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biology 121 > nerves and synapses > Flashcards

nerves and synapses Flashcards

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AP® Biology flashcards Biology 101 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
Q

what units are the electrical potential measured in?

A

volts (mV for cells) (millivolts)

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26
Q

what happens at the sodium-potassium exchange pump?

A

three sodium out/ two potassium in to maintain a stable resting membrane potential

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27
Q

what is the resting membrane potential of a neuron?

A

-70 mV

28
Q

what effect would decreasing the concentration of extracellular potassium ions have on the resting membrane potential of a neuron?

A

it would cause more potassium to leave the cell via leak channels, making the transmembrane potential of the nerve more negative

29
Q

list the three types of gated ion channels found in neurons

A

chemically gated ion channels

voltage gated ion channels

mechanically gated ion channels

30
Q

under what conditions do each of the gated ion channels found in neurons work?

A

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
Q

define gated ion channels

A

active channels in the plasma membrane that open or close in response to specific stimuli

32
Q

define graded potential

A

a change in the membrane potential that cannot spread far from the site of stimulation

33
Q

what kinds of channels do resting membrane potential, graded potential and action potential depend on?

A

resting membrane potential depends on leak channels

graded potential depends on chemically gated ion channels

action potential depends on voltage-gated ion channels

34
Q

describe the all-or-none principle in membrane potential

A

a given stimulus triggers either a typical action potential or no action potential at all - action potentials are always identical

35
Q

what factor accounts for the local currents associated with action potentials?

A

movement of sodium ions parallel to the inner and outer surfaces of the plasma membrane when chemically gated sodium channels have opened

36
Q

are the positive ions on the inside or outside of the cell at resting potential?

A

Negative on the iNside

pOsitive on the Outside

37
Q

do potassium ions freely diffuse out of the neural cell?

A

no

they pass through leak channels or are transported via the sodium-potassium pump (Na/K pump)

38
Q

which positively charged ions are found more on the outside of a neuron at rest?

A

sodium

39
Q

which positively charged ions are found more on the inside of a neural cell when it’s at rest?

A

potassium

40
Q

do sodium ions freely diffuse into the neural cell?

A

no

via leak channels and the sodium/potassium pump

41
Q

what makes a neuron negatively charged compared to the ECF?

A

negatively charged proteins on the inside

the sodium/potassium pump helps to maintain the balance

42
Q

what is the threshold for an action potential?

A

-55 mV

43
Q

define repolarisation

A

the return of the transmembrane potential to the resting potential after the cell has been depolarised

44
Q

name the types of cells that are capable of producing action potentials

A

excitable cells

  • neurons
  • muscle cells

(only in the axons of neurons)

45
Q

define what is meant by depolarisation

A

a shift from the resting membrane potential towards a more positive potential

46
Q

list the events involved in the generation and propagation of an action potential

A
  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
Q

compare the absolute refactory period with the relative refractory period

A

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
Q

define continuous propagation and saltatory propagation

A

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
Q

what’s the relationship between myelin and the propagation speed of action potentials

A

myelin greatly increases propagation speed

50
Q

what is a synapse?

A

a specialised site where the neuron communicates with another cell

51
Q

describe the components of a synapse

A

presynaptic cell

postsynaptic cell

neurotransmitters

synaptic cleft

52
Q

what are the chemical messengers released at the synapse called?

A

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
Q

what is the stimulus for the exocytosis of a neurotransmitter into the synaptic cleft?

A

an influx of calcium ions into the presynaptic nob

54
Q

contrast an electrical synapse with a chemical synapse

A

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
Q

define excitatory postsynaptic potential and inhibitory postsynaptic potential

A

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
Q

define hyperpolarisation

A

a shift from the resting potential in which the transmembrane potential becomes more negative

neuron can only respond to extra strong stimulus

57
Q

what is the term for the point in an action potential when the membrane is at its most depolarised? what is its voltage then?

A

peak action potential

+30 mV

58
Q

what happens during the hyperpolarisation stage of an action potential?

A

transmembrane potential drops below -70 mV because potassium channels are slow to close

neuron can only respond to extra strong stimulus

59
Q

what happens during repolarisation?

why does membrane potential change?

A

move back towards resting membrane potential

sodium channels are inactivated
potassium channels are activated.

60
Q

what physiology does dopamine play a role in?

A

motor control
emotion and reward
decreased prolactin
vomiting

61
Q

what pathophysiology does dopamine play a role in?

A

schizophrenia
parkinsons
addiction

62
Q

what physiology does serotonin play a role in?

A

(there are lots of serotonin (5HT) receptors):

digestion
sleep/wake
mood
appetite 
vomiting
63
Q

what pathophysiology does serotonin play a role in?

A

(there are lots of serotonin (5HT) receptors):

depression
mania
eating disorders

64
Q

what physiology does glutamate play a role in?

A

learning and memory

65
Q

what pathophysiology does glutamate play a role in?

A

epilepsy
chronic pain
drug dependence

66
Q

what pathophysiology does acetylcholine play a role in?

A

alzheimers

67
Q

what pathophysiology does noradrenaline play a role in?

A

bipolar disorder

depression

biology 121 (14 decks)

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