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Anatomy > The Nervous System > Flashcards

The Nervous System Flashcards

1
Q

What two systems maintain internal coordination?

A

Endocrine and nervous systems

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2
Q

Communicates by means of chemical, messengers (hormones) secreted into the blood

A

Endocrine system

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3
Q

Employs electrical and chemical means to send messages from cell to cell

A

Nervous system

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4
Q

What are the two major anatomical subdivisions of the Nervous System?

A
  1. Central Nervous System (CNS)
  2. Peripheral Nervous System (PNS)
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5
Q
  • brain and spinal cord enclosed in bony coverings
  • enclosed by cranium and vertebral column
A

Central nervous system (CNS)

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6
Q

All the nervous system except the brain and spinal cord; composed of nerves and ganglia

A

Peripheral nervous system (PNS)

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7
Q

A bundle of fibers (axons) wrapped in fibrous connective tissue

A

Nerve

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8
Q

A knot like swelling in a nerve where neuron cell bodies are concentrated

A

Ganglion

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9
Q

Carries sensory signals from various receptors to the CNS
- informs the CNS of stimuli within or around the body

A

Sensory (afferent) division

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10
Q

Carries signals from receptors in the skin, muscles, bones, and joints

A

Somatic sensory division

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11
Q

Carries signals from the viscera of the thoracic and abdominal cavities
- heart, lungs, stomach, and urinary bladder

A

Visceral sensory division

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12
Q

Carries signals from the CNS to gland and muscle cells that carry out the body’s response

A

Motor (efferent) division

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13
Q

Cells and organs that respond to commands from the CNS

A

Effectors

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14
Q

Carries signals to skeletal muscles
- output produces muscular contraction as well as somatic reflexes- involuntary muscle contractions

A

Somatic motor division

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15
Q

-Carries signals to glands, cardiac muscle, and smooth muscle
- involuntary, and responses of this system receptors are viscera, reflexes

A

Visceral motor division (autonomic nervous system)

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16
Q
  • tends to arouse body for action
  • accelerating heart beat and respiration, while inhibiting digestive and urinary systems
A

Sympathetic division

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17
Q
  • tends to have calming effect
  • slows heart rate and breathing
  • stimulates digestive and urinary systems
A

Parasympathetic division

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18
Q

Neurons respond to environmental changes called stimuli

A

Excitability (irritability)

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19
Q

Neurons respond to stimuli by producing electrical signals that are quickly conducted to other cells at distant locations

A

Conductivity

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20
Q

When electrical signal reaches end of nerve fiber, a chemical neurotransmitter is secreted that crosses the gap and stimulates the next cell

A

Secretion

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21
Q

What are the three general classes of neurons based on function?

A

Sensory, interneuron, motor

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22
Q
  • specialized to detect stimuli
  • transmit information about them to the CNS
  • begin in almost every organ in the body and end in the CNS
A

Sensory (afferent) neurons

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23
Q

Conducting signals toward CNS

A

Afferent

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24
Q

-lie entirely within the CNS
- receive signals Demi many neurons and carry out the intergrative function (process, store, and retrieve information and “make decisions” that determine how the body will respond to stimuli)
- 90% of all neurons are these
- lie between and interconnect the incoming sensory pathways and the outgoing motor pathways of the CNS

A

Interneurons (associated neurons)

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25
Q

-
Send signals out to muscles and gland cells (the effectors)
- motor because most of them lead to muscles
- efferent neurons conduct signals away from the CNS

A

Motor (efferent) neuron

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26
Q

The control center of the neuron
- also called neurosoma, cell body, or perikaryon
- has a single, centrally located nucleus with large nucleolus
- cytoplasm contains mitochondria, lysosomes, a Golgi complex, numerous inclusions, and extensive rough ER and cytoskeleton
- cytoskeleton consists of dense mesh of microtubules and neurofibrils (bundles of actin filaments)

A

Soma

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27
Q

Vast number of branches coming from a few thick branches from the soma
- resemble bare branches of a tree in winter
- primary site for receiving signals from other neurons
- the more of these a neuron has, the more information it can receive and incorporate into decision making
- provide precise pathway for the reception and processing of neural information

A

Dendrites

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28
Q

Originates from a mound on one side of the soma called the axon hillock
- cylindrical, relatively unbranched for most of its length
- branch extensively on distal end
- specialized for rapid conduction of nerve signals to points remote to the soma

A

Axon (nerve fiber)

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29
Q

Branches of axon

A

Axon collaterals

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30
Q

Cytoplasm of axon

A

Axoplasm

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31
Q

Plasma membrane of axon

A

Axolemma

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32
Q

What enclose and axon?

A

Schwann cells and myelin sheath

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33
Q

Little swelling that forms a junction (synapse) with the next cell

A

Synaptic knob

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34
Q
  • one axon and multiple dendrites
  • most common
  • most neurons in the brain and spinal cord
A

Multipolar neuron

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35
Q
  • one axon and one dendrite
  • olfactory cells, retina, inner ear
A

Bipolar neuron

36
Q
  • single process leading away from the soma
  • sensory from skin and organs to spinal cord
A

Unipolar neuron

37
Q
  • many dendrites but no axon
  • help in visual processes
A

Anaxonic neuron

38
Q

two-way passage of proteins, organelles, and other material along an axon

A

axonal transport

39
Q

movement down the axon away from the soma

A

anterograde transport

40
Q

movement up the axon toward the soma

A

retrograde transport

41
Q
  • support and protect the neurons
  • bind neurons together and form framework for nervous tissue
  • in fetus, guide migrating neurons to their destination
    -If mature neuron is not in synaptic contact with another neuron it is covered by glial cells
A

neuroglia or glial cells

42
Q

What are the four types of Neuroglia that only occur in CNS?

A
  1. oligodendrocytes
  2. ependymal cells
  3. microglia
  4. astrocytes
43
Q
  • form myelin sheaths in CNS
  • each arm like process wraps around a nerve fiber forming an insulating layer that speeds up signal conduction
A

oligodendrocytes

44
Q
  • line internal cavities of the brain
  • cuboidal epithelium with cilia on apical surface
  • secretes and circulates cerebrospinal fluid (CSF) (clear liquid that bathes the CNS)
A

ependymal cells

45
Q
  • small, wandering macrophages formed white blood cell called monocytes
  • though to perform a complete checkup on the brain tissue several times a day
  • wander in search of cellular debris to phagocytize
A

microglia

46
Q
  • most abundant glial cell in CNS
  • cover entire brain surface and most nonsynaptic regions of the neurons in the gray matter of the CNS
  • diverse functions: form a supportive framework; have extensions that contact blood capillaries that stimulate them to form a tight seal called the blood-brain barrier; convert blood glucose to lactate and supply this to the neurons for nourishment
A

astrocytes

47
Q

What two types of Neuroglia only occur in PNS?

A
  1. Schwann cells
  2. Satellite cells
48
Q
  • envelope nerve fibers in PNS
  • wind repeatedly around a nerve fiber
  • produce a myelin sheath similar to the ones produced by oligodendrocytes in CNS
  • assist in the regeneration of damaged fibers
A

Schwann cells

49
Q
  • surround the neurosomas in ganglia of the PNS
  • provide electrical insulation around the soma
  • regulate the chemical environment of the neurons
A

Satellite cells

50
Q

an insulating layer around a nerve fiber
- formed by oligodendrocytes in CNS and Schwann cells in PNS
- consists of the plasma membrane of glial cells (20% protein and 80% lipid)

A

myelin sheath

51
Q

production of the myelin sheath
- begins at week 14 of fetal development
- proceeds rapidly during infancy
- completed in late adolescence
- dietary fat is important to CNS development

A

myelination

52
Q

What are the segmented parts of the myelin sheath?

A
  1. Nodes of Ranvier
  2. Internodes
  3. Initial segment
  4. Trigger zone
53
Q

gap between segments

A

Nodes of Ranvier

54
Q

myelin-covered segments from one gap to the next

A

Internodes

55
Q

short section of nerve fiber between the axon hillock and the first glial cell

A

Initial segment

56
Q

the axon hillock and the initial segment
- play an important role in initiating a nerve signal

A

Trigger zone

57
Q

degenerative disorder of the myelin sheath
- oligodendrocytes and myelin sheaths in the CNS deteriorate
- myelin replaced by hardened scar tissue
- nerve conduction disrupted (double vision, tremors, numbness, speech defects)
- onset between 20 and 40 and fatal from 25 to 30 years after diagnosis
- cause may be autoimmune triggered by virus

A

multiple sclerosis

58
Q

formed by Schwann cells, basal lamina, and the neurilemma near the injury
- guides the growing sprout back to the original target cells and reestablishes synaptic contact

A

regeneration tube

59
Q

conduction speed of fibers: 0.5 to 2.0 m/s

A

small, unmyelinated fibers

60
Q

conduction speed of fibers: 3 to 15.0 m/s

A

small, myelinated fibers

61
Q

conduction speed of fibers: up to 120 m/s

A

large, myelinated fibers

62
Q

Living cells are ______

A

polarized

63
Q

charge difference across the plasma membrane
- about -70 mV in a resting, unstimulated neuron
- negative value means there are more negatively charged particles on the inside of the membrane than on the outside

A

resting membrane potential (RMP)

64
Q

a rapid up-and-down shift in the membrane voltage
- sodium ions arrive at the axon hillock
- depolarize the membrane at that point
- threshold

A

action potential

65
Q

critical voltage to which local potentials must rise to open the voltage-regulated gates (-55mV)

A

threshold

66
Q

polarity reversed from RMP

A

depolarization

67
Q

do not get weaker with distance

A

nondecremental

68
Q

once started goes to completion and cannot be stopped

A

irreversible

69
Q

the period of resistance to stimulation

A

refractory period

70
Q

What are the two phases of the refractory period?

A
  1. absolute refractory period
  2. relative refractory period
71
Q
  • no stimulus of any strength will trigger AP
  • as long as Na+ gates are open
  • from action potential to RMP
A

absolute refractory period

72
Q
  • only especially strong stimulus will trigger new AP
  • K+ gates are still open and any effect of incoming Na+ is opposed by the outgoing K+
A

relative refractory period

73
Q

synapses: first neuron in the signal path
- releases neurotransmitter

A

presynaptic neuron

74
Q

synapses: second neuron
- responds to neurotransmitter

A

postsynaptic neuron

75
Q

synapses: may synapse with a dendrite, soma, or axon of postsynaptic neuron to form axodendritic, axosomatic, or axoaxonic synapses

A

presynaptic neuron

76
Q

____ ______ of presynaptic neuron contains synaptic vesicles containing neurotransmitter

A

synaptic knob

77
Q

_____ ______ membrane contains proteins that function as receptors and ligand-regulated ion gates

A

postsynaptic neuron

78
Q
  • synthesized by the presynaptic neuron
  • released in response to stimulation
  • bind to specific receptors on the postsynaptic cell
  • alter the physiology of that cell
A

neurotransmitters

79
Q

employs acetylcholine (ACh) as its neurotransmitter
- ACh excites some postsynaptic cells (skeletal muscle)
- inhibits others

A

Cholinergic synapse

80
Q

any voltage change in the direction of threshold that makes a neuron more likely to fire
- usually results from Na+ flowing into the cell cancelling some of the negative charge on the inside of the membrane

A

excitatory postsynaptic potential (EPSP)

81
Q

excitatory brain neurotransmitters that produce EPSPs

A

glutamate and aspartate

82
Q

any voltage change away from threshold that makes a neuron less likely to fire
- neurotransmitter hyperpolarizes the postsynaptic cell and makes it more negative than the RMP making it less likely to fire
- produced by neurotransmitters that open ligand-regulated chloride gates (causing inflow of Cl- making the cytosol more negative)

A

inhibitory postsynaptic potential (IPSP)

83
Q

occurs when a single synapse generates EPSPs so quickly that each is generated before the previous one fades
- allows EPSPs to add up over time to a threshold voltage that triggers an action potential

A

temporal summation

84
Q

occurs when EPSPs from several different synapses add up to threshold at an axon hillock
- several synapses admit enough Na+ to reach threshold
- presynaptic neurons cooperate to induce the postsynaptic neuron to fire

A

spatial summation

85
Q

a process in which one neuron enhances the effect of another one
- combined effort of several neurons facilitates firing of postsynaptic neuron

A

facilitation

86
Q

process in which one presynaptic neuron suppresses another one
- opposite of facilitation
- reduces or halts unwanted synaptic transmission
- neuron 1 releases inhibitory GABA (prevents voltage-gated calcium channels from opening in synaptic knob and presynaptic neurons releases less or no neurotransmitter

A

presynaptic inhibitation

87
Q

What are the two subdivisions of the peripheral nervous system (PNS)?

A

Sensory division & motor division

Anatomy (10 decks)

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