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Anatomy And Physiology > Chapter 11 > Flashcards

Chapter 11 Flashcards

1
Q

Functions of the central nervous system

A

sensory: receive stimuli
integrative: analyze, make decision
motor: activate effector

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2
Q

Divisions of peripheral nervous system

A

Afferent
Efferent

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3
Q

Afferent

A

sensory, internal/external stimuli, brain to nerves

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4
Q

Efferent

A

motor, activate effectors, CNS to PNS

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5
Q

Two types of nervous tissue cells

A

neuron: excitable, high metabilic rate, action potential
glial cells: nonexcitable, protect neurons, 6 types

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6
Q

central nervous system

A

brain and spinal cord
neurons, glia
nuclei: cell body
tracts: bundles of nerve fibers of axons

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7
Q

peripheral nervous system

A

ganglia: cell bodies
peripheral nerves: axon bundles of neurons, blood vessels, and connective tissue

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8
Q

neurons

A

long-lived amitotic
high metabolic rate (glucose + O2)
excitable
action potential: electrical signal along neuron membrane

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9
Q

Neuron anatomy

A

nucleus
perikaryon (cytoplasm)
nucleoli
organelles
cytoskeleton
neurofilaments/neurotubules: transport
neurofibrils: support for dendrites + axon
nissl bodies: dense areas of RER and ribosomes (gray matter)
NO centrioles
NO mitotic spindle

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10
Q

dendrites structure and function

A

short processes branching off cell body
one or multiple
receive input and transfer it to cell body
more dendrites = more input possible

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11
Q

axon

A

axon hillock: connects to axon initial segment
sends electrical signal (AP) to another neuron/muscle/gland
Long axons: more myelin, collaterals (branches), telodendria at end of synaptic terminal

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12
Q

what is a synapse?

A

site of neuron to cell communication

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13
Q

what does the presynaptic cell do?

A

send message

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14
Q

what does the postsynaptic cell do?

A

receive message (neuron, muscle, gland)

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15
Q

What is the synaptic cleft?

A

the small gap between presynaptic membrane and postsynaptic membrane

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16
Q

where are neurotransmitters released?

A

from synaptic vesicles in synaptic (axon) terminal

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17
Q

axoplasmic transport

A

movement between cell body and synaptic terminal
transport neurotransmitters, enzymes, proteins, debris
Anterograde: body to synaptic terminal (neurotransmitter)
Retrograde: terminal to body (debris, rabies)

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18
Q

What is the most common type of neuron?

A

Multipolar neurons

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19
Q

Multipolar Neurons

A

Most common
All motor neurons
All interneurons

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20
Q

Bipolar Neuron

A

2 processes extend from body
limited - retina and ear

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21
Q

Unipolar Neuron

A

1 process extend from body
Sensory neurons of PNS

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22
Q

Sensory Neurons (types and receptors)

A

Somatic: external
Visceral: internal
Receptors: interoceptors, exteroceptors, proprioceptors

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23
Q

Interneurons (function/where)

A

Most abundant
Distribute sensory info
Mainly CNS

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24
Q

Motor Neuron (types)

A

Somatic: skeletal muscle, conscious control, CNS
Visceral: cardiac/smooth muscle, unconscious control, pre- or ganglionic neurons, CNS or PNS

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25
Q

Neuroglia (structure/function)

A

“nerve glue”
Supporting cells
Non-excitable in CNS/PNS
Smaller than neurons
Mitosis
Protect/nourish neurons
Physical Scaffolding
Critical for normal function at neural synapses

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26
Q

How many types of neuroglia are there?

A

6

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27
Q

Types of neuroglia

A

Satellite cells
Schwann cells
Oligodendrocytes
Astrocytes
Microglia
Ependymal cells

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28
Q

Satellite Cells

A

PNS
Surround neuron cell bodies in ganglia
Regulate O2, CO2, nutrient, and neurotransmitter levels around neurons in ganglia
Physically separate cell bodies in ganglion from surrounding cells

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29
Q

Schwann Cells

A

“Neurolemmocyte”
Surround axons in PNS
Myelinate peripheral axons for faster action potential propagation
Participate in repair process after injury
Damage = multiple sclerosis

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30
Q

Oligodendrocytes

A

Myelinate CNS axons
Provide structural framework
Prevent ion passage through axonal membrane

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31
Q

Astrocytes

A

Maintain blood-brain barrier
Controls substance into brain nervous tissue from blood
Protect from toxins
Provide structural support (cytoskeleton)
Regulate ion, nutrient, and dissolved gas concentrations between blood and interstitial fluid
Absorb/recycle neurotransmitters
Form scar tissue
Assist neuronal development of fetal brain
Occupy space of dying neurons

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32
Q

Microglia

A

Remove cell debris, waste, and pathogens by phagocytosis
Wander CNS + replicate in infection

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33
Q

Ependymal cells

A

Line ventricles (brain) and central canal (spinal cord)
Assist in producing, circulating, and monitoring of cerebrospinal fluid
Choroid plexus: produce cerebrospinal fluid, cilia to circulate CSF

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34
Q

Which cells are part of the PNS?

A

Schwann cells
Satellite cells

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35
Q

Which cells are part of the CNS?

A

Oligodendrocytes
Astrocytes
Microglia
Ependymal cells

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36
Q

White matter contains…

A

Myelinated axons

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37
Q

Grey matter contains…

A

Dense neuronal cell bodies
Dendrites
Unmyelinated axons

38
Q

Transmembrane potential

A

+/- ions held apart by selectively permeable membrane
Varies with cell activity
Electrical potential difference: voltage storage
Determined by activity of passive/active forces
Resting membrane potential: -70mV

39
Q

Passive forces acting across membrane

A

Chemical gradient: high to low conc. K+/Na+ distribution
Electrical gradient: ions, protein distribution difference, + in - out
Current: ion flow across membrane
Resistance: membrane restricts ion flow through closing/opening channels

40
Q

Electrochemical gradient for K+

A

Chemical gradient: K+ pushed out of cell
Electrical gradient: - inside, + outside
Net driving force: out of cell (weakened)

41
Q

Electrochemical gradient for Na+

A

Chemical gradient: Na+ into cell
Electrical gradient: - inside, + outside
Net driving force: into cell (strong)

42
Q

Active forces across membrane

A

Na+/K+ exchange pump (ATPase)
Powered by ATP
Carries 3Na+ out and 2K+ in
Balances passive forces of diffusion
Maintains resting potential: helps cell negativity

43
Q

Leak channels

A

Always open
Allow diffusion of ions from high to low conc.
Establish resting potential

44
Q

Gated channels (active)

A

Most closed at resting potential
Open/close in response to stimuli
Chemically gated
Voltage gated
Mechanically gated

45
Q

Chemically (ligand) gated channels

A

Open/close when bind to specific chemical
On dendrites/cell bodies of neuron
ex. acetylcholine receptor

46
Q

Voltage gated channels

A

In excitable membrane (generate ATP)
Open/close in response to change in membrane potential
Activation/inactivation gates
On axons: Unipolar, Multipolar neurons, t-tubules of muscle
ex. voltage gated K+, Na+, Ca2+ channels

47
Q

Mechanically gated channels

A

Response of physical distortion of membrane (touch, pressure, stretch, vibration)
On dendrites and cell bodies of neuron

48
Q

Depolarization

A

Inner surface membrane becomes less negative compared to resting potential
ex. Na+ moves in

49
Q

Repolarization

A

Removal of stimulus
Restore resting potential after depolarization
Combo of membrane channels
ex. K+, Na+ pump

50
Q

Hyperpolarization

A

Membrane more negative than resting
Increased loss of ions (K+ channels)

51
Q

Graded Potential

A

Local changes in transmembrane potential
Stimulus causes opening of chemically/mechanically gated channels on dendrite or cell body
- Causes local depolarization
Can’t spread far from site of stimulation (amount of depolarization decreases as distance from stimulus’ graded potential increases)

52
Q

Generation of Action Potential steps

A
  1. Depolarization to threshold: local currents, graded potential summation at axon hillock
  2. Activation of Na+ channels and rapid depolarization (positive feedback-loop)
  3. Repolarization: inactivation of Na+ channels and slow activation of K+ channels (+30mV)
  4. Hyperpolarization: return to normal, Inactivation gate open, activation gate closed)
53
Q

Refractory Period

A

Time during AP when 2nd AP can’t form in response to normal threshold stimulus

54
Q

Absolute refractory

A

Na+ channels max open or inactivated
K+ flow - opposing force
Small axon diameter = longer refractory period

55
Q

Relative refractory

A

Produce AP in response to larger than normal stimulus if local current brings more Na+ in to counteract K+ out

56
Q

Propagation

A

Message passed along axons by repeating the same events over and over (open voltage-gated channels)

57
Q

Continuous propagation

A

Unmyelinated axons
Very slow
AP begins at initial segment
Local current spreads in all directions
Axon hillock doesn’t respond to AP, has no VGSCs
AP propagated in chain reaction down axon
AP can’t travel backwards

58
Q

Saltatory propagation

A

Fast
Less ATP required
Local currents skip internodes and leap to nodes of ranvier
Myelin wrapped around axon prevents continuous propagation-resistance (Na+ diffuses through axoplasm)

59
Q

Factors affecting propagation speed

A
  1. Myelination
  2. Axon diameter: larger = faster
60
Q

Nerve fiber - Type A

A

Large
Myelinated
Fastest
ex. somatic sensory and motor fibers in skin, skeletal muscles, joint

61
Q

Nerve Fiber - Type B and C

A

Smaller
B is myelinated
C is unmyelinated
ex. visceral sensory and motor fibers in organs

62
Q

Chemical synapses

A

Not direct cell-cell attachment
Most neuron-neuron and all neuron to other cell (gland/muscle) synapses
Presynaptic cell: releases chemical (neurotransmitter)
Postsynaptic cell: may trigger AP

63
Q

Excitatory neurotransmitter

A

Leads to depolarization
Promote AP

64
Q

Inhibitory neurotransmitter

A

Leads to hyperpolarization
Suppress AP

65
Q

Cholinergic Synapses

A

Release acetylcholine
All NMJ (skeletal muscle)
All neuron-neuron in PNS
All parasympathetic neuromuscular and neuroglandary synapses

66
Q

Synaptic delay

A

Between arrival of AP at synaptic terminal and effect on post-synaptic cell
Reflects time Ca2+ influx and neurotransmitter release
Fewer synapses = shorter delay = faster response
ex. reflexes

67
Q

Synaptic fatigue

A

Neurotransmitter can’t recycle fast enough for demands, depends on RER production
Inactive until Ach replenished via recycling or anterograde transport

68
Q

Neuromodulators

A

Alter the rate of neurotransmitter release or post synaptic cell response to neurotransmitter
Released in synaptic cleft

69
Q

Norepinephrine (NE)

A

Adrenergic synapses
Excitatory (depolarize)
Uses neurons distributed in CNS and ANS

70
Q

Dopamine

A

CNS
Excitatory or inhibitory
Parkinsons (inhibitory)
Drugs and ADHD (Excitatory)

71
Q

Serotonin

A

CNS
Depends on receptor
Affect attention and emotional states (selective serotonin reuptake inhibitor)
Prozac, Zoloft, Lexapro, exercise

72
Q

Neuropeptides

A

Substance P and pain nerves

73
Q

Opioids (peptides)

A

Endorphins and pain control

74
Q

Gasses

A

NO and CO in PNS and CNS

75
Q

Metabotroic receptors

A

1st messenger (NT) binds to receptors coupled with G-protein
G-protein activates adenylate cyclase which makes cAMP
2nd messengers are ions/molecules inside the cell which open channels/activate enzymes

76
Q

Lipid-soluble gas

A

Diffusion
Bind to enzymes in cytosol
Produce 2nd messengers that affect cell activity
NO and CO at certain brain synapses

77
Q

Spatial summation

A

Stimuli from different synapses
Depolarization depends on amount of active synapses and distance from hillock
If axon hillock and initial segment reach threshold, neuron fires AP

78
Q

Temporal summation

A

Multiple stimuli at one synapse
More neurotransmitters released by single presynaptic knob = more gated channels open in axon hillock
Graded potentials increase
Axon hillock and initial segment reach threshold

79
Q

Trigger zone

A

Net summation of EPSPs and IPSPs determines whether an action potential is generated here

80
Q

Post-synaptic potentials

A

Graded potentials develop in postsynaptic membrane as a result of neurotransmitter binding
EPSP
IPSP

81
Q

EPSP

A

Causes membrane to depolarize, closer to threshold

82
Q

IPSP

A

Causes membrane to hyperpolarize, farther from threshold

83
Q

Frequency of AP is limited by what?

A

Refractory periods and availability of neurotransmitters

84
Q

Neuron pools

A

Billions of neurons that interpret and coordinate incoming/outgoing signals

85
Q

Neuronal circuit

A

Writing patterns of synaptic connections in pools

86
Q

Divergence

A

Amplifies signals
Depolarization of 1 neuron stimulates many pools

87
Q

Convergence

A

Stimulation and inhibition
Several neurons synapse on one postsynaptic neuron

88
Q

Reverberation

A

Branches from later neurons synapse with earlier ones
Sends impulses back through circuit again
Prolongs response to stimulus

89
Q

Serial processing

A

Info relayed in stepwise manner from one neuron to another

90
Q

Parallel processing

A

Requires divergence
Several neurons process same info at same time

Anatomy And Physiology (19 decks)

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