Intro And Electrophysiology (Lauren) Flashcards
what are the layers of the pericardial sac?
Parietal- outer fibrous layer
Visceral- inner layer
Pericardial fluid- lubricates the 2 layers
What are the 3 layers of the heart wall?
Epicardium- thin serous membrane on outer surface
Myocardium-muscular middle layer
Endocardium- thin serous membrane lining inner chambers
What are the 2 types of cells in the heart?
Myocardial cells with contractile ability
Conducting cells- pacemakers and the electrical conducting cells (bundle branches and purkinje fibers)
What are the points of contact between two myocardial cells called?
Intercalated discs
______ _________ in the intercalated disks permit rapid conduction of electrical impulses from one cell to the next
Gap Junctions
Myocytes all contract together as a single unit when stimulated. _________ hold the cells together during contraction
Desmosomes
What is the structure that electrically insulates the atria from the ventricles?
The cardiac skeleton/plate of fibrous connective tissue
Cardiac output= ______ X ______
CO= HR x SV
Where are baroreceptors located
Aorta
Carotid
The parasympathetic nervous system (slows/raises) the heart rate using (acetylcholine/epinephrine)
Slows
Acetylcholine
What are the 4 key properties of myocardial cells?
Automaticity- ability of certain cells to produce an electrical impulse independently
Excitability- ability to respond to an electrical stimulus
Conductivity- ability to transmit an electrical stimulus from cell to cell
Contractility- ability to contract when electrically stimulated
she had this in red
The ________ is the heart’s primary pacemaker, and its intrinsic rate is ____-____bpm.
SA node
60-100
The _________ acts as a ~gatekeeper~ for impulses reaching the ventricales by conducting impulses more slowly
AV node
***she said this like 3278y56789346 times
The (left/right) bundle branch branches into anterior and posterior fascicles to reach even father
Left
The intrinsic rate of the Purkinje fibers is _________ bpm
20-40
The intrinsic rate of the AV node is ______-______bpm
40-60
The polarized/resting state of myocardial cells consists of _______ charged ions inside the cell and ______ charged ions outside the cell
Negatively inside
Positively outside
The ________ _______ ________ is the difference in electrical charge between inside and outside the cell
Resting membrane potential
Which ions enter the cell when it is depolarized?
Na+
Ca++ (enter more slowly)
What is the absolute refractory period’/
After depolarization, the cell can not be depolarized again, no matter what
What is the purpose of the absolute refractory period?
Keeps wave of depolarization moving forward
Prevents spasms in one area
What is the relative refractory period?
In the late phase of depolarization, a very strong stimulus will cause depolarization
________ leads have electrodes of opposite polarity (positive and negative)
Bipolar
Which leads are bipolar?
Limb leads- I, II, III
Unipolar leads have only a (positive/negative) electrode and a reference point determined by the ECG machine
Positive
Movement toward a positive electrode will cause a ________ waveform
Positive
What is the difference between vectors and the axis?
Vectors: many small electrical currents in various directions
Axis: overall direction of the sum of the vectors
Which leads give you a view of the frontal plane of the heart?
Limb leads I, II, III
aVR
aVF
Which leads give you a view of the horizontal plane of the heart?
Precordial (Chest) leads V1 to V6
The _____ wave represents atrial depolarization
P
The _____ wave represents ventricular depolarization
QRS
The _____ Wave represents ventricular repolarization
T
Atrial repolarization is hidden in the ______ wave
QRS
