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biology 121 > nerves and synapses > Flashcards

nerves and synapses Flashcards

1
Q

what are the inhibitory neurotransmitters?

A

GABA; glycine

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2
Q

what are the excitatory neurotransmitters?

A

glutamate, aspartate

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3
Q

what are the chemical synapses that release actylcholine called?

A

cholinergic synapses

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4
Q

what are the types of cholinergic receptors?

A

muscarinic, nicotinic

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5
Q

what happens at the sodium-potassium exchange pump?

A

the sodium-potassium exchange pump maintains the cell’s resting potential by ejecting three sodium ions for every two potassium ions it brings in from the ISF
(3 Na+ out; 2 K+ in)

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6
Q

what effect would a chemical that blocks the voltage-gated sodium channels in the plasma membrane of a neutron have on its ability to depolarise?

A

if the voltage-gated sodium channels couldn’t open, sodium ions could not flood into the neutron and it would not be able to depolarise

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7
Q

describe four features of a polarised neuron

A

resting membrane potential
-70 volts
more K+ inside
more Na+ outside

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8
Q

what is dopamine and what does it act on?

what is its effect?

A

neurotransmitter
dopaminergic receptors
can be excitatory or inhibitory

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9
Q

what physiology does acetylcholine play a role in?

A

cognition

learning and memory

consciousness

motor control

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10
Q

what is glutamate and what does it act on?

A

main NT in brain

NMDA receptor

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11
Q

what physiology does noradrenaline play a role in?

A

arousal and mood

blood pressure

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12
Q

what are the monoamine NTs?

A 
noradrenaline
adrenaline
dopamine
5HT
histamine (excitatory)
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13
Q

define nerve

A

bundle of nerve fibres

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14
Q

what is the main neurotransmitter?

A

glutamate

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15
Q

name the structural components of a typical neuron

A

the cell body, the dendrites and the axon

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16
Q

compare presynaptic and postsynaptic cells

A

a presynaptic cell is usually a neuron

a postsynaptic cell can be a neuron or another type of cell such as a skeletal muscle fibre or gland

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17
Q

what are the functional classifications of neurons? what are the functions of each type?

A

sensory neurons transmit impulses from peripheral receptors to CNS

motor neurons transmit impulses (commands) from CNS to peripheral effectors

interneurons analyse sensory inputs and coordinate motor outputs

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18
Q

what is a ganglion?

A

a collection of neuron cell bodies in the PNS

it’s a little bulge, it’s where the synapses are

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19
Q

what are the three types of sensory receptors?

A

interoceptors
proprioceptors
exteroceptors

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20
Q

describe the difference between an action potential and a graded potential

A

action potentials are changes in the transmembrane potential that propagate along the membrane

graded potentials are changes in the transmembrane potential that cannot spread far from the initial site

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21
Q

define membrane potential

A

the unequal charge distribution between the inner and outer surfaces of the plasma membrane

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22
Q

what is another name for a graded potential?

A

a local potential

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23
Q

what is the simplest form of information processing in the nervous system?

A

the integration of stimuli by an individual cell

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24
Q

what is the resting membrane potential?

A

the resting membrane potential is the membrane potential of a normal, unstimulated cell

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25
what units are the electrical potential measured in?
volts (mV for cells) (millivolts)
26
what happens at the sodium-potassium exchange pump?
three sodium out/ two potassium in to maintain a stable resting membrane potential
27
what is the resting membrane potential of a neuron?
-70 mV
28
what effect would decreasing the concentration of extracellular potassium ions have on the resting membrane potential of a neuron?
it would cause more potassium to leave the cell via leak channels, making the transmembrane potential of the nerve more negative
29
list the three types of gated ion channels found in neurons
chemically gated ion channels voltage gated ion channels mechanically gated ion channels
30
under what conditions do each of the gated ion channels found in neurons work?
chemically gated channels operate when they bind to specific chemicals eg ACh receptors at the neuromuscular junction voltage-gated channels open or close in response to changes in the membrane potential mechanically gate channels operate in response to mechanical stimuli that physically distort the neuron's membrane surface - important in many sensory receptors
31
define gated ion channels
active channels in the plasma membrane that open or close in response to specific stimuli
32
define graded potential
a change in the membrane potential that cannot spread far from the site of stimulation
33
what kinds of channels do resting membrane potential, graded potential and action potential depend on?
resting membrane potential depends on leak channels graded potential depends on chemically gated ion channels action potential depends on voltage-gated ion channels
34
describe the all-or-none principle in membrane potential
a given stimulus triggers either a typical action potential or no action potential at all - action potentials are always identical
35
what factor accounts for the local currents associated with action potentials?
movement of sodium ions parallel to the inner and outer surfaces of the plasma membrane when chemically gated sodium channels have opened
36
are the positive ions on the inside or outside of the cell at resting potential?
Negative on the iNside | pOsitive on the Outside
37
do potassium ions freely diffuse out of the neural cell?
no they pass through leak channels or are transported via the sodium-potassium pump (Na/K pump)
38
which positively charged ions are found more on the outside of a neuron at rest?
sodium
39
which positively charged ions are found more on the inside of a neural cell when it's at rest?
potassium
40
do sodium ions freely diffuse into the neural cell?
no via leak channels and the sodium/potassium pump
41
what makes a neuron negatively charged compared to the ECF?
negatively charged proteins on the inside the sodium/potassium pump helps to maintain the balance
42
what is the threshold for an action potential?
-55 mV
43
define repolarisation
the return of the transmembrane potential to the resting potential after the cell has been depolarised
44
name the types of cells that are capable of producing action potentials
excitable cells - neurons - muscle cells (only in the axons of neurons)
45
define what is meant by depolarisation
a shift from the resting membrane potential towards a more positive potential
46
list the events involved in the generation and propagation of an action potential
1. depolarisation to threshold 2. activation of sodium channels and rapid depolarisation 3. inactivation on sodium channels and activation of potassium channels 4. closing of potassium channels
47
compare the absolute refactory period with the relative refractory period
the refractory period is the time between the initiation of an action potential and the restoration of the normal resting potential absolute refractory period: the membrane cannot respond to further stimulation, no matter how strong relative refractory period: membrane can only respond to larger-than-normal stimulus
48
define continuous propagation and saltatory propagation
continuous propagation happens along an unmyelinated axon; action potential affects every portion of membrane surface saltatory propagation: relatively rapid propagation between successive nodes of a myelinated axon
49
what's the relationship between myelin and the propagation speed of action potentials
myelin greatly increases propagation speed
50
what is a synapse?
a specialised site where the neuron communicates with another cell
51
describe the components of a synapse
presynaptic cell postsynaptic cell neurotransmitters synaptic cleft
52
what are the chemical messengers released at the synapse called?
neurotransmitters but penguin professor refers to them as neurocrines (any chemical secreted by a neuron); the term neurocrines includes NTs but also neurohormones and amino acids
53
what is the stimulus for the exocytosis of a neurotransmitter into the synaptic cleft?
an influx of calcium ions into the presynaptic nob
54
contrast an electrical synapse with a chemical synapse
in a chemical synapse, a neurotransmitter crosses the synaptic cleft electrical synapse: membranes of pre and postsynaptic cells are joined together by gap junctions
55
define excitatory postsynaptic potential and inhibitory postsynaptic potential
EPSP - graded depolarisation of a postsynaptic membrane by a NT released by a presynaptic cell IPSP - graded hyperpolarisation of a postsynaptic membrane after the arrival of a NT
56
define hyperpolarisation
a shift from the resting potential in which the transmembrane potential becomes more negative neuron can only respond to extra strong stimulus
57
what is the term for the point in an action potential when the membrane is at its most depolarised? what is its voltage then?
peak action potential +30 mV
58
what happens during the hyperpolarisation stage of an action potential?
transmembrane potential drops below -70 mV because potassium channels are slow to close neuron can only respond to extra strong stimulus
59
what happens during repolarisation? why does membrane potential change?
move back towards resting membrane potential sodium channels are inactivated potassium channels are activated.
60
what physiology does dopamine play a role in?
motor control emotion and reward decreased prolactin vomiting
61
what pathophysiology does dopamine play a role in?
schizophrenia parkinsons addiction
62
what physiology does serotonin play a role in?
(there are lots of serotonin (5HT) receptors): ``` digestion sleep/wake mood appetite vomiting ```
63
what pathophysiology does serotonin play a role in?
(there are lots of serotonin (5HT) receptors): depression mania eating disorders
64
what physiology does glutamate play a role in?
learning and memory
65
what pathophysiology does glutamate play a role in?
epilepsy chronic pain drug dependence
66
what pathophysiology does acetylcholine play a role in?
alzheimers
67
what pathophysiology does noradrenaline play a role in?
bipolar disorder | depression

biology 121 (14 decks)

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