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A&P 1 > Chapter 11: Fundamentals of the Nervous System > Flashcards

Chapter 11: Fundamentals of the Nervous System Flashcards

1
Q

Nervous System Functions

A

receive sensor info (sensory input); process and interpret sensory input (integration); generate a response (motor output via muscles or glands)

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2
Q

Effectors are..

A

muscles or glands

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3
Q

What are the two main divisions of the nervous system?

A

central nervous system (CNS)- brain and spinal cord only; peripheral nervous system (PNS)- other nerves that are not the brain and spinal cord, cranial nerves, spinal nerves, ganglia

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4
Q

CNS

A

interprets sensory input; dictates motor output based on reflexes, current conditions, and past experiences

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5
Q

PNS

A

links all parts of the body to central nervous system

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6
Q

What are the two types of nervous tissue cells?

A

neuroglia (glial) cells and neurons

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7
Q

Neuroglia Cells

A

glial cells; support cells; 10x more abundant than neurons

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8
Q

What are the four types of glial cells in the CNS?

A

astrocytes, microglial cells, ependymal cells, and oligodendrocytes

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9
Q

Astrocytes

A

most numerous and diverse type; interconnected via gap junctions; assist in exchanges between capilaries and neurons

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10
Q

Microglial Cells

A

defensive cells of CNS; transform into a type of macrophage that phagocytizes invading microorganisms

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11
Q

Ependymal Cells

A

ciliated cells that line central cavities of the brian and spinal cord; help CIRCULATE cerebrospinal fluid (CSF)

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12
Q

Oligodendrocytes

A

have processes that wrap around thick axons in the CNS forming thick myelin sheaths

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13
Q

What are the two types of glial cells in the PNS?

A

satellite cells and schwann cells

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14
Q

Satellite Cells

A

flattened cells that surround cell bodies of neurons in the PNS; thought to have same functions as astrocytes

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15
Q

Schwann Cells

A

surround thick axons in PNS forming thick myelin sheaths; functionally similar to oligodendrocytes

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16
Q

Neurons

A

nerve cells; the structural/functional units of the nervous system

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17
Q

Characteristics of Neurons

A

excitable; extremely long lived; amitotic (lose ability to divide); very high metabolic rate (require continuous supply of oxygen and glucose)

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18
Q

Structure of Neurons

A

all have a cell body and one or more processes

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19
Q

Neuron Cell Body

A

contains typical organelles; very large nucleus with distinct nucleolus, abundant mitochondria; most neuron cell bodies are in the CNS

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20
Q

Nuclei

A

cluster of cell bodies found in CNS

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21
Q

Ganglia

A

clusters of cell bodies found in PNS

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22
Q

Neuron Processes

A

extend from cell bodies; include dendrites and axon

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23
Q

Dendrite

A

main receptive region; 1 or more per neuron; convery INCOMING information (graded potentials) TOWARD CELL BODY

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24
Q

Axon

A

conducting region (generally conducts action potentials); only ONE per neuron

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25
Q

Nerve

A

cluster of axons in the PNS

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26
Q

Tract

A

cluster of axons in the CNS

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27
Q

Most long or large axons are…

A

Myelinated; covered with a fatty myelin sheath

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28
Q

Myelin Sheaths

A

protects and insulates AXONS; increases speed of action potential; formed by oligodendrocytes (CNS) or schwann cells (PNS)

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29
Q

ADD HOW MYELIN SHEATHS FORM

A
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30
Q

Dendrites are…

A

NEVER myelinated

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31
Q

Structural Classification of Neurons

A

based on number of processes extending from cell body; includes mulipolar, bipolar, and unipolar

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32
Q

Multipolar Neurons

A

many processes; all are dendrites except for single axon; most common and major type

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33
Q

Bipolar Neurons

A

two processes; 1 dendrite and 1 axon; rare, found in some special sensory organs

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34
Q

Unipolar Neurons

A

aka pseudounipolar; 1 process that spilts to form a two part axon; mainly in PNS

35
Q

Functional Classifications of Neurons

A

based on direction impulse travels in relation to CNS

36
Q

Sensory Neurons

A

aka afferent neurons; transmit impulses from sensory receptors TOWARD THE CNS; most are unipolar; cell bodies located in ganglia (PNS)

37
Q

Motor Neurons

A

aka efferent; transmit impulses AWAY FROM CNS to effector organs (muscles or glands); are multipolar; most cell bodies in CNS

38
Q

Interneurons

A

aka association neurons; lie between motor and sensory neurons in the CNS; multipolar; make up 99% of all neurons in the body

39
Q

Resting Membrane Potential

A

all cells are polarized meaning they have a difference in charge across the plasma membrane called a resting membrane potential; this change is generated with the help of membrane proteins that act as ion channels (gated or ungated)

40
Q

ADDD THE MEMRBANE PROTEIN STUFF

A
41
Q

Altering the Membrane Potential

A

only cells with excitable membranes (neurons and msucle cells) can alter their resting membrane potential in response to a stimulus (which changes the number of open ion channels)

42
Q

What two results are possible with respect to resting membrane potential?

A

depolarization or hyperpolarization

43
Q

What are the receptive areas of nerve cells?

A

dendrites and cell bodies

44
Q

Depolarization

A

increases probabaility of generating an action potential; becomes more positive; closer to threshold

45
Q

Hyperpolrization

A

K ions open and goes out (means positive goes out); chloride (negative) comes in; decresses probability of action potential; becomes more negative; further from threshold

46
Q

What two types of signals are produced in response to changing membrane potential?

A

graded potential or action potential

47
Q

Graded Potentials

A

short distance signals; short lived; local (does not travel far) changes in membrane potential; triggered by stimuli that open CHEMICALLY gated ion channels in dendrites (or cell body); signal decays with distance; can be depolarization or hyperpolarization

48
Q

If graded potential is strong enough…

A

it may trigger an action potential

49
Q

Action Potentials

A

long distance signals; brief reversal of membrane potential with a total voltage change of ~100mV; triggered by threshold stimulus; the graded potential was strong enough to open VOLTAGE gated ion channels in an axon; on/off or all or nothing; signal does not decay; always opens sodium voltage gated channels

50
Q

ADD VOLTAGE GATED NA AND K CHANNELS

A
51
Q

What is the trigger zone?

A

axon hilock

52
Q

What are the four events of the action potential?

A

1) resting state; 2) depolarization;3) repolarization; 4)hyperpolarization

53
Q

Resting State (1)

A

first step; only leakage Na and K ion channels are open; all voltage gated Na and K gates are close

54
Q

Depolarization (2)

A

second step; occurs when graded potential is strong enough to reach threshold (-50–55mV); NA activation gates open repidly and Na rushes in reversing the membrane polarity (changes inside to + and outside to-)

55
Q

Repolarization (3)

A

Na channels inactive and Na stops (but it slow and take more time than depolarization; not immediate); K opens SLOWLY and K exits returning membrane to resting state (inside - outside +)

56
Q

Hyperpolarization (4)

A

occurs when the membrane potential becomes more negative at a particular spot than the resting membrane potential (bc of the slow closure of K channels); Na voltage gated channels reset

57
Q

After hyperpolarization, have pre-stimulus conditions been restored to the trigger zone in the axon hilock?

A

NO; although polarity has returned to normal (inside - outside +); Na is higher inside and K is higher outside

58
Q

How does cell reestablish Na and K concentration gradient?

A

sodium potassium pump

59
Q

How does the CNS determine whether someone is shaking your hand or squeezing it?

A

based on the number/frequency of AP; strong stimuli generates APs more often that weak stimuli

60
Q

What is the conducting region of a nerve cell?

A

axon

61
Q

What is the secretory region of a nerve cell?

A

the end/axon terminals

62
Q

What prevents the AP from moving back toward trigger zone?

A

refractory period

63
Q

Absolute Refractory Period

A

neuron can not respond to another stimulus no mater how strong; occurs when Na volatge gates are open

64
Q

Relative Refractory Period

A

neuron able to respond to an exceptionally strong stimulus; occurs when most Na channels inactivated and some K channels are still open

65
Q

What are the two factors that affect propagation velocity?

A

axon diameter (large diameter = faster impulse); degree of myelination (thicker myelin sheaths = faster propagation)

66
Q

Demyelinating Diseases

A

attack cells that produce meylin; multiple sclerosis attacks oligodendrites in CNS; Guillian Barre Syndrom attacks schwann cells of PNS; lack of myelin sheaths converts saltaroy conduction to continuous conduction

67
Q

Synapses

A

transmit signals from 1 neuron to either another neuron, muscle cell, or gland

68
Q

Electrical Synapses

A

consist of gap junctions, so communication is rapid; abundant in embryonic nervous tissue; rare in adults; most replaced by chemical synapses

69
Q

Chemical Synapses

A

consist of the axon terminals of the pre synaptic neuron + neurotransmitter receptor on the post synaptoc cell; most abundant type (in adults); electrical signals (APs) converted to chemical signals (neurotransmitter)

70
Q

Synaptic Transmission Involves 6 Events

A

1) AP arrives at presynaptic axon terminal; 2) voltage gated calcium channels open and ca enter axon terminal (calcium is more concentrated on outside); 3) ca entry causes synaptic vesicles to release neurotransmitters (like ACh) into synaptic cleft (the stronger the stimulus, the more neurotransmitter released); 4) neurotransmitter diffuses across synapse and binds to receptors on membrane of postsynaptic neuron;5) binding of neurotransmitter opens chemically gated ion channels creating graded potentials (EPSP or IPSP); 6) neurotransmitter effects are terminated by: reuptake, enzymatic degredation, diffusion away from synapse

71
Q

EPSP

A

excitatory post synaptic potential; local depolarization of post synaptic membrane; initiated by neurotransmitter opening channels allowing na and k to SIMULTANEOUSLY; increases probability of post synaptic neuron generating an AP

72
Q

IPSP

A

inhibitory post synaptic potential; local hyperpolerization of post synaptic membrane; initiated by neurotransmitter opening channels allowing k or Cl to pass; decreases probability of post synaptic neuron generating an AP

73
Q

One post synaptic neuron can receive input from…

A

thousands of other neurons

74
Q

Neural Integration

A

to fire or not to fire; the summation of all EPSP and IPSP that reach the post synaptic axons trigger zone

75
Q

Temporal Summation

A

a SINGLE presynaptic neuron firing multiple times in close succession

76
Q

Spatial Summation

A

MULTIPLE presynaptic neurons firing at the same time

77
Q

Neurontransmitters

A

over 50 have been identified; most neurons produce and release more than one; some are excitatory; some are inhibitory; some are excitatory or inhibitory depending on receptor they bind to

78
Q

Acetylcholine

A

excite or inhibit; secreted in CNS and PNS; effects prolonged when AChE blocked (leads to tetanic muscle spasms)

79
Q

Norepinephrine

A

excite or inhibit; secreted by CNS and PNS; “feel good” neurotransmitter

80
Q

Dopamine

A

excite or inhibit; secreted from CNS and PNS; “feel good” neurotransmitter

81
Q

Serotonin

A

mainly inhibitory; secreted from CNS; plays role in sleep, appetite, nausea and migraines

82
Q

Endorphins

A

mainly inhibitory; secreted from CNS; natural opiates; inhibit pain

83
Q

Nitric Oxide (NO)

A

gas; excite or inhibit; secreted from CNS and PNS; viagra enhances NO action

A&P 1 (16 decks)

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