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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
Nerve
cluster of axons in the PNS
26
Tract
cluster of axons in the CNS
27
Most long or large axons are...
Myelinated; covered with a fatty myelin sheath
28
Myelin Sheaths
protects and insulates AXONS; increases speed of action potential; formed by oligodendrocytes (CNS) or schwann cells (PNS)
29
ADD HOW MYELIN SHEATHS FORM
30
Dendrites are...
NEVER myelinated
31
Structural Classification of Neurons
based on number of processes extending from cell body; includes mulipolar, bipolar, and unipolar
32
Multipolar Neurons
many processes; all are dendrites except for single axon; most common and major type
33
Bipolar Neurons
two processes; 1 dendrite and 1 axon; rare, found in some special sensory organs
34
Unipolar Neurons
aka pseudounipolar; 1 process that spilts to form a two part axon; mainly in PNS
35
Functional Classifications of Neurons
based on direction impulse travels in relation to CNS
36
Sensory Neurons
aka afferent neurons; transmit impulses from sensory receptors TOWARD THE CNS; most are unipolar; cell bodies located in ganglia (PNS)
37
Motor Neurons
aka efferent; transmit impulses AWAY FROM CNS to effector organs (muscles or glands); are multipolar; most cell bodies in CNS
38
Interneurons
aka association neurons; lie between motor and sensory neurons in the CNS; multipolar; make up 99% of all neurons in the body
39
Resting Membrane Potential
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
ADDD THE MEMRBANE PROTEIN STUFF
41
Altering the Membrane Potential
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
What two results are possible with respect to resting membrane potential?
depolarization or hyperpolarization
43
What are the receptive areas of nerve cells?
dendrites and cell bodies
44
Depolarization
increases probabaility of generating an action potential; becomes more positive; closer to threshold
45
Hyperpolrization
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
What two types of signals are produced in response to changing membrane potential?
graded potential or action potential
47
Graded Potentials
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
If graded potential is strong enough...
it may trigger an action potential
49
Action Potentials
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
ADD VOLTAGE GATED NA AND K CHANNELS
51
What is the trigger zone?
axon hilock
52
What are the four events of the action potential?
1) resting state; 2) depolarization;3) repolarization; 4)hyperpolarization
53
Resting State (1)
first step; only leakage Na and K ion channels are open; all voltage gated Na and K gates are close
54
Depolarization (2)
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
Repolarization (3)
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
Hyperpolarization (4)
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
After hyperpolarization, have pre-stimulus conditions been restored to the trigger zone in the axon hilock?
NO; although polarity has returned to normal (inside - outside +); Na is higher inside and K is higher outside
58
How does cell reestablish Na and K concentration gradient?
sodium potassium pump
59
How does the CNS determine whether someone is shaking your hand or squeezing it?
based on the number/frequency of AP; strong stimuli generates APs more often that weak stimuli
60
What is the conducting region of a nerve cell?
axon
61
What is the secretory region of a nerve cell?
the end/axon terminals
62
What prevents the AP from moving back toward trigger zone?
refractory period
63
Absolute Refractory Period
neuron can not respond to another stimulus no mater how strong; occurs when Na volatge gates are open
64
Relative Refractory Period
neuron able to respond to an exceptionally strong stimulus; occurs when most Na channels inactivated and some K channels are still open
65
What are the two factors that affect propagation velocity?
axon diameter (large diameter = faster impulse); degree of myelination (thicker myelin sheaths = faster propagation)
66
Demyelinating Diseases
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
Synapses
transmit signals from 1 neuron to either another neuron, muscle cell, or gland
68
Electrical Synapses
consist of gap junctions, so communication is rapid; abundant in embryonic nervous tissue; rare in adults; most replaced by chemical synapses
69
Chemical Synapses
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
Synaptic Transmission Involves 6 Events
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
EPSP
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
IPSP
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
One post synaptic neuron can receive input from...
thousands of other neurons
74
Neural Integration
to fire or not to fire; the summation of all EPSP and IPSP that reach the post synaptic axons trigger zone
75
Temporal Summation
a SINGLE presynaptic neuron firing multiple times in close succession
76
Spatial Summation
MULTIPLE presynaptic neurons firing at the same time
77
Neurontransmitters
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
Acetylcholine
excite or inhibit; secreted in CNS and PNS; effects prolonged when AChE blocked (leads to tetanic muscle spasms)
79
Norepinephrine
excite or inhibit; secreted by CNS and PNS; "feel good" neurotransmitter
80
Dopamine
excite or inhibit; secreted from CNS and PNS; "feel good" neurotransmitter
81
Serotonin
mainly inhibitory; secreted from CNS; plays role in sleep, appetite, nausea and migraines
82
Endorphins
mainly inhibitory; secreted from CNS; natural opiates; inhibit pain
83
Nitric Oxide (NO)
gas; excite or inhibit; secreted from CNS and PNS; viagra enhances NO action

A&P 1 (16 decks)

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