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50 Cards in this Set

  • Front
  • Back
What do motor neurons control?
They control motor units (groups of muscle cells under a single command)
What are Motor Units?
They are groups of muscle cells under a single command
What are myofibrils made of?
They are Proteins.
How many times more intracellular calcium is there than extracellular calcium?
There is 1000x more calcium inside a cell than outside.
How does extracellular Calcium get back into the muscle fiber?
Through an Active Transport pump, which uses ATP.
Neuromuscular junction
A functional connection between the distal end of a nerve fiber and the middle of a muscle fiber; consists of a synaptic knob and a motor end plate.
Synaptic Knob
The dilated tip of a nerve fiber, contains synaptic vessicles
Motor end plate
A depression in the sarcolemma, near the middle of the muscle fiber, that receives the synaptic knob. contains achetylcholine receptors.
Synaptic Cleft
A gap between the synaptic knob and motor end plate
Junctional folds
Invaginations of the membrane of the motor end plate (to increase surface area of the sarcolemma) where ACh receptors are especially concentrated
Neuromuscular Junction - Acetylcholine (ACh)
The neurotransmitter released by a somatic motor fiber that stimulates a skeletal muscle fiber (also used elsewhere in the nervous system).
Neurouscular Junction (NMJ) - ACh receptor
A transmembrane protein in the sarcolemma of the motor end plate that binds to ACh.
Acetylcholinesterase (AChE)
An enzyme in the sarcolemma and basal lamina of the muscle fiber in the synaptic region; responsible for degrading ACh and stopping the stimulation of the muscle fiber.
What do the lipid vesicles in the synaptic knob contain?
They contain ACh (Acetylcholine), a neurotransmitter.
Does Troponin or Tropomyosin cover the active site on the actin filaments? Which does Calcium bind to?
Troponin ONly marks the active site. Calcium binds to Troponin. That makes Tropomyosin (which covers the active site) roll out of the way. Active site is exposed for the myosin head to form cross-bridge attachment.
What are the steps of the excitation contraction coupling?
Wave of excitation reaches t tubes, calcium diffuses out of SR and binds to troponin, Troponin/tropomyosin complex changes shape, rolls out of way, Hydrolysis of ATP to ADP + Pi activates and cocks Myosin head, forms myosin/actin cross bridge (myosin acts like ATPase). Power stroke (Myosin head Pivots and shoves the Actin toward the M line. Cross bridge attachment breaks upon binding of a new ATP and myosin reactivates.
Where does a nerve come into contact with a muscle?
At the Neuromuscular Junction (NMJ).
What happens at the NMJ during Excitation (from book)?
A nerve signal arrives when calcium enters the synaptic knob. Acetylcholine (ACh is released), ACh binds to the receptor which opens the ligand-gated ion channel. End Plate Potential is created. Opening of voltage-gated ion channels, creation of action potentials.
What happens at the NMJ during Excitation (Dr. Harvey's explanation).
1-nerve impulse travels down, influx of Ca2+. 2-Opening of CA2+ channels, CA2+ enters. 3-Vesicles migrate downward. 4-receptor mediated exocytosis (ACh release) 5-binds to receptor 6-relese of sarcoplasmic Calcium. AFTER THS is when the calcium snows down and steps of contraction occur
What happens with Calcium at the arrival of a nerve signal?
Ca2+ enters the synaptic knob.
As long as ACh is hooked up at the NMJ, the musle contracts. What makes it stop contracting?
AChesterase (like an ach eraser. Think ACHeraserase). It goes into the synaptic cleft and erases the ACh
How does the bug poison RAID work?
It is an ACHesterase inhibitor. It doesn't let that "eraser" in and bug's muscles can't stop contracting. It flips and its legs flail until it dies (runs out of ATP)
What happens in Tetanus (poisonous kind)?
Musles lock up in tight paralysis or spasmodic paralysis if AChesterase is inhibited.
What kind of paralysis does botulism cause?
Think Botox. Flaccid paralysis, or decending paralysis.
What produces the ATP in the synaptic knob?
Muscle Contraction - Tension
Degree or "how much" of strength of contraction
The weight the musle is moving
What kind of contraction occurs when tension is greater than resistance? What does this build?
Isotonic. It builds endurance.
What kind of contraction occurs when resistance is greater than tension? What does it build?
Isometric contraction, builds power.
In terms of the length/tension relationship of muscle, what is optimal resting length?
Amount of tension generted by muscle depends on how stretched or contracted it was before it was stimulated. If the muscle is overly contracted, thick filaments butt against Z discs and fiber can't contract much more when it's stimulated. If it's overly stretched, there's so little overlap between thick/thin filaments that few cross bridges can form between myosin/actin. Therefore, the optimum resting length is important 2-2.24 um)
What is a latent period?
After stimulation, it takes a preparatory period of time before the contraction actually occurs.
A single contraction. Varies with stimulation frequency, Calcium concentration, length/tension relationship, temperature of the muscle, hydration of a muscle. Looks like one peak on myogram.
Wave Summation
When the resting muscle is stimulated, it contracts after the latent period. If not allowed to completely relax again, it contracts a bit more after another stimulation, and again. Doesn't go too far down between rising waves, each wave higher because it doesn't go completely down to resting.
Recruitment or MMU
Multiple motor unit stimulation, bringing more motor units into play.
Treppe like Steppes. Pattern of increasing tension with repetitive stimulation. Staircase phenomenon. Ca2+ concentration in cytosol raises because it doesn't get completely reabsored when stimuli arrive rapidly, causing stronger twitches/greater contraction. Goes pretty far down (not all the way, though) between peaks
Incomplete Tetanus
After stimulus and then rapid fire stimulus after latent period it flutters. Looks like Bart Simpson haircut.
Complete Tetanus
After stimulation and latent period a constant strong stimulus causes if you had to hold a really heavy thing up forever there's ony so long you could hold it up before fatigue sets in.
Myogram Vs. Myograph
Myogram is the report made by the myograph (machine). Think telegram/telegraph.
Where is Creatine Phosphate found? What creates it?
Creatine phosphate is found in muscle, exchange reaction CP + ADP -> ATP. Working out creates creatine phosphate.
What is myoglobin?
It is a globular protein in muscle which stores oygen. (Sounds like hemoglobin, which is what transports oxygen in blood FePr-).
Understanding Fast Twitch Muscle using domestic fowl.
Breast meat has fast twitch fibers. White meat. Low blood supply, anaerobic, low myoblobin (light color) low mitochondria (light color), high in glucose(white-when not breathing you burn sugar)
Understanding Slow Twitch Muscle using domestic fowl.
Leg meat, dark meat. Isotonic/endurance exercise like chickens running around. Aerobic, oxygen must be present, high blood supply (dark) high myoglobin (dark) high in mitochondria (dark) for aerobic metabolism, when breathing you burn fat so it is high in fat.
Are humans light or dark meat (fast or slow twitch)?
Humans aren't light or dark, more intermediate.
What kind of athletes have more fast twitch muscle fibers? What kind have slow twitch muscle fibers?
Sprinters are fast twitch, distance runners are more slow twitch.
Prime mover/agonist
Does the main movement of the muscle. Depends on muscle action. For forearm flexion, biceps is agonist or prime mover. Triceps is prime mover for extension.
Works with the prime mover.
Opposes or performs opposite action than prime mover. Depends on muscle action. For forearm flexion, triceps is antagonist and biceps is prime mover/agonist, but it is the opposite with flexion.
Origin of muscle
No movement, only attachment. Origin of biceps = shoulder. Insertion is on forearm inside.
On the moving bone. Origin of biceps = shoulder. Insertion is on forearm inside.
Where are the muscles that extend the forearm attached?
olecranon process