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UMU DPT Neuro > Chapter 2 > Flashcards

Chapter 2 Flashcards

1
Q

What are the 4 main components of a neuron?

A
  1. Soma
  2. Dendrite
  3. Axon
  4. Presynaptic Terminal
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2
Q

What organelles are associated with a neuron?

A
  1. Nucleus
  2. Golgi Body
  3. Lysosomes
  4. Mitochondria
  5. Endoplasmic Reticulum
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3
Q

What organelles are restricted to the soma of the neuron?

A

Nucleus, Golgi apparatus, and rough endoplasmic reticulum

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4
Q

Function of the soma?

A

Synthesizes a large quantity and variety of proteins used as neurotransmitters.

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5
Q

Function of an axon?

A

Output unit of the cell, specialized to send information to other neurons, muscle cells, or glands.

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6
Q

What is the function of the dendrites?

A

Branchlike extensions that serve as the main input sites for the cell.

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7
Q

What is the function of the presynaptic terminals?

A

Transmit elements of the neuron.

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8
Q

How do neurons transmit signals to other neurons?

A

Neurons transmit information about their activity via neurotransmitters from the presynaptic terminals into the synaptic cleft.

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9
Q

What is axoplasmic transport? And what are the 2 directions it travels in?

A

Axoplasmic transport is the mechanism for transporting substances along an axon. Occurs in two directions, anterograde and retrograde.

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10
Q

Compare anterograde to retrograde.

A

Anterograde: from the soma toward the presynaptic terminal
Retrograde: from the synapse back to the soma

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11
Q

Define bipolar cells and give an example.

A

Bipolar cells are classified based on the number of processes that directly arise from the cell body. There are 2 primary processes:
1. Dendritic root
2. Axon
Examples: Retinal bipolar cells in the eye.

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12
Q

Define multipolar cells and give an example.

A

Multipolar cells have multiple dendrites arising from many regions of the cell body and a SINGLE axon.
Example: spinal motor neuron, which projects from the spinal cord to innervate skeletal muscle fibers

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13
Q

Define pseudounipolar cells.

A

These are a subclass of bipolar cells. Appear to have a single projection from the cell body that divides into two axonal roots. They have two axons and no true dendrites.

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14
Q

Name the 4 types of membrane channels that allow ions to flow across the membrane.

A
  1. Leak channels
  2. Modality-gated channels
  3. Ligand-gated channels
  4. Voltage-gated channels
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15
Q

Define leak channels.

A

Leak channels allow a diffusion of a small number of ions through the membrane at a slow, continuous rate.

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16
Q

Define modality gated channels.

A

Specific to sensory neurons, modality gated channels open in response to mechanical forces.

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17
Q

Define ligand gated channels.

A

Ligand-gated channels open in response to a neurotransmitter binding to the surface of a channel receptor on a postsynaptic cell membrane.

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18
Q

Define voltage gated channels.

A

Voltage-gated channels open in response to changes in the electrical potential across the cell membrane.

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19
Q

Define resting membrane potential.

A

Value of the electrical potential across the membrane when a neuron is not transmitting information

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20
Q

What two forces determine ion distribution across the plasma membrane

A
  1. Electrical Gradient

2. Concentration Gradient

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21
Q

What 3 things maintain electrochemical gradient in neurons and membrane resting potential?

A
  1. Negatively charged molecules trapped inside the neuron.
  2. Passive diffusion of ions through leak channels.
  3. Na+ / K+ Pump
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22
Q

How many K+ and Na+ ions are pumped into and out of the cell with each cycle?

A

2 K+ ions are pumped in.

3 Na+ ions are pumped out.

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23
Q

When a sudden, brief change occurs in membrane potential the membrane is said to be either ______ or _______.

A

Depolarized or hyperpolarized.

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24
Q

Define depolarization.

A

Membrane is depolarized when the potential becomes less negative than the resting potential.

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25
Q

Define hyperpolarization.

A

Membrane is hyperpolarized when the potential becomes more negative than the resting potential

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26
Q

Compare depolarization and hyperpolarization when looking at the likelihood of a neuron to produce an action potential.

A

Depolarization increases the likelihood that the neuron will generate a transmittable electrical signal and is excitatory.
Hyperpolarization decreases the neuron’s ability to generate an electrical signal, and is inhibitory.

27
Q

Define modulation.

A

Small changes in the membrane’s electrical potential that alter the flow of ions across a cell membrane.

28
Q

Compare the receiving sites of sensory and motor neurons. This is looking at where the conduction of information begins.

A

Sensory neurons: receiving sites are the sensory receptors

Motor and interneurons: receiving sites are on the postsynaptic membrane

29
Q

Define local potential.

A

Initial change in membrane potential.

Spreads only a short distance along the membrane

30
Q

Define action potential.

A

Change from local results in depolarization.

Brief, large depolarization in electrical potential that is repeatedly regenerated

31
Q

What are the two categories of local potentials?

A
  1. Receptor potentials.

2. Synaptic potentials.

32
Q

Peripheral receptors have _____ gated channels.

A

Modality (open in response to mechanical forces such as stretch, compression, thermal changes, etc.)

33
Q

What are two ways that the strength of a local potential can be increased?

A
  1. Temporal summation

2. Spatial summation

34
Q

Define temporal summation.

A

Combined effect of a series of small potential changes that occur within milliseconds of each other.

35
Q

Define spatial summation.

A

Process by which either receptor or synaptic potentials generated in different regions of the neuron are added together

36
Q

True of false. Action potentials all considered to be all or none.

A

True. Every time sufficient stimuli are provided, an action potential will be produced.

37
Q

Name the sequence of three events that produce an action potential.

A
  1. Rapid depolarization. (Voltage gated Na+ channels OPEN)
  2. Decrease in NA+ conduction. (Channels CLOSE)
  3. Rapid repolarization (Voltage gated K+ channels open)
38
Q

True or false. Dr. Holt is the best neuro professor ever?

A

True. Definitely true.

39
Q

Define refractory period as it relates to the production of an action potential.

A

Period of hyperpolarization during which the membrane potential is even more negative than during resting (difficult to initiate a subsequent action potential)

40
Q

What are the two distinct states of the refractory period?

A
  1. Absolute refractory period.

2. Relative refractory period.

41
Q

Define absolute refractory period.

A

Membrane is unresponsive to stimuli.

42
Q

Define relative refractory period.

A

Membrane potential is returning to resting level and may be hyperpolarized

43
Q

Some axons may be specialized for faster action potential progression because of two structural adaptations:

A
  1. Increased diameter of the axon.

2. Myelination

44
Q

Define myelination and how it effects propagation of action potentials.

A

A sheath of proteins and fats surrounding an axon. Provides insulation, prevents current flow across the axonal membrane. Increases the speed of action potential propagation and the distance a current can passively spread. Thicker myelin leads to faster conduction.

45
Q

Define Nodes of Ranvier.

A

Small patches of myelinated axons which lack myelin.Specialized for active propagation of an action potential by allowing ion flow across the membrane.

46
Q

Define salutatory conduction.

A

Quick node-to-node jumping of action potential down a myelinated axon.

47
Q

Define afferent neurons.

A

Carry sensory information from the outer body toward the central nervous system.

48
Q

Define efferent neurons.

A

Relay commands from the central nervous system to smooth and striated muscles and to glands.

49
Q

Define interneurons.

A

Act throughout the nervous system, processing information locally or conveying information short distances; largest class of neurons.

50
Q

Compare divergence and convergence and how they contribute to the distribution of information throughout the nervous system.

A

Convergence: multiple inputs from a variety of cells terminate on a single neuron
Divergence: single neuron with many branches that terminate on a multitude of cells

51
Q

Define glial cells.

A

Cells which form a critical support network for neurons; glia also transmit information

52
Q

What function do microglial cells serve in the CNS?

A

Microglia act as the CNS immune system

53
Q

What are the three groups of Macroglial cells?

A
  1. Astrocytes
  2. Oligodendrocytes
  3. Schwann Cells
54
Q

What is the function of Astrocytes as it relates to CNS immunity?

A

Astrocytes act as scavengers, taking up extra K+ ions in the extracellular environment, removing chemical transmitters from the synaptic cleft between neurons, and cleaning up other debris in the extracellular space.

55
Q

What is the role of Oligodendrocytes?

A

Myelinate neurons in the CNS.

56
Q

What is the role of Schwann Cells?

A

Myelinate neurons in the PNS.

57
Q

What are some of the beneficial effects of neuroinflammation?

A

Initiates intervention by microglia (clean up and removal of debris).

58
Q

What are some of the harmful effects of Neuroinflammation?

A

Death of neurons and oligodendrocytes, inhibition of neural regeneration
Correlation between abnormal glial activity and neural damage in stroke, Alzheimer’s disease, Parkinson’s disease, and multiple sclerosis.

59
Q

What are some of the results of peripheral nervous system demyelination?

A

Results in disrupted proprioception (awareness of limb position) and weakness.

60
Q

Explain the cause of Guillain-Barre Syndrome?

A

Involves acute inflammation and demyelination of peripheral sensory and motor fibers
Occurs 2 to 3 weeks after a mild infection; in 2/3 of cases it is preceded by an intestinal infection that activates the immune system causing production of an antibody that mistakenly cross-reacts with the myelin sheath.

61
Q

Explain the symptoms of Guillain-Barre Syndrome.

A

Patients may have difficulty with chewing, swallowing, speaking, and facial expressions; pain can be prominent.
Patients most often report deep aching pain or hypersensitivity to touch
Onset is rapid, but followed by plateau then gradual recovery; recovery is usually complete.

62
Q

Explain the cause of Multiple Sclerosis?

A

Immune system produces antibodies that attack oligodendrocytes, producing plaques in the white matter of the CNS.

63
Q

What are some of the signs and symptoms of Multiple Sclerosis?

A

Signs and symptoms: weakness, lack of coordination, impaired vision, double vision, impaired sensation, and slurred speech; disruption of memory and emotions also possible.

64
Q

Define neural stem cells?

A

Immature and undifferentiated cells, precursors to both neurons and glial cells.

UMU DPT Neuro (2 decks)

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