A + P Nervous System I Flashcards

1
Q

two type of neural tissue

A

neurons

neuroglia

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2
Q

neurons function

A

send and receive signals

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3
Q

neuroglia function

A

support and protect neurons

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4
Q

nervous system anatomical division

A

Central Nervous System

Peripheral Nervous System

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5
Q

CNS

  • consists of
  • jobs
  • the brain is also…
A

consists of
-brain
-spinal cord
jobs
-integrates, processes, and coordinates sensory data and motor commands
the brain is also the seat of higher functions, such as intelligence, memory, learning and emotion

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6
Q

PNS

  • consists of…
  • functions
A
consists of
-cranial and spinal nerves
functions
-delivers sensory info to the CNS
-carries motor commands to the peripheral tissues and systems
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7
Q

PNS functional divisions

A

Sensory (afferent division)

motor (efferent division)

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8
Q

sensory division function

A

carries sensory information from receptors to CNS

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9
Q

motor division function

A

carries motor commands from CNS to PNS muscles and glands

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10
Q

motor division functional division

A

somatic nervous system

autonomic nervous system

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11
Q

somatic nervous system function

A

controls voluntary and involuntary skeletal muscle contraction

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12
Q

autonomic nervous system function

A

provides involuntary automatic regulation of smooth muscle, cardiac muscle,and glandular secretions

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13
Q

autonomic nervous system divisions

A
sympathetic division (SNS)
parasympathetic Division (PSNS)
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14
Q

SNS function

A

provides a stimulating effect

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15
Q

PSNS

A

provides a relaxing effect

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16
Q

neuron basic structure

A

cell body (soma)
axon
dendrites
synapse

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17
Q

cell body composition

A

single nucleus
cytoplasm (perikaryon: contains mitochondria, ribosomes, endoplasmic reticulum)
cytoskeleton (neurofilaments and neurotubules)

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18
Q

axon

  • capability
  • axon hillock
  • -what is it?
  • telodendria
  • -what is it?
A

capability
-long cytoplasmic process capable of propagating an electrical impulse known as an action potential
axon hillock
-wide base of the axon connected to the cell body
telodendria
-the distal end of the axon that is divided into finger-like branches called telodendria

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19
Q

dendrites

  • visual characteristics
  • function
A

visual characteristics
-slender processes that extend from the cell body, highly branched
-each branch contains dentritic spines (80-90% of total neuron surface area)
function
-dendritic spines receive information from other neurons

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20
Q

synapse

  • function
  • two cells of each synapse
A

function

  • a specialized site where the neuron communicates with another cell
  • two cells
  • -presynaptic cell (sends the message; usually a neuron)
  • postsynaptic cell (receives the message, can be another neuron or other type of cell)
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21
Q

types of synapses

  • neuromuscular
  • neuroglandular
A

neuromuscular
-synapse between a neuron and a muscle
neuroglandular
-synapse between a neuron and a gland

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22
Q

synaptic cleft

-what is it?

A

small gap between the pre-synaptic and post-synaptic cells

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23
Q

communication across synaptic cleft

-how?

A
  • presynaptic terminal releases chemical neurotransmitters

- neurotransmitter release is triggered by an action potential

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24
Q

neurons transmit electrical signals called impulses or _____

A

action potentials

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25
Q

neuron characteristics

  • lifespan
  • reproductive capability
  • metabolic rate
  • -result of the metabolic level
A
  • can live your whole life
  • amitotic
  • high metabolic rate - need more glucose and O2 than other cells
  • -can only live for a few minutes without O2
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26
Q

structural classification of neurons

A

anaxonic neurons
bipolar neurons
unipolar neurons
multipolar neurons

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27
Q

anaxonic neurons

  • location
  • visual characteristics
A
location
-found in the brain and sense organs
visual
-two or more processes
-dendrites cannot be distinguished from axons
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28
Q

bipolar neurons

  • location
  • visual characteristics
A

location
-found only in sensory organs (ex. receptor cells in the retina, nasal passages)
visual
-two processes that extend from the cell body: one is a fused dendrite and the other is an axon

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29
Q

unipolar neurons

  • location
  • visual characteristics
A

location
-found in the PNS in the dorsal root ganglia of the spinal cord, and the sensory ganglia of cranial nerves
visual
-contain a single very long axon emerging from the cells body
-axon consists of a central (proximal) process and a peripheral (distal) process receiving impulses from a sensory receptor

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30
Q

multipolar neurons

  • location
  • visual characteristics
A

location
-most common (99%) and the major neuron in CNS
visual
-two or more processes extend from the cell body
-all are dendrites except for a single long axon

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31
Q

functional classification of neurons

A

sensory (afferent) neurons
motor (efferent) neurons
inerneurons (association neurons)

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32
Q

sensory neurons

  • function
  • structural classification
A

function
-carry impulses toward the CNS
structural
-unipolar in that the cell bodies are found in the ganglia close to the spinal cord

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33
Q

motor neurons

  • function
  • structural classification
A

function
-carry impulses away from the CNS
structural
-multipolar cell bodies are located primarily in the CNS (cell bodies form the grey matter of the brain and spinal cord; axons form white matter)

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34
Q

interneurons

  • function
  • structural classification
A

function
-transfer impulses between sensory and motor neurons in the CNS
structural
-multipolar mostly

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35
Q

neuroglia (glial cells) characteristics

A

supporting cells of the nervous system

found primarily in the CNS

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36
Q

four types of neuroglia in the CNS

A

ependymal cells
astrocytes
oligodendrites
microglia

37
Q

ependymal

  • location
  • functions
A
location
-line the central canal of the spinal cord and ventricles of the brain
functions
-help produce CSF
-circulate CSF (primarily)
38
Q

astrocytes

  • functions
  • prevalence
A
functions
-secrete chemicals to maintain the blood-brain barrier
-form the structural framework for the CNS
-repair damaged nerve tissue
-control interstitial environment
-guide neuron development
prevalence
-largest and most numerous
39
Q

oligodendrites

-function

A

form the myelin sheaths around axons in the CNS (forming nodes and internodes)

40
Q

microglia

  • prevalence
  • function
  • function in injury
A

prevalence
-smallest and rarest
function
-contain thorny processes that touch and monitor the health of neurons
function in injury
-migrate toward injured cells and turn into macrophages to phagocytize neuronal debris and microorganisms

41
Q

PNS neuroglia types

A

satellite cells

schwann cells

42
Q

satellite cells

  • location
  • function
A

location
-surround neuron cell bodies within ganglia
function
-relatively unknown
-may play a role in regeneration of nerve and muscle tissue

43
Q

schwann cells

-location

A

surround and form myelin sheaths around the larger nerve fibers in the PNS

44
Q

membrane ion channel types

A

leak channels

gated channels

45
Q

leak channels

  • composition
  • characteristic
A
composition
-made of integral membrane proteins
characteristic
-always open
-involved in passive transport (diffusion and facilitated diffusion which requires no energy)
46
Q

gated channels

  • composition
  • changing protein shape requires…
A
composition
-made of integral membrane proteins
-have a molecular "gate" which is usually one or more protein molecules that can change shape to open or close the channel in response to various signals
changing protein shape requires...
-energy unlike leak channels
47
Q

types of gated cells

A

chemically-gated
voltage-gated
mechanically-gated

48
Q

chemically-gated

-open…

A

open in response when bound to a specific molecule (ligand), such as neurotransmitters

49
Q

voltage-gated

-open or close…

A

open or close in response to changes in the membrane potential, such as Na+, K+, and Ca2+ channels

50
Q

mechanically-gated

open or close…

A

open or close in response to physical distortion of the membrane surface, such as sensory receptors for touch, pressure, and vibration

51
Q

resting membrane potential

A

there is an electrical or potential difference between the two side of a neuron membrane
this difference is called the resting membrane potential (RMP)
factors responsible for the membrane potential involve the types of ions that are naturally found inside and outside of our cells

52
Q

where are Na+ and K+ concentrated

A

Na+ are concentrated outside of the cell membrane

K+ are concentrated inside the cells along with negatively charged proteins in the cytosol

53
Q

_____ tends to diffuse outward through _____ channels driven by the _____ _____ of _____ ions

A

K+
leak
concentration gradient
-K+

54
Q

_____ tends to diffuse into the membrane from the outside

A

Na+

55
Q

the membrane is more permeable to _____ than _____ so _____ diffuses out faster than _____

A

K+
Na+
K+
Na+

56
Q

the result of the previous

A

the cell experiences a net loss of + charges from the inside to the outside of the membrane resulting in an excess of - charges on the inside

57
Q

typical RMP

A

-70 mV

58
Q

why does the RMP remain stable

A

Na+-K+-ATPase pump

59
Q

when will changes in the RMP occur

A

when a stimulus either alters a membrane’s permeability to Na+ or K+
when a stimulus alters the Na+-K+-ATPase pump

60
Q

function of stimuli on the membrane

A

open gated ion channels

61
Q

opening of gated ion channels result

A

accelerates Na+ transport

-this causes a change in membrane potential

62
Q

result of Na+ transport increasing

-final membrane potential

A

depolarization of the cell
final membrane
-+30 mV

63
Q

result of K+ rushing out in response to Na+ rushing in

A

repolarization

64
Q

hyperpolarization

A

too much K+ rushes out and the membrane potential is more negative than the RMP

65
Q

graded potentials

  • location
  • characteristics
A

location
-occur in all nerve cells but only affect a limited portion of the cell membrane
characteristics
-can stimulate or inhibit glandular secretions, but the impulse is not great enough to affect a skeletal muscle or neuron as it diminishes rapidly with distance

66
Q

how does a GP happen?

-how is the RMP restored

A

some Na+ channels open and no K+ channels

leak channels and the Na+-K+-ATPase pump restore

67
Q

action potential

  • location
  • where does it begin and travel to in neurons
A

location
-can occur in skeletal muscle fibers and axons
where it begins
-begins in the axon hillock and travels the length of an axon toward a synapse

68
Q

how does an AP happen

-how is the RMP restored

A

APs involve the opening and closing of LOTS of Na+ and K+ channels
restored by leak channels and the Na+-K+-ATPase pump

69
Q

membrane threshold required to begin an AP

A

-60 mV

70
Q

phases of the AP

A
  • Na+ channels open at threshold and depolarization occurs
  • NA+ rushes into the cytoplasm and causes a rapid depolarization of the membrane
  • in less than (1 ms) the inner surface of the cell contains more + ions than - (+30 mV) and the Na+ channels close
  • this triggers K+ channels to open, driving K+ out of the cell and repolarizing the cell
  • as the RMP returns, both gates of the Na+ channels have closed and the K+ channels begin to close
  • -some K+ channels remain open and the membrane potential hyperpolarized
  • Na+-K+-ATPase pump repolarizes the cell quickly (1 ms)
71
Q

refractory period

-significance

A

the duration of time from threshold to the end of hyperpolarization
-during this time the membrane cannot respond normally to further stimulation

72
Q

how do neurotoxins like tetrodotoxin (TTX) from the puffer fish and other neurotoxins from poisonous snakes work?

A

block neuronal Na+ channels resulting in paralysis of respiratory muscles

73
Q

conduction of the AP

A

at the peak of the AP (+30mV) the inside of a given site of the membrane has an excess of + ions
the + ions spread along inner surface of the membrane towards the adjacent negative charges and produces a local current that depolarized adjacent portions of the membrane
the Na+ channels open adjacent portions of the membrane and new cycles of Na+ and K+ movement produce additional APs. This continues down the entire length of the axon

74
Q

axon types

-conduction speed

A

unmyelinated
-conduct impulses at a rate of 1 m/s
myelinated
-conduct impulses about 50x faster

75
Q

node of Ranvier

A

area where APs occur on myelinated axons (saltatory conduction) thereby allowing the impulse to skip the internodes and travel much faster

76
Q

multiple sclerosis physiology

A

progressive destruction of myelin sheaths accompanied by axon damage and scarring of neural tissue

77
Q

conduction of the AP

A

at the peak of the AP (+30mV) the inside of a given site of the membrane has an excess of + ions
the + ions spread along inner surface of the membrane towards the adjacent negative charges and produces a local current that depolarized adjacent portions of the membrane
the Na+ channels open adjacent portions of the membrane and new cycles of Na+ and K+ movement produce additional APs. This continues down the entire length of the axon

78
Q

axon types

-conduction speed

A

unmyelinated
-conduct impulses at a rate of 1 m/s
myelinated
-conduct impulses about 7x faster

79
Q

how are the neurotransmitter and AP terminated

A

degradation of the neurotransmitter by enzymes (AChE)
removal of the neurotransmitter by astrocytes or postsynaptic terminal where it is then destroyed by enzymes
natural diffusion of neurotransmitter away from the synapse

80
Q

multiple sclerosis physiology

A

progressive destruction of myelin sheaths accompanied by axon damage and scarring of neural tissue

81
Q

information transfer across a chemical synapse

A

nerve impulse reaches axon terminal containing synaptic vesicles with neurotransmitter (ex. Ach) inside each vesicle
Ca2+ gates open in the presynaptic axon terminal (depolarization has opened Na+ channels too) and Ca2+ floods into the terminal from the extracellular fluid
Ca2+ acts as a messenger instructing the synaptic vesicles to fuse with the axon membrane and empty in the synaptic cleft
the neurotransmitter binds with postsynaptic protein receptors, which change shape, causing a Na+ channel to open, Na+ influx, and an AP
termination of the neurotransmitter and AP

82
Q

how does Ca2+ leave the cell?

A

via a Ca2+ pump or is taken up by the mitochondria

83
Q

what happens to a severed nerve axon

A

the proximal segment swells and experiences some retrograde degeneration
Wallerian degeneration occurs in the distal segment
macrophages and Schwann cells then phagocytize debris from the axon and myelin sheaths to create a “channel” within the endoneurium for a new axon
growth factors secreted by Schwann cells and other molecules can form new axon “sprouts” on the proximal segment that will grow into new axons within the endoneurium “channel”
Schwann cells will remyelinate the new axons in the final phases of regeneration

84
Q

Wallerian degeneration

A

the myelin sheath and axon degenerate due to the absence of nutrients from the cell body

85
Q

how do neurons in the PNS die?

A

if a neuron dies then other neurons stimulated by its axon also die
death of a neuron occurs if damage occurs to (or close to) the cell body
cut or compressed axons can regenerate if the cell body remains intact

86
Q

labeling of a severed nerve axon

A

the end still attached to the cell body is labeled the proximal segment
the other end is the distal segment

87
Q

what happens to a severed nerve axon

A

the proximal segment swells and experiences some retrograde degeneration
Wallerian _______ occurs in the distal segment
macrophages and Schwann cells then phagocytize debris from the axon and myelin sheaths to create a “channel” within the endoneurium for a new axon
growth factors secreted by Schwann cells and other molecules can form new axon “sprouts” on the proximal segment that will grow into new axons within the endoneurium “channel”
Schwann cells will remyelinate the new axons in the final phases of regeneration

88
Q

Wallerian _________

A

the myelin sheath and axon degenerate due to the absence of nutrients from the cell body

89
Q

what happens if a nerve axon is completely severed and the surrounding connective tissue is severely damaged

A

Schwann cells may not be able to reach the proximal segment

the only way a new axon will grow is with surgical intervention