What are synapses that have acetyl choline as their NT called
Cholinergic synapses
2 of 34
At cholingeric synapses on the post SM what is present that breaks down the Acetyl choline into acetic acid and choline?
Very fast acting enzyme called acetylcholinerase in a hydrolysis reaction
3 of 34
What happens to these substances
Taken back into the synaptic knob and ATP from mitochondria is used to resynthesises the acetyl choline which is returned to the vesicles
4 of 34
Synapses that use noradrenaline affect
Heart Rate, Breathing rate, and brain activity
5 of 34
What is this similar to
hormone adrenaline which prepares the body for emergencies
6 of 34
What are NMJ
Specialised synapses between motor neurones and muscle fibres
7 of 34
What does nervous communication use? what does this mean?
Charged ions, therefore a severe electrical shock can harm the system
8 of 34
What does electricity affect
the junctions between muscles and nerves in a way that the muscles contract violently and stay contracted- impossible to let go when holding a live mains wire
9 of 34
Greater the electrically stimulation
the more the muscles contract
10 of 34
In the NMJ what is there
chemical synapse between the motor neurone and the muscle fibres working in similar way to neurone-neurone synapse
11 of 34
What do synapses give
More accurate muscle control than is possible by direct electrical stimulation because synapses can control small parts of each muscle separately
12 of 34
At the junctions what does the axon of the motor neurone form
a motor end plate- in this it divides to form fine branches ending in synaptic knobs
13 of 34
What do the branches run into
shallow troughs on the cell Surface membrane of the muscle fibre (sarcolemma)
14 of 34
What is the transmitter at NMJ in skeletal muscles
Acetyl choline
15 of 34
What does an Action potential (stimulation) in the motor neurone cause
Synaptic knob to release acetyl choline which diffuses across the NMJ, binds to receptors in the muscle fibre membrane (sarcolemma)
16 of 34
What does changes in these receptors on binding do
Increase permeability of the membrane to Na+ and K+
17 of 34
What is this sufficient to lead to
An AP along the sarcolemma and muscle fibre and results in muscle contraction
18 of 34
How does the muscle fibre respond
By contracting
19 of 34
What is there no at a NMJ
Summation
20 of 34
1 AP causes
1 muscle twitch
21 of 34
C synapse
Neurone to neurone, AP in neurone
22 of 34
NMJ
Neurone to muscle, no AP in muscle/sarcolemma, no summation, muscle response always excitatory never inhibitory, some have different Neurotransmitters
23 of 34
What are transmitters released in
tiny amounts- only 500-1000 molecules from each synaptic knob
24 of 34
What else can also affect synapses
Many other chemicals
25 of 34
What can drugs that affect transmitters or their binding sites have
powerful effects when given in fairly small doses
26 of 34
What do some chemicals (many of them from plants have)
a dramatic effect on the nervous system
27 of 34
What can blocking reabsorption of NT or causing more to be released do
turn synapse on- AP fired unless inhibitory
28 of 34
What does inhibiting the enzyme that normally breaks down the NT
Turn synapse on and keeps firing
29 of 34
By having a similar structure which tricks the post synaptic membrane and so the NT receptor allows drugs to bind to it
Synapse off- no activity in next neurone
30 of 34
By releasing NT from vesicles with or without impulses
Turns synapses on
31 of 34
By preventing vesicles from releasing NT
turns synapse off
32 of 34
By blocking receptors so the normal NT cannot bind
synapse off
33 of 34
By blocking the Na+ or K+ channels
off- stops activity
34 of 34
Other cards in this set
Card 2
Front
What are synapses that have acetyl choline as their NT called
Back
Cholinergic synapses
Card 3
Front
At cholingeric synapses on the post SM what is present that breaks down the Acetyl choline into acetic acid and choline?
Comments
No comments have yet been made