F214 Nervous System

These Cards will help to revise key information needed for exam preparation for A2 Biology

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How many neurones are found in the Human Body?
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What are these neurones?
Motor,sensory and relay neurones
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Describe the function of a motor neurone?
They Transmit action potenials to the Central Nervous system to the effector
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Describe the funtion of the sensory neurones?
Detect stimuli
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Describe the funtion of relay neurones?
Relays the potenial to the Central Nervous System
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What are the specialisations of neurones?
Very Long, has gated ion channels to control ions, has sodium/potassium pumps that use ATP out in and out of the cell, maintains a potenial difference across the membrane,surroned by mylein sheath, has a cell body ect.
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What is the resting potenial?
When the cell is polarised and the potenial difference is -60Mv
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How is resting potenial achieved?
The Na/K pumps transport more sodium ions out than potaasium into the cells
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What is a Nerve Impulse?
An action potenial or a slight deformation of the membrane therefore depoloarising the cell
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How is an action potenial achieved?
some Na channels open, slight depolarisation cause more Na channels to open hits the threshold, K ions diffuse out to polarise the membrane by hyperpolarisation (the cell cant be stimulated) one way transmission
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Name the structure of the synapse?
On the presynaptic: Many mitochondria, vesicles with Ach, calcium ion channels Post synaptic neurone: Na ion channels, Ach receptors
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What is the Funtction of a synapse?
stimulus-> Ca2+ channels open, Ca diffuses into axons membrane,ca stimulates movement of vesice containing Ach, Ach vesicles fuses( with memebrane) and is released by exocytosis, Ach diffuses through synaptic cleft binds to receptors on Na channel
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Whats Ach?
Ach is a neurotransmitter it stands for Aceytlcholine
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What is the equilibrium of synapses?
Ach needs to be broken down by Ache (Enzyme) back into ethanoic acid and choline, products are reabsorbed into pre-synaptic neurone
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Why does Ach need to be broken down?
Prevents the generation of action potenials( prevents fatigue)
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What is convergence?
2+ synapse to 1 post synpase, this amplifies action potenials
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What is divergence?
1 synapse to many post synapses, the signal can be dispersed all over the body
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What is acclimatisation?
stimulus-> after 1st action potenial is fired it will eventually use up all of Ach
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What is thought and memory?
Creation of specific pathways within the nervous system
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What is temporal summation?
it is where more than 3 impulses are needed to generate an action potenial
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What is Spatial summation?
where two synapses are needed for an action potenial to be fired
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(Dis)advantages of Myleinated neurones?
1/3 periphery neurones are inverterbrates, schwann cells wrap around axon, Impulses jump from nodes of ranvier(Saltortary conduction) conduction speed= 100-120ms
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(Dis)advantages of non-myleinated neurones?
all neurones in CNS are unmyelinated,1+ neurone involved, ion channels are close,2-20ms conduction
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Control of heart rate (Blood pH)
Chemoreceptors detect a drop in blood pH, signal travel along sensory, to the Medulla Obliangata, which then travels down the accelerator nerve to increase blood ph.
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Control of heart rate (Blood pressure)
Baroreceptors detect increase in blood pressure, travels along sensory to cardiovascular centre then doen the vagus nerve and reduces heart rate
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Control of heart rate (Stress)
Directly affects the SAN by Adrenaline. Fight or Flight response
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Other cards in this set

Card 2


What are these neurones?


Motor,sensory and relay neurones

Card 3


Describe the function of a motor neurone?


Preview of the front of card 3

Card 4


Describe the funtion of the sensory neurones?


Preview of the front of card 4

Card 5


Describe the funtion of relay neurones?


Preview of the front of card 5
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