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178 Cards in this Set
- Front
- Back
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What is the largest contributor to body mass by tissue?
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Skeletal muscle (mostly water)
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What is the most important contributor to body heat/temperature?
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Skeletal muscle via oxidative metabolism-negative feedback loop
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Skeletal muscle is considered a storehouse for energy What is the main energy molecule?
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Glycogen (glycolysis-occurs in absence of oxygen), also phophocreatinine (very short acting-can use biproduct creatinine to estimate renal function) and oxidative metabolism
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Skeletal muscle is the target of insulin and the antagonist of insulin is?
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Glucagon.
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What is the way glucose gets to the cell and how?
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GLUT 4 transporter or insulin dependent, facilitated diffusion, goes by CONCENTRATION GRADIENT OF GLUCOSE
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What is high inside sarcoplasm?
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Inside skeletal muscle cells there is a lot of K+ and proteins and mitochondria
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What is high outside of sarcoplasm?
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Na+, Ch-, Calcium (in SR)
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Bone to bone. Patellar/SCL
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Ligament
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Muscle to bone. Achilles
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Tendon
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A muscle fiber is made of muscle cells. What is a sarcomere?
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The functional unit of a skeletal muscle. Between the two Z tracks
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What is a motor unit?
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Bundle of muscle cells that are innervated by a single neuron.
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What is the name of the specific neuron that innervates certain skeletal muscle cells?
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Motor neuron
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What is an important characteristic of small motor units vs large ?
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Smaller muscles that must react rapidly have more nerve fibers for fewer muscle fibers (laryngeal muscle may have 2-3 fibers per motor unit) But larger muscles don't require fine control. May have 80-100 muscle fibers to motor unit.
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How does the body produce graded skeletal muscle contractions that are smooth?
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CNS sends weak signal then smaller motor units will be activated first. So smaller motor units then larger motor units (stronger the signal the more motor neurons will be recruited) Graded skeletal contraction
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What is another word for "recruited?"
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Depolarized
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What is another reason skeletal muscle contractions are smooth?
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Graded skeletal movement. Also with multiple fiber summation different motor units are activated asynchronously by spinal cord
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What is oxidative muscle?
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Slow, red, aerobic. Muscles where you need large force/long time (thigh muscles) Aerobic metabolism
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What enables oxidative muscle to work so well?
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Lots of mitochondria, Myoglobin (inside that grabs oxygen and holds it), has lots of blood vessels, smaller fibers
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What makes red muscle red?
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Myoglobin(iron containing)
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What is a fast twitch muscle?
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Glycolytic, white muscle that works very quick, large fibers(Alpha A), extensive SR for calcium release, less mitochondria. Ex. eye muscles
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What is the sarcoplasmic reticulum?
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Specialized endoplasmic reticulum that holds lots of Ca++. (Very little Ca++ in sarcoplasm)
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What is the purpose of transverse tubules?
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Run perpendicular to muscle fibers and help excitatory stimulus go through muscle
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Thick filament in skeletal muscle.
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Myosin.
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Thin filament
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Actin
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What holds muscles in place?
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Tendon!
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What is the connective tissue that holds the I and A bands in place ?
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Titan. Holds actin and myosin together.Very important part of sarcomere, without it things would be floating everywhere.
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Why is elastin important in skeletal muscle?
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Allows muscles to stretch.
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Describe the sarcomere anatomy. What is in the I band, A band, H zone?
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There are the Z disk on each end, then a space on each side called the I band with only actin in it. Then the A band has actin and myosin, and in the middle the H band with only myosin.
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What is the sarcomere anatomy like during skeletal muscle contraction?
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Z disks come closer, I band disappears. No longer just actin, now actin and myosin during contraction
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Describe the sliding filament mechanism.
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Calcium enters cell, myosin filaments creep along actin, overall length of sarcomere shrinks. A band stays the same, I bands shrink, H band disappears, z disks come together.
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What is the limiting factor of the sliding filament mechanism?
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Myosin length. Myosin heavy, won't overlap
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Describe myosin.
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2 molecules wrapped together, heavy chains. Have heads that possess ATPase activity(similar to GCPR) (make up cross-bridges) . Heads have high affinity for active sites on actin filament.
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What 3 things make up actin filaments?
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actin, tropomyosin, troponin
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What is the troponin complex glue?
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Keeps the actin and tropomyosin molecules together.
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*Where are the active sites that myosin heads have an affinity for?
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On the ACTIN MOLECULE...not the filament.
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At rest what hides actin molecule binding sites due to lack of Calcium?
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Tropomyosin molecule (clindrical)
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Describe the Troponin complex...
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complex of 3 proteins that play big role in muscle contraction. Troponin I (affinity for actin), Troponin T (for tropomyosin), Troponin C (calcium)
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What has to occur for tropomyosin to move and allow active sites to be exposed to myosin heads?
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Calcium binds to trop C and tropomyosin moves, active sites exposed, myosin heads bind (sliding filament mechanism occurs)
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What is the signaling mechanism for the sliding filament action to occur?
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Calcium.
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At rest myosin heads have what attached to them?
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ADP (Stored energy)
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When does myosin release ADP?
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After Calcium enters, tropomyosin moves and head binds to actin site, head bends and moves filament, releases ADP. (Still bent)
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What happens to the myosin head right after moves actin filament?
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In order to restore normal position, needs ATP. Myosin uses ATP to go back to upright position (reset) and changes ATP to ADP.
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Describe "power stroke"
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When active site of actin molecule causes confirmational change in myosin head, head tilts toward arm of cross-bridge. (Power stroke) Activated by stored energy.
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After death, the state of contracture known as rigor mortis is caused by what?
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Lack of ATP, which is required to cause separation of crossbridges from the actin filaments.
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What is coactivation ?
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How almost all body movements occur, caused by simultaneous contraction of agonist and antagonist muscles on opposite sides of joints. Controlled by motor control centers of brain and spinal cord.
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Which contracts with more force, elongated muscle or shortened muscle?
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Elongated muscle.
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How does the nervous system tell muscles to contract?
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Brain sends sensory to motor cortex.
Signal sent from spinal cord, goes in back/dorsal. Motor neurons come out ventral horns (front of spinal cord) |
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What is an end plate potential?
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The depolarization that happens in skeletal muscle cell due to #1 influx of Na+ #2 influx of Ca++.
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What specifically initiates this depolarization?
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Brain sending SENSORY info to motor cortex. To spinal cord. Spinal cord to motor neuron.
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Where are calcium voltage gated channels on the motor neuron?
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Presynaptic (Activated by influx of Na+, action potential spread, Ca+ goes in and causes vesicle release of ACH.
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Once Ach is released into the synapse what occurs?
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2 Ach must bind to post-synaptic receptors on neuron, causing Na+ channels to open. Na+ then enters through the end plate. (minute amt of Calcium enters and K+ leaves.)
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Which way does depolarization occur in skeletal muscle EPP?
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Moves both ways from end plate.
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What are the skeletal muscle sensors called that are activated by a change in voltage and contribute largely to muscle contraction?
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Dihydropyridine receptors.
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How does the SR contribute to muscle contraction?
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Storehouse of Ca+, so cause efflux of Ca+ into sarcoplasm=muscle contraction.
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What specifically opens door of SR?
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When voltage sensing dihydropyridine receptors are activated (from Na+, voltage change) they are coupled with Ryanodine receptors. These open SR door.
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What can you do to inhibit EPP/shut down muscle contraction? 3 Main things?
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1. Remove Ach from neuromuscular junction. 2. Repolarize Cell 3. Get rid of Calcium
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How do you remove Ach from NMJ?
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1. Shut down motor neuron (Take away Na+?)
2. Allow Ach to diffuse away from receptor 3. AchE-breaks Ach into Acetyl and Choline 4. Generic plasma cholinesterase(floats in blood) |
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How do you repolarize the cell?
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1. Potassium leaves
2.Pump out Na+ 3. Get rid of Ca+ (by SERCA and Colsequestrin) |
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Why do you get rid of Ca+?
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Stop cross bridge cycling.
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What pulls Ca+ out of a solution, located in the SR. Helps decrease concentration gradient?
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Colsequestrin. Aids the SERCA by making some of the Ca+ not count, decreases gradient
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What is SERCA?
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Sarcoplasmic calcium ATPase. Primary active transport for Ca+. Uses
ATP. |
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What 2 things are T-tubules rich in?
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Fast Na+ channels
Dihydrapyridine |
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What is the safety factor of NMJ?
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Lots of Ach receptors in folds, increase surface area, allows more channels. High safety factor.
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How do "stygmine" drugs affect skeletal muscle?
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Inhibit AchE, have more Ach circulating to bind to : Nicotinic Ach receptors
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What should you be cautious about when administering "stygmine" drugs?
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Used for paralytic reversal. Important to remember more Ach in brain=more conscientiously aware
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What class of drug is Succinylcholine?
What are it's major contraindications? |
Depolarizing neuromuscular blocker. Cannot use in pts with arrythmias, burn pts, renal failure pts.
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How does Sux work? What breaks it down?
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Acts like Ach and binds to nicotinic receptors. Basically hinges nicotinic door open for a long time allowing Na+ and Ca+ to enter cell resulting in EPP. This is mainly via VG Na+ channels. K+ flows into ECF. The cell is not able to repolarize because of constant loss of K+. To break down must diffuse away from NMJ, or be broken down by Generic plasma cholinesterase.
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3 main concerns with Sux...?
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1. Primary is loss of K+-only use for short procedures, don't give to diabetics, necrosis pts. Will see clench and then relax.
2. Fasciulation- refers to muscle spasm during initial infusion (first time nicotinic receptors open/Calcium release) 3. In area where EPP occured=VG Na+ channels are not able to reopen. This is only in the area of the NMJ-also the area where K+ is leaking out. |
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How do non-depolarizing neuromuscular blockers work?
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Decrease Na+ influx and Ca+ influx at receptor and skeletal muscle fiber.Block EPP, decrease presence of action potential. Antagonist to nicotinic channel. Can be reversed. Good for long procedure.
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What causes Malignant hyperthermia?
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Ryanidine activity increased. Excessive Ca+ release from skeletal muscle SR. Mutation in Ryanidine receptor. (It increases in response to anesthetic agents)
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3 Things that cause onset of MH?
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Halothane, generic volatile anesthetic rx, paralytics
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Hallmark signs of Malignant hyperthermia?
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Excessive heat, stiff, contractions, spasms (not convulsions)
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What causes the symptoms (heat) generated from MH?
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Mostly from mitochondria=oxidative metabolism. (some from crossbridge activity/SERCA using ATP)
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What to do if Malignant Hyperthermia occurs?
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Stop anesthetics, Dantrolene (inhibits ryanidine receptors slowing ATP use, decreasing heat)
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What kind of feedback loop is Malignant hyperthermia?
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Postive viscious cycle.
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Calcium channel blockers have 3 mechanisms of working. What are they and what are examples?
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Dihydropyridine (norvasc)
Non-Dihydropyridine(Verapamil) Both-Cardizem(decreases neural excitability by blocking Calcium; don't confuse with benzodiazepine that opens Cl- channels) |
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The adding together of individual twitch contractions to increase the intensity of overall muscle contraction.
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Summation
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When a contraction reaches its maximum, where there is no effect if you increase it anymore-no effect in contractile force of skeletal muscle you see tetanization. Why does this occur?
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Because enough calcium ions are maintained in the muscle sarcolplasm, even b/t action potentials that full contractile state is sustained without allowing any relaxation between action potentials.Really fast depolarization
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Muscle fiber stimulation at increased rate
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Temporal summation
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The recruitment of more and more neurons by electrical stimulation
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Quantal summation
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The response to stimuli in smooth muscle versus Cardiac and skeletal.
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Skeletal is graded by recruitment
Cardiac is All-or-none Smooth is changes in rhythm or tone |
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How are each of the following muscles excited?Skeletal, Cardiac, smooth?
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Skeletal muscle is excited by nerve supply, cardiac muscle is self excited, and smooth is self or induced.
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What binds to Calcium in smooth muscle?
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Calmodulin
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What connects Actin in smooth muscle?
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Dense bodies
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Which types of muscle are sensitive to extracellular Ca+?
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Cardiac and smooth muscle very sensitive. Skeletal not that sensitive to ECF Ca+.
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Which type of muscle requires least amount of energy for contraction?
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Smooth muscle.
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What is the amount of mitochondria in each of the 3 types of muscles (skeletal, cardiac, smooth)
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Smooth has the least. Cardiac has alot. Skeletal has good bit (not in fast twitch though)
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What types of muscle have electical coupling?
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Not skeletal. Cardiac have intercalated disc and gap junction. Smooth muscle has gap junction
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Put these in order based on fastest speed of conduction to lowest. Skeletal, Smooth, Cardiac muscle.
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Fastest contraction occurs in skeletal muscle, slower in cardiac, slowest in smooth muscle.
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Stretch-induced VSMC (smooth muscle) constriction is known as?
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myogenic constriction-cardiac example
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To prevent overperfusion, VSMC contract in response to stretch that occurs due to increases in blood pressure;this offsets the increased BP by constricting to inhibit elevated tissue blood flow (increases vascular resistance)...This is an example of
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Positive feedback loop. Not viscious. Body somehow stops it.
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What is preeclampsia an example of ?
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Increases in BP getting out of control. VSMC is out of control, vicious cycle (positive).
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If we only look at the way that VSMC affects tissue perfusion, lets say organ normally gets 100ml/minute of blood and bp increases for some reason causing tissue pressure to rise to 125ml/min...this causes VSMC to constrict in response to HTN which then decreases tissue/organ blood flow back to around 100ml/min. This is an example of what type of feedback from the organ perspective?
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Negative feedback.
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Stretch induced relaxation of bladder is an example of ?
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Negative feedback. The more it stretches, the more it relaxes.
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Type of muscle that constricts or relaxes based on where cell is located what types of receptors are there, and enyzmes
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smooth muscle
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What effect does Ach have on vascular smooth muscle vs GI smooth muscle?
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Vascular relaxes/dilates
GI contracts |
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What is an externally elicited action potential?
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In GI has spontaneous contractions/ relaxation. Sometimes Ach (outside stimulus) will cause spike in membrane potential.
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What causes smooth muscle oscillatory rhythm?
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Leaky to Na+ and / OR Ca+ at rest. Specifically Ca++ directly influences contraction and relaxation.
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Why is SA node a rhythm generator?
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It is leaky to Na #1 and Ca+ #2. Higher resting membrane permeabiltiy
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Smooth muscle has what kind of relationship with the SR and CA+
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Poorly develped SR. Dependent on ECF Ca++
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Smooth muscle is connected by? What is its electrical coupling mechanism?
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Dense bodies, Gap junctions
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Smooth muscle has what kind of filaments?
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Lots of Actin, little myosin
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What causes smooth muscle contraction?
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Ca+ enters cell via VG Ca+ (DHP-R) and combines with Calmodulin and then activates myosin light chain kinase. (Puts phosphate on myosin) Leads to cross bridge cycling.
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What inhibits smooth muscle contraction? (Several things)
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Specifically Myosin light chain phosphatase. It does this via cGMP.
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cGmp is a signaling molecule that that activates MLCP(stops smooth muscle contraction). What are some things that inhibit this allowing contraction?
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Phosphodiasterase blocks cGMP allowing smooth muscle contraction to occur.
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What is an inhibitory signal that activates MLCP?
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Nitric oxide synthase converts arginine into nitric oxide. NO diffuses into smooth muscle cell and Activates guanalyl cyclase. This converts GTP into cGMP. cGMP activates MLCP
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What stimulates Nitric Oxide synthase?
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Ach on endothelial vascular cell.
Nitro/isosorbide dinitrate |
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What is something that inhibits phosphodiesterase and what does it cause?
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Viagra inhibits phosphodiasterase . Causes increase in cGMP, causes vascular smooth muscle relaxation. BUT it also causes more cAMP in heart so have increased contractility and workload. (Heart attack/arrhythmia)
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Why is Ca+ important in Cardiac muscle?
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It is involved with depolarization and crossbridge cycling.
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How does Ca+ enter cardiac cell?
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Ca++ L-type channels (DHP-R)
transverse tubules |
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What is Calcium induced Calcium release?
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Excitation coupling in heart; Action potential occcurs(Na+ VG and L-type Ca+ channel). Calcium from SR released (poorly developed)
****The difference in cardiac vs skeletal at this point is that a large quantity of Ca+ ions enter the heart from ECF through the TRANSVERSE TUBULES!!! So strength of contraction is dependent on ECF Ca+!!!!! |
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What are the differences in depolarization of skeletal vs cardiac muscle?
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Skeletal muscle has DHP-R that just have to detect depolarization (voltage sensors)
In the heart, the DHP-R's are the L-Type Ca++ channnels. Ca+ has to enter sarcoplasm via DHP-R's and detect volatage changes. |
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How does the heart get rid of Ca+?
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SERCA (ATP) and plasma membrane Ca ATPase (ATP) Both primary transport. Na+/Ca+ antiporter.
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What is cardiac muscle made of?
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Hybrid of skeletal and smooth muscle
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Calcium has an antiporter. Describe it.
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antiporter or counter transporter or exchanger. Uses energy spent from ATPase. Pumps 1 Ca+ for around 3 Na+(coming into cell). This is secondary active transport
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Why do you need 3 Na+'s for 1 Ca+ in the cardiac Na+/Ca+ antiporter?
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Because calcium is double charged, need to replace that positive inside cell. Also because Ca+ is going against a steep concentration gradient.
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If there is damage to the heart, ie heart attack, ischemic event...what can occur with electrolytes?
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Can cause ATPase to not get enough energy and result in increased ICF Na+
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What is the latch mechanism
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Smooth muscle perserves force of contraction, able to use less energy. The myosin head can remain attached even without ATP.
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Some examples of smooth muscle functions in the body?
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Airway-small muscles that are active in asthmatics, GI tract (slows), esophagus (coordinated) , pupillary (fast acting)
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Fastest Neurons
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A-alpha/ or A myelinated
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Detects fine touch sensory (pin prick)
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A-alpha
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Myelinated nerves conduction type
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salutatory
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Examples of Fine touch sensory
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pin prick
fast twitch (glycolytic motor neurons in eye) proprioceptors tendon and stretch receptors |
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Type of receptor slightly (half) of A alpha neurons size, detect pinpoint and vibration.
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A Beta
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A beta detect vibration, is it low or high frequency?
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Low frequency, less energy. A alpha also detect
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Smaller myelinated neuron that conducts fast pain signals
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A delta . Relays messages to slow oxidative muscle (sciatic nerve to leg)
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Ocular muscle- fast or slow
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Fast twitch
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Type of neurons present in CNS
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Class B-Intermediate group
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Conduct dull, slow, aching pain.
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Class C neurons. Small and unmyelinated.
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Type of receptor that senses slow dull aching pain.
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Free nerve endings. Located all over the place.
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The closer to the spinal cord what is blocked first?
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Motor before sensory!!!!!
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The process that occurs in skeletal muscle where neurons are fired frequently causing more Ca+ to stay in the cell and cause stronger contraction in muscle until point where there is maximal constant contraction
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Tetany
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Frequency modulation in nerves where action potentials are generated in a certain amount of time
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Neural Temporal
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What is the measurement for neural temporal stimulation? Can neurons have tetany? Why?
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Hz (cycle/sec)
No tetany in neurons VG Na+ channels have to have certain time to reset Absolute refractory period |
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Where does post synaptic modulation in neuron occur?
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soma(cell body) and dendrite
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Where does pre synaptic modulation occur on neuron?
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Axon-usually inhibiton
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What does EPSP stand for and mean?
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excitatory post synaptic potentials. Increase cells permeability to Na+, and anything that can cause depolarization
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IPSP is caused by what?
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increase permeability Cl- or K()
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What does GABA mediated mean?
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Involved with presynaptic modulation, axon, allows Cl- to enter cell, prevents Ca+ from entering, vesicles released, ....referred to as inhibitory interneurons.
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Depolarization of a neural membrane to the point where it is close to an action potential but has not reached threshold potential. Ex. Sensory neurons
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Facilitation
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Process of turning mechanical/chemical stimuli into electrical stimulus
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sensory signal transduction...This is caused by a receptor potential.
So whatever sensory receptor you have being excited, it's job is to change the membrane potential |
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How does sensory signal transduction work? What is an example?
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Ex. Pressure sensitive receptor (Pacinian corpuscle) An electrical signal is made almost always produced because of the physical coupling of receptor to Na+ Channels in neuron (that physically dislodge and allow Na+ in-cell depolarizes-electrical signal made)
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Sensory receptor that is less sensitive to a stimuli overtime is said to have ?
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Adaption, or adapted.
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Why is adaption a good quality for sensory receptors? What are two examples of neurons that adapt well?
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Adaption is good because it keeps CNS from having to process too many signals(sensory overload). Ex. Pacinican corpuscle in mid dermis. Superficially the Meissner's corpuscle (lips & fingertips)
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What determines a sensory neurons ability to adapt?
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Tissue dependent
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What are a few examples of sensory neurons that do not adapt well?
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Superficially Merkel disks
Ruffinis end organ Baroreceptors (slow) Free nerve endings (little to none) Golgi tendon aparatus(Do not adapt) Osmoreceptors (Do not adapt) RELAY CRITICAL INFORMATION |
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Which mechanoreceptors do not adapt at all?
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Macula in the vestibular apparatus
Golgi tendon (stretch/tendon) Osmoreceptors Free nerve endings (Little to none)-Pain |
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Receptors that react only when change is taking place?
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Rate receptors or movement receptors... fast adapting.
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Sensory receptor that detects pressure and pain. A delta and C fibers.
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Free nerve endings, located everywhere
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Mechanoreceptor that is at bottom of hair follicle, Abeta and A delta (Slow adaption)
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Hair movement receptors
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Mechanoreceptor that detects low frequency and adapts quickly, detects pressure.
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Meissners corpuscle. Very superficial, detect low frequency vibration and pressure in fingertips. A- Alpha and A beta. (sense changes)...low frequency is important
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Mechanoreceptor that senses continuous pressure and is located superficially?
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merkel disk is pressure sensing, slow adapting (constant pressure sensor), A-alpha and A-Beta. Critical information.
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Mechanoreceptor located in deep subdermal area, senses pressure and high frequency vibrations. Adapts fast.
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Pacinian Corpuscle
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What kind of nerve fibers correlate with Pacinian corpuscle?
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A-Alpha, A-Beta, A-Delta
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Mechanoreceptor in middle dermis, senses stretch. Slow adaption.
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Ruffini's end organ. A-Alpha, A-Beta.
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Location of slow adapting mechanoreceptor that controls blood pressure via negative feedback.
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Carotid body and aorta. Sense increased stretch and increase neural firing, inhibit SNS, increase PNS, increase diuresis in kidneys.
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Are Baroreceptors able to adapt fast or slow...why?
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Adapt slow to ensure problem corrected.
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Non-adapting stretch/tension of tendon mechanoreceptor. A-Alpha
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Golgi Tendon.
Ex. Patellar tendon and knee reflex. Very fast. Also involved with muscle inhibition and reflex arc. |
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Osmoreceptors are where? What do they do?
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Osmoreceptors are in the anterior hypothalamus.
They inhibit or stimulate release fo ADH from posterior pituitary, they regulate osmolarity. |
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Where are the chemoreceptors that regulate blood CO2?
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Carotid and Aortic Bodies and ventral medulla. Sense elevated Co2 and increase respiratory response.
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Carry non-nociceptive information
(Large nerve fibers vs small) |
Large.
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Little to no adaption
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nocicetors (free nerve endings.)
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Nerve fibers that carry pain signals
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A-delta is fast pain. myelinated
C-fiber is slow pain . unmyelinated. |
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How does increased ECF K+ stimulate nociceptors
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Increases membrane permeability, causing to be more electropositive, increases firing of nerve endings (free nerve endings)
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Made by arachadonic acid. Increase interstitial pressure and cause pain
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prostagladins
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Act directly and indirect to increase sensitivity to nociceptors. Can increase tissue hydrostatic pressure and press on nerves. (Ace inhibitors increase this)
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Bradykinin
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Blocking a nerve with lidocaine. Which would be easier,myelinated or non?
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myelinated, less Na+ channels
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Blocking a A-alpa nerve and a A-Gamma nerve with Lidocaine. Which is easier to block?
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A Gamma because it is smaller and has less Na+ channels
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In a peripheral nerve, if you are blocking with lidocaine, what is easiest to block first?
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More superficial nerves.
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So you are about to block a peripheral sensory nerve with Lidocaine. You are given a nerve with C-fibers and A-delta fibers. What should you note?
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This is only a sensory neuron so I must just consider size and location. So even though C-fibers are unmyelinated, size takes precedence in this situation. Because they are smaller they will be located in the superficial part of the circle. They have overall less Na+ channels and will be blocked first. So, the pt will lose (slow/burn/aching pain first)
BEFORE FAST PAIN |
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In a neuron that contains sensory and motor neurons, what will happen if injected with Lidocaine?
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Location of motor fibers in a nerve are thought to be located more peripherally. (This is as we move more proximally we get and are more likely to carry motor and sensory) So in this case myelination and size do not matter.
You lose motor before pain |
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Benefits to anesthetizing closer to site.
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Less anesthetic/side effects, more specialized effects, less med used
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Blocking a nerve with lidocaine. Which would be easier,myelinated or non?
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myelinated, less Na+ channels
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Blocking a A-alpha nerve and a A-Gamma nerve with Lidocaine. Which is easier to block?
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A Gamma because it is smaller and has less Na+ channels
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|
|
In a peripheral nerve, if you are blocking with lidocaine, what is easiest to block first?
|
More superficial nerves.
|
|
|
So you are about to block a peripheral sensory nerve with Lidocaine. You are given a nerve with C-fibers and A-delta fibers. What should you note?
|
This is only a sensory neuron so I must just consider size and location. So even though C-fibers are unmyelinated, there size takes precedence in this situation. Because they are smaller they will be located in the superficial part of the circle. They have overall less Na+ channels and will be blocked first. So, the pt will lose (slow/burn/aching pain first)
BEFORE FAST PAIN |
|
|
In a neuron that contains sensory and motor neurons, what will happen if injected with Lidocaine?
|
Location of motor fibers in a nerve are thought to be located more peripherally. (This is as we move more proximally and are more likely to carry motor and sensory) So in this case myelination and size do not matter.
You lose motor before pain |
|
|
Benefits to anesthetizing closer to site.
|
Less anesthetic/side effects, more specialized effects, less med used
|
