membrane
(like a battery)

Question 3

(Nerve Action Potentials)
what is an ion channel

Answer 3

allows ions to move by diffusion

Question 4

(Nerve Action Potentials)
what is the resting membrane potential?

Answer 4

70mv

Question 5

(The Resting Membrane Potential)
what is the elements that can leak?

Answer 5

cytosol high in K+
interstitial fluid high in Na+
(sodium-potassium pumps)

Question 6

(The Resting Membrane Potential)
what gets let through easily and what gets leaked poorly?

Answer 6

potassium can leak easy
sodium leaks poorly

Question 7

(The Resting Membrane Potential)
what does RMP depend on?

Answer 7

relative leakage channel numbers

Question 8

name some action potentials (AP)

Answer 8

series of active events
channels actively open and close

Question 9

(active potential)
what is the required voltage threshold that is needed to reach

Answer 9

• 55 mv

Question 10

(action potential)
what is the stimulus

Answer 10

any event bringing membrane to threshold

Question 11

(action potential)
after the arrival of a stimulus
what is the depolarizing phase?

Answer 11

membrane potential rises and becomes positive

Question 12

(action potential)
after the arrival of a stimulus
what is the repolarizing phase?

Answer 12

potential restored to resting value
may overshoot = hyperpolarizing phase
then recovery to rest

Question 13

(action potential events)
what could happen if the stimulus is not strong enough to reach threshold

Answer 13

Na+ channels open
K+ channels then open
sodium/potassium pump

Question 14

(action potential events)
what happens when the Na+ channel opens?

Answer 14

Na+ ions enter the cell from the extracellular fluid
depolarization (positive membrane potential)

Question 15

(action potential events)
what happens when K+ channels open?

Answer 15

K+ leave the cell
repolarization (negative membrane potential)

Question 16

(action potential events)
what happens with the sodium/potassium pump

Answer 16

restores original ion concentration

Question 17

how can coffee effect nervous transmission

Answer 17

stimulant
lowering the threshold level of the nerve
increasing the possibility for a stimulant to result in a nerve potential

Question 18

how can alcohol effect nerve transmission

Answer 18

acts as a depressant
increases threshold
decreases the possibility of a stimulus to result in a nerve action potential

Question 19

how can local anaesthetics effect nerve transmission

Answer 19

generation of nerve action potentials can be prevented by local anaesthetics (novocaine, xylocaine)
these drugs prevent the opening of sodium-gated channels in the nerve cell membrane (pain messages are not carried from the site of injury back to the CNS)

Question 20

what keeps the nerve impulses going in the right direction

Answer 20

refractory period

Question 21

in terms of conduction of nerve impulses what is a unmyelinated fibre?

Answer 21

its the continuous conduction

Question 22

what happens to nerve impulses with myelin

Answer 22

saltatory conduction
can only be triggered at nodes of Ranvier

Question 23

what happens with synaptic transmission

Answer 23

triggered by voltage change of the action potential

Question 24

what is the name for sending neuron?

Answer 24

presynaptic

Question 25

what is the name of the receiving neuron?

Answer 25

postsynaptic

Question 26

what does neurotransmitter mean?

Answer 26

a chemical that carries signal across the synaptic cleft

Question 27

name the three presynaptic events

Answer 27

action potential arrives at the presynaptic end bulb
opens voltage-gated Ca+ channels
Neurotransmitter (NT) released into cleft

Question 28

what happens when the voltage-gated Ca+ channels open?

Answer 28

Ca+ flows into the cell from synaptic cleft
increased Ca+ concentration in the presynaptic cell
exocytosis of synaptic vesicles

Question 29

name the four postsynaptic events

Answer 29

NT binding at postsynaptic receptors
chemical trigger of ion channels
may depolarise or hyperpolarise postsynaptic cell membrane
if threshold reached at axon hillock

Question 30

how does neurotransmitter get removed from synaptic transmission?

Answer 30

diffusion
destroyed by enzymes in cleft
transported back into the presynaptic cell
destroyed by neuroglia

Question 31

(Neurotransmitters)
Acetylcholine (Ach)

Answer 31

common in PNS
may be stimulatory or inhibitory

Question 32

(Neurotransmitters)
amino acids

Answer 32

glutamate
aspartate
gamma-aminobutyric acid (GABA)
glycine

Question 33

(Neurotransmitters)
Modified amino acids

Answer 33

norepinephrine (NE), dopamine (DA), serotonin (5-HT)

Question 34

(Neurotransmitters)
Neuropeptides

Answer 34

endorphins

Question 35

name some chemicals that affect synaptic transmission

Answer 35

botulinum toxin
curare
nerve agents

Question 36

what is botulinum toxin

Answer 36

inhibits the release of acetylcholine
inhibits muscle contraction (paralysis)

Question 37

what is curare

Answer 37

competes for acetylcholine receptor sites on muscle cell
muscle relaxant (used in surgical procedures

Question 38

what is nerve agents

Answer 38

inactivates acetylcholinesterase
leads to tetanus (paralysis)