cardiac muscles can conduct nervous impulses known as
action potentials
what value is given to resting membrane potential
-90mv
define depolarisation
response in muscle cells causing contraction- one cell can stimulate a wave of adjoining cells to contract
define repolarisation
the depolarised cell returning to resting potential and getting ready for next contraction
what are the 3 phases of an ECG
p phase, QRS phase and T phase
what occurs at p phase
arterial depolarisation
what occurs at the QRS phase
ventricular depolarisation
what occurs at the t phase
ventricular repolarisation
when does arterial repolarisation occur
also during QRS complex but too small to be noticeable compared to the ventricular depolarisation
explain the 6 stages of an ECG, beginning with the p stage
- p- sa node sends impulse across atria, they contract(depolarise) 2. interval- impulse stops at av node allowing for all blood to drain into ventricles 3. QRS- impulse passed onto ventricles, ventricular depolarisation occurs at apex and atrial repolarisation is complete. 4. interval- ventricular depolarisation complete and starts to repolarise. 5. T- ventricular repolarisation begins at apex 6. interval- repolarisation complete and cycle repeats with atria filling with blood and sa node ready to release impulse
which nervous system regulates HR
autonomic nervous system
if somebody is experiencing >100 bpm what would the condition be called
Tachycardia
if somebody is experiencing <60 bpm what would their condition be called
bradycardia
what is the common word used for myocardial infarction (MI)
heart attack
