Muscle Flashcards
Motor unit definition
Somatic motor neuron together with all of the muscle fibers that it innervates
What surrounds muscle fibers
Sarcolemma
Muscle fibers going from big to small starting at muscle itself
Muscle to fascicle to fiber to myofibrils to filaments
Thin filaments
Actin
Thick filaments
Myosin
What makes up the Iband. what is in the middle of the Iband.
Myosin.
Z disc
What makes up the a band. What is in the middle of the A band. Why does the middle look the way it does
Thick filaments. h band. The H band is only myosin where as the rest of the a band has Actin also
Summarize excitation contraction coupling
release of ACH from nerve fiber, ACH binds to receptors on sarcolemma, opens ligand gated channels, Sodium defuses in producing depolarization, action potential produced. AP conducted a long transverse tubules, voltage gated CA channels open, CA released channels in SR open, CA diffuses into sarcoplasm, CA binds to troponin, stimulating contraction.
What is treppe
Ability to evoke stronger contractions after subsequent contractions. Staircase effect
Iso tonic contraction
Muscle is contracting during shortening. Iso means same tonic means strength
Isometric contraction
Contraction without muscle shortening. Holding a dumbbell with partially flexed arm
Concentric contraction
Iso tonic contraction where muscle shortens
Eccentric contraction
I so tonic contraction where muscle length and
What two things are different in cardiac muscle from skeletal muscle
Cardiac muscle does not require neural stimulation to contract – cardiac cells have own pacemaker. Action potentials are conducted from one of cardiac cell to another via intercalated disks
What six things are different between smooth and skeletal muscle
Not striated, no transverse tubules, calmodulin calcium binding instead of troponin, calcium enters from extracellular fluid and sarcoplasmic reticulum, nerve stimulation not required, gap junctions in most
Describe calcium reception and smooth muscle cells
Calcium binds to calmodulin which activates myosin light chain kinase. MLCK phosphoralyses myosin heads and allows for cross bridge attachment
Single unit smooth muscle cells
Connected by gap junctions
Multiunit smooth muscle cells
Not connected by gap junctions
Synapses en passant
Autonomic neurons have varicosities that release neurotransmitters along the length of the smooth muscle cell
Myosin head mechanism of function in skeletal muscle
ATPase enzyme splits ATP into ADP and phosphate activating crossed bridge. Phosphate is released to undergo a power stroke. ADP is then released and cross bridge is detached.
H I and a bands – which shorten during contraction
H and I bands decrease a bands stay same length
What surrounds the muscle
Epimysium
What surrounds the fascicles
Perimysium
What surrounds the muscle cells
Endomysium
What does troponin I do
Inhibits crossbridge binding
What does troponin T do
Binds to tropomyosin
What does troponin C do
Binds to calcium
Dihydropyridine and ryanodine receptors
Dihyrdro voltage gated ca receptors
Ryanodine ca release channels
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