Skeletal Muscle Flashcards
what are some functions of skeletal muscle
produce skeletal movement, posture maintenance, supports viscera, guard entrances and exits, maintain body temp, store nutrients
what of the muscle fibre can be seen under light microscopy
dark bands (A bands) which are anisotropic with polarised light, and light bands (I bands) which are isotropic with polarised light. can also see centre of A band = H band which is bisected by a thin dark line (Z disc)
what is the epimysium?
surrounds each muscle and is composed of dense irregular connective tissue.
function = to maintain structural integrity whilst allowing movement. has inward projections called fasciculi which divide muscles into compartments of muscle fibre bundles
what is the perimysium?
surrounds each fasiculus, i.e in the muscles of the limbs
what is the endomysium
encases each muscle fibre in a fascicle. consists of connective tissue (collagen) and reticular fibres.
define myocyte
muscle cell
define sarcolemma
plasma membrane
defone sarcoplasm
cytoplsam
define sarcoplasmic reticulum
smooth ER
define sarcosome
mitochindria
define sarcomere
functional unit of muscle
write a note to describe the structure of sarcomeres
has myofilaments (actin and myosin) and regulatory proteins (troponin and tropomyosin)
-Z disks border the sarcomere + anchor actin
- actin and troponin-tropomyosin complex projects from Z discs towards centre of sarcomere
- myosin strands project form the centre of sarcomere towards the Z disks to form the thick filaments
describe the different bands in a sarcomere
I band = adjacent portion of two successive sarcomeres
A band = the length of the thick filaments
H band = zone in the middle of A band with no thin filaments. is bisected by the M line
describe the sliding filament theory
movement of thin filaments towards the centre = greater overlap which reduces the width of I and H bands but does not affect the A band
