3.2: skeletal muscle

types of muscle:

cardiac, smooth, skeletal

cardiac muscle:

-make up walls of ___

-striated/ nonstriated, ____ contractions

heart, striated, involuntary

smooth muscle:

-make up walls of ____

-straited/ nonstriated, ____ contractions

hollow organs, nonstriated, involuntary

skeletal muscle:

-attached to ___

-straited/ nonstriated, ____ contractions

bones, striated, voluntary

properties of bones:

-___: muscles shorten

-____: muscles lengthen

-____: response to stimuli

contractibility, extensibility, excitability

muscle fiber microanatomy:

-multinucleated, meaning _____

-____: densely packed sacromeres

-sacromeres made up of ______

contain multiple nuclei to produce more proteins, myofibrils, thin & thick filaments

sacromeres: 

-Z disc:

-M line: 

line ends of sacromere, anchor thin filaments, center of sacromere, anchor thick filaments

thick filaments made up of ____ ___

-tails group together into thick filaments

-heads bind to ___ ___ to form __ __

myosin protein, thin filaments, cross bridge

thin filaments made up of __ ___

actin protein

regulatory proteins:

regulate cross bridge formation

striations form from:

overlap of thick & thin filaments

neural control:

-somatic neurons travel from ____ to ____ ___

-neurotransmitter junction:

CNS, skeletal muscle, contact point between motor neuron and muscle fiber

sarcoplasmatic reticulum

-surrounds each ___

-stores and releases ___

-attach to t-tubules, which penetrate through plasma membrane

myofibril, Ca+

t-tubules:

-forms ___ network

-___ continuous throughout extracellular surface

-transmit ___ ___ to cell interior

-initiate Ca+ release from _____ _____

neural, lumen, electrical signals, sarcoplasmatic reticulum

action potential:

-at rest, the plasma membrane is polarized: ____ charge inside, ____ charge outside

negative, positive

depolarization: allows for ___ ___

-____ stimulus opens up Na+ ion channel

-allows Na+ ions to flow through, increase/ decrease internal charge

-wave of depolarization spreads from one ___ to the next

muscle contraction, electrical, t tubule

tropomyosin

regulatory protein in thin filaments

low calcium in cytoplasm causes tropomyosin to:

block actin active site. myosin can’t bind, which prevents muscle contraction

high calcium in cytoplasm causes tropomyosin to:

move away from active site, allowing for myosin binding to thin filament, causing muscle contraction

how does crossbridge work

calcium ions need to be released by sarcoplasmatic reticulum. tropomyosin moves away from actin active site. myosin head binds to actin and pulls towards the M line, allowing for overlap of myosin over thin filamenth

what does ATP do in the crossbridge process

ATP is required to break the myosin to actin bond

repolarization: causes ___ ___

-___ ions leaves cell

-decreased/ increased internal charge

-regulatory proteins return to actin site and prevent muscle contraction

muscle relaxation, K+

refractory period: muscle fibers can’t be stimulated

-___ gets pumped in while ____ gets pumped out to reset charge

Na+, K+

rigor mortis: _____ that happens 3-4 hrs after death

-muscles still perform contractions due to:

-because ATP is no longer synthesized, ___

muscle contraction, leakage of Ca+ from sarcoplasmatic reticulum, cross bridge can’t be broken and contraction remains