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Neuroscience > Chapter 2 - Physical and Electrical Properties of Cells > Flashcards

Chapter 2 - Physical and Electrical Properties of Cells Flashcards

1
Q

Organelles of a neuron

A

nucleus, Golgi bodies, mitochondria, lysosomes, endoplasmic reticulum
Soma = nucleus, Golgi apparatus, rough endoplasmic reticulum

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2
Q

Dendrites

A

branch-like extensions that serve as the main input sites for the cell
- specialized to receive information from other cells

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3
Q

Axon

A

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

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4
Q

presynaptic terminal

A

finger-like projections that are the transmitting elements of the neuron
- presynaptic membrane

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5
Q

synaptic cleft

A

space between neurons

  • serves as the site for interneuronal communication
  • neurotransmitters path
  • post synaptic membrane
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6
Q

Bipolar cells

A

2 appendages
dendrite -> body -> axon
ex: retinal cells

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7
Q

Pseudounipolar cells

A

appear to have a single projection from the cell body that divides into two axonal roots(peripheral and central)
- exclusively sensory
peripheral axon -> />body> -> central axon

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8
Q

Multipolar cells

A

multiple dendrites arising from many regions of the cell body and single axon

  • neurons in the cerebellum and motor neurons
  • receive a lot of information then through 1 axon
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9
Q

electrical potential

A

across a membrane exists when the distribution of ions creates a difference in electrical charge on each side of the cell membrane

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10
Q

Membrane channels

A

leak channels
modality-gated channels
ligand-gated channels
voltage-gated channels

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11
Q

Afferent neurons

A

incoming information into a structure

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12
Q

efferent neurons

A

information leaving a structure

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13
Q

interneurons

A

convey information short distances between neurons

- common in gray horn of the spinal cord

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14
Q

Leak channels

A

non-gated

  • lets a few ions across
  • allows diffusion of a small number of ions through the membrane at a slow continuous rate
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15
Q

Modality-gated channels

A

responds to sensory stimuli(pressure, stretch, temp, etc)

- in sensory neurons

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16
Q

Ligand-gated channels

A

responds to neurotransmitters binding to the surface of a channel receptor on a postsynaptic cell membrane

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17
Q

Voltage-gated channels

A

electric potential is reached across the cell membrane to open

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18
Q

Glial cells

A

provide structure of the nervous system

  • also perform some transmission of information
  • Macroglia and microglia
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19
Q

Macroglia

A

Large glial cells

1) Astrocytes
2) Oligodendrocytes
3) Schwann cells

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20
Q

Astrocytes

A

star-shaped macroglial cells found throughout the CNS

  • direct role in cell signaling
  • stimulated by adjacent neurons or by mechanical changes(shape or pressure)
  • do not have synapses and do not generate action potentials
  • exchange calcium(diffused)
  • connections to blood vessels to pull nutrients and pass it on to neurons
  • help with cleanup and regulate synaptic activity
  • might interfere negatively with nerve regeneration
  • components of the blood-brain barrier
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21
Q

Oligodendrocytes

A

make up the myelin in CNS

  • Macroglial cells
  • wraps around multiple axons with multiple layers
  • better at maintaining charge, so faster transmission
22
Q

Schwann cells

A

Macroglial cells that make up the myelin in PNS

  • when peripheral nerves are inflamed, cells act as phagocytes
  • usually wraps around only one axon
23
Q

Microglial cells

A

act as phagocytes

  • kill off any injured or aging neurons
  • have been linked with neuro degenerative diseases
  • attracted by proteins secreted by dying cells
  • essential for normal healing following stroke, brain injury or CNS infection
  • abnormal activity contributes to neural damage
24
Q

Myelin sheath

A

insulator of neuron(80% lipid, 20% protein)

- prevents current flow across the axonal membrane

25
Q

Nodes of Ranvier

A

small patches of myelinated axons that lack myelin

  • every 1 to 2mm
  • contain high densities of Na and K channels
  • generates new action potential to pass on through the axon(saltatory conduction)
26
Q

resting membrane potential

A

the value of the electric potential across the membrane when the neuron is not transmitting information

  • maintained by:
    1) negatively charge molecules trapped inside
    2) leak channels
    3) Na - K pump
27
Q

Na - K Pump

A

uses ATP to actively move ions across the membrane against their electrochemical gradient

  • carries two K ions into the cell
  • carries three Na ions out of the cell
28
Q

Depolarization

A

when the potential becomes less negative than the resting potential(excitatory)

29
Q

Hyperpolarized

A

potential becomes more negative than the resting potential(inhibitory)

30
Q

action potential

A

a brief, large depolarization in electrical potential that is repeatedly regenerated along the length of the axon

  • is all-or-none
  • caused by a sudden influx of Na through voltage-gated channels
  • can be started by the summation of local potentials depolarizing the membrane beyond a voltage threshold level
31
Q

Sequence for developing an action potential

A

1) deformation of a peripheral pressure receptor
2) change in local membrane potential of the sensory ending
3) development of an action potential in the sensory axon
4) release of transmitter from the sensory neuron presynaptic terminal
5) binding of transmitter to the ligand-gated channel on the postsynaptic cell membrane
6) activation of synaptic potential in the postsynaptic membrane

32
Q

Local potentials

A

not strong enough to send impulse through neuron

  • receptor potential
  • synaptic potential
  • can spread only passively and confined to a small area of the membrane
33
Q

receptor potential

A

receptor stimulated

- most are depolarizing

34
Q

synaptic potentials

A

action of the neurotransmitter on the membrane channel determines if it is depolarizing or hyperpolarizing
- graded in amplitude and duration

35
Q

temporal summation

A

the combined effect of a series of small potential changes that occur within milliseconds of each other
- boosts signal

36
Q

spatial summation

A

the process by which local potentials generated in different regions of the neuron are added together
- boosts signal

37
Q

Action potential production sequence

A

1) rapid depolarization due to opening of voltage-gated Na channels
2) decrease in Na conduction due to closing of the channels
3) rapid repolarization due to the opening of voltage-gated K channels

38
Q

refractory

A

when it is more difficult to initiate an action potential

  • absolute refractory period
  • relative refractory period
39
Q

absolute refractory period

A

the membrane is unresponsive to stimuli

- Na channels cannot be reopened at this time

40
Q

relative refractory period

A

occurs during the latter part of the action potential

  • membrane potential is returning toward its resting level and may even be hyperpolarized
  • stimulus must be stronger than normal to cause action potential
41
Q

convergence

A

the process by which multiple inputs from a variety of cells terminate on a single neuron

42
Q

divergence

A

the process whereby a single neuronal axon may have many branches that terminate on a multitude of cells

43
Q

peripheral neuropathies

A

involve destruction of the myelin surrounding the largest, most myelinated sensory and motor fibers

  • results in disrupted proprioception and weakness
  • Guillain-Barre syndrome
44
Q

Guillain-Barré syndrome

A

acute inflammation and demyelination of peripheral sensory and motor fibers
- immune system creates antibodies that attack Schwann cells
- decreased sensation and skeletal muscle paralysis
- affected cranial nerves
- deep aching pain or hypersensitivity to touch
- most often complete recovery
Treatment:
1) plasmapheresis = filtering blood plasma to remove antibodies
2) intravenous immunoglobulin therapy = neutralizes antibodies and decreases inflammation

45
Q

CNS demyelination

A

damage to the myelin sheaths in the brain and spinal cord

- multiple sclerosis

46
Q

Multiple sclerosis

A

occurs when the immune system produces antibodies that attack oligodendrocytes(patches of demyelination)

  • weakness, lack of coordination, impaired vision, impaired sensation, slurred speach
  • onset between ages 20-40 in women
  • correlation with vitamin D levels
  • avoid high temps and excessive exertion
  • vitamin D, stress management, exercise, medical management to slow progression of disease
47
Q

Relapsing/remitting MS

A

begins with alternating relapses and remissions

48
Q

secondary progressive MS

A

continuous neurologic decline with fewer or no relapses

49
Q

primary progressive MS

A

steady functional decline from time of onset with predominantly spinal cord symptoms

50
Q

progressive relapsing MS

A

begins with steady functional decline with superimposed relapses and partial remissions
- function never really recovers during remissions

Neuroscience (14 decks)

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