Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Physiology (MPP 3202) > Ch. 7 The Nervous System: Neurons and Synapses > Flashcards

Ch. 7 The Nervous System: Neurons and Synapses Flashcards

1
Q

What is included in the Central Nervous System (CNS)

A

Brain and spinal cord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is special about the CNS?

A

It is encased in the spine and skull

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is included in the Peripheral Nervous System (PNS)

A

Cranial and spinal nerves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Define Neurons

A

Conduct impulses but generally cannot divide

–but can repair if severed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Define Glial Cells (neuroglia)

A

Support the neurons and cannot conduct impulses, but can divide
–work together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Neurons

A

Respond to chemical and physical stimuli
–pain, pressure, heat…

Conduct electrochemical impulses (action potential)

Release chemical regulators (at synapse)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Neurons enable perception of?

A
  1. Sensory stimuli
  2. Learning
  3. Memory
  4. Control of muscles (voluntary and involuntary) and glands
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Can neurons divide? Can neurons repair?

A

Most neurons cannot divide, but can repair

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is included in the structure of a neuron?

A

Cell body
Dendrites
Axons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Neuron Structure: Cell Body

A

Contains the nucleus and other organelles; cluster in groups

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Clustered groups of cell bodies in the CNS are called ____.

A

Nuclei

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Clustered groups of cell bodies in the PNS are called ____.

A

Ganglia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Neuron Structure: Dendrites

A

Receive impulses and conducts a graded impulse toward the cell body

Shorter projections than axon; project off cell body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Neuron Structure: Axon

A

Conducts action potentials away from the cell body

Axon is a long projection (can be up to 1 meter long)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Neuron Structure: Axon Hillock

A

Area where axon meets cell body; action potentials generate here then propagate out

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is Axonal Transport?

A

An active process needed to move organelles and proteins from the cell body to axon terminals

Require energy (b/c it’s an active process)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Axonal Transport: Fast

A

Component moves vesicles (neurotransmitters)

In vesicles, so it’s exocytosis bulk transport

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Axonal Transport: Slow

A

Components move microfilaments, microtubules, and proteins

aka Cytoskeleton

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Axonal Transport: Anterograde Transport

A

From cell body to dendrites and axon

Cell body –> away

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Axonal Transport: Retrograde Transport

A

From dendrites and axons to cell body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

The functional classification of neurons is based on?

A

The direction impulses are conducted

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Sensory Neurons

A

Conduct impulses from sensory receptors to CNS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Motor Neurons

A

Conduct impulses from CNS to target organs (muscles or glands)

2 branches:
Somatic motor neurons
Autonomic motor neurons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Somatic Motor Neurons

A

Responsible for reflexes (which are involuntary) and voluntary control of skeletal muscles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Autonomic Motor Neurons

A

Innervate voluntary targets such as smooth muscle, cardiac muscle, and glands

Subdivided into Sympathetic and Parasympathetic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Autonomic Motor Neurons: Sympathetic

A

Emergency situations; “fight or flight”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Autonomic Motor Neurons: Parasympathetic

A

Normal functions; “rest and digest”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What are nerves?

A

Bundles of axons located outside the CNS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Nerves that are compose of sensory and motor neurons are known as?

A

Mixed nerves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Are most nerves mixed nerves?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Some of the cranial nerves have ____ fibers only.

A

Sensory

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

A bundle of axons in the CNS is called a ____.

A

Tract

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What are neuroglia (glial cells)?

A

Cells that are non-conducting but support neurons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What are the 2 types of neuroglia in the PNS?

A
  1. Schwann cells (neurolemmocytes)

2. Satellite cells (ganglionic gliocytes)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What are the 4 types of neuroglia in the CNS?

A
  1. Oligodendrocytes
  2. Microglia
  3. Astrocytes
  4. Ependymal cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Neuroglia: Schwann Cells

A

aka Neurolemmocytes

in PNS

Form myelin sheaths around peripheral axons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Neuroglia: Satellite Cells

A

aka Ganglionic Gliocytes

in PNS

Support cell bodies w/in the ganglia of the PNS
–secrete growth factors, etc.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Neuroglia: Oligodendrocytes

A

in CNS

Form myelin sheaths around the axons of CNS neurons

analogous to Schwann cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Neuroglia: Microglia

A

in CNS

Migrate around CNS tissue and phagocytize foreign and degenerated material

Mobile, move around

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Neuroglia: Astrocytes

A

in CNS

Regulate external environment of neurons

Play important role in BBB, regulate tight junction w/in endothelial cells, associate w/ endothelia cells too

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

Neuroglia: Ependymal Cells

A

in CNS

Line ventricles and secrete cerebrospinal fluid (CSF)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Blood Brain Barrier (BBB)

A

Capillaries in brain do not have pores between adjacent cells but are joined by tight junctions

Substances can only be moved by very selective processes of diffusion through endothelial cells, active transport, and bulk transport

Movement is transcellular not paracellular

Astrocytes regulate formation of BBB and support cell bodies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Neurons have a resting potential of ____.

A

-70mV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Resting Membrane Potential

A

Established by large negative molecules in side cell

Na+/K+ pumps

Permeability of membrane to positively charged, inorganic ions

45
Q

At rest, there is a ____ concentration of K+ inside the cell and a ____ concentration of Na+ outside the cell.

A

High; High

46
Q

The resting membrane potential is close to the equilibrium of ____.

A

K+

47
Q

Membrane Potential: Depolarization

A

Occurs when positive ions enter the cell (usually Na+)

Membrane potential becomes less negative

48
Q

Membrane Potential: Hyperpolarization

A

Occurs when positive ions leave the cell (usually K+) or negative ions (Cl-) enter the cell

Membrane potential becomes more negative

49
Q

Depolarization of the cell is ____.

A

Excitatory

50
Q

Hyperpolarization of the cell is ____.

A

Inhibitory

51
Q

K+ Leakage Channels

A

Not gated (always open)

Increase permeability to K+

52
Q

Voltage-Gated K+ Channels

A

Open when a particular membrane potential is reached; closed at resting potential

53
Q

Na+ voltage-gated channels are closed at rest; the membrane is ____ permeable to Na+ at rest.

A

Less

54
Q

Voltage-Gated Na+ Channels

A

Open if membrane potential depolarizes to -55mV (threshold)

Sodium rushes in due to electrochemical gradient

Membrane potential climbs toward sodium equilibrium potential

These channels are deactivated at +30mV.

55
Q

If Voltage-Gated Na+ channels open, Na+ moves in…which is what direction on the concentration gradient?

A

Down the concentration gradient

56
Q

Refractory Period

A

Channel is inactivated, but not closed all the way

57
Q

Voltage-Gated K+ Channels

A

At around +30mV, voltage-gated K+ channels open, and K+ rushes out of the cell following the electrochemical gradient.

Makes the cell depolarize back toward the potassium equilibrium potential

58
Q

What is the threshold membrane potential?

A

-55mV

59
Q

Action Potentials: Postive Feedback Loop

A

At threshold membrane potential (-55mV), voltage-gated Na+ channels open, and Na+ rushes in. As cell depolarizes, more Na+ channels are open, and the cell becomes more and more permeable to Na+

Known as a positive feedback loop

Causes an overshoot of membrane potential
–membrane potential reaches +30mV

60
Q

Action Potentials: Negative Feedback Loop

A

At +30mV, Na+ channels close, and K+ channels open

Results in repolarization of membrane potential

Known as negative feedback loop

61
Q

Once the threshold has been reached, will an action potential happen?

A

Yes

62
Q

Will the size of the stimulus affect the size of the action potential?

A

No, it will always reach +30mV

It may recruit more neurons though

63
Q

Will the size of the stimulus affect action potential duration?

A

No, but it will make action potentials occur more frequently

64
Q

Refractory Period

A

Action potentials can only increase in frequency to a certain point. There is a Refractory Period after an action potential when the neuron cannot become excited again.

65
Q

Absolute Refractory Period

A

Occurs during the action potential. Na+ channels are inactive (not just closed)

66
Q

Relative Refractory Period

A

When K+ channels are still open. Only a very strong stimulus can overcome this.

Still in hyperpolarization stage.

67
Q

T/F: Each action potential remains a separate, all-or-none event.

A

True

68
Q

Why is the refractory period important?

A

B/c we have to reset the resting membrane potential in order to fire another action potential

69
Q

Conduction of Nerve Impulses

A

When an action potential occurs at a given point on a neuron membrane, voltage-gated Na+ channels open as a wave down the length of the axon.

The action potential at one location serves as the depolarization stimulus for the next region of the axon.

Refractory period is good b/c it keeps depolarization moving down the axon.

70
Q

What are the 2 types of conduction?

A
  1. Unmyelinated

2. Myelinated

71
Q

Conduction: Unmyelinated

A

Axon potentials are produced down the entire length of the axon at every patch of membrane.

Conduction rate is slow b/c so many action potentials are generated and each one is an individual event.

Amplitude of each action potential is the same - conducted w/o decrement.

72
Q

Is Unmyelinated Conduction organized or unorganized?

A

Unorganized and chaotic

73
Q

Conduction: Myelinated

A

Myelin provides insulation, improving the speed of cable properties.

Nodes of Ranvier allow Na+ and K+ to cross the membrane every 1-2mm.

Na+ ion channels are concentrated at the nodes.

Action potentials “leap” from node to node.

This is called Saltatory Conduction.

74
Q

What are the Nodes of Ranvier?

A

Spaces between myelination.

75
Q

Is Myelinated Conduction organized or unorganized?

A

Organized

76
Q

How is action potential conduction speed increased (2 things)?

A
  1. Increasing diameter of neuron
    - -reduces resistance to spread of charges via cable properties (ability to conduct through cytoplasm, which is poor due to high resistance and leak of ions ‘out’ through membrane)
  2. Myelination b/c of saltatory conduction
77
Q

Discuss the neuron speed of a thin, unmyelinated cell vs. a thick, myelinated cell.

A

Thin, unmyelinated neuron speed is 1.0m/sec

Thick, myelinated neuron speed is 100m/sec

78
Q

Action potential can be describe as?

A

All or none

79
Q

What is a synapse?

A

Functional connection between a neuron and the cell it is signaling

80
Q

Synapse in the CNS

A

In the CNS, the second cell is another NEURON

81
Q

Synapse in the PNS

A

In the PNS, the second cell will be in a MUSCLE or GLAND; often called myoneural or neuromuscular junctions.

82
Q

Presynaptic Neuron

A

The first neuron when one neuron is signaling another

Can signal the dendrite, axon, or cell body of a second neuron

83
Q

Postsynaptic Neuron

A

The second neuron when one neuron is signaling another

84
Q

Synapses can be ____ or ____.

A

Electrical; Chemical

85
Q

Electrical Synapses

A

Occur in smooth muscle and cardiac muscle, between some neurons of the brain, and between glial cells

86
Q

Electrical Synapses: Glial Cells

A

Remember, glial cells do NOT conduct impulses (and glial cells are support cells)!

Yet the neuron will send information to the glial cell (via electrical synapses) to tell the glial cell about the support needed so it can do its job.

87
Q

In electrical synapses, the cells are joined by ____ ____.

A

Gap junctions

88
Q

Stimulation of electrical synapses causes phosphorylation or dephosphorylation of ____ ____ to open or close the channels.

A

Connexin proteins

89
Q

Chemical Synapses

A

Most synapses involve the release of a chemical called a neurotransmitter from axon terminal.

The synaptic cleft is very small, released neurotransmitter can readily diffuse across this space

90
Q

Is the space w/in a chemical synapse tightly joined?

A

No, it is not tightly joined (this allows for neurotransmitters to easily diffuse)

91
Q

Where is the neurotransmitter enclosed?

A

In synaptic vesicles in the axon terminal

92
Q

How are neurotransmitters released?

A

When the action potential reaches the end of the axon, voltage-gated Ca2+ channels open.

Ca2+ stimulates the fusing of synaptic vesicles to the plasma membrane and exocytosis of the neurotransmitter.

93
Q

Discuss Ca2+ concentrations inside and outside the cell.

A

Low Ca2+ inside cell

High Ca2+ outside cell

94
Q

____ is the signal for neurotransmitter release.

A

Calcium (Ca2+)

95
Q

Actions of the Neurotransmitter

A

Neurotransmitter diffuses across synapse, where it binds to a specific receptor protein

  • -neurotransmitter is referred to as the ligand
  • -results in the opening of chemically regulated ion channels (aka ligand-gated ion channels)
96
Q

Acetylcholine (ACh)

A

ACh is a neurotransmitter that directly opens ion channel when it binds to its receptor.

97
Q

Excitatory ACh

A

In some areas of CNS, in some autonomic motor neurons, and in all somatic motor neurons

98
Q

Inhibitory ACh

A

In some autonomic motor neurons

99
Q

Nicotinic ACh receptors

A

Can be stimulated by nicotine

Found on the motor end plate of skeletal muscle cells (neuromuscular junction), in autonomic ganglia, and in some parts of CNS

100
Q

Muscarinic ACh receptors

A

Can be stimulated by muscarine (from poisonous mushrooms)

Found in CNS and plasma membrane of smooth and cardiac muscles and glands innervated by autonomic motor neurons

101
Q

The ANS (autonomic nervous system) uses which 2 receptors?

A

Nicotinic ACh receptors and Muscarinic ACh receptors

102
Q

Agonists

A

Drugs that stimulate a receptor
–ex: ACh

Mimics natural ligand for that receptor

103
Q

Antagonists

A

Drugs that inhibit a receptor

–ex: Beta-blockers

104
Q

Acetylcholinesterase (AChE)

A

AChE is an enzyme that inactivates ACh activity shortly after it binds to the receptor
–terminates ACh signal

Hydrolyzes ACh into acetate and choline, which are taken back into the presynaptic cell for reuse (will recycle it and make more ACh)

105
Q

What are Monoamines?

A

Regulatory molecules derived from AAs

106
Q

Monoamines: Catecholamines

A

Derived from tyrosine; include dopamine, norepinephrine, and epinephrine

107
Q

Monoamines: Serotonin

A

Derived from L-Tryptophan

108
Q

Monoamines: Histamine

A

Derived from histidine

109
Q

Monoamine Action and Inactivation

A

Like ACh, monoamines are made in the presynaptic axon, released via exocytosis, diffuse across the synapse, and bind to specific receptors.

They are quickly taken back into presynaptic cell (called reuptake) and degraded by monoamine oxidase (MAO).

Physiology (MPP 3202) (32 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions