Nervous System- Co-ordination Flashcards

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1
Q

What is in the cell body of a neuron?

A

RER to produce neurotransmitters

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2
Q

What is the function of a Dendron?

A

Carry nerve impulse to the cell body

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3
Q

What does an axon do?

A

Carries the impulse away from the cell body

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4
Q

What is the purpose of the Schwann cells and what does it produce?

A

To protect and provide insulation which makes the myelin sheath which increase speed of cell conduction

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5
Q

Where are the Nodes of Ranvier?

A

They are between myelinated areas

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6
Q

What is a nerve impulse?

A

The self propagating wave of electrical disturbance which travels along the surface of an axon

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7
Q

What are the 4 characteristics of the resting potential?

A

1) 3Na+ ions move out for every 2K+ ions that move in
2) Most Na channels are closed
3) Most K channels are open
4) Na/K pump which requires ATP

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8
Q

What are the characteristics of the action potential?

A

1) Temporary reversal of the charge of the membrane
2) Na+ channels open and K+ channels close
3) Na+ ions flood the axon, because Na+ ions are positively charged it becomes more positive inside the membrane

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9
Q

Why does hyperpolarisation occur?

A

Due to an overshoot of K+ ions

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10
Q

Which factors increase the speed of an impulse?

A

1) The myelin sheath- prevents the potential forming in myelinated areas so the potential is forced to the Nodes of Ranvir (Salutatory Conduction)
2) Diameter- greater the diameter of the axon the greater the speed of conduction
3) Temperature- higher temp means a faster nerve impulse. ATP for active transport utilises enzymes from respiration

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11
Q

What is the refractory period?

A

The time period between 2 action potentials which is due to Na+ channels being temporarily closed.

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12
Q

What are the 3 purposes of the refractory period?

A

1) Limits the number of action potentials
2) Produces discreet impulses
3) Ensures the action potential are unidirectional

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13
Q

What is the structure of a synapse?

A

Presynaptic membrane which contains synaptic vesicles, synaptic cleft, post synaptic membrane which contain receptor sites

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14
Q

What are the 2 functions of a synapse?

A

1) unidirectional action potential

2) filters out low level stimuli

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15
Q

What happens when an action potential reaches the presynaptic membrane?

A

Neurotransmitters is released and fuses with presynaptic membrane, then the neurotransmitter crosses the cleft and binds to receptors at the postsynaptic membrane which generates a new action potential.

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16
Q

What happens at the synapse?

A

1) The action potential reaches the presynaptic membrane causing Ca2+ channels to open and Ca2+ to move into the presynaptic area
2) Influx of Ca2+ causes presynaptic vesicles, containing ACh, to fuse with the presynaptic membrane and the neurotransmitter is released
3) ACh diffuses past the cleft to the postsynaptic membrane
4) ACh binds to ACh receptors at the postsynaptic membrane which causes Na+ channels to open
5) Influx of Na+ generates new action potential

17
Q

What is required to reform Acetyl and Choline?

A

ATP released by mitochondria

18
Q

What are the differences between the hormonal and nervous system?

A
Hormonal
1) Chemicals
2) Transmitted by blood
3) Slow
4) General- travel to all areas of the body but target specific organs
5) Wide spread response
6) Irreversible
Nervous
1) Nervous impulses 
2) Transmitted by neurones
3) Fast
4) Specific- travels to specific areas of the body 
5) Localised response 
6) Reversible 
7) Effect is more intense
19
Q

What are 2 examples of chemical mediators?

A

1) Histamine- causes dilation of blood vessels and increases permeability of capillaries
2) Prostaglandin

20
Q

What is a neuromuscular junction (NMJ)?

A

Where a neurone meets a muscle

21
Q

What are the key difference between NMJ and cholinergic synapse?

A

1) NMJ’s are only excitatory
2) NMJ only between neurone and muscle
3) NMJ has no threshold value
4) NMJ’s have no summation

22
Q

How is a resting potential maintained?

A

1) 3 Na+ out, 2 K+ in using Na/K pump
2) Creates a chemical gradient which makes Na+ try to re-enter the axon and K+ to leave
3) Na+ channels are closed, K+ channels are open
4) K+ moves out which causes a more positive environment
5) K+ ions move back into the axon until an equilibrium is formed
6) No more net movement and electrical gradient becomes balanced