CH 12 Flashcards
(170 cards)
1
Q
Which two organ systems are primarily responsible for coordinating the other bodily systems so as to maintain homeostasis?
A
Endocrine System
2
Q
Basic Steps of the nervous system maintaing homeostasis
A
- Information received by sensory receptors is transmitted to CNS
- Information is processed and an appropriate response is determined
- A command is issued to effectors such as muscles or glands
3
Q
What are the 2 major anatomical subdivisions of the nervous system?
A
Central and Peripheral nervous systems
4
Q
What is the knotlike swelling in a nerve where neuron cell bodies are found?
A
Ganglion
5
Q
What part of the PNS carries signals from various receptors to the CNS?
A
Sensory division
6
Q
What Two organ systems are dedicated to internal coordination, communication between the other systems, and maintaining the overall homeostasis of the body?
A
They are the endocrine system, which communicates by means of hormones, and the nervous system which sends quick electrical and chemical messages from cell to cell.
7
Q
Taken together, the sensory and motor subdivisions make up which of the following?
A
Peripheral nervous system
8
Q
Where do sensory (afferent) neurons send their signals?
A
To the brain and spinal cord
9
Q
The motor division of the PNS is further divided into what two categories?
A
Somatic motor division , carries signals to skeletal muscles
Visceral motor division (ANS) , carries signals to glands, cardiac muscle, and smooth muscle
10
Q
Which term is another name for the autonomic nervous system?
A
Visceral Motor Division
11
Q
The sensory division of the PNS is divided into what two categories?
A
Somatic sensory division, carries signals from receptors in the skin, muscles, bones, and joints
Visceral sensory division, carries signals from organs of the thoracic and abdominal cavities
12
Q
Which division inhibits digestion?
A
Sympathetic , further division of Visceral motor division (ANS) , arouses body for action
13
Q
Which division of the PNS carries signals from the CNS to glands and muscle cells?
A
Motor
14
Q
The visceral motor division of the PNS is also called the autonomic division. What are the functions of this division?
A
Stimulating smooth muscle, accelerating or decreasing heartbeat, controlling gland secretion
15
Q
Which terms refers to the part of the PNS that carries signals from various receptors to the CNS?
A
Sensory division
16
Q
What are the two subdivisions of the ANS?
A
Sympathetic division, arouses the body for action and inhibits digestion
Parasympathetic division, calms body and promotes digestion
17
Q
Sensory, association and motor are the three classes of what?
A
Neurons
18
Q
The motor division is also called?
A
Efferent division
19
Q
Neurons that convey information to the CNS are called sensory neurons or?
A
Afferent neurons
20
Q
Which term is another name for the autonomic nervous system?
A
Visceral motor division
21
Q
Which fundamental physiological property of neurons allows them to send signals quickly over long distances?
A
conductivity
22
Q
What are the effectors of motor neurons?
A
muscle and gland cells
23
Q
3 functional classes of neurons
A
Sensory neurons, motor neurons, interneurons
24
Q
What are the major cytoplasmic inclusions in a neuron?
A
glycogen granules, melanin, lipid droplets, lipofuscin (golden brown pigment produced when lysosomes degrade worn-out organelles. Also called “wear and tear granules” , most abundant in old neurons.
25
Which type of neuron lies entirely within the CNS and carries out the integrative function of the nervous system?
Interneuron, they process store and retrieve info and make decisions. Make up about 90% of neurons in the body
26
Which term is used to describe motor neurons because they send signals away from the CNS and out to muscle and gland cells?
Efferent
27
Which term applies to the small swellings at the distal end of the axon of a neuron that contain synaptic vesicles?
Axon terminals
28
What organelles are found inside the cell body (soma) of a mature neuron?
Rough ER, Nucleus, Mitochondria
29
What are the structural categories of neurons?
Unipolar, bipolar, anaxonic, and multipolar
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The processes of a neuron that usually receive signals from other neurons are called?
Dendrites
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Neurons with numerous dendrites and a single axon are structurally classified as?
Multipolar
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Axon Hillock
A mound located on one side of the soma from which the axon originates
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Axoplasm
Cytoplasm of the axon
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Axolemma
Plasma membrane of the axon
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Axon collateral
Branch the originates from an axon
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Neurons that have one axon and one dendrite, such as olfactory cells, certain neurons of the retina, and sensory neurons of the inner ear, are classified as?
Bipolar
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At its distal end, an axon has an extensive complex of fine branches called what?
Terminal arborization
38
Neurons with a single process extending from the soma, such as the neurons that carry sensory signals to the spinal cord, are classified structurally as ______ neurons.
Unipolar
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Neurons that have multiple dendrites but no axons, and which do not produce action potentials, are called ______ neurons.
Anaxonic
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Axonal Transport
the two-way passage of proteins, organelles, and other materials along an axon
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2 different kinds of axonal transport
Anterograde transport, movement away from the soma down the axon
Retrograde transport, movement up the axon toward the soma
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Motor protein used in Anterograde transport
Kinesin
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Motor protein used in Retrograde transport
Dynein
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What is the most common structural type of neuron?
Multipolar
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Describe Slow Axonal Transport
Works in a stop and go fashion, used to renew worn-out axoplasmic components in mature neurons
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Functions of Neuroglia
They bind neurons together and provide a supportive scaffold, they protest the neurons and help them function
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Satellite Cells
In the PNS; surround somas of neurons in ganglia, provide electrical insulation, regulate chemical environment of neurons
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Schwann Cells
In the PNS; form neurilemma around all PNS fibers and myelin around most of them; aid in regeneration of damaged nerve fibers
49
Ependymal Cells
In the CNS; line cavities of the brain and spinal cord; secrete and circulate CSF
50
Microglia
In the CNS; phagocytize microorganisms, foreign matter, and dead nervous tissue
51
Which glial cell produces and helps circulate cerebrospinal fluid?
Ependymal Cells
52
Which type of transport, fast or slow, is used to move mitochondria, synaptic vesicles, and small molecules such as glucose toward the distal end of an axon?
Fast, anterograde axonal transport
53
What is the approximate ratio of glial cells to neurons?
10 to 1
54
Neuroglial cells that act as macrophages within the CNS are ______.
Microglia
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What neuroglial cell is found in the peripheral nervous system?
Satellite Cell
56
Which type of cell plays a role in the establishment of the blood-brain barrier?
Astrocyte
57
In the CNS, myelin is produced by glial cells called?
Oligodendrocytes
58
What two types of neuroglia are found only in the peripheral nervous system?
Schwann cells and satellite cells
59
Can slow axonal transport be either anterograde or retrograde?
No, it is always anterograde
60
What are the functions of astrocytes?
Secrete nerve growth factors, form blood-brain barrier, regulate chemical composition of tissue fluid, convert blood glucose to lactate for neurons to use for fuel
61
Which type of glial cell produces the myelin sheath in the PNS?
Schwann cell
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What term refers to the thick outermost coil of a Schwann cell?
Neurilemma
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What term refers to the segment of an axon between the axon hillock and the first glial cell?
Initial segment
64
Slow axonal transport is always anterograde. What about fast axonal transport?
It ca be either anterograde or retrograde
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The region that plays an important role in initiating a nerve signal and is formed by the axon hillock and the initial segment is the ______.
Trigger zone
66
The myelin sheath is composed mostly of which of the following?
Lipids
67
What term refers to the gaps between segments of myelin along an axon?
Nodes of Ranvier
68
Are Unmyelinated nerve fibers (axons) in the PNS are enveloped in Schwann cells?
YES. Although the Schwann cell's plasma membrane does not spiral repeatedly around the axon as it does when forming a myelin sheath, it does fold once around each axon to form the neurilemma.
69
What term refers to the outermost layer of myelin, containing the nucleus and cytoplasm of the Schwann cell?
Nurilemma
70
What are the factors that influence the speed of nerve signal conduction?
Presence of Myelin and diameter of axon
71
In order for a peripheral nerve fiber to regenerate what must it have?
The soma and at least some of the neurilemma intact
72
Between the nodes of Ranvier are myelin-covered segments of axon encircled by Schwann cells. What term refers to these segments?
Internodes
73
What type of glial cell aids in regeneration of damaged peripheral nerve fibers by forming a regeneration tube to help reestablish the former connection?
Schwann cells
74
How will the speed of signal conduction of a neuron with a large diameter, myelinated axon compare to a neuron with a small diameter, unmyelinated axon?
Signal conduction will be faster because of myelination even though the diameter is larger
75
Stages of Regeneration of a Nerve Fiber
1. Degeneration of axon and myelin distal to injury
2. Swelling of soma; dispersal of Nissl bodies
3. Sprouting of axon growth processes
4. Growth process enters regeneration tube
5. Reestablishment of synaptic contact
76
What regenerates faster, damaged nerve fibers in the CNS or the PNS?
Damaged nerve fibers in the CNS CANNOT regenerate, only nerve fibers in the PNS
77
What best describes an electrical current?
The movement of charged particles like ions
78
What term is used to refer to a cell membrane across which there is a separation of electrical charge, so that one side is more positive and the other side is more negative?
Polarized
79
What term refers to the voltage difference (electrical potential) across the plasma membrane of a neuron when it is at rest and not engaged in electrical signaling?
Resting Membrane Potential (RMP)
80
Electrical currents in neurons are due primarily to the flow of what through gated channels?
Ions like sodium and potassium
81
3 factors that contribute to the formation of the negative RMP
1. There is a higher concentration of K in the intracellular fluid compared to the extracellular fluid
2. Outward K diffusion causes pos and neg charges to accumulate on either side of the membrane
3. Open leak channels in the plasma membrane allow K to diffuse across the membrane down its concentraion gradient
82
What term refers to the flow of charged particles from one point to another?
Current
83
What has the greatest influence on the RMP, Na or K? Why?
K (potassium) because the plasma membrane is more permeable to K than any other ion
84
What contributes to the development of the resting membrane potential in neurons?
K is more concentrated in the ICF than in ECF. K flows freely out of the cell down its concentration gradient. As the ICF grows increasingly neg and neg membrane potential starts
85
Is Na more concentrated in ECF or ICF?
It is about 12x more concentrated in ECF than ICF
86
What creates electrical currents in neurons?
Movement of ions through channels
87
Function of Na-K pump
It moves 3 Na out of the cell and 2 K into the cell, helps maintain the proper ion distribution across the membrane to achieve RMP
Accounts for about 70% of energy (ATP) required by nervous system
88
A shift in membrane voltage to a value that is more negative than the resting membrane potential is called?
Hyperpolarization
89
Properties of Action Potentials
All or none, nondecremental (signal maintains amplitude) , Self-propagating
90
What term refers to the upward change in membrane potential during an action potential?
Depolarization
91
Describe voltage-gated Na and K channel activity at RMP
Both types of voltage-gated channels are closed
92
Describe voltage-gated Na and K channel activity when Depolarization begins
Voltage-gated Na channels open; voltage gated K channels open more slowly
93
Describe voltage-gated Na and K channel activity when Repolarization begins
Voltage gated Na channels inactive, voltage gated K channels remain open longer
94
Do Action potentials occur only where there are voltage-gated ion channels?
Yes, if a local potential arrives at the trigger zone where the voltage-gated channels are more abundant, it can generate the action potential
95
What term refers to the period of time after a nerve cell has responded to a stimulus in which it cannot be excited by a threshold stimulus?
Refractory period
96
During which part of the action potential do most voltage-gated sodium channels open?
Depolarization
97
Properties of the Absolute Refractory period
It occurs during the depolarization and repolarization phases of the action potential, no stimulus of any strength will trigger a new action potential, it refers only to a small patch of membrane; other parts of the neuron can still be stimulated while a small area of it is refractory
98
What does The all-or-none law of action potentials state?
A neuron will fire at maximum voltage if a stimulus depolarizes it to threshold
99
describe signal conduction in unmyelinated axons
a wave of depolarization opens more voltage gated channels immediately distal to the action potential
100
Saltatory conduction refers to what term?
Leaping
101
Properties of signal conduction along myelinated fibers
Action potentials occur only at the nodes of ranvier, there are few voltage gated ion channels at the myelin-covered internodes and many channels at the nodes of ranvier, ions can be exchanged with the ECF ONLY at the nodes of ranvier
102
At a synapse, the neuron that releases neurotransmitter is the ______ neuron.
presynaptic
103
An axon contacts the dendrite of another neuron. What type of synapse is this?
Axodendritic
104
In electrical synapses, electrical signals move quickly from cell to cell through what?
gap junctions
105
At a synapse, the neuron that responds to the neurotransmitter is the ______ neuron.
postsynaptic
106
Properties of Neurotransmitters
They bind to receptors and alter the physiology of the postsynpatic cell, they are synthesized by presynaptic neurons, they are released in response to stimulation
107
Which scientist conclusively demonstrated that neurons communicate by releasing chemical messages?
Otto Loewi
108
Neurotransmitters that are classified as amino acids
Glutamate, GABA, aspartate, glycine
109
In myelinated axons, does the signal conduction move faster through the internodes or through the nodes of ranvier?
through the internodes!
110
Neurotransmitters that are classified as monoamines (!)
Epinephrine, norepinephrine, dopamine, serotonin, and histamine. Subdivision catecholamines = epinephrine, norepinephrine, dopamine
111
Chemical Categories of Neurotransmitters
1. Acetylcholine
2. Amino acid
3. Monoamines (biogenic amines)
4. Purines (ATP)
5. Gases
6. Neuropeptides (2 to 40 amino acids)
112
What neuropeptides act as analgesics (pain relievers)?
Enkephalins
113
What term refers to a synapse that releases acetylcholine from the presynaptic axon terminal?
Cholinergic
114
Some neurotransmitters can have either excitatory or inhibitory effects depending on what?
The type of receptors on the postsynaptic cell
115
At a GABA-ergic synapse, the postsynaptic receptor for the GABA neurotransmitter is which type of channel?
Chloride
116
Which group of neurotransmitters are synthesized from amino acids by removal of the -COOH group?
Monoamines!
117
Order of events in an adrenergic synapse after norepinephrine binds to its receptor
1. G protein dissociates from receptor protein
2. G protein binds to adenylate cyclase
3. Adenylate cyclase is activated
4. ATP is converted to cycilc AMP by adneylate cyclase
5. Cyclic AMP induces multiple effects in the cell
118
Order of events at a cholinergic excitatory synapse after signal arrives
1. Opening of calcium gates in synaptic knob as nerve signal arrives
2. Exocytosis of ACh; diffusion across synaptic cleft
3. Binding of ACh to receptors on postsynaptic neuron
4. Opening of sodium gates on post-synaptic membrane allowing influx of sodium
5. Depolarization of postsynaptic plasma membrane
119
Stimulation of the postsynaptic neuron will end when nerve signals stop arriving at the presynaptic axon terminal or when what else occurs?
neurotransmitter is removed from post synaptic receptors
120
GABA has an inhibitory effect on postsynaptic neurons because it does what?
opens chloride channels
121
What term describes the ability of neurons to process information, store and recall it, and make decisions?
neural integration
122
Neural integration is based on the combining together of what?
postsynaptic potentials
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Factors that would cause postsynaptic stimulation to end
Diffusion of neurotransmitter from the synaptic cleft into the ECF
Reuptake of neurotransmitter into the presynaptic knob
Cessation of signals in the presynaptic nerve fiber
Enzymatic degradation of neurotransmitter in the synaptic cleft
124
When do EPSPs usually occur?
When sodium channels open (bringing membrane potential to threshold)
125
Do neurons with more synapses have greater information-processing capability?
Yes, the chemical synapes are the decision making devices and the more that are present, the more information-processing and decision making that is possible
126
Inhibitory postsynaptic potentials is usually due to the opening of which type of ion channels?
Chloride or potassium
127
Which neurotransmitters are excitatory to some cells and inhibitory to others, depending on the type of receptors on the target cells?
Acetylcholine and Norepinephrine
128
When a single synapse generates EPSPs so quickly that each is generated before the previous one fades, what is this process called?
Temporal Summation
129
Which neurotransmitters produce IPSPs?
Glycine and GABA
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When EPSPs from several synapses add up to threshold at the axon hillock, this process is called what?
Spatial Summation
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The nervous system must interpret quantitative and qualitative information about its environment, thus it converts information to a meaningful pattern of action potentials. This process is called neural...?
Coding
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Firing additional neurons as a stimulus becomes stronger is an example of?
Recruitment
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What term refers to the conversion of stimulus information into a meaningful pattern of action potentials?
Neural coding
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Different sensory receptors in the skin respond to different types of stimuli. The brain can infer the type of stimulus detected by which nerve fibers are activated. What is this called?
Labeled line coding
135
Principal types of neural circuits
Parallel after-discharge circuit, reverberating circuit, diverging circuit, converging circuit
136
A single motor neuron stimulating hundreds of skeletal muscle cells is an example of which type of circuit?
Diverging circuit
137
What is the role of neural pools in the CNS?`
To process information
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The respiratory center of the brain receives input from other parts (i.e from receptors for blood chemistry in arteries and stretch receptors in the lungs) to set a pattern of breathing. This is an example of which type of circuit?
Converging
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The ability of a neuron to enhance the effect of another neuron is called what?
Presynaptic facilitation
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In a which type of circuit will one input signal cause a prolonged and repetitive output because a neuron late in the circuit restimulates a neuron earlier in the circuit?
Reverberating
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The pathway of neurons within a neural pool is called its what?
Neural circuit
142
The ability of synapses to change is called synaptic plasticity. Which term refers to the neuronal pathways formed during learning?
Memory traces
143
Why would the synapses of a memory trace undergo synaptic potentiation?
To allow easier signal transmission along the pathway
144
Which type of memory is important as you read (e.g. remembering the previous words in a sentence)?
Immediate memory
145
What type of output will occur when a parallel after-discharge circuit is stimulated?
Output will last longer than the stimulus lasts
146
Looking up a new phone number and then dialing it from memory utilizes which type of memory?
Working memory
147
Making it easier to transmit signals across a synapse is called?
Synaptic Facilitation
148
What type of stimulation is caused by rapid, repetitive signals arriving at a synaptic knob, causing progressively larger quantities of calcium to accumulate and leading to synaptic facilitation?
Tetanic Stimulation
149
Synapses are not fixed for life. In response to experience, they can be modified to make transmission easier or harder. The ability of synapses to change is called synaptic...?
Plasticity
150
Synapses in a certain pathway can be modified to allow signals to travel more easily across "trained" synapses. Which term refers to the process of making transmission easier?
Potentiation
151
Memories lasting for a few hours, such as recalling an incident earlier in the day, may be due to which of the following?
Posttetanic potentiation
152
Immediate memory, which is the ability to hold something in mind for a few seconds, might be based on activity in which type of neural circuit?
Reverberating
153
Which type of memory can store the most information?
Long-term
154
Which type of memory allows you to remember things from up to a few hours ago?
Short-term
155
2 types of long term memory
Explicit (declarative) and implicit (emotional & procedural) memory
156
Explicit (declarative) memory
Retention of facts that can be put into words - numbers, names ,dates, etc. You must think to remember these things
157
Implicit (emotional/procedural) memory
the memory of things that come reflexively or unconsciously like emotional memories and procedural memories - retention of motor skills like how to tie shoes, play the piano, etc
158
Which may be the basis for learning and long-term memory at the neuronal level?
Long-term potentiation
159
Memories lasting for a few hours, such as remembering what someone said to you earlier in the day may involve posttetanic potentiation. This occurs because of which of the following?
Calcium remains elevated in the synaptic knob and causes a later signal to release a large burst of neurotransmitter
160
Symptoms of Alzheimer disease
Reduced attention span, loss of the ability to talk or eat, memory loss, deterioration of personality
161
Parkinson disease is due to the progressive degeneration of dopamine-releasing neurons in which brain area?
Substantia nigra
162
Long-term potentiation may be involved in long term memory. What are the molecular changes that occur in long term potentiation?
The release of nitric oxide which triggers more glutamate release, binding of glutamate to NDMA receptors, Entrance of calcium into the dendrite
163
Alzheimer disease affects about what percentage of the US population over the age of 65?
11%
164
Common symptoms of Parkinson disease
Progressive loss of motor function, slurred speech, change in gait; smaller and slower steps
165
Which disease is associated with the shrunken folds of cerebral tissue, neurofibrillary tangles and senile plaques containing beta-amyloid protein?
Alzheimer disease
166
Multiple Sclerosis (MS)
A disease of the myelin sheath. The oligodendrocytes and myelin sheath of the CNS deteriorate and are replaced by hard scar tissue. Nerve conduction is disrupted causing a range of symptoms like double vision, blindness, tremors, numbness, or speech defects. Many people can live with it for decades
167
Tay-Sachs
Hereditary disorder seen mainly in infants of eastern european jewish heritage. Results from abnormal accumulation of glycolipid GM2 (ganglioside) in the myelin sheath. Disrupts nerve signal and causes blindness, dementia, and loss of coordination. Most die by age 3 or 4.
168
Electrical Potential
Difference in concentration of charged particles from one point to another
169
What causes hyperpolarizatino?
Because K channels stay open slightly longer than Na channels therefore slightly more K leaves the cell and sodium gates are closed.
170
What is the nerve signal?
A traveling wave of excitation produced by self-propagating action potentials
