cardiac cycle/heart sounds Flashcards
driving force in cvs
heart
distribution vessels in cvs
arteries
exchange vessels in cvs
capillaries
reservoir for blood in cvs
veins
why is a cvs needed
diffusion slow over x >1mm
what does the SAN create
pacemaker potentials
Phase 0 of A/V AP’s
RAPID DEPOLARISATION:
vg NA channels
Na influx
VGCCs start to open slowly
Phase 1 of A/V AP’s
EARLY REPOLARISATION
Na channels close
Phase 2 of A/V AP’s
PLATEAU PHASE
VGCCs fully open - Ca influx
K channel starts to open slowly
Phase 3 of A/V AP’s
RAPID REPOLARISATION
VGCC channels close
K channels open fully - K EFFLUX
Phase 4 of A/V AP’s
RESTING PHASE
Normal action of Na-K pump
Membrane impermeable to Na
Membrane permeable to K
Where is electrical activity first generated
SAN
What does contraction of myocardium generate
pressure changes within chambers
valves open and close depending on what
pressure changes in chambers
blood flow from venous return to pulmonary circulation
SVC, IVC RA tricuspid RV pulmonary semilunar valve pulmonary arteries lung circulation
blood flow from pulmonary to systemic circulation
lung circulation pulmonary veins LA mitral valve LV Aortic semilunar valve aorta Systemic circulation
step 1 electrical conduction
electrical activity generated at SAN spreads out via gap junctions