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Anatomy > Chapter 13- Neural Tissue > Flashcards

Chapter 13- Neural Tissue Flashcards

1
Q

nervous system

A

coordinate all body systems

  • accomplished by the transmission of signals
  • body parts to CNS
  • CNS to body parts
  • Electrochemical signaling
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2
Q

endocrine system

A

slower scale

-uses chemicals in the blood stream called hormones

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3
Q

general makeup of NS

A
  • many organs, each composed of several tissue
  • connective tissue
  • blood vessels
  • neurons
  • neuroglia
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4
Q

2 groups of NS

A

CNS
-brain and spinal chord
PNS
-cranial and spinal nerves (ganglia)

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5
Q

CNS makeup

A

brain and spinal chord

  • covered by meninges (house fluid)
  • starts as a hollow tube
  • bathed in cerebrospinal fluid
  • integration center
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6
Q

PNS makeup

A

consists of cranial and spinal nerves that contain both sensory and motor fibers
-connects CNS to muscles, glands, and all receptors
-brings info to and from CNS
(only sensory OR motor neurons)

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7
Q

PNS: 2 types

A

Afferent division= sensory
Efferent division= motor
–somatic (conscious control)
–autonomic (unconscious)

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8
Q

Receptors

A

detect stimuli

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9
Q

sensory

A

afferent PNS

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10
Q

integrative

A

CNS

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11
Q

motor

A

efferent PNS

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12
Q

effector

A

muscle/gland

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13
Q

Nervous tissue

A 
neurons
-structural and functional units
-excitable
-amitotic (unrepairable)
Neuroglia cells
-accessory cells
-act like connective tissue
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14
Q

3 major structures of neurons

A

soma
dendrites
axon

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15
Q

soma

A

cell body

-mononucleate

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16
Q

soma consists of

A

nissi bodies: ribosomes clusters, give gray color
axon hillock: connects soma to axon
perikaryon: region around the nucleus
neuronfibrils: cytoskeleton that extend into dendrites/axons; gives shape

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17
Q

dendrites

A
  • respond to neurotransmitters
  • short, branched, unmyelinated
  • specialized for contact with other neurons
  • conducts impulses towards the cell body
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18
Q

axon

A
  • only one cell
  • conducts nerve impulses away from soma
  • can give off collaterals (branches at end)
  • end in synaptic terminals
  • produce neuraltransmitters
  • may contact one of three things: another neuron, muscle fibers, gland
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19
Q

myelin sheath

A

glial cells that may wrap around the axon

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20
Q

axonal transport (axoplasmic flow)

A

movement of cellular materials (NOT signals) through axon

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21
Q

anterograde

A

away form soma; neurotransmitters, organelles, nutrients

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22
Q

retrograde

A

toward soma; degraded materials to be recycled and extracellular substances

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23
Q

axoplasma

A
  • cytoplasm of an axon
  • consists of
  • few organelles
  • cytoskeletal proteins
  • -form cytoskeleton
  • -maintain shape
  • generate axonal transport
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24
Q

axolemma

A 
-plasma membrane of an axon
consists of:
-collaterals: side branches
-telodendria: terminal extensions
-synaptic terminal: contains synaptic vesicles; where neuron contacts pstsynaptic cell
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25
Q

structural classification of neurons

A

anaxonic
bipolar
unipolar
multipolar

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26
Q

anaxonic

A

small neurons
axons can not be distinguished from dendrites
-CNS, especially interneurons that coordinate special senses
no axon

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27
Q

bipolar

A
  • several small dendrites converge onto one (one really long dendrite, looks like axon)
  • dendrite and axon separated by soma
  • unmyelinated
  • sensory neurons of special sensory organs
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28
Q

unipolar

A
  • pseuod-unipolar
  • several small dendrites converge onto one large one
  • dendrite and axon continuous
  • usually myelinated
  • majority of sensory neurons in PNS
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29
Q

multipolar

A
  • many dendrites extend from soma
  • long axon
  • myelinated
  • majority of motor neurons in PNS
  • spinal interneurons in CNS
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30
Q

Afferent Neuons

A

Have sensory function

  • cell body usually are outside CNS
  • have receptor ends on dendrites or are associated with receptor cells in sense organs
  • carry impulses from peripheral body parts to brain or spinal cord
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31
Q

afferent neruon receptors

A

exteroceptors: touch, temperature, pressure, light, chemicals
proprioceptors: monitor muscle and skeleton position
interoceptors: monitor internal systems (digestion, respiration, urinary)

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32
Q

Interneurons

A
  • only in CNS
  • classified based on effects
  • -excitatory
  • -inhibitory
  • most abundant
  • -link 2 or more neurons
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33
Q

efferent neurons

A

have motor function

  • cell body usually are inside CNS
  • carry impulses from the brain or spinal cord to peripheral body parts
34
Q

somatic efferent neurons

A

controls skeletal muscle

35
Q

autonomic/visceral efferent neurons

A

smooth muscle/glands

36
Q

neuroglial cells in PNS

A

satellite

schwan cell

37
Q

neuroglial cells in CNS

A

astrocytes
oligodendrocytes
ependymal cells
microglia

38
Q

Astrocytes

A 
largest and most common
star shaped
functions:
-structure and repair
-metabolism
-regulate ions and nutrition
-guide neurons to targets
-form blood-brain barrier
39
Q

oligodendrocytes

A

like astrocytes but smaller
functions
-form myelin in CNS
-sequester debris

40
Q

Microglia

A

-smallest and least common
-derived from myeloid cells
functions:
-help support neurons
-phagocytosis
-increase in number during injury or disease

41
Q

ependymal

A

-columnar/cuboidal
-microvilli on luminal surface
-joined by gap junctions
functions:
-help produce cerebrospinal fluid
-form porous layer
-monitor CSF composition

42
Q

satellite

A

associated with soma
assist with exchange of nutrients
isolates neuron from extraneous stimuli

43
Q

schwann cells

A

produce myelin in PNS
encloses axons of longer peripheral nerves
functions:
-support neurons
-prevent contact
-myelinate large PNS axons (myelin sheath)

44
Q

unmyelinated axons

A
  • appear gray
  • many axons associate with a single schwann cell
  • CNS: no glial cells
45
Q

myelinated

A
  • appear white
  • CNS: oligodendrocytes myelinate part of several axons
  • PNS: schwann cell myelinates part of one axon
46
Q

myelin structure

A
  • myelin
  • neurilemma
  • nodes of ranvier
47
Q

myelin

A

plasma membrane of schwann cell wrapped around axon

48
Q

neurilemma

A

part of schwann cell that contains cytoplasm

49
Q

nodes of ranvier

A

gaps in myelin sheath

50
Q

myelination process

A

starts at week 14 and completed by age 2-3 years

51
Q

myelin functions

A

isolate axons

increase rate of action potential

52
Q

regeneration of nerve fibers: PNS

A

can regenerate a fraction of axons

  • schwann cells participate in process
  • called wallerian degeneration
53
Q

wallerian degeneration

A

regeneration of PNS axons

54
Q

steps of nerve regeneration

A
  1. injury separates axon from cell body
    - distal portion of axon will deteriorate along with myelin sheath
  2. macrophages clean up
    - some schwann cells remain
    - get thin basement membrane and layer of CT around schwann cells
  3. forms hollow tube leading to original connection of axon
    - proximal end sprouts
    - sprout may grow into tube
  4. remaining schwann cells produce new myelin around growing axon
    - new axon grows 3-4mm/day
55
Q

repair in CNS

A

more limited

  • degeneration occurs after injury
  • oligodendrocytes do not proliferate
  • proximal end sprouts but has no tube to follow
  • astrocytes produce scar tissue and chemicals blocking regrowth
  • generally results in paralysis
56
Q

irritability

A

ability to respond to stimuli

57
Q

excitability

A

ability to transport and impulse

58
Q

action potential

A

an electrical impulse changing the permeability of a membrane

59
Q

nerve impulse

A

AP moving down an axon

  • impulse travels faster when:
  • -axon is myelinated
  • -has a larger diameter
60
Q

synapse characteristics

A 
functions as control/transmission point
site of communication between
-sensory structure and neuron
-neuron and effector
-2 neurons
-any two cells with gap junctions
61
Q

electrical synapse

A
  • gap junctions cause the exchange of charged ions between two cells
  • communicating charge through ions
62
Q

chemical synapse: definition

A

chemicals are released by one cell and travel to another

63
Q

chemical synapses: about

A
  • synaptic vesicles house neurotransmitter
  • only exist in the presynaptic cell
  • release neurotransmitter into the synaptic cleft
  • receptors on post-synaptic membrane register the neurotransmitter
  • proliferates AP from one cell to the next
  • communication in one direction only
  • only axons have synaptic vesicles
64
Q

steps at chemical synapse

A
  1. AP reaches synaptic knob of presynaptic neuron
  2. neurotransmitter released
  3. neurotransmitter crosses cleft and binds to receptors in post-synaptic membrane
    - change in permeability results, can be excitatory or inhibitory
  4. neurotransmitter is then removed from synaptic cleft
    - permeability returns to original state
65
Q

neuronal pools

A
  • receive impulses from afferent fibers (input)
  • impulses carried away on efferent fibers (output)
  • afferent fibers can branch manny times as they enter a pool
66
Q

types of neuronal pools

A 
convergence
divergence
serial processing
parallel processing
reverberation
67
Q

serial processing

A

one neuron to another in series

68
Q

divergence

A

when impulse leaves a pool, it may spread into several output fibers
-allows impulse to be amplified

69
Q

convergence

A

single nerve in pool may receive impulses from 2 or more incoming fibers

  • if lead to same nerve they are said to converge
  • allows summation of impulses from different sources
70
Q

parallel processing

A

processing information from several neurons at once

71
Q

reverbration

A

positive feedback continues activity of circuit

  • enhances signal so happens repeatedly
  • promote a behavior, keep responding same way
72
Q

facilitation: threshold

A
  • one neuron may receive either excitatory and inhibitory stimuli from multiple neurons
  • the net effect of all this input results in a net charge. if this charge is positive enough it will result in AP
  • this point where AP can be produced is known as threshold
73
Q

facilitaiton: facilitated

A

if a neuron is excited, but still below threshold:
-no impulse, but nerve is more excitable to next impulse
-nerve is said to be facilitated
whole system allows for multiple sources to manage nervous system

74
Q

CNS structures

A

nuclei
center
tracts

75
Q

nuclei

A

collection of neuron cell bodies

76
Q

center

A

collection of neuron cell bodies working together

77
Q

tracts

A

bundles of axons

78
Q

PNS structures

A

ganglia

nerves

79
Q

ganglia

A

collection of neuron cell bodies

80
Q

nerves

A

bundles of axons

Anatomy (19 decks)

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