Stuff to know Flashcards
Phase 1 (Initial Rapid Repolarization)
Na+ quits flooding into the cell, Ca+ continues to enter slowly
cell begins to become neutral, starts to drop to 0 mV
This completes the QRS complex
Phase 0 (Electrical Excitement)
Ventricular depolarization (beginning of QRS complex) Na+ floods quickly into cell, Ca+ moves slowly into cell Cell becomes positive on the inside and negative on the outside
Phase 2 (Plateau Stage)
Ca+ continues to enter cell, slowing down repolarization
Na+/K+ pump begins moving Na+ out and K+ into the cell
This is represented by the ST segment
Phase 3 (Repolarization)
Na+/K+ pump kicks it into gear, repolarizing the cell
This is represented by the T wave
Phase 4 (Recovery Period)
Cell is at rest and prepared for another depolarization
Inside of the cell has a negative charge and the outside has a positive charge
EKG returns to the isoelectric line
When is Absolute Refractory Period
Na+ channels are closed
No stimulus can initiate an action potential
Occurs during phases 0-2
When is Relative Refractory Period
A stronger than normal stimulus can cause an action potential to occur early
Occurs during phase 3
Vulnerable period = time when a small stimulus could cause and action potential
Causes R on T phenomenon
Action potential
the stimulation of myocardial cells by a change in the membrane electrical charge that subsequently spreads across the myocardium
Transmembrane Action Potential (TAP)
the line recorded on the EKG
Threshold Potential (TP)
the point at which depolarization will automatically occur
what mV is the baseline of an EKG at
-90 mV
At what mV will a cell depolarize no matter the stimulus
-60 mV
what does the QRS complex peak at
+20 to 30 mV
Name off how the blood flows through the heart
Inferior / Superior Vena Cava->Right Atrium->Tricuspid Valve->RIGHT Ventricle->Pulmonic (Semilunar) Valve->Pulmonary Arteries->Lungs->Pulmonary Veins->Left Atrium->LEFT Ventricle-> Mitrial (Bicuspid) Valve->Left ventricle->Aortic (Semilunar) Valve->Aorta->Systemic Circulation
Thin innermost layer
Endocardium
Thick muscular layer
Myocardium
Thin outer layer
Epicardium
Sac that surrounds the heart
Pericardium
How many cc’s of fluid is in the Pericardial Cavity
25 cc’s of fluid between the Pericardium and the Epicardium
What is the top of the heart called
BASE
What is the bottom of the heart called
APEX
When is the heart contracting
Systole
When is the heart relaxing
Diastole
Why is diastole longer than systole
to allow the ventricles enough time to fill
What side is the TRIcuspid valve
think TRI (as in RIght) there are three lung lobes on the right as in Tricycle
What side is the MitraL valve
L for the Left side (Bicuspid) Bicycle
The AV valve that has 3 “cusps” for the same number of lobes on that side
The Tricuspid Valve
The AV valve that has 2 “cusps” on that side for the same number of lung lobs
Bicuspid (MITRAL VALVE)
When the AV valves close
ventricles are in systole
When the semilunar valves close
the atria are in systole
What is preload
Volume entering ventricles
What is Afterload
resistance left ventricles must overcome to circulate blood
what is the pressure in the ventricles at the end of diastole
Preload
What is Afterload
resistance of the periphery
What is contractility
the ability to contract
What is Starling’s Law
Preload and afterload effect contractility
What causes a lot of work for the left ventricle, enlarging it so it can’t keep up
Hypertension
What drugs effect the contractility of the heart
Inotropic
Properties of a cardiac cell
Automaticity
initiates its own impulse
Properties of a Cardiac Cell
Rhymiticity
keeps the beat
Properties of a Cardiac Cell
Conduct impulse to cell
Conductivity
Properties of Cardiac Cell
Ability to contract
Contractility
*not seen on the monitor because it is mechanical not electrical
what is the term for electrical activity
Heart Rate
What is the term for mechanical activity
Pulse Rate (what we get when we check the pulse)
Heart rate and pulse rate are not interchangeable true or false
true. they do not mean the same thing
What is the first wave on an EKG represent
the P Wave lets you know the SA node is firing
depolarization of the atria (atrial contraction)
if the P wave is absent what becomes the next pacemaker?
AV node (40-60 BPM)
what does it mean when the P wave ends
atrial depolarization is likely complete
Polorized
the cell is charged but resting, the membrane is not permeable, and current is not flowing
Depolarized
the cell is discharging, the membrane is permeable and current flows
Repolarized
the cell is working to recharge, the cells membrane is permeable
Angina
exertion induced pain caused by myocardial ischemia, substantial pain, radiating to arms, jaw, back
lasts 3-5 minutes
goes away with rest, is the same episode to episode
can lead to injury and infarction
Unstable Angina (USA)
Angina that changes in intensity, frequency, duration
symptoms occur at rest
last 20 minutes or longer
severe or new onset “its different then my usual pain”
Unstable Angina (USA)
Acute ischemic event without tissue death
Non Q wave MI (NQMI)
Acute ischemic event with tissue death, no Q wave develops on EKG
Q-Wave MI (QMI)
Acute ischemic event with tissue death, Q-wave develops on EKG, tend to be larger infarcts
