20.1-20.5 Flashcards
Pathway of the Cardiac Action Potential
Sinoatrial node, atrioventricular node, atrioventricular bundle, right and left branches, purkinje fibers
Radiate action potential upside the heart
Purkinje Fibers
100BPM; main pacemaker of the heart
Sinoatrial node
Cardiac Action Potential
Depolarization, Plateau, Repolarization
Open voltage-gated Na channels; leaky potassium channels. -90mv
Depolarization (first step of cardiac Action Potential
Caused by calcium inflow, slow Ca channels opening and K is released out when K channels open
Plateau (second step of cardiac action potential)
Closure of Ca channels and K outflow when additional K channels open
Repolarization (last step of cardiac Action potential)
Recording of electrical signals; Composite record of Action potentials produced by all of the heart muscle fibers during each heart beat
Electrocardiogram ECG
Represents atrial depolarization, which spreads from the SA node through contractive fibers in both atria
P Wave
Where a controlled contraction begins; systole
PR Interval
Delay between SA node and AV node
PQ interval
Represents rapid ventricular depolarization; precedes contraction
QRS complex
When ventricular contraction happens
S-T segment
Ventricular Repolarization, causing relaxation
T wave
Degree of stretch on the heart before it contracts
Preload
Forcefulness of contraction of individual ventricular muscle fibers
Contractility
Pressure that must be exceeded before ejection of blood from the ventricles can occur
Afterload
Phase of contraction
Systole
Phase of relaxation
Diastole
Heart sound when tri and bi closes
S1
Heart sound when Aortic valve closes
S2
How much blood leaves the heart each minute
Cardiac Output
Difffence between maximum cardiac output and cardiac output at rest
Cardiac reserve
More stretch, more contraction
Frank-Starling Law of the Heart
