Nervous System (1/4) Flashcards
Spinal Nerves
Thirty one pair of mixed nerves arise from the spinal cord and supply all parts of the body except the head
They are named according to their point of ______
___ Cervical (______)
___ Thoracic (______)
___ Lumbar (______)
___ Sacral (______)
___ Coccygeal (___)
Issue
8; C1-C8
12; T1-T12
5; L1-L5
5; S1-S5
1; C0
Nerve Plexuses
All ventral rami except T2-T12 form interlacing nerve networks called ______
Each muscle receives a nerve supply from more than one ______ ______
Damage to one spinal segment ______ completely _______ a muscle
Plexuses
Spinal Nerve
Cannot, Paralyze
Brachial Plexus
Formed by ______ and ____ (C4 and T2 may also contribute)
Brachial plexus gives rise to the nerves that innervate the _____ ______
C5-C8, T1
Upper Limb
Brachial Plexus
There are four major branches of this plexus
______ - Five ventral rami (______)
______ - Upper, middle, and lower, which form divisions
______ - Anterior and posterior serve the front and back of the limb
______ - Lateral, medical, and posterior fiber bundles
______
Roots; C5-T1
Trunks
Divisions
Cords
Branches
Brachial Nerves: Plexus
______ ______: second most common postop peripheral neuropathy
______: innervates the deltoid and teres minor
_______: sends fibers to coracobrachialis, biceps brachii, and brachialis (______ at elbow)
______: branches to most of the flexor muscles of forearm and opponens pollicis (______ of forearm, ______ of wrist, ______ of thumb, ______ of lateral three fingers)
Brachial Plexus
Axillary
Musculocutaneous; Flexion
Median, Prontation, Flexion, Opposition, Flexion
Brachial Nerves: Plexus
______: supplies the flexor carpi ulnaris and half of the flexor digitorum profundus (_____ of wrist, ______ of fingers, ______ of medial two fingers)
______: supplies ALL extensors of arm and forearm muscles (______ at elbow, ______ of forearm, ______ of wrist and fingers)
________ ______: can be blocked to reduce pain from tourniquet inflation during IV regional neural anesthesia
Ulnar, Flexion, Adduction, Flexion
Radial, Extension, Supination, Extension
Intercostobrachial Nerve
Neuron
Basic ______ ______ of CNS; around _____ billions of neurons
Responsible for _______ and _______ of nerve impulses
________ cells: produce myelin sheath which wraps around axon, providing insulation
_____ of ______: gaps in myelin sheath
_________ are synthesized in the _____ _____ and transported to synaptic knobs
Building Block, 100
Integration, Transmission
Schwann
Node of Ranvier
Neurotransmitters
Neuron
Neurons follow an ______ or _____ law in regard to action potentials
_______ _______: node to node jumping of depolarization
______ results slow or blocked conduction, such as seen with ______ ______ (nerve impulse conduction disorder)
All, Nothing
Saltatory Conduction
Demyelination, Multiple Sclerosis
Neurons
_______ neuron: short axon process arising from one side of the cell body, and a short dendritic process arising from the opposite site. Ex: ______ ______ neurons, including those found in the ____, _____, and ____
_______ neuron: has single large extension from its cell body. They are found in lower ______, but never in ______
________ neuron: present in _____ ______ ganglia
Bipolar, Special senses
Eyes, Ears, Nose
Unipolar, Invertebrae, Humans
Pseudounipolar, Dorsal Root
Neurons
_______ neuron: comprised of one axon and multiple dendritic processes; they are the most common type of neuron in the ______ and ______ ______
Other types of neurons include _______, ______, and ________
Multipolar
Brain, Spinal Cord
Sensory, Motor, Interneuron
Depolarization
Makes the cell membrane potential less ______ due to movement of positively charged ____ ions into the cell ( increased _______)
Negative, Na+
Excitability
Repolarization
The change that occurs after depolarization that returns membrane potential back to its ______ ______. Repolarization results from the movement of positively charged ____ ions out of the cells
Resting Potential
K+
Hyperpolarization
Makes the membrane potential more _______ due to movement of negatively charged ____ ions into the cell (reduced ______)
Negative, Cl, Excitability
Inward Current
The flow of _______ charge into the cell. Inward current ______ the membrane potential
Positive, Depolarizes
Outward Current
The flow of ______ charge out of the cell. Outward current ______ the membrane potential
Positive, Hyperpolarizes
Action Potential
Property of _____ cells (nerve and muscle) tha consists of a rapid _______ followed by ______ of the membrane potential
Excitable, Depolarization
Repolarization
Threshold
The membrane potential at which an action potential is _______
At threshold potential, net ______ current becomes larger than net ______ current
The resulting depolarization becomes self sustaining and gives rise to ______ of action potential
If net inward current is less than net outward current, no _____ _____ will occur
Inevitable
Inward, Outward
Upstroke
Action Potential
Resting Membrane Potential
Measured potential difference across the cell membrane (____ to ____ mV)
At rest, the nerve membrane is far more ______ to K+ than to ____
Leaky ___ channels are responsible for resting membrane potential
The ______ pump maintains resting membrane potential
-70 to -90 mV
Permeable, Na+
K+
Na+/K+
Action Potential
Action potential, or “______ ______” is a property of excitable cells that consists of a rapid depolarization (interior becomes less _______) followed by repolarization of membrane potential
Upstoke: Inward ___ movement; _______ blocks these voltage sensitive Na+ channels
Downstroke: Outward ___ movement; Outward flow of K+ _______ the membrane potential
Both ions flow by ______ _______
Nerve Impulse
Negative
Na+, Lidocaine
K+, Hyperpolarizes
Simple Diffusion
Absolute Refractory Period
Period during which another actional potential cannot be elicited, no matter how _____ the stimulus. This is due to closure of ______ gates of ____
Large, Inactivation, Na+
Relative Refractory Period
Period during which an action potential can be elicited only if a ______ than usual stimulus is provided
Refractory period protects the cell from _____ ______, allowing a recovery period between the action potentials
Larger
Over-Excitation
Signal Transmission (Myelination)
______ cells surround the nerve axon, forming a _____ ______
Sheath is interrupted every ____ mm
______ of _______ (Na+/K+ channels). Action potential can only occur at the _____
______ nerve fibers travel ______
Schwann, Myelin Sheath
1-3 mm
Node of Ranvier
Myelinated, Faster
Multiple Sclerosis
Disease where _____ _____ is destroyed secondary to an _______ reaction
MS is an immune mediated inflammatory selective ______ of CNS
High incidence at higher _____; more common in women and those living in the _____ _____
1:1000 in US have this disease, female to male ratio is _____; with whites of ______ descent having highest incidence
Myelin sheath, Autoimmune
Demyelination
Latitudes, North Pole
2:1, European
Multiple Sclerosis
Multiple foci of CNS demyelination of _____ _____
Characterized by ______ and ______
Signs and symptoms might include?
Diagnosed by?
Treatment: IV ______ to relieve acute symptoms. MS is _____ now
White Matter
Remissions and Relapses
Numbness, Transient sensory deficit, Pain, Fatigue, Optic Neuritis, Hemiparesis, Bladder & Bowel Incontinence, Loss of memory, Personality changes
MRI (Visible Plaques)
Steroids, Curable
Multiple Sclerosis (Anesthetic Conditions)
Avoid ______ surgery during relapse
Any ______ may worsen the symptoms
______ ______ blocks with caution
Avoid ______ in paresis, will lead to ________
Avoid ______ in body temperature
Elective
Technique
Peripheral Nerve
Succinylcholine, Hyperkalemia
Increase
Local Anesthetics
Procaine, Cocaine, Lidocaine, Bupivacaine
Blocks voltage sensitive ____ channels and inhibits conduction of _____ from periphery to CNS
Local anesthetics slow the rate of ______ of the nerve action potential such that the ______ potential is not reached
As a result, an action potential cannot be ______ in the presence of local anesthetic, resulting in conduction _______
Na+, Impulses
Depolarization, Threshold
Propagated, Blockade
The Motoneuron - Vesicle Formation
- ) ______ vesicles: formed from budding Golgi and are transported to the terminal by ______ “streaming”
- ) Acetylcholine is formed in the ______ and is transported into the vesicles
- ) Acetylcholine filled vesicles occasionally fuse with the post-synaptic membrane and release their contents, causing ____-_____ potentials in the post-synaptic membrane
Synaptic, Axoplasm
Cytoplasm
End-Plate
The Motoneuron - Acetylcholine Release
- ) AP begins in the _____ _____ of the spinal cord
- ) Local _______ opens voltage gated ___ channels
- ) An increase in the ______ ___ triggers the fusion of synaptic vesicles with the pre-synaptic membrane and release of _______ (exocytosis)
Ventral Horn
Depolarization, Ca++
Cytosolic Ca++, Acetylcholine (Ach)
Neuromuscular Junction
The NJ is the synapse between axons of ______ and ______ muscles
The neurotransmitter released from presynaptic terminal is ________, and the postsynaptic membrane is the ______ receptor
Motoneurons, Skeletal
Acetylcholine, Nicotinic
Events at Neuromuscular Junction
- Synethesis and storage of Ach in the ______ terminal
- Acetyl CoA + Choline = _____ _____
- Catalyzed by ______ ________
Ach is stored in ______ ______
- Depolarization of the pre-synaptic teerminal opens ___ channels
- ____ uptake causes release of Ach into ______ ______
Pre-synaptic
Acetyl Choline
Choline Acetyltransferase
Synaptic Vesicles
Ca++
Ca++, Synaptic Cleft
Events at Neuromuscular Junction
- Diffusion of Ach to _______ membrane (muscle end plate) and binding Ach to ______ receptor
- The nicotinic receptor is also a ____ and ____ ion channel
- Channels open up and increase ____ and ____ conductance - Depolarization and AP occur in the muscle ____ ______
- Muscle ______ occurs
Postsynaptic, Nicotinic
Na+, K+
Na+, K+
End Plate
Contraction
Events at Neuromuscular Junction
- _______ of Ach
- Ach is degraded by ______ ________ (AchE) on the muscle end plate
- Choline is reuptaked by presynaptic terminal for ______
- AchE inhibitors, such as ______, block the ______ and increase the action of _______
- _______ is also used to reverse neuromuscular blockade
Degradation
Acetyl Cholinesterase
Recycling
Neostigmine, Degradation, Ach
Physostigmine
Events at Neuromuscular Junction
- Hypocalcemia _____ neurotransmitter release, while Hypercalcemia _____ neurotransmitter release
- Hypomagnesemia ______ neurotransmitter release, while Hypermagnesemia ______ neurotransmitter release (antagonistic actions)
Decreases, Increases
Increases, Decreases
Chemical Synapses
- An AP causes _______ of presynaptic terminal
- ____ enters the presynaptic terminal, causing release of ________ into synaptic cleft
- Neurotransmitter diffuses across synaptic cleft and combines with receptors on the post synaptic membrane, causing change in membrane _______ and _______
Depolarization
Ca++, Neurotransmitter
Permeability, Potential
Chemical Synapses
- Excitatory neurotransmitter _______ the post synaptic membrane by opening ____ channels (__ influx)
- Inhibitory neurotransmitter ______ the post synaptic membrane by opening ___ channels (___ efflux) or ____ channels (___ influx)
Depolarizes, Na+, Na+
Hyperpolarizes, K+, K+
Cl-, Cl-
Botulinus Toxin
(Clostridium botulinum) - from bad bottle of _____ (like honey)
Action: Blocks release of ___ from presynaptic terminals
Effect on neuromuscular transmission: Total _____, ______ paralysis “floppy baby” syndrome
Food
Ach
Blockade, Flaccid
Curare
(Arrow Poison)
Action: Competes with ___ for receptor on _____ end plate
Effect on neuromuscular transmission: Decreases ___, paralysis of ______ muscles and death
Ach, Motor
EPP, Respiratory
Neostigmine
Action: Inhibits ______ ______ (enzyme)
Effect on neuromuscular transmission:
______ and ______ action of ___ at muscle end plate
Acetyl Cholinesterase
Prolongs, Enhances, Ach
Hemicholinium
Action: Blocks ______ of ______ into presynaptic terminal
Effect on neuromuscular transmission: ____ Ach stores from presynaptic terminals
Re-uptake, Choline
Depletes
Amioglycosides
(Lambort Eaton Syndrome)
Action: Antibodies block ___ channels
Effect of neuromuscular transmission: No _____ of Ach, secondary to a lack of ____ release
A major sign and symptom of this antibiotic might include _____ _____
Ca++
Release, Ca++
Muscle Weakness
Black Widow Spider
Action: ______ release of Ach
Effect on neuromuscular transmission: ________
Excessive
Convulsions
Myasthenia Gravis “Grave muscle weakness”
- Antibodies bind to ____ receptors. This is an ______ reaction
- This _____ the number of Ach receptors (Ach cannot _____, therefore there is no _____ contraction)
- Signs ans symptoms: Double ______, difficulty _______ and ______, ______ muscle weakness and fatigue, _____ speech, _______ eyelids
- IV _______; a short acting ________ inhibitor, causes temporary improvement
Ach, Autoimmune
Reduces, Attach, Muscle
Vision, Swallowing, Speaking, Skeletal, Slurred, Droopy
Edrophonium, Cholinesterase
Myasthenia Gravis “Grave muscle weakness”
- Treatment: _____ inhibitors, such as _______ will prevent the degradation of ____ and prolong the action of ____ at the muscle end plate, partially compensating for the reduced number of ______
- Thymectomy: tumor in ______ may be the actual cause of the ______ production; it will need to be removed
AchE, Physostigmine
Ach, Ach, Receptors
Thymus, Antobody
Lambert Eaton Myasthenic Disease
Antibodies against ______ channels markedly reduce release of ____
Associated with underlying ______, such as ____ ____ lung cancer
Calcium, Ach
Malignancy, Small Cell
Lambert Eaton Myasthenic Disease
Repetitive nerve stimulation demonstrates and increase in the motor action potential (contrasted with the decrease response in patient with true myasthenia gravis) Why?
Acetylcholine released at the nerve ending by the nerve impulse normally binds with acetylcholine ______
This evokes ______ ______ in the muscle
In Myasthenia Gravis, ______ ______ ______ binds to the acetylcholine receptor and ______ the action of ____
Bound antibody evokes _____-_____ destruction of muscle ____ _____
Receptors
Action Potential
Anti-Acetylcholine Receptor Antibody, Inhibits, Ach
Immune-Mediated, End Plate
Neuromuscular Function (Recap)
Normal transmission involves depolarized-induced influx of ___ through voltage gated channels. This stimulates the release of ____ from synaptic ______ at the active zone, and into the synaptic cleft.
Ach binds to Ach receptors and ______ the postsynaptic muscle membrane
Ca++, Ach, Vesicles
Depolarizes
Neuromuscular Disorder (Recap)
Disorders of neuromuscular transmission result from:
Blockage of ____ channels. Examples of these are? (List 2)
Impairment of ___ mediated ____ release (List 1)
Antibody induced degradation of ____ receptors (List 1)
Ca++; Lambert-Eaton Syndrome, Aminoglycoside ABX
Ca++, Ach; Botulinum Toxin
Ach; Myasthenia Gravis
