Med-Surg Ch. 32 Cardiovascular System Flashcards
What are the three layers of the heart and the surrounding sack called?
Inner: Endocardium
Middle: Myocardium
Outer: Epicardium
Surrounding sack: Pericardium
What are the inner and outer layers of the pericarial sac called?
Inner - visceral layer
Outer - parietal layer
What lubricates the parietal space between the epicardium and the pericardium?
Paricardial fluid (approximately 10 to 15 mL)
What are the four valves in the heart called?
Mitral, Tricuspid, Pulmonic, and Aortic
True or false: Blood flows into the heart’s two main coronary arteries during systole (contraction of the myocardium)?
False
Blood flows into the coronary arteries during diastole (relaxation of the myocardium)
What are the two main branches of the left coronary artery called? What parts of the heart to they supply blood to?
The left anterior descending artery and the left circumflex artery.
They supply blood to the left atrium, the left ventricle, the interventricular septum, and a portion of the right ventricle
Which coronary artery often causes the more serious defects in cardiac conduction when blocked?
The right coronary artery (because it supplies blood to the AV node and the bundle of His in 90% of people)
True or false: The “coronary sinus” is a large channel that empties blood from the coronary veins into the right atrium?
True
What is the electrical impulse that travels through nerve tissue to trigger a contraction called?
An action potential
What do the following waves of the electrocardiogram (ECG) signify:
- ) P wave
- ) QRS complex
- ) T wave
- ) U wave (if present)
- ) P wave: Depolarization of the atria
- ) QRS complex: depolarization of the AV node throughout the ventricles
- ) T wave: Repolarization of the ventricles
- ) U wave: Either repolarization of the Purkinje fibers or associated wtih hypokalemia.
What is systole?
Contraction of the myocardium, resulting in ejection of blood from the ventricles.
What is diastole?
Relaxation of the myocardium, allowing blood to fill the ventricles.
What is cardiac output? What is the equation that equals cardiac output?
The amount of blood pumped by each ventricle in 1 minute.
CO = Stroke volume x Heart Rate
What is the cardiac index?
The CO divided by the body surface area (BSA). This number adjusts to changes in body size. Normal CI is 2.8 to 4.2 L per minute per meter squared.
What factors can affect cardiac output?
- ) HR
2. ) SV (affected by preload, contractility, and afterload)
What is the Frank-Starling law that applies to cardiac output?
To a point, the more the myocardial fibers are stretched, the greater their force of contraction. Defines “preload”, “contractility”, and “afterload”
What is preload?
The volume of blood in the ventricles at the end of diastole, before the next contraction. Determines the amount of stretch placed on myocardial fibers.
*Can be increased by conditions such as MI, aortic stenosis, and hypervolemia.
What increases contractility of the heart? What effect does an increase in contractility have?
Contractility can be increased by epinephrine and norepinephrine. Increasing contractility raises the SV by increasing ventricular emptying.