Definitions Flashcards
(27 cards)
Autorhythmicity
beating rhythmically in absence of external stimuli
sinus rhythm
heart controlled by sino-atrial node
normal resting heart rate
60-100 bpm
bradycardia
resting heart rate of less than 60 bpm
tachycardia
resting heart rate of more than 100 bpm
chronotropic effects
those that change heart rate
myocardium
muscular tissue of the heart
K+ conductance
opening and closing of channels allowing K+ in/out of the cell
inward rectifier K+ channels
little K+ out the cell, large influx of K+
Ik1
hyperpolarising outward current of K+ ions via Kir channels
plateau phase (action potentials)
Membrane potential maintained near the peak of action potential
for a few hundred milliseconds
AP
action potential
pacemaker potential
slow depolarisation of membrane potential towards a threshold
phase 0
rising phase in action potential
phase 4
resting membrane potential
Gk
K+ conductance
Ito
current transient outward
gap junctions
protein channels that form low resistance electrical comm pathways between myocytes
refractory period
period following an AP in which it isn’t possible to produce another AP
stroke volume (SV)
volume of blood ejected by each ventricle per heart beat
afterload
resistance into which heart is pumping
cardiac output (CO)
volume of blood pumped by each ventricle per minute
diastole
heart ventricles relax and fill with blood
systole
heart ventricles contract and pump blood into the aorta (LV) and pulmonary artery (RV)
