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LIFESCI 7C > Neuron Structure & Function + The Nervous System > Flashcards

Neuron Structure & Function + The Nervous System Flashcards

1
Q

What is the function of sensory neurons?

A

receive and transmit information about an anima;’s environment or its internal physiological state

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2
Q

What is the function of interneurons?

A

receive and transmit information received by sensory neurons and transmits it to motor neurons

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3
Q

What is the function of motor neurons?

A

signal a muscle or gland to cause a response in the body

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4
Q

Where are stimuli received by the neuron?

A

dendrites

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5
Q

Where are synaptic stimuli summed?

A

axon hillock

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6
Q

____ potentials travel through the cell body
____ potentials travel through the axon

A

graded; action

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7
Q

What is membrane potential?

A

a difference in electrical charge across the cell membrane

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8
Q

Resting membrane potential is ____ mV

A

-70

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9
Q

Na+ moves ____ the cell through the ____ Na+ channel

A

into; voltage-gated

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10
Q

K+ moves ____ the cell through the ____ K+ channel

A

out; voltage-gated

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11
Q

The sodium-potasium pump pumps ____ Na+ ions ____ the cell and ____ K+ ions ____ the cell.

A

3 Na+ ions; out
2 K+ ions; into

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12
Q

True or False:
The sodium-potassium pump pumps a net positive charge of ions into the cell.

A

False

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13
Q

At resting potential:
Membrane potential is more negative/positive inside the cell than outside.

A

negative

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14
Q

At resting potential:
There is a greater/lower concentration of Na+ ions outside the cell than inside.

A

greater

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15
Q

At resting potential:
There is a greater/lower concentration of K+ ions inside the cell than outside.

A

greater

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16
Q

Threshold potential is ____ mV.

A

-55

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17
Q

What happens at threshold potential?

A

Na+ voltage-gated ion channels open and the action potential fires.

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18
Q

What is depolarization?

A

an increase in membrane potential from a negative resting potential

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19
Q

List the steps of an action potential.

A
  1. resting
  2. depolarization
  3. peak action potential
  4. repolarization
  5. hyperpolarization
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20
Q

At peak action potential:
Membrane potential is more negative/positive inside the cell than outside.

A

positive

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21
Q

At peak action potential:
There is a greater/lower concentration of Na+ ions outside the cell than inside.

A

lower

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22
Q

At peak action potential:
There is a greater/lower concentration of K+ ions inside the cell than outside.

A

higher

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23
Q

How are chemical gradients formed?

A

from concentration differences

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24
Q

How are electrical gradients formed?

A

from charge separation

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25
Q

What is the flow of chemical gradients?

A

high concentration –> low concentration

26
Q

What is the flow of electrical gradients?

A

positive –> negative

27
Q

What kind of ion channels are primarily present at the neuron’s dendrites? Why?

A

ligand-gated ion channels
neurotransmitters bind to these channels in the post-synaptic neuron

28
Q

What are the two types of graded potentials?

A

excitatory postsynaptic potential (EPSP)
inhibitory postynaptic potential (IPSP)

29
Q

What happens when a dendrite receives an EPSP?

A

cell depolarizes
more likely to initiate an action potential

30
Q

What happens when a dendrite receives an IPSP?

A

cell hyperpolarizes
less likely to initiate an action potential

31
Q

What are the conditions of an action potential occurring?

A

if the sum of EPSPs and IPSPs reach the threshold potential

32
Q

How does no summation occur?

A

multiple EPSPs widely spaced in time do not set off an action potential

33
Q

How does temporal summation occur?

A

multiple EPSPs arrive quickly at a single synapse

34
Q

How does spatial summation occur?

A

single EPSPs arrive at the same time at different synapses

35
Q

How does cancellation occur?

A

an EPSP and IPSP cancel each other out and no action potential occurs

36
Q

How does action potential propagation occur?

A

depolarization spreads through the axon and triggers more voltage-gated sodium channels to open and more action potentials to occur

37
Q

What is the role of myelin?

A

insulates the axon and increases the rate of action potentials

38
Q

True or False:
Strong stimuli (more concentration) in the synapse cause neurons to fire more frequent action potentials.

A

True

39
Q

True or False:
Synapses are fixed.

A

False
Synapses are not fixed, which allows for neuroplasticity and learning/memory.

40
Q

Where are voltage-gated channels found in the neuron?

A

cellular membrane

41
Q

Where are ligand-gated channels found in the neuron?

A

dendrites

42
Q

What are the steps of synapse communication?

A
  1. stimulated by the action potential
  2. voltage-gated Ca2+ channels open
  3. vesicles at the axon terminals respond to Ca2+ by fusing with the pre-synaptic membrane
  4. vesicles perform exocytosis to release neurotransmitters into the synaptic cleft
  5. neurotransmitters bind to ligand-gated ion channels in the post-synaptic membrane
  6. neurotransmitters are re-absorbed into the pre-synaptic terminal and stored until the next action potential arrives
43
Q

What are the two divisions of the nervous system?

A

central nervous system and peripheral nervous system

44
Q

What are the components of the central nervous system?

A

brain and spinal cord

45
Q

What are the components of the peripheral nervous system?

A

sensory and motor nerves

46
Q

What are the two divisions of the peripheral nervous system?

A

somatic and autonomic

47
Q

What is the somatic nervous system responsible for?

A

controlling voluntary activity

48
Q

What is the autonomic nervous system responsible for?

A

controlling involuntary activity

49
Q

What are the two divisions of the autonomic nervous system?

A

parasympathetic and sympathetic

50
Q

What does the parasympathetic nervous system do?

A

rest and digest

51
Q

What does the sympathetic nervous system do?

A

fight or flight

52
Q

What are afferent neurons?

A

send information toward the CNS

53
Q

What are efferent neurons?

A

send information away from the CNS

54
Q

True or False:
Simple reflex circuits go through the CNS.

A

False
Simple reflex circuits bypass the brain.

55
Q

How does the patellar reflex work?

A
  1. patellar tendon is struck
  2. stretch receptor in muscle responds by sending a signal along the sensory
  3. sensory neuron synapses with motor neuron in the spinal cord
  4. motor neuron sends signal to muscle, which contracts
  5. inhibitory interneuron inhibits contraction of the muscle
56
Q

What is the purpose of the sodium-potassium pump?

A

to maintain resting membrane potential by pumping a net negative charge
(more cations are pumped out the cell than inside)

57
Q

What happens if a myelinated and unmyelinated neuron arrive at different dendrites and deliver EPSPs?

A

No spatial summation would occur because the myelinated neuron would arrive at the dendrite before the unmyelinated neuron

58
Q

What is the refractory period of the action potential?

A

The point at which hyperpolarization is occurring; no action potential could occur at this time while the K+ ions are still closing

59
Q

What would happen if the Na+ and K+ voltage gated channels opened at the same time?

A

no action potential would occur
the movement of ions would “cancel” each other out

60
Q

How does morphine affect the synapse over time?

A
  • increases synaptic activity over time
  • to maintain homeostasis, the body decreases the number of receptors in the post-synaptic membrane in order to decrease synaptic activity back to normal
61
Q

What is an agonist?

A

a molecule (usually a drug) that mimics existing neurotransmitters

LIFESCI 7C (8 decks)

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