Ch. 16 Flashcards
___________ is the product of heart rate and stroke volume and is the vital event necessary to maintain blood flow through the cardiovascular system.
Cardiac Output
Systolic pressures greater than ____ mm Hg generally ensure adequate perfusion of tissues
90
The ventricles will fill with blood during _____ (at rest) and eject blood into the pulmonary artery and aorta during ______.
diastole
systole
Regarding the electrocardiographic tracing, all of the following are true EXCEPT:
a. repolarization of atrial muscle cells is represented by the P wave.
b. the QRS-complex represents depolarization of ventricular muscle cells
c. the S portion of the QRS complex represents a return to the baseline (isoelectric point).
d. the U wave is theorized to represent repolarization of the papillary muscles and Purkinje fibers
a. repolarization of atrial muscle cells is represented by the P wave.
When multiplying heart rate times stroke volume, the produce is:
cardiac output
Depending on the cause and severity of an arrhythmia, treatment may include which of the following?
a. cardiac pacemakers or ICD devices
b. ablation therapy
c. cardioversion external shock therapy
d. all of the above might be useful in treating an arrhythmia
d. all of the above might be useful in treating an arrhythmia
Rhythmic contraction and relaxation of the chambers of the heart are controlled by principal cell types to include which of the following?
1. working cardiac cells
2. specialized neural conductive cells
3. striated muscle cells
a. 1, 2
b. 1, 3
c. 2, 3
d. 1, 2, and 3
a. 1, 2
All of the following are true of atrial fibrillation EXCEPT:
a. it is always fatal
b. it is caused by additional ectopic pacemaker firings in the atria that exceed SA node firings.
c. the atria syncytium quivers instead of fully contracting.
d. formation of atrial emboli is a potential complication
a. it is always fatal
To ensure a normal sequence for each cardiac cycle, each P wave should be followed by a:
QRS Complex
When the resting membrane potential is reversed, ______ occurs and myocardial cells are stimulated to contract.
Depolarization
All of the following are visible on an ECG tracing EXCEPT:
a. depolarization of atrial muscle
b. atrial contraction
c. depolarization of ventricular muscle
d. repolarization of ventricular muscle
b. atrial contraction
For analysis of an ECG tracing, which of the following below indicates regular rhythm?
1. QRS complexes (RR intervals) are consistent for evaluating ventricular rhythm.
2. The duration of the QRS complex exceeds 0.20 seconds (five small squares on the ECG)
3. Intervals between P waves (PP intervals) are consistent for atrial rhythm.
a. 1, 2
b. 1, 3
c. 2, 3
d. 1, 2, and 3
b. 1, 3
Action Potential
Processes of depolarization and repolarization of the cardiac membrane
Arrhythmia
Irregularity of cardiac actions associated with psychologic or pathologic interruption of the neuro conductive tissues of the heart (also synonymous with dysrhythmia)
Automaticity
Process whereby cardiac cell membranes spontaneously depolarize at recurrent periods
Asystole
There is no evidence of any cardiac neuro conductive activity (full cardiac arrest)
Bradycardia
Slowness of the heartbeat as evidenced by slowing of the pulse rate to less than 60 beats per min
Cardiac Cycle
Events that occur from the beginning of one ventricular contraction (systole) until the beginning of another
Cardiac Output
Amount of blood ejected from the ventricles each minute; calculated as the product of stroke volume times heart rate
Depolarization
Myocardial cells are stimulated to contract
Fibrillation
Quivering concentration of cardiac muscle fibers
Repolarization
Myocardial muscle cells relax
Tachycardia
Heart rate above 100 beats/min
What is observed from an ECG or an electrocardiogram?
The action potentials of the atrial and ventricular muscle cells
The SA node is also known as ____ of the heart.
the pacemaker
Summary of Events of a Cardiac Cycle:
Only three are observed on an ECG.
1) SA Node fires (not visible on EKG)
2) Depolarization of atrial muscle: P Wave
3) Atrial contraction (not visible on EKG)
4) Depolarization of AV node (not visible on EKG)
5) Repolarization of atrial muscle (not visible on EKG)
6) Depolarization of ventricular muscle (QRS Complex)
7) Contraction of ventricular muscle (not visible)
8) Repolarization of ventricular muscle: T Wave
What is one of the most common cardiac arrhythmias?
Atrial Fibrillation
What are some common treatments of cardiac arrhythmias?
Drug Therapy
External Shock Therapy
Pacemakers and ICDs
Diastolic pressures greater than ____ mm Hg generally ensure adequate perfusion of tissues
60
Resting membrane potential is maintained by an active transport mechanism called the _______
Sodium potassium ion pump
What is observed on an ECG tracing?
action potentials of the atrial and ventricular muscle cells
Represents depolarization of atrial muscle cells on an EKG is the:
P Wave; SA Node fires
Represents depolarization of ventricular muscle cells on an EKG is the:
QRS Complex
Repolarization of ventricular muscles on an EKG is the:
T Wave
Represents repolarization of the papillary muscles and Purkinje fibers:
U Wave
Each cardiac cycle begins with a spontaneous neural impulses generated by the ____
SA Node
The depolarization period is ____
Short
Mediastinal drains (small chest tubes) are used after _____
Cardiac Surgery, to drain residual blood from the mediastinum
