Heart lecture

P Wave

SA and atria depolarization

QRS complex

ventricular depolarization, begin to contract

T wave

ventricular repolarization

P-R interval

beginning of atrial excitation→ beginning of ventricular excitation

S-T segment

entire ventricular myocardium depolarized

Q-T interval

beginning of ventricular depolarization → ventricular repolarizarion

Arrhythmias

irregular heart rythyms

Fibrillation

rapid/irregular contractions, circulation ceases - used defibillator to interupt twitching

Ectopic focus

SA node goes bad (abnormal pacemaker), AV node can takeover BUT heartbeat changes to 40-60 bpm

Extrasystole

Premature contraction- ectopic focus of small region of heart that triggers impulse before SA node can which delays next impulse

Typically caused by too much caffiene or nicotine

What happens if the AV node is blocked?

Heart block: fewer impulses go through, going to need a pacemaker

Systole

heart contraction

Diastole

heart relaxation

Cardiac cycle

blood flow through heart during one complete heartbeat