cardiac muscle Flashcards
what is the flow of blood in the heart called?
closed circuit
superior + inferior vena cava carry ______ O2 blood to the _____ atrium
low; right
blood flows from right atrium through the _____ valve to right ventricle
tricuspid (right AV)
when the right ventricle contracts, where does blood go?
pulmonary trunk/arteries to lungs
what separates the right ventricle from the lungs?
pulmonary semilunar valve
where does oxygenated blood return to?
left atrium
blood flows from left atrium through the ____ valve to left ventricle
bicuspid (mitral/left AV)
when the left ventricle contracts, where does blood go?
ascending aorta to the rest of the body
what separates the left ventricle from the aorta?
aortic semilunar valve
what happens at the capillaries
O2 moves into tissues and CO2 moves out
atria
upper/receiving chambers
ventricles
lower, discharging chambers
atrial syncytium
all atrial muscle fibers depolarize + contract together. act as a weak primer pump
ventricular syncytium
all ventricular muscle fibers depolarize + contract together. main pumping force of blood
ventricular systole
period of ventricular muscle contraction
ventricular diastole
period of ventricular muscle relaxation
atrial systole
period of atrial muscle contraction
atrial diastole
period of atrial muscle relaxation
excitatory + conductive fibers
generate + carry electrical signals through cardiac muscle
what is the order of where an AP goes in the heart?
SA node > AV node > bundle of his (AV bundle) > bundle branches > purkinje fibers
intercalated discs
cells membranes that separate individual cardiac muscle cells and are connected to each other
desmosomes
physically joins adjacent myocardial cells together to prevent them from pulling apart
gap junction
electrically joins myocardial cells togehter
fascia adherens
anchoring site for actin filaments
fibrous skeleton
connective tissue framework that separates/insulates the atrial syncytium from ventricular syncytium
functional syncytium
all of the cells within a network contract simultaneously
what is considered to be the pacemaker of the heart?
sinoatrial (SA) node
why is the SA node considered to be the pacemaker of the heart?
because of its leaky sodium channels
what causes nodal action potentials
leakage of sodium in until threshold is reached
what happens at threshold?
voltage gated calcium channels open + calcium rushes IN
sympathetic stimulation of cardiac muscle
norepinephrine activates beta-1 on SA node to increase heart rate
parasympathetic stimulation of cardiac muscle
ACH binds to muscarinic cholinergic receptors on SA node to slow heart rate down
Phase 4 of cardiac action potentials
Resting membrane potential
Phase 0 of cardiac muscle action potential
Upstroke or depolarization
Phase 1 cardiac muscle action potential
Initial repolarization
Phase 2 of cardiac action potentials
Plateau
Phase 3 of cardiac action potentials
Final repolarization
Phase 4 characteristics
-85 to -90 mV. Na+/K+ pump and K+ leak channels
Phase 0 characteristics
Depolarization. Na+ rushes in through voltage gated channels
Phase 1 characteristics
Initial repolarization. K+ leaves the cell
Phase 2 characteristics
Plateau. Open Ca2+ channels. Ca2+ in and K+ out
Phase 3 characteristics
Final repolarization. All K+ channels open. K+ leaves the cell
