Chapter Eleven: Functional Organization of Nervous Tissue Flashcards
1
Q
What are the five functions of the Nervous System?
A
- Maintaining Homeostasis
- Receiving Sensory Input
- Integrating Information
- Controlling Muscles and Glands
- Establishing and Maintaining
2
Q
Name the Four things that compose the Nervous System:
A
- Brain
- Spinal Cord
- Nerves
- Sensory Receptors
3
Q
The Central Nervous System is composed of what two things?
A
Brain and Spinal Cord
4
Q
The Peripheral Nervous System is composed of what two things?
A
Sensory Receptors and Nerves
5
Q
What is this?
- ending of neurons or separate, specialized cells
- detect temperature, pain, touch, pressure, light, sound, and odors
A
Sensory Receptors
6
Q
What is this?
- a bundle of axons and their sheaths that connects CNS to sensory receptors, muscles, and glands
A
Nerve
7
Q
What type of nerve?
- originate from the brain; 12 pairs
A
Cranial Nerves
8
Q
What kind of nerve?
- originate from spinal cord; 31 pairs
A
Spinal nerves
9
Q
What is this?
- Collection of neuron cell bodies outside CNS
A
Ganglion
10
Q
What is this?
- extensive network of axons, and sometimes neuron cell bodies, located outside CNS
A
Plexus
11
Q
What are the two divisions of the PNS?
A
Sensory and Motor
12
Q
What division of the PNS?
- transmits action potentials from receptors to CNS
A
Sensory
13
Q
What division of the PNS?
- transmits action potentials from CNS to effectors (muscles, glands)
A
Motor
14
Q
The sensory division of the PNS is also known as…
A
afferent
15
Q
The motor division of the PNS is also knows as the…
A
Efferent
16
Q
What is this?
- from CNS to skeletal muscles
- voluntary
- cell body in CNS and axon extends muscle
- Single Neuron System
- Synapse
A
Somatic Nervous System
17
Q
What is this?
- one neuron runs from CNS to effector
A
Single Neuron System
18
Q
What is this?
- junction of a nerve cell with another cell. E.g., neuromuscular junction is a synapse between a neuron and skeletal muscle cell
A
Synapse
19
Q
What is this?
- from CNS to smooth muscle, cardiac muscle, and certain glands
- subconscious or involuntary control
A
Autonomic Nervous System
20
Q
What Nervous system is the Two neuron system a part of?
A
Autonomic Nervous System
21
Q
What is this?
- first neuron from CNS to ganglion
- second neuron from ganglion to effector
A
Two Neuron System
22
Q
What are the two divisions of the ANS?
A
Sympathetic and Parasympathetic
23
Q
What division of ANS?
- prepares body for physical activity
A
Sympathetic
24
Q
What division of ANS?
- regulates resting or vegetative functions such as digesting food or emptying of the urinary bladder
A
Parasympathetic
25
What is this?
- plexuses within the wall of the digestive tract
- can control the digestive tract independently of the CNS
- considered part of ANS because parasympathetic and sympathetic neurons contribute to the plexi
Enteric Nervous System
26
What type of cell?
- support and protect neurons
Glial Cells
27
What is this?
- also known as nerve cells
- receive stimuli and transmit action potentials
Neurons
28
What are the three parts of the neuron?
1. Cell Body
2. Dendrites
3. Axons
29
What part of the neuron is responsible for input?
Dendrites
30
What part of a neuron is responsible for output?
Axons
31
What part of the Neuron Cell Body (Soma)?
- short, often highly branched
Dendrites
32
What part of the Neuron Cell Body?
- has rough E.R: primary site of protein synthesis
Nissl Substance
33
What part of the Neuron Cell Body?
- small protuberance where axons synapse with dendrite
Dendritic Spines
34
What are the five parts of the Axon?
1. Trigger Zone
2. Axoplasm
3. Axolemma
4. Presynaptic Terminals
5. Synaptic Vesicles
35
What part of the axon?
- site where action potentials are generated
- axon hillock
- initial segment: beginning of axon
Trigger Zone
36
What part of the axon?
- cytoplasm
Axoplasm
37
What part of the axon?
- Plasma Membrane
Axolemma
38
What are the three types of neurons?
1. Sensory
2. Motor
3. Interneurons
39
What type of neuron?
- action potentials toward CNS
Sensory or Afferent
40
What type of neuron?
- action potentials away from CNS
Motor or Efferent
41
What type of neuron?
- located within CNS and connect one neuron to another
Interneurons or Association Neurons
42
What are the three structural classifications of neurons?
1. Multipolar
2. Bipolar
3. Pseudo-unipolar
43
What structural classification of neurons?
- most neurons in CNS; motor neurons
Multipolar
44
What structural classification of neurons?
- sensory neurons in retina of the eye and nose
Bipolar
45
What structural classification of neurons?
- sensory neuron of peripheral nervous system
Pseudo-unipolar
46
Glial Cells if the CNS: Astrocytes
- processes form _________ that cover the surfaces of neurons and blood vessels and the pia matter
feet
47
Glial Cells of the CNS: Astrocytes
- Regulate what substances reach the CNS from the…
blood
48
Glial Cells of the CNS: Astrocytes
- produce chemicals that promote __________ _______________ to form blood-brain barrier
tight junctions
49
Glial Cells of the CNS: Astrocytes
- regulate extracellular brain __________ composition
fluid
50
Glial cells of the CNS: Astrocytes
- integral in healing following damage and stores…
Glycogen
51
Glial Cells of the CNS: Ependymal Cells
- Lines brain ventricles and ___________ _________ central canal
spinal cord
52
Glial Cells of the CNS: Ependymal Cells
- specialized versions of ependymal form choroid….
plexuses
53
What part of Ependymal Cells secretes cerebrospinal fluid?
Choroid Plexus
54
Glial Cells of the CNS: Ependymal Cells
- ___________ help move fluid through the cavities of the brain
Cilia
55
Glial Cells of the CNS: Ependymal Cells
- Have long processes on basal surface that extend within the __________ tissue, may have astrocyte-like functions
brain
56
What type of Glial Cell of the CNS?
- specialized macrophages
- responds to inflammation, phagocytize necrotic tissue, microorganisms, and foreign substances that invade the CNS
Microglia
57
What type of Glial Cell of the CNS?
- have cytoplasmic extensions that surround axons
- form myelin sheaths if surrounding axon
- single (of these) can form myelin sheaths around portions of several axons
Oligodendrocytes
58
What type of Glial Cell of the PNS?
- wrap around portion of only one axon to form myelin sheath
- wrap around many times
- during developments, as cells grow around axon, cytoplasm is squeezed out and multiple layers of cell membrane wrap the axon
Schwann Cells
59
What type of Glial Cell of the PNS?
- surround neuron cell bodies in sensory and autonomic ganglia
- provide support and nutrients
- help control microenvironment
- protect neurons from heavy metals
Satellite Cells
60
What type of axon?
- myelin protects and insulates axons from one another, speeds transmission, functions in repair of axons
- not continuous - nodes of ranvier
- degeneration of myelin sheaths occur in multiple sclerosis and some cases of diabetes mellitus
Myelinated Axons
61
What type of axon?
- rest in invaginations of Schwann cells or oligodendrocyytes
- not wrapped around the axon
- gray matter
Unmyelinated Axon
62
What nervous system?
- capable of axon regeneration following injury
- Schwann cells secrete substances required for regeneration
PNS
63
What nervous system?
- axon regeneration is very limited
CNS
64
What type of matter?
- unmyelinated axons, cell bodies, dendrites, glia
- PNS
- Brain
- Spine
Gray Matter
65
What type of matter?
- myelinated axons
- CNS
- Brain
- Spine
White Matter
66
Gray matter, in the brain, is located in the…
outer cortex and inner nuclei
67
Gray matter in the spine is in the…
deeper portion
68
Gray matter in the PNS is in the….
ganglia
69
White matter, in the CNS, is located in….
nerve tracts that propagate action potentials from one area to another
70
White matter in the brain is located….
deeper
71
White matter in the spine is located more…
superficial
72
Cells produce electrical signals called….
Action Potentials
73
Electrical properties result from what two things?
1. Ionic concentration differences across plasma membrane
2. Permeability of membrane
74
Ion concentrations are a result of what two processes?
1. Na+/K+ pump
2. membrane permeability
75
High concentration of Na and Cl- ions __________ and high concentration of K+ and proteins on the inside
outside
76
Steep concentration gradient of Na+ and K+, but in ____________ directions
opposite
77
Proteins are synthesized ________ the cell
inside
78
Proteins are ____________ charged
negatively
79
Gated ion channels open and close because of some sort of ____________
stimulus
80
When gated ion channels open, they change the __________________ of the cell membrane
permeability
81
In Leaky Ion Channels, protein repels Cl-, they move…
out
82
In Leaky Ion Channels, the concentration of K+ is higher inside than out; move…
out
83
In Leaky Ion Channels, the concentration of Na+ is higher outside than in; move….
in
84
Leaky Ion channels:
always open and responsible for permeability when membrane is at….
rest
85
To establish resting membrane potential, the number of charged molecules ions inside and outside the cell need to be nearly…
equal
86
To establish resting membrane potential, the concentration of K+ needs to be higher _________ than __________ the cell and the opposite for Na+
inside
outside
87
What is this?
- unequal distribution of charge exists between the immediate inside and immediate outside of the plasma membrane: 70 to -90mV
Potential Difference
88
At equilibrium, there is very __________ movement of K+ or other ions across the plasma membrane
little
89
Establishing the Resting Potential:
K+ leaks out down…
concentration gradient
90
Establishing the Resting Potential:
K+ leaks in due to attraction to…
proteins
91
What three things do not have a great effect on resting potential since there are very few leakage channels for these ions?
1. Na+
2. Cl-
3. Ca2+
92
Ion concentrations are maintained by what kind of pump?
Na/K
93
Establishing the Resting Potential:
For each ATP that is consumes, three ____ moved out, two ____ moved in
Na
K+
94
Establishing the Resting Potential:
Outside of the plasma membrane is slightly…
positive
95
Gated Ion channels open and close because of some sort of….
stimulus
96
Gated Ion Channels influence the _____________ of the cell membrane
permeability
97
What kind of gated ion channel?
- open or close in response to ligand such as ACh binding to receptor protein
- receptor proteins are usually glycoproteins. E.g., acetylcholine binds to acetylcholine receptor on a Na+ channel
- Channel opens, Na+ enters the cell
Ligand-gated
98
What kind of gated ion channel?
- open or close in response to small voltage changes across the cell membrane
- at rest, membrane is (-) on the inside compared to outside
- when cell is stimulated, that relative charge changes and these channels either open or close
- Types: Na+, K+, Ca2+
Voltage-gated
99
What kind of gated ion channel?
- respond to touch and other forms of mechanical stimulation of the skin
Mechanically-gated channels
100
What kind of gated ion channel?
- respond to temperature changes in the skin
Temperature-gated
101
What is this?
- potential difference becomes smaller or less polar
Depolarization
102
What is this?
- potential difference returns to normal
Repolarization
103
What is this?
- Potential difference becomes greater or more polar
Hyperpolarization
104
Changing the resting membrane potential: K+
- in resting membrane, K+ movement in and out through the leakage channels is…
equal
105
Changing the Resting Membrane Potential: K+
- If gated K+ channels open, more K+ diffuses out but this is opposed by the negative charge that starts to develop as the K+ diffuses out which causes…
Hyperpolarization
106
Changing the Resting Membrane Potential: Na+
- Change the concentration of Na+ inside or outside the cell -> little effect because few leak and gated channels remain…
closed
107
Changing the Resting Membrane Potential: Na+
- when gates open, Na+ diffuses in, ________________ the membrane
depolarizing
108
Changing the Resting Membrane Potential: Ca2+
- If extracellular Ca2+ concentration decreases -> Na+ gates open ->….
depolarization
109
Changing the Resting Membrane Potential: Ca2+
- If extracellular concentration of Ca2+ increases -> Na+ gates close -> ______________ or __________________
repolarization
hyperpolarization
110
Changing the Resting Membrane Potential: Ca2+
- If gated Ca2+ channels open, Ca2+ diffuses into the cell, causing…
depolarization
111
What five things do graded (local) potentials result from?
1. Ligands binding to receptors
2. Changes in charge across membrane
3. Mechanical Stimulation
4. Temperature Changes
5. Spontaneous change in permeability
112
Graded potentials:
- magnitude varies from small to large can depend on one of these three things…
1. Stimulus
2. Strength
3. Frequency
113
Graded (local) potentials can ________ or add onto each other
summate
114
Graded (local) potentials can cause…
action potentials
115
Depolarization phase is followed by the….
repolarization phase
116
Depolarization, in terms of action potentials, is more…
positive
117
Repolarization, in terms of action potentials, is more…
negative
118
Afterpotential, in terms of action potentials, has slight…
hyperpolarization
119
A large enough graded potential may cause the membrane to reach…
Threshold
120
What is this?
- no matter how strong the stimulus, as long as it is greater than threshold, then an action potential will occur
All-or-none principle
121
Depolarization Phase:
What kind of Voltage gated channels open rapidly as the threshold is reached?
Na+
122
Depolarization Phase: Voltage-gated Na+ channels
- activation gate: allows Na+ to diffuse in; opens at…
threshold
123
Depolarization Phase: Voltage-gated Na+ channels
- inactivation gate: open during rest and depolarization; closed during _______________ to prevent passage of Na+
repolarization
124
Depolarization Phase:
What is this?
- Na+ diffuses into cell, causing depolarization
- Depolarization causes more voltage-gated Na+ channels to open -> more Na+ diffuses into the cell
Positive Feedback
125
Voltage-gated K+ channels open at threshold and open at the same time as Na+ but more ____________. More Na+ diffuses into the cell than K+ diffuses out
slowly
126
Repolarization phase:
Inactivation gates of voltage-gated Na+ channels close -> decreased Na+ into cell ->…
repolarization
127
Repolarization Phase:
- Voltage-gated K+ channels continue to open > increased K+ out of the cell —>…
Repolarization
128
Repolarization Phase:
Return of resting membrane potential causes activation gates in voltage-gated Na+ channels to __________ and inactivation gated to __________
close
open
129
What is this?
- sensitivity of area to further stimulation decreases for a time
Refractory Period
130
What are the two types of Refractory Periods?
Absolute and Relative
131
What type of Refractory Period?
- complete insensitivity exists to another stimulus
from beginning of action potential until near end of repolarization
- no matter how strong the stimulus, a send action potential cannot be produced
Absolute
132
What type of Refractory Period?
- period of hyperpolarization
- voltage-gated K+ channels still open
- A stronger-than-threshold stimulus can initiate another action potential
Relative
133
Action Potential Frequency:
Threshold stimulus generates a…
single action potential
134
Action Potential Frequency:
Strength of stimulus is measured by ____________ and ______________ of action potentials
frequency and duration
135
Action Potential Frequency:
Stronger stimulus -> increased…
action potential frequency
136
Graded potentials at trigger zone cause action potential if they reach…
threshold
137
Action potential in one site causes action potential at the next location. It cannot go backwards because initial action potential site is in a _____________ period which ensures one-way conduction of impulse
Refractory Period
138
Saltatory Conduction occurs in myelinated…
axons
139
Saltatory Conduction:
Action potentials form at one node of…
Ranvier
140
Saltatory Conduction
Current travels through _______________ region
myelinated
141
Saltatory Conduction
Action potentials form at each successive node of…
Ranvier
142
The speed of conduction is faster in ____________ than in non-myelinated
myelinated
143
In myelinated axons, _________ act as insulation forcing ionic currents to jump from node to node
lipids
144
In myelinated axons, speed is affected by thickness of the…
myelin sheath
145
The diameter of axons is large and conducts ____________ than small-diameter
faster
