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Happlec midterms > Nervous System > Flashcards

Nervous System Flashcards

1
Q
A
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2
Q

Nervous System Functions

A
  1. Receiving sensory input
  2. Integrating information
  3. Controlling muscles and
    glands
  4. Maintaining homeostasis
  5. Establishing and
    maintaining mental activity
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3
Q

Main Divisions of Nervous System

A
  1. Central nervous system (CNS)
  2. Peripheral nervous system (PNS)

Sensory division
* Conducts action potentials from sensory receptors
to the CNS
Motor division
* Conducts action potentials to effector organs
Somatic nervous system
* Transmits action potentials from the CNS to skeletal
muscles.
Autonomic nervous system
* Transmits action potentials from the CNS to cardiac
muscle, smooth muscle, and glands
Enteric nervous system
* A special nervous system found only in the digestive
tract.

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4
Q
  • Conducts action potentials from sensory receptors to the CNS
A

Sensory division

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5
Q
  • Conducts action potentials to effector organs
A

Motor division

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6
Q
  • Transmits action potentials from the CNS to skeletal
    muscles.
A

Somatic nervous system

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7
Q
  • Transmits action potentials from the CNS to cardiac
    muscle, smooth muscle, and glands
A

Autonomic nervous system

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8
Q
  • Transmits action potentials from the CNS to cardiac
    muscle, smooth muscle, and glands
A

Autonomic nervous system

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9
Q
  • A special nervous system found only in the digestive
    tract.
A

Enteric nervous system

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10
Q

Examples of Sensory Input

Examples of Motor Output

A
  1. Light, sound, taste, touch, temperature, pain, pressure, etc.
  2. Movement, changes in metabolism, heart rate, breathing rate, etc.
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11
Q

Cells of the Nervous System

A

Neurons
* receive stimuli, conduct action potentials, and
transmit signals to other neurons or effector organs.

Glial cells
* supportive cells of the CNS and PNS
* carry out different functions that enhance neuron
function and maintain normal conditions within
nervous tissue.

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12
Q
  • receive stimuli, conduct action potentials, and
    transmit signals to other neurons or effector organs.
A

Neurons

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13
Q
  • supportive cells of the CNS and PNS
  • carry out different functions that enhance neuron
    function and maintain normal conditions within
    nervous tissue.
A

Glial cells

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14
Q

Neurons
A neuron (nerve cell) has a:
* ___________ –contains a single nucleus
* ___________
–a cytoplasmic extension from the cell body
-receives information from other neurons and
transmits the information to the cell body
*__________ –a single long cell process that leaves
the cell body at the axon hillock and conducts
sensory signals to the CNS and motor signals
away from the CNS

A

Cell body
Dendrite
Axon

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15
Q

*___________ –contains a single nucleus

A

Cell body

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16
Q
  • ___________
    –a cytoplasmic extension from the cell body
    -receives information from other neurons and
    transmits the information to the cell body
A

Dendrite

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17
Q

*__________ –a single long cell process that leaves
the cell body at the axon hillock and conducts
sensory signals to the CNS and motor signals
away from the CNS

A

Axon

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18
Q

Structural Types of Neurons

A

Mutipolar
Bipolar
Pseudo-unipolar

19
Q
  • has a single process extending
    from the cell body, which
    divides into two processes
  • extensions function as a single
    axon with small, dendrite-like
    sensory receptors at the
    periphery.
A

Pseudo-unipolar

20
Q
  • two processes: one
    dendrite and one axon.
  • located in some sensory
    organs
A

Bipolar

21
Q

-has many dendrites and a
single axon
-makes up mostly the
neurons within the CNS
and nearly all motor
neurons

A

Multipolar

22
Q
  • the supportive cells of the CNS and
    PNS.

Astrocytes
Ependymal cells
Microglial cells
Oligodendrocytes
Schwann cells

A

Glial Cells

23
Q
  • major supporting cells in the CNS.
  • stimulate or inhibit the signaling
    activity of nearby neurons
    -form the blood- brain barrier.
A

Astrocytes

24
Q
  • line the cavities in the brain
    that contains cerebrospinal
    fluid.
A

Ependymal cells

25
Q
  • act in an immune function in the
    CNS.
A

Microglial cells

26
Q
  • provide myelin to neurons in
    the CNS.
A

Oligodendrocytes

27
Q
  • provide myelin to neurons in the
    PNS.
A

Schwann cells

28
Q
  • specialized layers that
    wrap around the axons of
    some neurons (a.k.a.
    myelinated)
  • formed by
    ___________ in the CNS
    and
    ___________ in the PNS.
  • excellent insulator that
    prevents almost all ion
    movement across the cell
    membrane.
A

Myelin Sheath

oligodendrocytes
Schwann cells

29
Q
  • Gaps in the myelin sheath that occur about
    every millimeter.
  • Ion movement can occur
A

nodes of Ranvier

30
Q
  • increases the speed and efficiency of action
    potential generation along the axon.
A

Myelination of an axon

31
Q
  • is a disease of the myelin
    sheath that causes loss of muscle function.
A

Multiple sclerosis

32
Q

__________
- lack the myelin sheaths.
- rest in indentations of the oligodendrocytes in
the CNS and the Schwann cells in the PNS.

A typical small nerve, which consists of axons of
multiple neurons, usually contains more
unmyelinated axons than myelinated axons.

A

Unmyelinated axons

33
Q

Organization of Nervous Tissue

The nervous tissue varies in color due to the
_________________ of myelinated axons.

Nervous tissue exists as ________ and ________

_______ consists of groups of neuron cell
bodies and their dendrites, with very little
myelin.

_______ consists of bundles of parallel
axons with their myelin sheaths and are
whitish in color.

A

abundance or absence

gray matter and white
matter

Gray matter

White matter

34
Q

Membrane Potentials

Resting membrane potentials and action
potentials occur in neurons.
- mainly due to:
1. differences in concentrations of ions across the
membrane
2. membrane channels
3. the sodium-potassium pump.

Membrane channels include :
Leak channels are always open, whereas gated
channels are generally closed, but can be opened due
to voltage or chemicals.

A
35
Q

__________ are always open are and ions can
“leak” across the membrane down their
concentration gradient.

Because there are 50 to 100 times more K+ leak
channels than Na+ leak channels, the resting
membrane has much greater permeability to K+
than to Na+; therefore, the K+ leak channels have
the greatest contribution to the resting
membrane potential.

A

Leak channels

36
Q

________
- closed until opened by specific signals
- can change the membrane potential and
responsible for the action potential

__________- opened by
neurotransmitters or other chemicals
__________- opened by a change in
membrane potential.

A

Gated Membrane Channels

Chemically gated channels
Voltage-gated channels

37
Q

__________
- compensates for the constant leakage of ions
through leak channels.
- required to maintain the greater concentration
of Na+ outside the cell membrane and K+ inside.
- actively transports K+ into the cell and Na+ out
of the cell.
It is estimated that the ____________
consumes 25% of all the ATP in a typical cell and
70% of the ATP in a neuron.

A

Sodium-Potassium Pump

38
Q

______________
exists because of:
* The concentration of K+ being higher on the inside of
the cell membrane and the concentration of Na+ being
higher on the outside
* The presence of many negatively charged molecules,
such as proteins, inside the cell that are too large to
exit the cell
* The presence of leak protein channels in the
membrane that are more permeable to K+ than it is to
Na+

Na+ tends to diffuse into the cell and K+ tends to
diffuse out.
In order to maintain the resting membrane
potential, the sodium-potassium pump recreates
the Na+ and K+ ion gradient by pumping Na+ out of
the cell and K+ into the cell

A

Resting Membrane Potential

39
Q

_____________
- allow conductivity along nerve or muscle
membrane
Voltage-gated Na+ and K+ channels
- responsible for action potential
- closed during rest

________
- movement of Na+ that causes the inside of the cell
membrane to become positive,
- if large enough, Na+ enters the cell so that the local
potential reaches a THRESHOLD VALUE.
This threshold depolarization causes voltage-gated Na+
channels to open, generally at the axon hillock.

The opening of these channels causes a massive, 600-
fold increase in membrane permeability to Na+.
Voltage-gated K+ channels also begin to open.
As more Na+ enters the cell, depolarization continues at
a much faster pace, causing a brief reversal of charge –
the inside of the cell membrane becomes positive
relative to the outside of the cell membrane.
The charge reversal causes Na+ channels to close and Na+
then stops entering the cell.
During this time, more K+ channels are opening and K+
leaves the cell, resulting in repolarization.

At the end of repolarization, the charge on the cell
membrane briefly becomes more negative than the
resting membrane potential; this condition is called
hyperpolarization and occurs briefly.
Action potentials occur in an all-or-none fashion
All-or-none refers to the fact that if threshold is
reached, an action potential occurs; if the threshold
is not reached, no action potential occurs.
The sodium-potassium pump assists in restoring the
resting membrane potential.

A

Action Potential

Depolarization:

Active Potential
1. Resting membrane potential
2. Depolarization
3. Repolarization

40
Q

Action potentials are conducted SLOWLY in
_________ axons and more RAPIDLY in
_________ axons.
Action potentials along unmyelinated axons
occur along the entire membrane.
Action potentials on myelinated axons occur in a
jumping pattern at the nodes of Ranvier.
This type of action potential conduction is called
SALTATORY CONDUCTION.

A

unmyelinated
myelinated

41
Q

Axon Conduction Speed
- The varies widely
- based on the diameter of axon fibers.
Medium-diameter, lightly myelinated axons
- action potentials at the rate of about 3 to
15 meters per second (m/s).
Large-diameter, heavily myelinated axons
conduct action potentials at the rate of 15 to 120
m/s.

A
42
Q

_________
- involuntary reaction in response to a stimulus
applied to the periphery and transmitted to the
CNS.
- allow a person to react to stimuli more
quickly than is possible if conscious thought is
involved.
- mostly occurs in the spinal cord or brainstem
rather than in the higher brain centers.

A ____________ is the neuronal pathway by which a
reflex occurs and has five basic components.

A

Reflex

reflex arc

43
Q

Neuronal Pathway

_________
- two or more neurons synapse
with the same postsynaptic
neuron.
- allows information transmitted in
more than one neuronal pathway to
converge into a single pathway.

_________
- an axon from one neuron divides
and synapses with more than one
other postsynaptic neuron.
- allows information transmitted
in one neuronal pathway to
diverge into two or more
pathways.

The CNS has simple
to complex
neuronal
pathways

A

converging pathway

diverging pathway

Happlec midterms (3 decks)

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