CH 11 Flashcards

1
Q

5 functions of the nervous system:

A
Sensory input
Integration
Control of muscles/glands
Homeostasis
Center for mental activities
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2
Q

Sensory Input

A

Sensory receptors monitor external and internal stimuli

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3
Q

Integration

A

the brain and spinal cord process and respond to sensory input

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4
Q

Homeostasis regulates…

A

other systems to maintain a constant internal environment

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5
Q

Control of muscles and glands

A
  • Skeletal m. contract when stimulated by NS

- Smooth m., cardiac m., and glands are also under nervous control

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6
Q

center for mental activities

A

the brain is the center of mental activities including memory, emotions, thinking, and consciousness

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7
Q

Central nervous system (CNS)

A
  • composed of the brain and spinal cord

- processes, integrates, stores, and responds to information from the PNS

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8
Q

Peripheral Nervous System (PNS)

A
  • Nervous tissue external to the CNS
  • Composed of sensory receptors and nerves
  • detects stimuli and transmits information to the CNS and receives information from the CNS
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9
Q

PNS: Sensory Receptors

A

Ends of neurons or separate, specialized cells that detect: temperature, pain, touch, pressure, light, sound, odors

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10
Q

PNS: Nerve

A

-Bundle of axons and sheaths that connect CNS to sensory receptors, muscles, and glands

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11
Q

PNS: How many cranial nerves and where do they originate?

A

12; the brain

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12
Q

PNS: How many spinal nerves and where do they originate?

A

31; the spinal cord

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13
Q

PNS: Ganglion (singular)

A

collection neuron cell body located external to the CNS

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14
Q

PNS: Plexus

A

Extensive network of axons, and sometimes neuron cell bodies, located outside of the CNS

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15
Q

PNS: Sensory Division

A
  • Afferent

- Transmits action potentials from receptors to CNS

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16
Q

PNS: Motor Division

A
  • Efferent

- Transmits action potentials from CNS to effectors

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17
Q

PNS: motor division

A
  • transmits APs from the CNS to effector organs

- composed of 2 subdivisions: somatic nervous system and autonomic nervous system (ANS)

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18
Q

Somatic nervous system

A

innervates skeletal m.

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19
Q

Autonomic nervous system (ANS)

A

Innervates cardiac m.

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20
Q

Subdivisions of the ANS:

A

Sympathetic, parasympathetic, enteric

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21
Q

what does to innervate mean?

A

to form a synapse with and transmit a AP

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22
Q

PNS: Autonomic Division

A
  • Unconscious control
  • Two neuron system
  • sympathetic division
  • parasympathetic division
  • enteric division
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23
Q

PNS: Autonomic Division: Two Neuron System

A
  1. ) From CNS to ganglion

2. ) From ganglion to effector

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24
Q

PNS: Autonomic Division: Sympathetic Division

A
  • Always active at basal levels but is most active during states of heightened stress
  • Responsible for the fight or flight response
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25
Q

PNS: Autonomic Division: Parasympathetic Division

A
  • bring internal variables down
  • regulates resting functions
  • slows the body down
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26
Q

PNS: Autonomic Division: Enteric Division

A
  • controls digestive activities

- housed within the digestive tract

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27
Q

Will the sympathetic and parasympathetic divisions be activated at the same time?

A

no, they have a push/pull type of relationship

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28
Q

CNS consists of…and corresponds with…

A

brain and spinal cord…PNS

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29
Q

PNS consists of…and corresponds with…

A

-Nervous tissue outside the CNS
-Sensory receptors and nerves

2 way comms with CNs, talks to motor division, receives input from sensory division

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30
Q

Motor Division consists of…and corresponds with…

A

-carries APs away from CNS in cranial nerves or spinal nerves….. talks to ANS and somatic nervous system

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31
Q

the sensory division consists of…and corresponds with…

A

-transmits APs away from sensory receptors to the CNs….

only talks to PNS

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32
Q

Somatic Nervous system consists of…and corresponds with…

A

-innervates skeletal m.

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33
Q

ANS consists of…and corresponds with…

A

innervates cardiac m., smooth m, and glands… talks to sympathetic div., parasympathetic div, and enteric nervous system

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34
Q

the sympathetic division consists of…and corresponds with…

A
  • most active during physical activity

- fight or flight

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35
Q

the parasympathetic division consists of…and corresponds with…

A
  • regulates resting functions

- calm/at rest

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36
Q

the enteric nervous system consists of…and corresponds with…

A

controls the digestive system

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37
Q

Neurons

A

excitable cells that receive stimuli and transmit APs to other neurons or effector organs

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38
Q

What are neurons composed of?

A
  • cell body (soma)
  • dendrites
  • axons
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39
Q

Dendrites

A

receive incoming information

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40
Q

axons

A

send outgoing information

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41
Q

Neuroglia (glial cells)

A
  • non-neural cells
  • cells that surround and support the functions of neurons
  • account for over half of the brain’s weight
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42
Q

Neuron: Cell body (soma)

A
  • contains the nucleus, nucleolus, and nissl substance

- mitochondria, golgi apparatus and other organelles are present

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43
Q

Neuron: Dendrites

A

Short, branched cytoplasmic extensions of the cell body

-conduct electric signals toward the cell body

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44
Q

Neuron: Axon

A
  • cytoplasmic extension of the cell body

- transmit APs to other cells

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45
Q

Nissl substance

A
  • an aggregate of rough ER and free ribosome

- primary site of protein synthesis in the neutron

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46
Q

what are clusters of cell bodies in the CNS called?

A

nuclei

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47
Q

what are clusters of cell bodies in the PNS called?

A

ganglia

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48
Q

Neuron Structure: Axon

A
  • Trigger zone
  • Most neurons have one un-branched axon (most branches, if present, are called collateral axons)
  • presynaptic terminal
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49
Q

Trigger Zone

A
  • Part of the neuron where the axon originates

- APs are generated here

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50
Q

Presynaptic Terminal

A
  • branched terminus of an axon (10,000 or more)
  • form synapses
  • contain vesicles with neurotransmitters
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51
Q

What are the 3 categories that neurons are classified into according to the direction in which APs are conducted:

A
  • sensory (afferent) neurons
  • motor (efferent) neurons
  • interneurons (association)
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52
Q

sensory (afferent) neurons

A

conduct APs towards the CNS

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53
Q

motor (efferent) neurons

A

conduct APs away from CNS, towards muscles or glands

54
Q

interneurons (association)

A

conduct APs from one neuron to another neuron within the CNS

55
Q

What are the 3 categories that neurons are classified into according to the number of processes that extend from the neuron cell body

A
  • multipolar
  • bipolar
  • unipolar
56
Q

multipolar

A
  • have several dendrites and a single axon

- interneurons and motor neurons

57
Q

Bipolar

A
  • Have a single axon and dendrite

- components of sensory organs

58
Q

Unipolar

A
  • Have a single axon

- most sensory neurons

59
Q

Neuroglia

A
  • provide a supportive scaffolding for neurons
  • segregate and insulate neurons
  • guide young neurons to the proper connections
  • promote health and growth
60
Q

Neuroglia of the CNS

A
  • astrocytes
  • microglia
  • ependymal cells
  • oligodendrocytes
61
Q

Neuroglia of the PNS

A
  • satellite cells

- schwann cells

62
Q

Neuroglia of the CNS: Astrocytes

A
  • cling to neurons and cover capillaries
  • support and brace neurons and blood vessels
  • influence the functioning of the blood-brain barrier
  • regulate what substances reach the CNS from the blood
63
Q

Neuroglia of the CNS: Astrocytes: Blood Brain Barrier

A
  • protects neurons from toxic substances
  • allows the exchange of nutrients and waste products between neurons and blood
  • prevents fluctuations in the composition of the blood from affecting the functions of the brain
  • lipid soluble can get through; imperfect
64
Q

Neuroglia of the CNS: Ependymal Cells

A
  • line the ventricles of the brain and the central canal of the spinal cord
  • some are specialized to form choroid plexuses
65
Q

Neuroglia of the CNS: Ependymal Cells: Choroid plexuses

A
  • found within certain regions of ventricles
  • secrete cerebrospinal fluid
  • cilia help move fluid through the cavities of the brain
66
Q

Neuroglia of the CNS: Microglia

A
  • specialized macrophages
  • become mobile and phagocytic in response to inflammation
  • phagocytes monitor the health of neurons
67
Q

Phagocytize

A
  • necrotic tissue (dead and damaged neurons)
  • microorganisms
  • foreign substances that invade the CNS
68
Q

Neuroglia of the CNS: Oligodendrocytes

A
  • form myelin sheaths around the axons of CNS neurons

- a single Oligodendrocyte can form myelin sheaths around portions of several axons

69
Q

Neuroglia of the PNS: Schwann Cells (nuerolemmocytes)

A
  • form myelin sheath around part of the axon of a PNS neuron

- unlike Oligodendrocytes, schwann cells form a myelin sheath around a portion of only one axon

70
Q

Neuroglia of the PNS: Satellite Cells

A
  • support and nourish neuron cell bodies within ganglia

- protect neurons from heavy metal poisons by absorbing them and reducing their access to neuron cell bodies

71
Q

Axon: Myelinated

A
  • The PM of a schwann cells or Oligodendrocyte repeatedly wraps around a segment of an axon to form the myelin sheath
  • conducts APs rapidly
  • Node of ranvier
72
Q

Myelin and its functions

A
  • whitish, fatty, segmented sheath around most long axons
  • protection
  • electrically insulates
  • increases the speed of nerve
  • impulse transmission
73
Q

Node of Ranvier

A

Gap in the myelin sheath

74
Q

Axons: Un-myelinated

A
  • rest in invaginations of Schwann cells or oligodendrocytes
  • surround each axon, but don’t wrap around it many times
  • conduct APs slowly
75
Q

Nervous tissue is organized into what 2 categories…

A

white matter and gray matter

76
Q

White matter

A
  • myelinated axons
  • propagates APs
  • forms nerve tracts in the CNS and nerves in the PNS
77
Q

Gray Matter

A
  • collections of neuron cell bodies, un-myelinated axons, dendrites, neuroglia
  • forms cortex and nuclei in the CNS and ganglia in the PNS
  • integrative functions
78
Q

Action potentials are…

A

electrical signals produced by cells

79
Q

When APs are received from sensory cells…

A

it can result in sensations of sight, hearing and touch

80
Q

Electrical properties of cells result from:

A
  • ionic concentration difference across the PM

- permeability characteristics of the PM

81
Q

What is in greater concentration outside of the cell?

A

Na+ (sodium)
Ca2+ (calcium)
Cl- (chloride)

82
Q

what is in greater concentration inside of the cell?

A

K+ (potassium)

negatively charged molecules, such as proteins

83
Q

Negatively charged proteins are synthesized….

A

inside of the cell and cannot diffuse out of it

84
Q

Concentration gradients result from:

A
  1. ) Na/K pump

2. ) Permeability characteristics of the PM

85
Q

Na/K Pump:

A
  • moves ions by active transport

- K+ are moved int he cell while Na+ are moved out of the cell

86
Q

Leak channels

A
  • always open
  • K+ leak channels are more numerous than Na leak channels
  • PM is more permeable to K+ than to Na+ when at rest
87
Q

Gated ion channels

A

include ligand gated ion channels, voltage gated ion channels and other gated ion channels

88
Q

Electrical Signals: Gated ion Channels

A
  • Open and close in response to stimuli

- change permeability of the cell membrane when opened

89
Q

Ligand-gated ion channels

A
  • open or close with the biding of a specific ligand (neurotransmitters)
  • common in glands and nervous and muscles tissue
90
Q

Ligand

A

a molecule that binds to a receptor

91
Q

Receptor

A

a protein or glycoprotein that has a receptor site to which a ligand can bind

92
Q

voltage gated ion channels

A
  • open and close in response to small voltage changes across the PM
  • abundant in nervous and muscle tissue
93
Q

Other gated ion channels open and close in response to…

A

physical deformation of receptors

touch receptors, temperature receptors

94
Q

Touch Receptors

A

respond to mechanical simulation

95
Q

temperature receptors

A

respond to temperature changes

96
Q

At RMP, the inside of the cell is negatively charges compared to the outside of the cell..how?

A

due mainly to the tendency of positively charged K+ to diffuse out of the cell, opposed to the negative charge that develops inside the PM

97
Q

T/F: Na+, Cl- and Ca2+ do not have a great impact on the RMP

A

True, there are few leakage channels for these ions

-if leakage channels alone were responsible for RMP, Na and K concentrations would eventually equalize.

98
Q

RMP is maintained by the…

A

Na/K Pump

99
Q

When is the RMP established?

A

when the movement of K+ out of the cell is equal to their movement into the cell

100
Q

Depolarization

A
  • a decrease in the RMP (less polar)

- movement of RMP toward zero, becomes less negative

101
Q

What causes depolarization?

A
  • Decrease in the K+ concentration gradient
  • decrease in membrane permeability to K+
  • increase in membrane permeability to Na+ or Ca2+
  • decrease in extracellular Ca2+ concentrations
102
Q

What is the opposite of depolarization?

A

Hyper-polarization… NOT re-polarization

103
Q

Hyperpolarization

A
  • increase in the RMP (more polar)

- movement of RMP further away from zero

104
Q

What causes hyper-polarization?

A
  • increase in the K+ concentration gradient
  • increase in membrane permeability to K+, Cl-
  • decrease in membrane permeability to Na+
  • increase in extracellular Ca2+ concentrations
105
Q

Electrical signals: graded potentials

A
  • do not reach threshold
  • smaller changes in the RMP
  • confined to a small area of the PM
106
Q

An increase in the membrane permeability to Na+ can cause…

A

a graded depolarization

107
Q

An increase in the membrane permeability to K+ or Cl- can result in…

A

graded hyperpolarization

108
Q

Action potential

A
  • larger change in RMP that can spread over the entire surface of the cell
  • starts with a graded depolarization to a level called threshold
109
Q

APs occur in what 3 phases:

A

Depolarization
Re-polarization
Afterpotential

110
Q

APs occur in…

A

all or none fashion and are of the same magnitude, no matter how strong the stimulus

111
Q

AP Phases: Depolarization

A

Na diffused into the cell through voltage-gated ion channels

112
Q

AP Phases: Repolarization

A
  • voltage-gated Na channels close

- Voltage-gated K channels open and K diffuses out of the cell

113
Q

AP Phases: Afterpotential

A

a brief period of hyperpolarization following repolarization

114
Q

Absolute refractory period

A
  • the time during an AP when a second stimulus (no matter how strong) cannot initiate another AP
  • completely insensitive to another stimulus
115
Q

relative refractory period

A

the time during which a stronger-than-threshold stimulus can evoke another AP

116
Q

AP: Frequency

A

number of APs produced per unit of time in response to stimuli

117
Q

4 types of stimulus:

A

subthreshold
threshold
submaximal
maximal or supramaximal

118
Q

subthreshold stimulus

A

produces a graded depolarization

119
Q

threshold stimulus

A

produces a single AP

120
Q

submaximal stimulus

A

produces an increasing frequency of APs as the strength of the stimulus increases

121
Q

maximal or supramaximal stimulus

A

produces a maximum frequency of APs

122
Q

Can we produce a “greater” AP?

A

No, but we can produce a higher frequency; all APs have the same magnitude

123
Q

what does RMP sit at?

A

-70

124
Q

APs generate ionic currents that stimulate..

A

voltage-gated Na channels in adjacent regions of the PM to open—> leads to the production of new APs

125
Q

Propagation occurs most rapidly in…

A

myelinated, large-diameter axons

126
Q

reversal of the direction of AP propagation is prevented by…

A
  • the absolute refractory period

- prevents the ionic current from stimulating the production of an AP in the reverse direction

127
Q

APs: Propagation: Saltatory Conduction

A
  • in myelinated axons, APs from one node of ranvier generate ionic currents that flow toward the next node of ranvier
  • currents appear to jump from one node of ranvier to the next; allows us to send APs rapidly
128
Q

in a myelinated axon, APs are generated at…

A

successive nodes of ranvier

129
Q

what moves faster, unmyelinated or myelinated?

A

myelinated; unmyelinated takes baby steps, not jumps

130
Q

in unmyelinated axons…

A

APs are generated immediately adjacent to previous APs