Nervous coordination Flashcards

1
Q

What does the nervous system involve

A

-detection of stimuli by receptors
-transmission of nerve impulses by neurons
-response by effectors

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2
Q

Types of neurons

A

-sensory neuron
-relay neuron
-motor neuron

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3
Q

structure of the neuron

A

-dendrites
-cell body
-nucleus
-axon
-myelin sheath
-nodes of ranvier
-schwann cell
-terminal end branch

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4
Q

function of the nucleus

A

found in the cell body and contains the DNA which codes for neurotransmitters

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5
Q

function of dendrites

A

extensions of the cytoplasm of the cell body receiving chemical signals from other neurons at the postsynaptic membrane

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6
Q

function of cell body

A

contains the nucleus and groups of ribosomes needed to synthesise neurotransmitters

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7
Q

function of axon

A

long extension of the cytoplasm that transmit impulses away from cell body towards the terminal ends

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8
Q

function of myelin sheath

A

formed as schwann cells grow around the axon
provide electrical insulation
speeds up transmission

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9
Q

function of schwann cells

A

surround peripheral nerves and forms myelin sheath
K+ and Na+ ions cannot diffuse through

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10
Q

function of terminal end branch

A

connect to other neurons or effectors

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11
Q

How is resting potential established

A

high conc of Na+ on outside of neuron
high conc of K+ on the inside of the neuron
many Na+/K+ pumps that move
3 NA+ out and 2K+ in
via ATP hydrolysis

Na+ voltage gated channel proteins are closed
Na+ pumped out cannot diffuse back in
K+ channel proteins are leaky
K+ can diffuse back out

net result= more positive on outside than inside

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12
Q

How a nerve impulse is transmitted

A

membrane is stimulated
action potential is where the membrane reaches a threshold and becomes depolarised
an action potential is the reversal of the resting potential
-70mV to 40mV

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13
Q

process of depolarisation

A

stimulus causes membrane to become more permeable to Na+ ions
Na+ channel proteins are open
higher conc of Na+ outside the cell
Na+ ions rapidly diffuse into the cell via FD
higher conc of Na+ inside the cell reverses action potential
inside is more positive
K+ voltage gated channel proteins remain closed
high conc of + ions is action potential

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14
Q

process of repolarisation

A

once the internal potential reaches +40mV
Na+ ion voltage gated channel proteins close
K+ voltage gated channel proteins open
more K+ ions inside than outside
K+ ions diffuse out down a conc gradient

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15
Q

process of hyperpolarisation

A

K+ ion channel proteins remain open longer than needed to reach action potential
inside of the cell more negative to -90mV
sodium potassium pump restores the resting potential back to -70mV

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16
Q

The all or nothing principle

A

above the threshold the full sized action potential is given regardless of the increase in the size of the stimulus

17
Q

the refractory period definition

A

the time taken to restore the resting potential potential

18
Q

what is the impulse transmission along the axon

A

action potential acts as a stimulus to adjacent polarised areas of the membrane and this causes the action potential to be passed along

19
Q

what is saltatory conduction

A

impulse travels by jumping from one node of ranvier to the next node of ranvier
to increase the rate of transmission

20
Q

how does temperature affect the rate of transmission

A

increase in temp
increase in kinetic energy
increase in the rate of diffusion
increase the rate of conduction

21
Q

how does axon diameter affect the rate of transmission

A

the larger the axon diameter
the greater the speed of conductance
larger membrane surface area
increase in number of channel proteins

22
Q

process of synaptic transmission

A

action potential arrives
ca2+ channel opens
ca+ ion diffuse into the presynaptic neuron via facilitated diffusion
vesicles fuse with presynaptic membrane to release acetylcholine via exocytosis
ACh bind to receptors
Na+ channels open allowing Na+ into postsynaptic neuron
K+ channels open allowing K+ out into the cleft
enzyme acetylcholinesterase hydrolyses acetylcholine into choline and ethanoic acid using water to break the etser bond

23
Q

types of neurotransmitters

A

excitatory
inhibitory

24
Q

type of inhibitory neurotransmitter

25
how do inhibitory neurotransmitters work
resting potential hyperpolarized less likely to reach threshold in postsynaptic membrane cannot generate action potential
26
what is the neuromuscular junction
a synapse between a motor neuron and a muscle cell uses acetylcholine which binds to recptors
27
adaptations to muscular junctions that differentiate them from synapses
1. lots of folds, increase in surface area for more enzymes 2. more receptors 3. always triggers a response
28
what is summation
the build up of neurotransmitters within the synapse
29
what are the two types of summation
spatial temporal
30
process of spatial summation
different neurons converge at a single synapse action potentials arrive from several different neurons release of enough neurotransmitter to reach threshold and cause an action potential
31
process of temporal summation
only one presynaptic neuron impulses arrive in rapid succession giving a cumulative effect sufficient to depolarise the post synaptic neuron