muscle Flashcards
what is muscle tissue specialised for?
contraction
what are the 3 types of muscle?
skeletal
cardiac
smooth
what is the control and structure of the 3 types of muscle?
skeletal:voluntary, striated
cardiac:involuntary, striated
SM:involuntary, non-striated
describe skeletal muscle tissue
elongated, cylindrical cells-muscle fibres
multiple peripherally located nuclei-multinucleated
1 fibre can span whole muscle length
mostly made of protein
describe skeletal muscle
attached to skeleton
voluntary movement of skeleton
subconscious movement-balance/posture
tendons attach muscle to skeleton
what is skeletal muscle composed of?
skeletal muscle tissue
nervous tissue
bv
connective tissue
what does endomysium do?
separate individual muscle fibres
what is a fasciculi?
groups of muscle fibres grouped together
what does perimysium do?
loose CT
surrounds each fasciculeq
what is epimysium?
dense CT
externally surrounds entire muscle
how is skeletal muscle cell structure specialised for contration?
each cell packed full of numeroud myofibrils
arrangement give striated appearance
describe the electron-microscopic structure of skeletal muscle
myofibrils composed of repeating myofilaments
dark bands=myosin
light bands=actin
light bands dissected by Z Lines, divide myofibril into contractile unit sarcomeres
what is the sliding filament mechanism of sarcomeres?
a conformational change causes the filaments to slide over each other causing the sarcomere to shorted-contract
describe control in skeletal muscle
mainly voluntary
somatic motor neurons innervate
individual motor neurons innervate several muscle fibres
1 neuron + muscle fibres it innervates=motor unit
what is a sarcolemma?
invaginates into sarcoplasm to form membranous T tubules
continuous with extracellular space
what is a sarcoplasmic reticulum?
modified smooth ER
Ca2+ concentrated w/I SR`
what is the function of cardiac muscle?
specialised for continuous autonomous contractions
pump blood through CVS
what is the structure of cardiac muscle?
elongated, branched cylindrical cells
1 or 2 centrally located nuclei
striated
what is the macroscopic heart structure?
pericardium -outer supporting tissue layer myocardium -cardiac muscle tissue endocardium -single layer of endothelial cells
describe the histological structure of cardiac muscle
individual cardiac muscle fibres surrounded by reticular CT supports rich capillary network
specialised intercellular junctions (intercalated discs) anchor adjacent cardiac cells together
what are EM similarities between cardiac and skeletal muscle?
sarcomere arrangement T tubules sarcoplasmic reticulum numerous mitochondria glycogen & lipid granules sliding-filament mechanism
what are EM differences between cardiac and skeletal muscle?
autonomous (involuntary) SR-slowly leaks Ca2+ intercalated discs conducting system-modified cardiac cells modulated by external autonomic/hormonal stimuli
describe the conducting system of the heart
initiated at sinoatrial node L&R atria contract AV node AV bundle of his purkinje fibres cardiac muscle fibres
how does contraction of cardiac muscle occur?
intrinsic contractile ability -pacemaker cells(SAN) -slow release Ca2+ from SR rate modulated by: -autonomic nervous stimulation -hormonal stimulation
