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Neuro > Week 2 > Flashcards

Week 2 Flashcards

1
Q

What does the cell body (soma of a neuron contain?

A

nucleus, Golgi apparatus, mitochondia, nucleic acids, usual organelle

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2
Q

What is the function of the cell body?

A

Synthesizes a large quantity and variety of proteins used as neurotransmitters

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3
Q

What do dendrites do?

A

receive information from other neurons (input sites for the cell)

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4
Q

Where do axons arise and end?

A

arise from axon hillock

end in presynaptic terminals

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5
Q

What is the length of an axon?

A

from long (greater than a meter) to short (less the 100um)

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6
Q

What is the function of an axon?

A

Specialized to send neural signals away to other neurons, muscle cells or glands (= “output unit” of the cell)

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7
Q

What is a pre-synaptic terminal?

A

Site of communication between neurons, and between a neuron and a muscle or a gland

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8
Q

What are the elements of a pre-synaptic terminal?

A

presynaptic terminals: fingerlike projections transmitting element of the cell
synaptic cleft: space between neurons
post-synaptic terminal

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9
Q

Vetebrate neurons are classified as:

A

bipolar cells

multipolar cells

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10
Q

Bipolar cells have:

A

2 primary processes from cell body
-dendritic root
axon

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11
Q

Pseudounipolar cell

A

subclass of bipolar cells; sensory neurons having two axons

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12
Q

Peripherial axon:

A

transits signals from the periphery to cell body

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13
Q

central axon

A

conduct signals to the spinal cord

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14
Q

How do neurons distinguish from most other cells?

A

by bioelectrical properties and intercellular communications

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15
Q

How do neurons function?

A

rapid changes in the electrical potential across the cell membrane

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16
Q

What is electrical potential?

A

difference in electrical charge carried by ions on each side of the cell membrane.

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17
Q

What are the four types of membrane channels?

A

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

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18
Q

What does a modality gated channel open in response to?

A

mechanical forces (stretch or touch), temperature changes or chemicals; specific to sensory neurons

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19
Q

What does a ligand gated channel open in response to?

A

response to a neurotransmitter binding to the surface of a channel receptor on a postsynaptic cell membrane

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20
Q

What does a voltage gated channel open in response to?

A

in response to changes in the electrical potential across the cell membrane.

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21
Q

What is a leak channel?

A

non gated channel

A small number of ions leak at a slow, continuous rate

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22
Q

What causes gated channels to open and close?

A

‘Gated’ membrane channels open in response to a stimulus and close when the stimulus is removed

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23
Q

What are the three types of electrical potentials?

A

Resting membrane potential
Local potential
Action potential

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24
Q

What is the value of the resting membrane potential?

A

-40 mV to -80 mV

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25
Q

What occurs when two forces are balanced?

A

electrochemical equilibrium

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26
Q

What maintains electrochemical gradient in neurons and membrane resting potential?

A
  • Passive diffusion of ions through leak channels in the cell membrane
  • Na+/K+ pump
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27
Q

What is depolarized?

A

the membrane potential becomes less negative than the resting membrane potential

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28
Q

What is hyperpolarized?

A

the membrane potential becomes more negative

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29
Q

What does hyperpolarization do?

A

decreases the neuron’s ability to generate an electrical signal, and its inhibitory

30
Q

What is local potential?

A

Initial change in membrane potential

31
Q

How do local potentials spread?

A

spread passively, confined to a small area of the membrane

-spread only a short distance along the membrane

32
Q

What can increase the strength of a local potential?

A

temporal and spatial summation

33
Q

What is temporal summation?

A

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

34
Q

What is spatial summation?

A

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

35
Q

What is an action potential?

A

a large depolarizing signal actively propagated along an axon by repeated generation of a signal

36
Q

_____ depolarization is typically sufficient to trigger an AP

A

15mV

37
Q

What is threshold stimulus intensity?

A

stimulus intensity sufficient to produce an action potential

38
Q

What are the 3 events that produce an action potential?

A
  1. Rapid depolarization (voltage-gated Na+ channels open)
  2. Decrease in Na+ conduction (channels closed)
  3. Rapid repolarization (voltage-gated K+ channels open)
39
Q

What happens during the refractory period?

A

Na+ channels become inactivated immediately after opening for an AP and require a specific amount of time before they can be activated again for a subsequent AP

40
Q

What is the function of the refractory period?

A

to promote forward propagation of an AP while preventing backward flow

41
Q

Refractory period is also a period of:

A

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

42
Q

Why will some axons be specialized for faster action potentials because of 2 structural adaptions:

A

increased diameter

myelination

43
Q

What does an increased diameter of the axon do?

A

speed of transmission is faster in larger-diameter axons.

44
Q

What does myelination do?

A

increases efficiency of conduction of AP by decreasing the inherent leakiness of the membrane

45
Q

What is myelination?

A

a sheath of proteins and fats surrounding an axon; Provides insulation, prevents current flow across the axonal membrane

46
Q

Thicker myelin leads to what?

A

faster conduction and greater chances for AP propagation

47
Q

What are nodes or ranvier?

A

small patches of myelinated axons which lack myelin

48
Q

What is saltatory conduction?

A

quick node-to-node jumping of AP down a myelinated axon

49
Q

Afferent neurons:

A

carry sensory information from the outer body toward the CNS

50
Q

Efferent neurons:

A

relay commands from the CNS to smooth and striated muscles and to glands

51
Q

Interneurons:

A

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

52
Q

What is convergence?

A

multiple inputs from a variety of cells terminate on a single neuron

53
Q

What is divergence?

A

single neuron with many branches that terminate on a multitude of cells

54
Q

Ratio of glial cells to neurons in the brain:

A

3:1

New literature : 9:1

55
Q

Glial cells:

A

form a critical support network for neurons

56
Q

Types of glia cells:

A

macroglia
microglia
glial stem cells

57
Q

Types of macroglia:

A

astrocytes
oligodendrocytes
schwann cells

58
Q

What are astrocytes?

A
  • star shaped macroglia found throughout the CNS
  • primarily in gray matter
  • act as scavengers
59
Q

What stimulates astrocytes?

A

signals from adjacent neurons or by mechanical changes

spread waves of Ca2+ to neighboring astrocytes

60
Q

What do oligodendrocytes and schwann cells do?

A

-form myelin sheath and are found primarily in white matter

61
Q

What do oligodendrocytes myelinate?

A

neurons in the CNS

62
Q

What do Schwann cells myelinate?

A

neurons in the PNS

63
Q

What are microglial cells?

A
  • phagocyte that resides in CNS
  • act as immune system of CNS
  • activated during development of nervous system following injury, infection or disease
64
Q

What are glial stem cells?

A
  • found throughout developing and adult brain
  • immature and undifferentiated cells
  • retain capacity to proliferate and generate
65
Q

What is neuroinflammation?

A

the response of the CNS to infections, diseases and injuries

66
Q

What is a beneficial effect of neuroinflammation?

A

when reactive microglia clean up and remove debris

67
Q

What is a harmful effect of neuroinflammation?

A
  • Death of neurons and oligodendrocytes, inhibition of neural regeneration
  • Correlation between abnormal glial activity and neural damage
68
Q

What is peripheral neuropathy?

A

any pathological change involving peripheral nerves

69
Q

What does peripheral neuropathy result in?

A

destruction of myelin surrounding the largest, most myelinated sensory and motor fibers
-disrupted proprioception and weakness

70
Q

What are the 4 types of MS?

A

relapsing/remitting
secondary progressive
primary progressive
progressive relapsing

Neuro (23 decks)

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