A&P muscular system assessment 3

skeletal muscle

voluntary, attached to bones

cardiac muscle

involuntary, striated, walls of heart

smooth muscle

involuntary, non striated, walls of hollow organs

functions of muscles

excitatory, 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?

the 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 and 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 C, troponin T, troponin I, 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

how does an action potential travel from the sarcolemma to the muscle fibers?

Ach binds to receptors, opens sodium/potassium gates, sends action potential from sarcolemma along T-tubules to muscle fibers

events at neuromuscular junction

action potential reaches axon terminal, opens calcium gates, calcium causes Ach to be released, Ach diffuses across synaptic cleft and binds to receptors, causes ion channels to open and create action potential, acetylcholinesterase breaks down Ach in synaptic cleft

excitation-contraction coupling stage of action potential

action potential hits terminal cisternae, opens calcium gates, calcium binds troponin, tropomyosin moves to expose myosin binding sites