- if potential difference reaches the threshold, a response will be stimulated. if not, no response will be stimulated. -change in potential difference will always be the same. - stronger stimulus = more frequent action potentials, not stronger action potentials.

nerves Flashcards by Red Mieth

All-Or-Nothing

if potential difference reaches the threshold, a response will be stimulated. if not, no response will be stimulated.
-change in potential difference will always be the same.
stronger stimulus = more
frequent action potentials, not stronger action potentials.

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stages of stimuation

Resting potential -70
Depolarisation -55 - +40
repolarisation + 40 - -70
hyperpolarisation-70 and below

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Refractory period

time after action potential where a neurones membrane cant be stimulated again.

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What does the refractory period do?

makes sure the wave of depolarisation travels in one direction.

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Factors affecting speed of impulse

myelination increases due to ability to perform saltatory conduction
temperature due to kinetic energy and movement if ions
axon diameter due to large SA for movement of ions across cell membrane

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neurotransmitter you must remember and its enzyme (that breaks it down)

acetylcholine and acetylcholine esterase

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gap between two nerve cells

synapse, synaptic cleft

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synaptic knob

end of presynaptic neurone

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why is there lots of mitochondria in the presynaptic knob?

Energy is needed to synthesise neurotransmitters

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two diff types of neurotransmitters

excitatory- generate action potential, cause Na+ ion channels to open

Inhibitory- prevent action potential from being generated
e.g potassium ion channels being opened, k+ leave the cell and membrane is prevented from establishing action potential.

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what happens to the postsynaptic membrane after inhibitory neurotransmitters?

hyperpolarisation

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spatial summation

multiple postsynaptic neurones required to establish an action potential across post synaptic membrane

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Temporal summation

a buildup of neurotransmitters required to establish an action potential. (multiple nerve impulses within a short space of time)

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neuromuscular junction

arriving action potential depolarises memrane if presynaptic knob, Ca²+ ion channels open.
Ca²+ causes vesicles containing acetylcholine to be released.
New process:
acetylcholine bind to receptors on sarcolemma (called nicotinic cholergic receptors)
Na+ ions flow into cell, membrane becomes depolarised.
action potential generated flows down T- tubules
voltage gated Ca2± ion channel protiens open and Ca2+ diffuse into sarcoplasmic reticulum.
Ca2+ binds to tropanin and tropomyosin.

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region of medulla oblongata that controls heartrate

cardiovascular centre

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gaps between schwann cells

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nodes of ranvier

High CO2/low 02