how chemical synapse happens

Question 1

step one of chemical synapse

Answer 1

action potential is propagated down the axon to the pre synaptic bouton

Question 2

step two of chemical synapse

Answer 2

pre synaptic bouton is depolarised as the Ca2+ ion channels open. low conc. of Ca2+ on the inside of the cell and high on the outside creates a driving force for the ca to get in. voltage gated Ca2+ channels open

Question 3

step 3 of chemical synapse

Answer 3

Ca2+ ions trigger the release of the neurotransmitter from the vesicles, the vesicles are triggered to move closer to the membrane and the contents are released.

Question 4

step 4 of chemical synapse

Answer 4

neurotransmitter is released into the synaptic cleft, the vesicle doesn’t go into the cleft only its contents

Question 5

step 5 of chemical synapse

Answer 5

neurotransmitter binds to its specific receptors on the post synapse

Question 6

step 6 of chemical synapse

Answer 6

Na+ channels open local depolarisation of post synaptic cell- Na+ ions go down their conc. gradient. this is followed by the re-polarisation of the membrane

Question 7

step 7 of chemical synapse

Answer 7

Na+ depolarisation followed by re-polarisation called the excitatory post synaptic potential (EPSP)

Question 8

DEpolarisation

Answer 8

excitatory

Question 9

HYPERpolarisation

Answer 9

inhibitory

Question 10

how is synapse switched off?

Answer 10

excess transmitter released into the cleft is removed by the an enzyme that degrades and stops the transmitter working on the receptor
it may also be taken back to the glia or the bouton and reused.
this removal requires energy

Question 11

Acetylcholine

Answer 11

excitatory neurotransmitter
causes DEpolarisation
at the nerve -muscle (somatic) and nerve-gland (autonomic) synapses.
stimulates gated Na+ channels when it binds and there is a depolarisation of the cell that it flows in

Question 12

Glutamate

Answer 12

primary excitatory in the brain
causes DEpolarisation at all excitatory synapses in the brain
stimulates gated Na+ and Ca2+ channels.
when the cations go into the cell it will go from being relatively negative to very positive

Question 13

GABA

Answer 13

inhibitory transmitter in the CNS
causes HYPERpolarsation
the membrane becomes more negative than the RMP binding of the GABA causes Cl- ions to flow into the cell, lowering the membrane potential.

Question 14

Noradrenaline

Answer 14

autonomic motor system

Question 15

EPSP

Answer 15

excitatory post synaptic potentials
drives the membrane potential towards the threshold
it is it big enough and more is released then at he synapse the membrane potential will be bigger and will go above the threshold and action potential will happen

Question 16

Spatial summation of synaptic inputs

Answer 16

spatial means in space, we are adding inputs across the dendrites
the axon hillock is like a small hill there is a threshold that must be exceeded to go over the hill and these different inputs will add up and exceed the threshold and an action potential will happen.

Question 17

Temporal Summation of synaptic inputs

Answer 17

temporal means in time
we will see ESPS’s come in one after another, one action potential causes another and this goes on
differences in multiple inputs, there is a build up of EPSP at one synapse.

Question 18

IPSP

Answer 18

inhibitory post synaptic potential
causes hyperpolarisation
it keeps the MP away from the threshold
have to look at these as well as the EPSP when adding inputs at the axon hillock.

Question 19

Divergence

Answer 19

information from a single sensory organ may diverse to arrive at different brain regions
provides an opportunity to amplify signals and control points

Question 20

convergence

Answer 20

information from different brain regions may converse on a single motor-neurone that excites a single muscle group
this provides redundancy in electronics and control points
neurons come together and drive the final pathway.