Force Generation Flashcards
how are cardiac myocytes coupled?
electrically via gap junctions
what provides mechanical adhesion between adjacent myocytes?
desmosomes
what is the contractile unit of muscle?
myofibrils
what produces muscle tension?
sliding of actin filaments over myosin filaments
what is required for muscle contraction and relaxation?
ATP
what is needed to switch on cross bridge formation?
calcium ions
what are the two regulatory proteins found on actin?
tropomyosin
troponin
what needs to occur to allow cross bridge formation?
conformational change in actin
caused by calcium binding to troponin
where are calcium ions normally stored?
sarcoplasmic reticulum
what is the release of calcium from the SR in cardiac muscle dependent on?
the presence of extracellular calcium
what does the refractory period prevent?
generation of tetanic contraction
what is the refractory period?
a period following an action potential in which it is not possible to produce another
what is the stroke volume?
the volume of blood ejected by each ventricle per heartbeat
how do you calculate SV?
end diastolic volume (EDV) - end systolic volume (ESV)
what does the frank starling mechanism describe?
relationship between venous return, EDV and SV
higher the EDV = higher SV
