ch.1: basic principles Flashcards
1790
Galvani- frog legs dance w/Electrical activity
1880
- Ludwig and Waller
- hearts rhythmic electrical stimuli on skin
- electrodes
1901
- Einthoven “godfather”
- invented EKG machine
T/F: EKG and ECG are different from each other?
False. Same thing different letter
What does an EKG do?
- record electrical activity in heart
- heart rate and rhythms
- depolarization and repolarization of <3 muscle
What is depolarization?
Contraction
What is repolarization?
Fill up, refill, relaxing, expanding
What are the 2 phases of the cardiac cycle?
Contraction and Relaxation
Myocytes
- Myocardial cells
- negatively charged @ rest
What happens to myocytes during depolarization?
They become positive resulting in contraction
What comes after a contraction?
Repolarization
What are intercalated discs?
allows myocardial cells to communicate and work in unison with each other and transmission of impulse from one to the next
What does SA node mean?
Sinus node or sinal atrial node
Where is the SA node located?
upper-posterior wall of right atrium
What is the dominant pacemaker called?
SA node
T/F: The SA node contracts both atria?
True. Right and Left. automatically
What does the SA node generate on EKG?
- “P” wave
- tells us atrium contracts
Where is the AV node located?
above trio-ventricular valves (floor of right atrium)
What does the AV node do?
- Electrical conduction between atria and ventricles
- allows for pause (flat line @ baseline) on EKG
- blood flow from atria to ventricles
What does the bundle of HIS do?
carries impulse from AV node to bundle branches
What makes up the ventricular conduction system?
- HIS bundle
- L/R bundle branches
- Purkinje fibers
What does the bundle of HIS generate on EKG?
produces the QRS complex
What is the inherent rate of the SA node?
60-100 bpm
What is the inherent rate of the Atria?
60-80 bpm
What is the inherent rate of the AV node?
40-60 bpm
What is the inherent rate of the ventricles?
20-40 bpm
What is the order of the electrical system of the heart?
- SA node
- AV node
- Bundle of HIS
- L/R branches
- Purkinje fibers
What is the ST segment?
- beginning phase of ventricular repolarization
- horizontal segment of baseline follows QRS complex
What is the T wave?
- rapid phase of ventricular repolarization and is full of blood
- follows QRS complex
what is the QT interval?
- beginning of Q wave and end of T wave
- duration of ventricular systole
- less than 1/2 of total R-R interval
What does overdrive suppression do?
tells atrial foci, AV node, and ventricles to not contract
how long should the QT interval be?
less than 1/2 the total R-R interval
what isn’t shown on an EKG?
cant see atrial repolarization on EKG bc its hidden in/during ventricle depolarization
What makes up the QRS complex?
the HIS bundle
What is the order of inherent heart rate?
- SA node
- atria foci (1st backup)
- AV node (2nd backup)
- ventricles (purkinje, 3rd backup)
