Peripheral Nerve Anatomy and Physiology - Travis' Lecture Flashcards
1
Q
3 divisions of CNS
A
Spinal Cord
Brain Stem
Brain
2
Q
Autonomic nuclei of SNS and PSNS innervates what 3 things.
A
Cardiac muscle
Smooth muscle
Organs (not under out control)
3
Q
Peripheral Nervous System (PNS) includes all the neural tissue outside the ______.
A
CNS
4
Q
______ are sensory structures that detect changes in the internal or external environment.
A
Receptors
5
Q
The _______ ________ of the PNS brings information to the CNS from receptors in peripheral tissue and organs.
A
Sensory division
6
Q
Information processing includes the ______ and _______ of information in the CNS
A
Integration Distribution
7
Q
The ______ ________ of the PNS carries motor commands from the CNS to peripheral tissues and systems.
A
Motor division
8
Q
Somatic NS controls _____ muscle contractions
A
Skeletal
9
Q
(Per Image from slides). ANS provides autonomic regulation of what 4 components? Travis only listed 3.
A
Smooth muscle Cardiac muscle Glands Adipose
10
Q
______ are target organs who activities change in response to neuronal commands.
A
Effectors
11
Q
Somatic NS includes both receiving ____information and relaying _____ commands to muscles.
A
Sensory Motor
12
Q
Cell body of a neuron.
A
Soma
13
Q
______ receive information and transmit to the cell body. (part of neuron)
A
Dendrites
14
Q
“Functional unit” of a neuron. Carries response of a neuron in the form of a propagated action potential.
A
Axon
15
Q
Supports and insulate axon Supply metabolites and distribute neurotransmitters
A
Schwann
16
Q
Segments of neuron that do not contain myelin? Responsible for conduction propagation thru _____ channels.
A
Nodes of Ranvier Sodium
17
Q
Why are nodes of ranvier thought to be the site of action of local anesthetics.
A
No myelin sheet means limited diffusion barriers for locals to get into the axon.
18
Q
Nodes of Ranvier are responsible for _____ conduction.
A
Saltatory
19
Q
(neuron component) Releases electric signal from presynaptic cell. Synapse with effector cell or another nerve cell.
A
Axon terminal
20
Q
Space between axon terminal and dendrite (pre and post-synaptic area).
A
Synaptic cleft.
21
Q
(PNS components) Surrounds perineurium Composed of connective tissue and holds fascicles together.
A
Epineurium
22
Q
(PNS components) Connects tissue which surrounds each nerve fiber fascicle.
A
Perineurium
23
Q
(PNS components) Surrounds and embeds axon within the fasciculi.
A
Endoneurium
24
Q
A bundle of axons together
A
Fasciculi
25
Epineurium, perineurium and endoneurium are all types of _______ tissue that function as _____ in which local anesthetics must diffuse through in order to get to specific axons of neurons.
Connective Barriers
26
Which is a myelinated vs unmyelinated and label the parts.
a. myelinated
b. unmyelinated (all purple is single schwan cell)
A. Node of Ranvier
B. Axon
C. Myelin Sheeth
D. Axon
27
(Unmyelinated nerve) A single _____ cell covers several axons in a bundle.
Schwann
28
(Large Nerves) The schwann cells cover a single axon and form several layers of the liquid \_\_\_\_\_\_.
Myelin
29
Compared to unmyelinated nerves, myelinated nerves are...
Larger
Conduct impulses faster
More difficult to block with locals
30
Myelinated nerves work by ______ conduction.
Saltatory
31
Label
1. Node of Ranvier
2. Nucleus of Schwann cell
3. Myelin sheath
4. Plasma membrane of axon
5. Neurofibrils, microfilaments, and microtubules
6. Neurofibriles, microfilaments, and microtubules
7. Plasma membrane of axon
8. Axon
9. Myelin Sheath
10. Neurilemma
11. Nucleus of Schwann cell
12. Neurilemma (Sheath of Schwan cell)
32
The nerve membranes of the postsynaptic neurons have _____ which bind the neurotransmitters released from the _Presyn or postsyn_ terminals.
This is ______ mediated and is different from the electrical transmission down the axon.
receptors
presynaptic
chemically
33
Label
1. end of axon
2. synaptic knob
3. synaptic cleft
4. dendrite
5. mitochondria
6. synaptic vesicle containing neurotransmitter substances
7. pre-synaptic membrane
8. post-synaptic membrane
9. protein receptor
10. ion channel
34
Label
a. Propogation
b. Depolarized
c. Resting
d. Resting
35
Label
1. Refractory
2. Depolarized
3. Resting
36
Review
37
Review
38
4 types of A Fibers
1. A alpha- motor and sensory
2. A beta- motor and sensory
3. A gamma- motor
4. A delta- sensory
39
Which type of A Fiber does this describe?
## Footnote
Largest diameter, (15-20 µm) most heavily myelinated FAST
Somatic motor function, skeletal muscles, joints, muscle length/force, proprioception
A alpha- motor and sensory
40
Which type of A Fiber does this describe?
## Footnote
Small (1-4 µm) : pain and cold temperature sensation
A delta- sensory
41
Which type of A Fiber does this describe?
## Footnote
(4-15 µm) almost as fast as a alpha
Touch, pressure, proprioception
A beta- motor and sensory
42
Which type of A Fiber does this describe?
## Footnote
( 3-6 µm) Innervate muscle spindle fibers, skeletal muscle tone, joints
A gamma- motor
43
Which type of A Fiber does this describe?
## Footnote
(4-15 µm) almost as fast as a alpha
Touch, pressure, proprioception
Also skeletal muscles joints
A beta- motor and sensory
44
Which type of Fiber does this describe?
## Footnote
Same size as delta
Slower conduction (less myelination that A)
Make up the preganglionic autonomic nerves
"B" Fiber
45
Which type of Fiber does this describe?
## Footnote
**Smallest** of all fibers (**0.3-1 µm**)
**Unmyelinated** and **slowest**
**Postganglionic sympathetic** nerves and **afferent sensory** nerves
Autonomic functions, **pain, warm and cold temperature, touch**
C Fibers
46
(Differential Block)
In most types of nerve blocks loss of function follows a similar pattern in this order.
1. Autonomic function
2. Pain
3. Touch and temperature
4. Motor function
5. proprioception
47
Differential block may be influenced by the rate of ______ of the local across barriers and \_\_\_\_\_\_\_the of nerve fiber types with the peripheral nerve
Specific anatomy factors of specific axons also play into differential blockade. Whether if the nerve is myelinated or not and its location in the actual peripheral nerve.
Diffusion
Location
48
**Nociception** or pain perception takes place when a signal is carried to the brain via _____ \_\_\_\_\_\_\_ nerve fibers.
Sensory afferent
49
A delta and C fibers have their cell bodies in the _______ \_\_\_\_\_\_ \_\_\_\_\_\_\_\_\_\_
synapse with second order neurons in dorsal horn and carry impulse to different parts of the spinal cord and the brain.
Dorsal root ganglia
50
REMEMBER: A delta fibers are responsible for ___________ pain.
Duration of pain = duration of \_\_\_\_\_\_\_.
Fast, sharp
Stimulus
51
REMEMBER: C fibers are responsible for _____________ pain
Duration of pain exceeds the duration of stimulus
Slow, chronic
52
What is associated with this ascending pathway?
(I think this was an FYI in lecture at this point in time)
**Lateral Spinothalamic Tract**
Transfer of pain and temperture
53
What is associated with this ascending pathway?
(I think this was an FYI in lecture at this point in time)
**Crude touch and pressure**
Anterior Spinothalamic Tract
54
What is associated with this ascending pathway?
(I think this was an FYI in lecture at this point in time)
**Several Spino-cerebellar Tracts**
Unconscious sensation and proprioception
55
What is associated with this ascending pathway?
(I think this was an FYI in lecture at this point in time)
**Dorsolateral** **Column Medial** **Lemniscal Tract**
Proprioception
56
FYI
Try to label if you just want to!
FYI
57
Pain activation: What is stimulated
**Free nerve ending** stimulated within different muscles, tissues, glands via pain stimulus
58
Pain pathway transmission occurs by what 2 fibers?
A-Delta
C-Fibers
59
In A-delta and C-fiber pain transmission, cell bodies in dorsal root ganlia carry what 2 main signals?
(example: touch, pressure...)
Pain
Temperture
60
Pain fibers A-delta and C-fibers enter, ascend or descend in the tract of \_\_\_\_\_, and then cross over in the spinal cord to the lateral spinothalamic tract to the brain.
Lissauer
61
When **fibers cross over** in the spinal cord, what is the word that describes this?
**Decusate**
62
**A-delta:** first order neurons to connect at which Rexed Lamina?
**A-delta:** first order neurons to connect at **Rexed Lamina** **1,5.**
63
**A-delta fibers:** Release _______ to bind to ___ and ____ receptors on postsynaptic membrane.
Hint: Potentially how Ketamine exerts its pain controlling mechanism. Does not allow binding of this receptors to send pain receptors to the brain.
Release **glutamate** to bind to **AMPA** and **NMDA** receptors on postsynaptic membrane
64
**C fibers**: terminate primarily in rexed lamina __ and \_\_\_, and interneurons transmit to lamina \_\_.
C fibers: terminate primarily in rexed lamina **2 and 3** and interneurons transmit to lamina **5**
65
C-fibers: Release _____ to bind to NK-1 (neurokinin-1) receptors on ______ membrane
C-fibers: Release **substance P** to bind to NK-1 (neurokinin-1) receptors on **postsynaptic** membrane
66
Second order neurons cross from Rexed Lamina (and other lamina in the dorsal horn) to & ascend via _________ \_\_\_\_\_ spinothalamic tract.
Second order neurons cross from Rexed Lamina (and other lamina in the dorsal horn) to & ascend via **contralateral lateral** spinothalamic tract
67
Review this
Review this
68
What is released into these interneurons from C-fibers? How pain transmission is achieved in spinal cord.
**Substance P**
69
\_\_\_\_\_\_\_\_\_-releasing neurons also synapse on these interneurons to reduce pain impulses. This neuron decreases the release of what _________ which reduces the action potential and decreases pain transmission.
hint: Know as **Descending** pathway important in modulation of pain signals.
**_Enkephalin_-releasing neurons** also synapse on these interneurons to reduce pain impulses. This neuron decreases the release of **_Substance P_** which reduces the action potential and decreases pain transmission.
hint: Know as **Descending** pathway important in modulation of pain signals.
How spinal opioids work.
70
**How spinal opioids work.** Diffuse into _____ \_\_\_\_\_\_ where they are able to bind to the ______ receptors and block ______ release. Primarily mediated by mu-2 (primarily spinal pain control). mu-1 was mostly superspinal
How spinal opioids work. Diffuse into **substantia** **gelatinosa** where they are able to bind to the **opioid** receptors and block **substance P** release. Primarily mediated by mu-2 (primarily the spinal pain control). mu-1 mostly superspinal
71
(Topic: membrane potential in the neuron)
\_\_\_\_\_\_\_ ________ exist in nearly all cell membranes and refer to the **difference in charge between** the **outside** and **inside** of the cell
**Electrical potentials** exist in nearly all cell membranes and refer to the difference in charge between the outside and inside of the cell
72
(Topic: membrane potential in the neuron)
In the neuron, ________ leak channels located in the ______ lipid bilayer (cell membrane of the neuron) allow \_\_\_\_\_to leak out down a concentration gradient into extracellular space leaving electrically charged proteins behind within the neuron.
(Topic: membrane potential in the neuron)
In the neuron, **potassium** leak channels located in the **axolemma** lipid bilayer (cell membrane of the neuron) allow **K+** to leak out down a concentration gradient into extracellular space leaving electrically charged proteins behind within the neuron.
This leaves the **inside of the cell relatively negative** compared with the outside creating the membrane potential
NOTE: The **resting membrane potential** in excitable tissues is **determined mostly by K+**
73
All other ions are impermeable in the resting neuron because _____ and ____ channels are closed
All other ions are impermeable in the resting neuron because **Na+ and Ca++** channels are closed
74
Describe what is happening in the diagram.
1. Neuron resting at -70 mV
2. Impluse transmitted down axon
3. Sodium channels open
4. Sodium rushes into cell
5. Threshold potential reached = -50 mV
6. Na channels open and Na continues to rush in
7. -\> inside neuron briefly POSITIVE + 30 mV - Depolarized
8. Inactivation gate closes Na channel
9. Refractory state
75
Membrane potential maintained by movement of ___ in and out of the nerve cell
Membrane potential maintained by movement of **ions** in and out of the nerve cell
76
The **Na+/K+ pump** actively transports Na+ out and K+ in to the cell, & also _______ “leak” channels constantly send K+ out of the cell. Requires _____ to push ions againsts their concentration gradiet.
1. ___ Na out and ___ K in
2. RMP \_\_\_\_\_\_\_
3. This ATPase pump requires energy to pump against the concentration gradient.
The **Na+/K+ pump** actively transports Na+ out and K+ in to the cell, & also **potassium** “leak” channels constantly send K+ out of the cell. .
1. **3 Na out** and **2** **K in**
2. RMP **-70**
3. This ATPase pump requires energy to pump against the concentration gradient.
77
Na+/K+ channel requires _____ to push ions against their concentration gradient.
Requires energy to push ions againsts their concentration gradient
78
Membrane Potential
During initial depolarization __ is moving ____ a concentration into neuron; potassium is _____ the cell. During repolarization: it has to pump Na back out of neuron and resequester the K back into neuron to reestablish _____ membrane potential thru the _____ Channel.
Membrane Potential
During initial depolarization **Na** is moving **down** a concentration into neuron; potassium is **leaving** the cell. During repolarization: it has to pump Na back out of neuron and resequester the K back into neuron to reestablish **negative** membrane potential thru the **Na/K** Channel.
79
Neuronal Action Potential
## Footnote
Neurons have voltage-gated \_\_\_\_and ___ channels that open in response to a stimulus and produce \_\_\_\_\_\_\_\_\_\_\_\_.
Neuronal Action Potential
## Footnote
Neurons have voltage-gated **Na+** and **K+** channels that open in response to a stimulus and produce **depolarization**.
80
Neuronal Action Potential
## Footnote
Once a stimulus has occurred, (i.e. touching a hot stove) conductance to Na+ and K+ increases. If the conductance is enough to reach Threshold which is approximately \_\_\_\_mV then depolarization will occur.
Neuronal Action Potential
## Footnote
Once a stimulus has occurred, (i.e. touching a hot stove) conductance to Na+ and K+ increases. If the conductance is enough to reach Threshold which is approximately **-50mV** then depolarization will occur.
81
\_\_\_\_\_\_\_\_\_\_\_\_ occurs when the voltage-gated Na+ channel snaps open and Na+ flows inward.
**Depolarization** occurs when the voltage-gated Na+ channel snaps open and Na+ flows inward.
82
Depolarization
## Footnote
Na flows inward: For a very brief time the inside of the membrane becomes ______ and outside \_\_\_\_\_\_\_\_. (membrane potential \_\_\_mV)
Depolarization
## Footnote
Na flows inward: For a very brief time the inside of the membrane becomes **positive** and outside **negative**. (membrane potential **+30mV**)
83
\_\_\_\_\_\_\_\_\_\_ State
1. The **Na+ channel** now **closes** in a different configuration (the _______ state.)
2. When the Na+ channels begin to change their configuration to\_\_\_\_\_\_\_\_, voltage-gated ___ channels open and ___ begins to flow out of the cell.
3. When the voltage-gated Na+ channels are in the this state it is referred to as the ______ \_\_\_\_\_\_\_\_ \_\_\_\_\_\_\_\_\_\_.
**Inactivated State**
1. The Na+ channel now **closes** in a different configuration (the **inactivated state**.)
2. When the Na+ channels begin to change their configuration to **inactivated**, voltage-gated **K+** channels open and **K+** begins to flow out of the cell.
3. When the voltage-gated Na+ channels are in the inactivated state it is referred to as the **Absolute Refractory Period**
84
In which state of membrane activity, can local anesthetics bind to Na channels?
Local anesthetics bind to Na channels in the **inactivated/open** channel state.
Cannot bind them in the closed state!
85
Phase of return to -70mV membrane potential.
A return to -70mV membrane potential is called **Repolarization.**
86
After repolarization has occurred the Na+/K+ pump will extrude the ____ that entered and recapture the _____ that was lost and restore the ion balance.
After repolarization has occurred the Na+/K+ pump will extrude the **Na+** that entered and recapture the **K+** that was lost and restore the ion balance.
87
Review
Review
88
On any given axon the Na+ channels can be found in **three states:**
On any given axon the Na+ channels can be found in three states:
1. **Resting-closed**
2. **Activated-open**
3. **Inactivated-closed**
89
Local anesthetics must bind what channel in the inactivated or open state.
**Local anesthetics must bind** the **Na+** channel in the **inactivated or open state.**
## Footnote
**Cannot bind in closed state.**
90
Conduction block with local anesthetics is dependent on what?
conduction block with local anesthetics is **frequency** dependent
91
Describe frequency dependence of conduction block.
**Frequency dependence** of conduction block.
The more often the nerve is firing the more opportunity the local anesthetic has to “catch” the Na+ channel in the open or inactivated state.
92
What terms/phrase describes this process?
The more time you stimulate that nerve the more opportunities that local will have to bind to the inactivated state because more time is spent in these states.
**Use-dependent Block**
or
**Phasic Block**
