A&P muscular system assessment 3

skeletal muscle

voluntary, striated, attached to bones

cardiac muscle

involuntary, striated, walls of heart

smooth muscle

involuntary, non striated, walls of hollow organs

functions of muscles

excitability, contractility, extensibility, elasticity, movement, body posture, stabilize joints

what is an action potential?

message sent down axon through excitable membranes

what is resting membrane potential?

charge of a muscle membrane when no action potential is occurring; -70mV; kept stable by diffusion

what is depolarization?

all sodium gates open

what is repolarization?

sodium gates close, potassium gates open

what is hyperpolarization?

too much potassium after repolarization is fixed by sodium-potassium pumps

2 types of gated ion channels

chemically gated ion channels, voltage gated ion channels

parts of a skeletal muscle

tendon, epimysium, perimysium, fascicle, endomysium, muscle fiber, sarcolemma, myofibril, myofilament, mitochondria, sarcoplasm, sarcoplasmic reticulum, glycosome, myoglobin, T-tubule, actin, myosin, triad

parts of a sarcomere

H band, A band, I band, Z line, M line, actin, myosin, myosin head, ATP binding site, tropomyosin, troponin, dystrophin, titin/connectin, actin binding site

parts of a neuromuscular junction

axon, axon terminal, sarcolemma, synaptic cleft, synaptic vesicle, Ach, Ach receptor, calcium channels, SNARE, acetylcholinesterase

rigor mortis

stiffness of every muscle in body after death, calcium diffuses uncontrollably and causes cross bridge cycle to begin

sarcomere

contractile unit of muscle fiber

motor unit

one motor neuron and all muscle fibers it innervates

what does acetylcholinesterase do?

breaks down Ach in synaptic cleft so action potential stops

what can cause a muscle contraction to stop?

action potential stops, no calcium, death - no more ATP

motor unit summation

relationship between number of stimuli and muscle tension

what is the size principle of muscle recruitment?

small fiber motor units recruited first, then medium fibers, then large fibers

what is muscle tone?

some muscles contract during inactivity to keep body position and joint stability

what increases contractile force of a muscle?

stimulus frequency, number of muscle fibers recruited, muscle size, length tension relationship

what is the length tension relationship?

sarcomere resting length can’t be too long or too short to get optimum contraction

isometric contraction

muscle tension, no movement; push against wall

isotonic contraction

muscle tension with movement, muscle lengthens or shortens; weight lifting

4 ways muscles get energy during exercise

0-5 s, ATP; 0-10 s, creatine phosphate combines ADP and phosphate to make ATP; 0-2 min, glycolysis, anaerobic, makes lactic acid; 2+ min, aerobic respiration

possible causes of muscle fatigue

ionic imbalances, inorganic phosphates, reduced ATP, high magnesium, low glycogen

EPOC

excess post-exercise oxygen consumption

what must happen for a muscle to return to pre-exercise condition?

replace myoglobin, get rid of lactic acid, replace glycogen, replace ATP

what adaptations can occur as a result of aerobic exercise?

more capillaries, mitochondria, and myoglobin; greater endurance; fast glycolitic muscle fibers become fast oxidative muscle fibers

what adaptions can occur as a result of resistance training exercise?

hypertrophy/larger fibers, more glycogen and myofibrils, strength

3 types of muscle fibers and their uses

slow oxidative, endurance; fast oxidative, intermediate; fast glycolytic, power

prime mover/agonist

produces main specific movement, opposite joint from antagonist

antagonist

produces opposing/reverse movement

synergist

helper muscles, fixate bone