muscles Flashcards
What division of the nervous system supplies skeletal muscle with its innervation?
somatic - voluntary movement
Components of skeletal muscle cells
Sarcolemma: the outer membrane of a muscle cell
Sarcoplasm: the cytoplasm of a muscle cell
Sarcoplasmic reticulum: the smooth endoplasmic reticulum of a muscle cell
sarcomeres: mitochondria
what are myofibrils composed of?
actin and myosin myofilaments
facilitate muscle contraction
what is the sliding filament model?
response to nervous signals at motor end plates,
leading to a wave of depolarisation of the sarcolemma (membrane)
stimulating release of Ca2+ from the SR.
how does a muscle contract?
Ca2+ binds to troponin on actin filament (thin)
revealing myosin (thick) binding site that was hidden by tropomyosin
myosin head binds and pulls actin towards M line shortening sarcomere
what allows sarcomeres to return to their original length?
titin - spring mechanism
triads run along the junction between the A- and I-band, what muscle?
skeletal muscle
how are cardiac cells joined to allow for electrical/mechanical signals to pass?
intercalated discs
T-tubules and SR in ? form a diad
cardiac muscle
what generates APs in cardiac muscles?
pacemaker cells
what do satellite cells do in skeletal muscles?
allow for hypertrophy and partial repair
why is damage cardiac muscles turned to fibrous scar tissue?
although cardiac muscle is more resistant to injury
it does not regenerate
retain the capacity to divide and has a high capacity for repair
smooth muscle
how are cells arranged in smooth muscle?
they are fusiform (spindle shaped)
have a cigar shaped single nucleus
why is contraction slower in smooth muscle?
lack of interaction b/w actin and myosin
no troponin therefore myosin binds via phosphorylation than ATPase
