Neurons and Synapses and Impulses

34 cards


 
  
Created Feb 9, 2014
by
hrbaylis

 

 
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1
what are neurons
 
nerve cells that make up the nervous system
often elongated and carry messages at high...
2
what are the 2 parts of the nervous system
 
central nervous system (CNS): brain and spinal cord
peripheral nerves that connect all...
3
how do neurons carry electrical impulses long distances in the body
 
using elongated structures called nerve fibres/ axons
4
what are sensory neurons
 
carry nerve impulses from receptors to CNS
5
what are motor neurons
 
carry impulses from CNS to effectors (muscle and gland cells)
6
what are relay neurons
 
carry impulses within CNS from one neuron to another
7
what is a synapse
 
a junction between 2 neurons
8
what is the synaptic cleft
 
the plasma membranes of 2 neurons are separated by a narrow flui-filled gap called the synaptic...
9
what are neurotransmitters
 
messages passed across the synapse in the form of chemicals 
10
what direction do neurotransmitters always travel in
 
from the pre-synaptic neuron to the post-synaptic neuron
11
what initiates the stages of synaptic transmission
 
a nerve impulse reaches the end of the pre-synaptic neuron
12
what does the arrival of the impulse do to the membrane of the neuron
what does this...
 
depolarization of the pre-synaptic membrane
causes voltage-gated calcium channels to...
13
what does an influx of calcium ions cause
 
vesicles of neurotransmitter move to pre-synaptic membrane and fuse with it
meaning...
14
what happens when the neurotransmitter diffuses across synaptic cleft
 
neurotransmitter binds to receptors in the post-synpatic membrane
15
describe the receptors on the post-synaptic membrane
what happens with them
 
they are transmiited-gated ion channels
they open when neurotransmitter binds
sodium...
16
what does soduim diffusion into post-synaptic neuron cause
 
depolarisatin of this membrane (post synaptic)
17
what does depolarisation pass on as
 
an action potential
18
what occurs to prevent continous synaptic transmission
 
neurotransmitter in synaptic cleft is rapidly broken down
calcium ions are pumped out...
19
what is a resting potential
 
the electrical potential across the plasma membrane of a cell that is not conducting an impulse
20
how do neurons pump ions across their plasma membranes
what is pumped in and what is...
 
by active transport
sodium is pumped out of neuron
potassium is pumped into neuron
21
what are the charges in an outside the neurons and why is this
what does this cause
 
the inside develops a net negative charge because of the presence of chloride and other negatively...
22
what is an action potential
 
the reversal and restoration of the electrical potential across the plasma membrane of a cell,...
23
what happens when an impulse passes along a neuron
 
sodium and potassium ions are allowed to diffuse across the membrane through voltage-gated...
24
what happens to the electrical potential across the membrane
what is this called
 
it is initially reversed but is then restored
an action potential
25
what does an action in one part of the neuron cause
 
causes an action potential to develop in the next section of the neuron
26
why does this happen
 
because of diffusion of sodium ions between the region with an action potential amd the region...
27
what does these ion movements, local currents, cause
 
they reduce the resting potential
28
if the potential rises above the threshold level what happens
 
voltage-gated channels open
29
when the channels open and sodium ions diffuse into the neuron down the concentration gradient,...
 
this reduces the membrane potential and causes more sodium channels to open
30
what does the entry of more positively charged sodium ions cause
 
the inside of the neuron develops a net positive chrge compared to the outside - the potential...
31
what does this polarisation causes
 
potassium channels open after a short delay
ions diffuse out of neuron down concentration...
32
what does the exit of positively charged potassium ions cause
 
the inside of the neuron develops a neg negative charge again compared with the outside - the...
33
how are the concentration gradients of sodium and potassium across the membrane restored
 
by the active transport of sodium ions out of neuron and potassium into neuron
34
what does it mean when the resting potential has been restored
 
the neuron is then ready to conduct another nerve impulse 


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