lectures - muscle tissue + anatomy

what are the functions of muscle tissue

enables movement to occur

participates in body's thermoregulation by producing heat

what percent of the total body mass does muscle constitute

30-40% of total body mass

are muscles a major drain on energy efficiency

yes

what are the many names of a muscle cell

muscle fiber, myofiber, muscle cell

what is special about muscle cells

can indefinitely retain ability to change physiology and function via physiological and functional plasticity

define myofibril

specialized organelles of muscle tissue

what are the contractile units of myofibrils

sarcomeres

what makes up sarcomeres

made up of myofilaments (stress filaments)

describe myofilament arrangement in myofibril

arranged within myofibril to form series of repeating sarcomeres

in the order of most to least abundance, what are the myofilaments in the myofibril

myosin, microfilaments/actin filaments, troponin; tropomyosin

the alignment of sarcomeres across muscle fiber results in

visible striations of light and dark bands

describe cardiac muscle

striated due to presence of sarcomeres

fibers are interdigitated, branched, and vary in length

from top to bottom, what are the layers of connective tissue of skeletal muscle

epimysium

perimysium

endomysium (basal lamina)

what does the epimysium wrap

multiple 2° bundles to contain entire muscle

what does the perimysium wrap

bundles of muscle fibers to form fascicles

1° bundle - 20-40 muscle fibrs

2° bundle - groups of multiple 1° bundles

what does the endomysium (basal lamina) wrap

single muscle fiber (1000-2000 myofibrils)

what is included in each bundle of the epimysium

at least 1 vein + at least 1 artery + bundles of motor nerves

what is included in each bundle of perimysium

blood vessels + adipose tissue + motor nerve endings + aff/eff PNS neurons

what is included in each bundle of endomysium

blood vessels + organelles + extracellular protein-filled fluid + nutrients