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25 Cards in this Set
- Front
- Back
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Describe what happens at the pre-synaptic neurone in a cholinergic synapse |
An action potential arrives causing voltage gated calcium ion channel which then opens. Calcium ions diffuse into the synaptic knob. This influx of calcium ions causes synaptic vesicles to fuse with the membrane and they then release neruotransmitters |
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Which enzyme is present in the post-synaptic neurone of a cholinergic synapse |
Acetylcholinesterase
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In neuromuscular junctions what are the receptors called |
Nictotinic cholinergic synapses |
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What are the three differences between cholinergic synapses and neuromuscular junctions |
1) There are clefts in the post-synaptic membrane which stores acetylcholinesterase 2) The muscular junction is never inhibitory 3) There are more receptors |
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How do inhibitory neurones work |
They release inhibitory neurotransmitters which will hyperpolarise the post-synaptic membrane by allowing the influx of a negative ion such as CL- |
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How does temporal summation work in synapses |
The same neurone will release several lots of neurotransmitter in a short time which then builds up and reaches the threshold potential |
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How does spatial summation work |
Several neurones will fire neurotransmitters at the same time. This will have an accumulative effect as they combine to depolarise the membrane more strongly
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How may spatial summation result in no action potential being produced anyway |
One neurone may produce inhibitory neurotransmitters whilst the other will produce exitory neurotransmitters and the effects of the two will cancel each other out. |
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State 4 ways in which drugs may affect the activity of synapses |
1) Agonists are the same shape as neurotransmitters and mimic their action at receptors. 2) Some block receptors so fewer receptors are activated 3) Some inhibit the enzyme which breaks down the nuerotransmitter so continual stimulation occurs 4) Stimulate an increase or decrease in neurotransmitter |
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Describe the structure of skeletal muscle |
Made up of bundles of cells called muscle fibers. These then contain many muscle protein filaments |
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What is the name given to the cell membrane of the muscle fibre cells |
The sarcolemma |
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How are T tubules formed in muscles |
Bits of the sarcolemma fold inwards and stick to the sarcoplasm which then form the transverse tubules which spread electrical impulses. |
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Organelles in the muscle fibres? |
There are more mitochondria as this is needed to produce the ATP and they are multinucleate |
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What activates the ATP breakdown |
The calcium ions that are released activate the enzyme ATP-ase |
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What is the purpose of phosphocreatine |
ATP is made by the phosphorylation of ADP using a phosphate group |
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Which type of receptors detect pressure |
Baroreceptros |
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Where are chemoreceptors located |
In the carotid artery and in the aorta and in the medulla |
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Where are the baroreceptors located |
In the vena cava and the aorta |
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What neurone action is taken when there is high blood pressure |
The parasympathetic nervous system secretes acetylcholine onto the SAN |
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What neurone action is taken when there is low blood pressure |
The sympathetic nervous system secretes nor adrenaline onto the SAN |
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What neurone action is taken when there is a low pH |
There is high Co2 and so the sympathetic nervous system releases noradrenaline onto the SAN |
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What neurone action is taken when there is a high pH |
There is a low Co2 concentration and so the parasympathetic nervous system releases acetylcholine onto the SAN |
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What are some important functions of reflexes |
1) Avoiding predation 2)Helping with balance and posture 3) Avoiding damage to bodily tissues |
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Where is histamine stored |
In mast cells and basophilos |
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Where are prosglandins made- |
most body cells |
