Point where 1 neurone communicates with another or an effector. Important in linking diff neurons & so coordinating activities
1 of 22
What do synapses transmit?
Info , NOT impulses, from 1 neurone to another, by NEUROTRANSMITTERS (chemicals)
2 of 22
Structure of a synapse (SoaS): Synaptic cleft
Small gap which separates neurons (20- 30 nm wide)
3 of 22
SoaS: Presynaptic neurone
Neurone that releases neurotransmitter (ONLY made in presynaptic n NOT post) .
4 of 22
SoaS: Synaptic Knob
Swollen portion at the end of a neurons axon
5 of 22
SoaS: What does the synaptic knob contain & Why are they required?
Many mitochondria & lots of ER. Required to make neurotransmitter, takes place in axon
6 of 22
SoaS: Where is the neurotransmitter stored?
Synaptic vesicles
7 of 22
SoaS: What happens after neurotransmitter is released from vesicle?
Diffuses to postsynaptic neurone, which contains specific receptor proteins on its membrane to receive it.
8 of 22
Features of synapse (FoS): What is Unidirectionality?
Synapse can only pass info in 1D (From presynaptic neurone to postsynaptic, Acts like valves )
9 of 22
FoS: What is the effect of low-frequency APs?
Release of insufficient concs of neurotransmitter to trigger new AP in postsynaptic n.
10 of 22
FoS: They can however in Summation, how?
Causes rapid build up of neurotransmitter in the synapse by 2 methods
11 of 22
FoS: Name & explain 1st method of Summation
SPATIAL SUMMATION- Lots of diff presynaptic ns together release neurotransmitters which exceeds TV of postsynaptic n-> Triggers new AP
12 of 22
FoS: Name & explain 2nd method of Summation
TEMPORAL SUMMATION- Single presynaptic n releases neurotransmitters + times in v.short period. If conc exceeds TV of postsynaptic n -> triggers new AP
13 of 22
Inhibition: Define Inhibitory synapses
Some synapses make it less likely that a new AP will be made at postsynaptic n
14 of 22
Inhibition: How do Inhibitory synapses function? (8 STEPS)
1) Presynaptic n produces a type of neurotransmitter that binds to Chloride ion protein channel on postsynatic n 2) = opening of channel 3) Allows Cl- ions to pass channel (facilitated diffusion) into postsynaptic n
15 of 22
Continued...
4) Binding of neurotransmitter = opening of K+ protein channels nearby 5) K+ move out of postsynaptic n & into synapse 6) = inside of postsynaptic n + negative & outside + positive ( membrane potenti-80mv) 7) -> HYPERPOLARZATION
16 of 22
Continued...
8) -> new AP less likely created d.t larger amounts of Na+ needed to produce one.
17 of 22
Functions of Synapse (FoS):- Synapses act as junctions, allowing: (1)
1) Single impulse along 1 neurone to initiate new impulses in a no. of diff neurones at synapse (Allows single stimulus to create no. of simultaneous responses) 2)
18 of 22
FoS:Synapses act as junctions, allowing: (1)
2) A no. of impulses to combine at synapse. Allows nerve impulses from receptor reacting to diff stimuli to give a single response.
19 of 22
FoS: What happens when an action potential reaches the synaptic knob?
Vesicle membrane fuses with presynaptic membrane and releases neurotransmitter.
20 of 22
FoS: What happens after the neurotransmitter is released out of synaptic knob?
Neurotransmitter diffuses across SYNAPTIC CLEFT to bind specific receptor proteins (found ONLY on postsynaptic n)
21 of 22
FoS: How is an new AP created in the postsynaptic neurone? Synapses that produce new APs this way is called what?
Neurotransmitter binds with receptor protein. -> EXCITATORY SYNAPSE.
22 of 22
Other cards in this set
Card 2
Front
What do synapses transmit?
Back
Info , NOT impulses, from 1 neurone to another, by NEUROTRANSMITTERS (chemicals)
Comments
No comments have yet been made