Week 4 - Central & Peripheral Nervous System Flashcards
(218 cards)
1
Q
Direction - Midline
A
Line down the middle of a person
2
Q
Direction - Medial
A
Toward the midline
3
Q
Direction - Lateral
A
Away from the midline
4
Q
Direction - Proximal
A
Needs a reference point first
(1) Closer to the midline than (2) the other place
EX: (1) Elbow is proximal to the (2) wrist
5
Q
Direction - Distal
A
Needs a reference point first
(1) Away from the midline than (2) the other place
EX: (1) Fingers are distal to the (2) elbow
6
Q
Direction - Superior
A
Towards the top or head of the body
7
Q
What is another name for “Superior” direction?
A
Cephalic
8
Q
Direction - Inferior
A
Towards the lower part of the body
9
Q
What is another name for “Inferior” direction?
A
Caudal
*Literally means “toward the tail”
10
Q
Direction - Anterior
A
Towards the front of the body
11
Q
What is another name for “Anterior” direction?
A
Ventral
*Literally means “toward the stomach”
12
Q
Direction - Posterior
A
Towards the back of the body
13
Q
What is another name for “Posterior” direction?
A
Dorsal
14
Q
The body has a _______ nervous system
A
Single
15
Q
What are the first 2x sections of the nervous system?
A
1) Central
2) Peripheral
16
Q
What does the Central Nervous System further divide into? (2x)
A
1) Brain
2) Spinal Cord
17
Q
The components of the central nervous system are enclosed within and protected by what?
A
Bony compartments
18
Q
What compartment is the brain protected by?
A
Skull
19
Q
What compartment is the spinal cord protected by?
A
Vertebral column
20
Q
What 2x things are the Peripheral Nervous System composed of?
A
1) Nerves
2) Ganglia
21
Q
What 2x things are part of the Peripheral Nervous System - Nerves?
A
1) Cranial
2) Spinal
22
Q
How many nerve pairs do the Cranial Nerves have?
A
12 pairs
23
Q
How many nerve pairs do the Spinal Nerves have?
A
31 pairs
24
Q
Why are they called Cranial Nerves?
A
Because they have their origin in various parts of the BRAIN
25
What does the "pairs" part mean in nerve pairs? (remember what kind of sides)
There is a Left side & Right side
26
Why are they called Spinal Nerves?
Because they have their origin in various parts of the SPINAL CORD
27
What 2x sections are the Peripheral Nerves further divided into?
1) Afferent (Sensory)
2) Efferent
28
What does Afferent stand for? (think of direction)
TOWARDS something
29
The Afferent peripheral nervous system is carrying sensory impulses ______ the central nervous system
Towards
30
What 2x locations does the Afferent peripheral nervous system move sensory impulses to?
1) Brain
2) Spinal Cord
31
What does Efferent stand for? (think of direction)
AWAY from something
32
The Efferent peripheral nervous system is carrying sensory impulses ______ from the central nervous system
Away
33
What 2x bodily locations does the Efferent peripheral nervous system move sensory impulses to?
1) Skeletal Muscle Fibers [somatic]
2) Smooth Muscle of autonomic areas (bladder, uterus, kidneys, lungs) [autonomic]
34
What is the Somatic Motor component?
- Where we conduct impulses from the central nervous system to skeletal muscle fibers
- Brings about skeletal muscle CONTRACTION
35
Somatic Motor system is under voluntary or involuntary control?
Voluntary (conscious) control
36
What 2x sections are the Efferent peripheral nervous system further divided into?
1) Somatic (voluntary)
2) Autonomic (involuntary)
37
What 2x sections are the Autonomic nervous system further divided into?
1) Sympathetic
2) Parasympathetic
38
Autonomic Motor system is under voluntary or involuntary control?
Involuntary (not conscious) control
39
Name the 2x steps of an Afferent Pathway
1) Pathway starts at a sensory receptor in a bodily location (i.e. Finger)
2) Sensory receptor is excited and sends impulses toward the spinal cord through 1x neuron
40
Name the 2x steps of an Efferent Pathway
1) Pathway starts in a neuron of the spinal cord
2) Impulse is sent from the spinal cord toward the skeletal muscle through 1x neuron
41
What type of Efferent Pathway is a skeletal muscle contraction part of? (spinal cord --> skeletal muscle)
Somatic Motor Pathway
42
Name the 2x steps of an Autonomic Efferent Pathway
1) Pathway starts in the spinal cord
2) The first motor neuron (pre-ganglionic neuron) synapses with the post-ganglionic neuron at the autonomic ganglion
Pre-Ganglion --> Autonomic Ganglion <-- Post-Ganglion
43
What is another name for First Motor Neuron?
Pre-Ganglionic Neuron
44
What is the Autonomic Ganglion?
The place where the Pre-Ganglionic Neuron and Post-Ganglionic Neuron join together in the autonomic nervous system
45
How many neurons are involved in the Autonomic Efferent Pathway?
2
46
What is a Neuron?
The basic STRUCTURAL component of the nervous system
47
What are 2x other different names of a Neuron?
1) Nerve Cell
2) Nerve Fiber
48
What is another name for the Neuron Cell Body?
Neuron Soma
*Soma means "body"
49
What are the 5x components of the Neuron Cell Body?
1) Nucleus (very large)
2) Nucleolus
3) Mitochondria (quite a few)
4) Golgi Apparatus (well developed)
5) Ribosomes (many)
50
What kind of proteins is a neuron making that has a nucleus, nucleolus, mitochondria, Golgi apparatus, and ribosomes?
Neurotransmitters
51
What are Nissl Bodies?
Equivalent to the Endoplasmic Reticulum, but for a neuron (protein synthesis)
52
What do Dendrites do?
To conduct impulses from a point of origin on the dendritic membrane down to the nerve cell body
53
Neurons can have how many Dendrites?
Zero [or] 1x [or] Many
54
Dendritic membranes have very few voltage gated what?
Voltage Gated Sodium Channels
55
Nerve cell body has very few voltage gated what?
Voltage Gated Sodium Channels
56
Dendrites are ______ _______ ________ of action potentials
Very Poor Conductors
57
What is Electrotonic Conduction?
The passive spread of electrical signals along a cell membrane without the involvement of voltage-gated channels
58
The nerve cell body has a rich concentration of what?
Electrolytes
59
How did Electrolytes get its name?
Because they can conduct electrical impulses
60
What 2x components help the neuron favor Electrotonic Conduction?
1) Rich concentration of Electrolytes in the cytoplasm
2) Large diameter of the nerve cell body
61
What is the Axon Hillock?
Where the nerve cell body meets with the Axon
62
What is the pathway of a nerve impulse through a neuron? (from dendrites to presynaptic terminals) (7x)
1) Impulse is sent through the cytoplasm of the Dendrites
2) Moves down to the Nerve Cell Body
3) Moves down to the Axon Hillock
4) If resting gets to threshold at the Axon Hillock, there is conduction of action potentials from the Axon Hillock down to the terminal portion of the Axon
5) Axon can move impulses to the Collateral Axon (if it has one)
6) Moves down to Telodendria
7) Ends at Presynaptic Terminals (or Terminal Buttons)
63
When impulses get to the Axon Hillock, they are what?
- Summed up
- Bring the Axon Hillock membrane TO threshold
- OR bring the resting membrane potential of the axon FURTHER AWAY FROM threshold
64
The Axon is a _____ _______ _______ of action potentials
Very Good Conductor
65
What does an Axon do?
To conduct the impulse from the nerve cell body to the terminal portion of the axon
66
Neurons have how many Axons?
1
(all neurons have 1x axon)
67
What does a Collateral Axon do?
Can send impulses to multiple tissues
68
The Axon and each Collateral Axon will terminate in what?
Telodendria
69
Each Telodendrion terminates where?
Presynaptic Terminals
70
What are the 2x other names for Presynaptic Terminals?
1) Terminal Buttons (boo-tohns)
2) Presynaptic Membranes
71
What is a Schwann Cell? (2x)
- Cells that cover the Axon
- Forms the myelin sheaths around axons in the peripheral nervous system
72
What is the Node of Ranvier? (2x)
- Areas not covered by the Schwann Cell
- Only area along a myelinated axon where action potentials CAN occur
73
Can action potentials occur at a Schwann Cell?
NO!
74
Name the 3x types of Neurons
1) Multipolar
2) Bipolar
3) Unipolar/Pseudounipolar
75
What are 3x characteristics of a Multipolar Neuron?
*Where is the Cell Body on the Axon?
1) Many Dendrites
2) ONE Axon [1x]
3) Found in: Brain, Spinal cord, and Peripheral Nervous system (i.e. somatic neurons)
*Cell body is at the END of the Axon
76
What are 4x characteristics of a Bipolar Neuron?
*Where is the Cell Body on the Axon?
1) ONE Dendrite [1x]
2) ONE Axon [1x]
3) Sensory Afferent Neurons (to CNS)
4) Found in: Rods & Cones of Retina (Cranial Nerve 2), Olfactory Neurons (Cranial Nerve 1)
*Cell body is at the END of the Axon
77
What are 2x characteristics of a Unipolar Neuron?
*Where is the Cell Body on the Axon?
1) NO True Dendrites [0]
2) Almost all sensory neurons
*Cell body is IN THE MIDDLE of the Axon.
*Axon has 2x directions -- one end is Sensory Receptors, and the other end is to the CNS
CNS ---- (Cell Body) ---- Sensory Receptors
78
What does Neuroglia mean?
The glue that holds the nervous system together
79
Name the 5x types of Neuroglial Cells
1) Astrocytes
2) Ependymal Cells (Ciliated & Non-Ciliated)
3) Microglia
4) Oligodendrocytes
5) Schwann Cells/Neurolemmocytes
80
What does "Astro" mean?
Star! (star-shaped)
81
What does "Cyte" mean?
Cell
82
What is the structure of an Astrocyte?
Star-shaped cell that has extensions, which wraps around capillaries in the brain
83
Where are Astrocytes found?
In the BRAIN
(and the spinal cord to some extent)
84
What are 2x components of the blood brain barrier?
1) Astrocyte extensions that wrap around capillaries in the brain
2) Tight junctions of the capillary endothelial cells
85
What are Tight Junctions?
The place where capillary endothelial cells join together in the brain
86
What is the purpose of the blood brain barrier?
To keep toxins and potentially damaging substances from moving out of the bloodstream and getting into the brain
87
What is a clinical example of a drug that can cross the blood brain barrier to treat a disease?
- Giving Levodopa (L-DOPA) to treat Parkinson's (treatment for this disease is Dopamine)
- L-DOPA crosses the blood brain barrier and converts into Dopamine
88
What 2x places are the Ependymal Cells the lining of?
1) Ventricles of the brain
2) Passageways between various ventricles
89
What do the Non-Ciliated Ependymal Cells form?
Choroid Plexus
90
What does the Choroid Plexus do?
To synthesize cerebrospinal fluid (CSF) from plasma of blood
91
What do Cilia on Ependymal Cells do?
Moves cerebrospinal fluid (CSF) from ventricle to ventricle
92
What is Ependymoma?
Cancer of the Ependymal Cells (rare brain tumor)
93
What is Astrocytoma?
Tumor from Astrocytes
(widespread brain tumor -- can be cancerous or benign)
94
What is another name for Astrocytoma?
Gliomas
95
What is a Microglial Cell?
Resident macrophages in the brain that phagocytose old, worn out neurons and anything potentially damaging to brain tissue
96
Microglial Cells are part of what other system? (think phagocytes)
Innate Immune System
97
What do Oligodendrocytes do?
Forms the myelin sheaths around axons in the central nervous system
98
All of the axons in the central nervous system are what?
Myelinated
99
A single oligodendrocyte can myelinate how many axons? (not a number)
Multiple
100
How much does each extension of an oligodendrocyte cover on an axon? (length)
1 millimeter
101
In between adjacent oligodendrocytes are what?
Nodes of Ranvier
102
What do Schwann Cells do?
Form the myelin sheaths in the peripheral nervous system
103
True or False: All axons in the PERIPHERAL nervous system are myelinated.
False
*NOT ALL AXONS in the peripheral nervous system are myelinated
104
True or False: All axons in the CENTRAL nervous system are myelinated.
True
105
In Unmyelinated Axons, where does the action potential have to occur?
At every single segment of the axon
106
In Myelinated Axons, where does the action potential have to occur?
Only at the Nodes of Ranvier
107
What does the root word "saltare" mean?
To leap, jump, or dance
108
What is Saltatory Conduction?
Describes how action potentials are generated along a myelinated axon
109
What important event occurs at threshold?
Voltage Gated Sodium Channels OPEN
110
Along a myelinated axon, what happens to sodium ions? (3x)
- Sodium ions move through the axoplasm to the next node
- Moves the next node from resting potential to threshold potential (++/-- --> --/++)
- This keeps happening at each Node of Ranvier
111
Is an action potential conducted along a MYELINATED Axon faster or slower than an Unmyelinated Axon?
Faster
112
Is an action potential conducted along a UNMYELINATED Axon faster or slower than an Myelinated Axon?
Slower
113
What are the 3x types of Nerve Fibers?
1) Type A
2) Type B
3) Type C
114
How many sub-types of Type A nerve fibers are there?
4
115
What are the 4x sub-types of Type A nerve fibers?
1) Alpha
2) Beta
3) Gamma
4) Delta
116
Type A nerve fibers are ______ _________
All Myelinated
117
Type C nerve fibers are _____ _________
All Unmyelinated
118
Type B nerve fibers are ____________
Myelinated
119
Of the 4x sub-types of Type A nerve fibers, which one has the largest diameter of myelinated fibers?
Alpha
120
Type B nerve fibers make up what type of fibers?
Autonomic Preganglionic Fibers
121
True or False: You will find Type C nerve fibers in the central nervous system
FALSE
*Type C nerve fibers are all UNMYELINATED, so you will NOT find them in the central nervous system (all axons in the CNS are myelinated)
122
What is the diameter range of Unmyelinated fibers in micrometers?
0.5 - 2.0 micrometers
123
What is the diameter range of Myelinated fibers in micrometers?
1.0 - 20.0 micrometers
124
True or False: The larger the diameter, the greater the speed of conduction
True
125
What is the conduction velocity (m/sec) of unmyelinated Type C nerve fibers?
0.5 - 2.0 m/sec
126
What is the conduction velocity (m/sec) of myelinated Type A nerve fibers?
6.0 - 120.0 m/sec
127
What is the conduction velocity (m/sec) of Type A-alpha nerve fibers?
60.0 - 120.0 m/sec
128
120.0 m/sec is longer than what?
A football field! (wowzas)
129
What are the 5x Sensory Functions of Type A-ALPHA nerve fibers?
1) Muscle spindles (primary ending)
2) Muscle tendon (Golgi tendon organ)
3) Hair receptors
4) Vibration (Pacinian corpuscle)
5) High discrimination touch (Meissner's expanded tips)
130
Where are the muscle spindles and Golgi tendon bodies?
Attached to the skeletal muscle fibers
131
What do muscle spindles and Golgi tendon bodies do? (3x)
- As the tension on the skeletal muscle fibers change (muscle contracts and relaxes), the muscle spindles and Golgi tendon bodies receive that input
- They send messages through the Type A-alpha nerve fibers to the CNS
- Sensory information developed is called Proprioception
132
What is Proprioception?
How the brain knows where the body is in time and space
133
Type A-alpha nerve fibers send ____________ information to the CNS
Proprioceptive
134
What is the motor function of Type A-alpha nerve fibers?
Skeletal Muscle (coordinated movements)
135
Why are hair receptors important with lower animals? (not humans)
Because they sense their environment with their whiskers and hair receptors
136
What are the 5x Sensory Functions of Type A-BETA nerve fibers?
1) Muscle spindle (secondary ending)
2) Hair receptors
3) Vibration (Pacinian corpuscle)
4) High discrimination touch (Meissner's expanded tips)
5) Deep pressure and touch
137
What are the 6x Sensory Functions of Type A-GAMMA nerve fibers?
1) Muscle spindle (secondary ending)
2) Hair receptors
3) High discrimination touch (Meissner's expanded tips)
4) Deep pressure and touch
5) Pricking pain
6) Cold
138
What are the 5x Sensory Functions of Type A-DELTA nerve fibers?
1) Hair receptors
2) Deep pressure and touch
3) Pricking pain
4) Cold
5) Warmth
139
What are the 5x Sensory Functions of Type C nerve fibers?
1) Crude touch and pressure
2) Tickle
3) Aching pain
4) Cold
5) Warmth
140
Type A-alpha nerve fibers primarily affect the ________ ________ and ________ _________ sensory functions. (think of the first 2x on the list)
1) Muscle spindle (primary ending)
2) Muscle tendon (Golgi tendon organ)
141
What is Highly Discrimination Touch?
When you close your eyes and you have an object in your hand that you can describe to someone
142
What type of pain does Type A-DELTA nerve fibers sends?
Prickling, sharp, acute pain
FAST
143
What type of damage can Type A-DELTA nerve fiber pain cause?
Tissue damage
144
What is a real life example of Type A-DELTA nerve fibers signaling pain to make you respond quickly?
When you put your hand on a hot stove, you pull your hand away quickly to prevent damage to your tissues
145
What is the difference between "deep pressure & touch" and "crude touch & pressure"?
- Crude touch & pressure that does NOT damage tissues (just soft touch)
- Deep pressure & touch DOES damage tissues
146
What type of pain does Type C unmyelinated nerve fibers cause?
Dull, aching, chronic, suffering pain
SLOW
147
Post-Ganglionic Autonomic Fibers are sent through what type of fibers?
Type C Unmyelinated Fibers
148
What is a Nerve?
A bundle of axons located in the Peripheral Nervous System (PNS) that provides a pathway for electrical impulses
149
What is a Tract and where is it located?
- Located in the CENTRAL Nervous System (CNS)
- Bundle of axons and their myelin sheaths
150
What is Gray Matter and where is it located (3x)?
- Located in the CENTRAL Nervous System (CNS)
- Towards the center part of the Spinal Cord
- Towards outer part of the Brain
- Cluster of nerve cell bodies and their associated dendrites (often where axons synapse on the dendrites)
151
What is White Matter and where is it located (3x)?
- Located in the CENTRAL Nervous System (CNS)
- Towards the outside of the Spinal Cord
- Towards the inside/center part of the Brain
- Composed of Tracts (bundles of axons and their myelin sheaths)
152
What is a Nucleus and where is it located?
- Located in the CENTRAL Nervous System (CNS)
- Cluster of gray matter positioned within the white matter
153
What is a Ganglion (2x) and where is it located?
- Located in the PERIPHERAL Nervous System (PNS)
- Cluster of nerve cell bodies and their dendrites
- Where axons synapse with dendrites
154
What are most nerves described as?
Mixed Nerves
155
Why are most nerves described as Mixed Nerves?
Because they transmit different types of information (motor, sensory, or autonomic information)
156
What is a Fascicle?
Bundles of axons that transmit information (each fascicle can transmit different types of information)
157
What 2x areas do Tracts connect each other to?
1) Spinal Cord to the Brain & vice versa
2) One part of the brain to other parts of the brain
158
What type of information is being sent through an Ascending Tract?
Sensory Information (up to the brain)
159
What 2x types of information is being sent through an Descending Tract?
1) Somatic Motor Impulses to skeletal muscle fibers
2) Autonomic Impulses to tissues innervated by the autonomic nervous system (ANS)
160
What are 2x types of Tracts?
Ascending & Descending Tracts
161
What is a Synapse (3x)?
- Where an axon terminates and releases a neurotransmitter
- Neurotransmitter diffuses across the synaptic cleft and binds to receptors on the post-synaptic membrane
- Brings about a response in the post-synaptic membrane
162
What 3x things could the Post-Synaptic Membrane be?
1) Dendrites
2) Target tissues or organs
3) Another axons
163
What is the term for an axon that synapses with another axon?
Axo-axonic Synapse
164
What is the pathway for a Chemical Synapse to the post synaptic membrane? (8x)
1) Action potential travels down the axon along the membrane
2) Action potential reaches the voltage gated calcium channels and opens them
3) Calcium diffuses with it's electrochemical gradient (out --> in)
4) When the axoplasm is flooded with calcium, the synaptic vesicles release their neurotransmitter contents into the synaptic cleft
5) Neurotransmitters diffuse across the synaptic cleft and bind to target receptors on the post-synaptic membrane
6) Sodium Ion Channel opens and sodium diffuses into the post-synaptic membrane
7) Resting Potential moves to Threshold
8) Action potential occurs along the post-synaptic membrane bi-directionally
165
What is the name of the process that is used as an example for a Chemical Synapse?
Calcium Dependent Exocytosis of Neurotransmitter
166
True or False: Most neurotransmitters are released into the synapse by the Sodium Dependent Exocytosis of Neurotransmitter
FALSE
*Released by the CALCIUM Dependent Exocytosis of Neurotransmitter
167
When an Inhibitory Neuron causes an action potential on a Presynaptic Neuron, what happens?
Inhibitory Neuron releases neurotransmitters that DECREASES the other neurotransmitters on a synaptic cleft
168
When an Excitatory Neuron causes an action potential on a Presynaptic Neuron, what happens?
Excitatory Neuron releases neurotransmitters that INCREASES the other neurotransmitters on a synaptic cleft
169
What are 2x examples of a removal of the neurotransmitter from the synapse?
1) Acetylcholine
2) Norepinephrine
170
What is the pathway of Acetylcholine through a synapse? (11x)
1) A vesicle is full of Acetylcholine
2) Acetylcholine is released into the synaptic cleft by Calcium Dependent Exocytosis of Neurotransmitter
3) Acetylcholine diffuses across the cleft
4) Binds with Acetylcholine receptors on the post-synaptic membrane
5) Response occurs at the post-synaptic membrane
6) Acetylcholine detaches from the receptor and is enzymatically broken down by Acetylcholinesterase
7) Splits into Acetic Acid (acetate) and Choline
8) Acetic Acid (acetate) moves out of the synaptic cleft, into the blood, to the liver to be metabolized
9) Choline is taken back up into the pre-synaptic terminal
10) Choline binds with Acetyl portion of Acetyl CoA to form more Acetylcholine
11) Cycle restarts!
171
What are Acetylcholine receptors called?
Cholinergic Receptors
172
What 2x clinical examples take advantage of Acetylcholine continuing to be present in the synaptic cleft?
- Give Neostigmine (acetylcholinesterase inhibitor) to reverse paralysis and regain muscle function
- Give Pyridostigmine to patients with Myasthenia Gravis (autoimmune disease that destroys acetylcholine receptors at muscle fibers, making the patient weak)
173
What is the pathway of Norepinephrine through a synapse? (***)
1) A vesicle is full of Norepinephrine
2) Norepinephrine is released into the synaptic cleft by Calcium Dependent Exocytosis of Neurotransmitter
3) Norepinephrine diffuses across the cleft
4) Binds with Norepinephrine receptors on the post-synaptic membrane
5) Response occurs at the post-synaptic membrane
6) Norepinephrine is released from the receptor
7) Norepinephrine is taken back up into the pre-synaptic membrane by a Re-Uptake Pump
8) Most of the Norepinephrine is repackaged to restart the cycle
9) Not packaged Norepinephrine is broken down by an enzyme called Monoamine Oxidase (MAO)
10) Inactive metabolites are created
174
What are the receptors that Norepinephrine binds to?
Adrenergic Receptors
175
What does MAO stand for?
Monoamine Oxidase
176
What happens when you give a Monoamine Oxidase Inhibitor (MAOI)?
- Norepinephrine is not broken down by MAO to create inactive metabolites
- Increase in Norepinephrine to be repackaged and released into the synaptic cleft
177
What do you use MAOI's for?
Depression
*Increased Norepinephrine levels makes you feel good (i.e. runners high)
178
What is a bad side effect of taking MAOI's?
Increase in Norepinephrine causes cardiovascular implications (nobody really takes MAOI's anymore because of this)
179
What are Excitatory Post-Synaptic Membrane Potentials (EPSP)?
Impulses or neurotransmitters that bind to the post-synaptic membrane causes an EXCITATORY response of the post-synaptic membrane
180
What are Inhibitory Post-Synaptic Membrane Potentials (IPSP)?
Impulses or neurotransmitters that bind to the post-synaptic membrane causes an INHIBITORY response of the post-synaptic membrane
181
Any ligand that binds to its receptor on the post-synaptic membrane and brings it CLOSER to threshold is classified as what?
Excitatory Post-Synaptic Potential
182
Any ligand that binds to its receptor on the post-synaptic membrane and brings it AWAY from threshold is classified as what?
Inhibitory Post-Synaptic Potential
183
An Excitatory Post-Synaptic Potential causes depolarization or hyperpolarization?
Depolarization
184
An Inhibitory Post-Synaptic Potential causes depolarization or hyperpolarization?
Hyperpolarization
185
What is the pathway of an Excitatory Post-Synaptic Membrane Potentials (EPSP)? (7x)
1) Synaptic vesicle is full of Norepinephrine
2) Norepinephrine is released from the terminal button by Calcium Dependent Exocytosis
3) Norepinephrine binds to post-synaptic membrane receptors (ligand gated sodium channels)
4) Sodium diffuses with its electrochemical gradient from the synapse to the cell (out --> in)
5) If enough sodium diffuses into the cell, resting potential moves up to threshold (excitatory)
6) Threshold causes opening of voltage gated sodium channels
7) Generation of an action potential along the entire post-synaptic membrane
186
What is the pathway of an Inhibitory Post-Synaptic Membrane Potentials (IPSP)? (8x)
1) Synaptic vesicle is full of Norepinephrine
2) Norepinephrine is released from the terminal button by Calcium Dependent Exocytosis
3) Norepinephrine binds to post-synaptic membrane receptors (ligand gated chloride channels and potassium channels)
4) Chloride and Potassium both move with their electrochemical gradients
5) Chloride moves from the synapse to the cell (out --> in) [negative charges in]
6) Potassium moves from the cell to the synapse (in --> out) [positive charges out]
7) Negative charge of the cell moves resting potential away from threshold (inhibitory)
8) Inhibition of action potentials from the post-synaptic membrane
187
What 2x type of drugs are used to open chloride channels and cause hyperpolarization of post-synaptic membranes?
- Propofol
- Benzodiazepines (i.e. Versed)
188
What are the 2x types of Summation?
1) Spatial
2) Temporal
189
What is Spatial Summation?
2 or more impulses occurring on different dendritic membranes at the same time
(different membranes & same time)
190
What is Temporal Summation?
Impulses arriving over time at the same dendritic membrane
(different impulses & same membrane)
191
What is the pathway of Spatial Summation? (5x)
1) Action Potential 1 occurs on one dendrite
2) Action Potential 2 occurs on the opposite side on another dendrite
3) Both action potentials move down to the axon hillock
4) At the axon hillock, the 2x action potentials are combined/summed up to reach threshold
5) Generation of an action potential down the length of the axon
192
What is the pathway of Temporal Summation? (5x)
1) Multiple action potentials move down one dendrite together and arrive at different times
2) Action potentials move down to the axon hillock
3) Generation of an action potential down the length of the axon
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If impulses arrive at the axon hillock very slowly and the magnitude of those impulses are low, what will happen at the axon hillock?
Nothing! Threshold is not reached
The 1st impulse fizzled out by the time the 2nd arrives
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What will happen at the axon hillock with the following combination of impulses?
Excitatory
Inhibitory
Excitatory
Inhibitory
Excitatory (with temporal summation)
Excitatory action potential will occur at the axon hillock
(The first 4x combos cancel each other out and you're left with Excitatory at the end)
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If you have 3x Excitatory and 3x Inhibitory impulses all of the same magnitude, what happens at the axon hillock?
Nothing! They all cancel each other out
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Whatever happens at the axon hillock is the _____ ______ of all the impulses arriving.
Net Sum
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What is the Reflex Arc? (3x)
- The basic functional component of the nervous system
- Sensory Input
- Motor or Autonomic Output
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What is the basic STRUCTURAL component of the nervous system?
Neuron
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What is the basic FUNCTIONAL component of the nervous system?
Reflex Arc
200
What is the pathway of a Reflex Arc from the sensory receptors of the skin to the skeletal muscle fibers? (7x)
1) Sensory receptors in the skin receive stimuli
2) Generates an action potential
3) Action potential conducted towards the Central Nervous System (CNS) -- Afferent Pathway
4) Action potential moves through a Unipolar Neuron to the Spinal Cord
5) Action potential in the Spinal Cord synapses with the Efferent Somatic Motor Pathway
6) Impulse is sent to the skeletal muscle fiber
7) Contraction or moving away from the painful stimuli occurs in the skeletal muscle fiber occurs
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What does Converge mean?
To come together
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What does Diverge mean?
To separate
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What is an example of a Convergent Pathway?
Two different neurons that both of the axons synapse with the dendrites of 1x neuron
#1 + #2 ---> #3
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What is an example of a Divergent Pathway?
- One neuron & One axon has divided into collaterals
- Collateral synapsing onto 2x different neurons
#1
#3 < #2
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What is a Uni-Directional Action Potential? (2x)
- An action potential generated along the axon
- From the axon hillock down to the terminal portion of the axon
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Why doesn't the action potential go back up to the nerve cell body?
Very few voltage gated sodium channels
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Why are Collaterals important in divergent pathways?
Impulse can be transmitted to multiple areas
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What are the 3x important aspects of a Divergent Pathway sending 1x impulse to the skeletal muscle and another 1x impulse to the brain?
The Brain can:
1) Interpret the sensation
2) Localize it to a certain area of the body
3) Formulate an appropriate response
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What happens to an impulse from the brain if a person likes to walk on hot coals (likes pain)?
The brain can send impulses and information down to the motor pathway to overcome the pain
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What is the Oscillating Pathway/Circuit?
Characterized by periods of activity and periods of fatigue
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What is an example of a Feedback Oscillating Pathway/Circuit?
1) Impulse moves from left (input) to right (output)
2) Impulse meets a collateral point in the Output section
3) Collateral point synapses back to the dendrites of its own nerve cell body
4) Feedback is provided to the nerve cell body
5) Response at the axon hillock is the net sum of Input Feedback and Output/Collateral Feedback
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What 2x types of impulses can occur in an Oscillating Pathway/Circuit?
1) Excitatory (+)
2) Inhibitory (-)
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Name 2x examples of Oscillating Pathways
1) Respiratory Cycle
(when active, person breathes in; when fatigue, person breathes out)
2) Sleep Wake Cycle
(when active, person is alert; when fatigue, person is sleepy)
214
What is Nerve Fiber Repair after an injury? (3x)
1) Axon is severed
2) If the axon STAYS WITHIN reasonable proximity to the other half, there can be regeneration of the axon
3) Pathway is re-established overtime and the muscle returns to its normal size
215
What is Nerve Fiber Non-Repair after an injury? (3x)
1) Axon is severed
2) If the axon is FAR AWAY from the other half, the muscle atrophies and there is no regeneration
3) Muscle remains atrophied
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What happens to an axon that was innervating a muscle that is now completed severed?
The muscle atrophies (de-enervated)
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How fast does an axon regenerate on average?
1mm every 2-3 days
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True or False: If the nerve cell body (neuron soma) is injured, then that nerve is completely dead and never regenerates
True
