Disorders of Cardiac Function Flashcards
What is the Pericardium?
3-layer sac surrounding heart.
What is the Myocardium?
middle layer of striated muscle made of sarcomeres.
What is the Endocardium?
innermost heart lining.
How does the myocardium work?
Cells contain many large mitochondria for energy to pump continuously.
Forms atria and ventricles.
Cardiac muscles require calcium for contraction.
How does the endocardium function?
Outer layer of the endocardium contains blood vessels and some nerve fibers of the cardiac conduction system.
What do the valves of the heart do?
Valves promote antegrade (forward direction) blood flow.
Separate atria and ventricle chambers.
What are the two valves?
Semilunar valves
Atrioventricular valves
What are the components of
Atrioventricular valves/ what do they do?
Mitral valve (bicuspid) and tricuspid valve
Prevent retrograde (backward direction) blood flow from ventricle into atria
What are the components of
Semilunar valves/ what do they do?
Pulmonic and aortic valves
Prevent retrograde (backward direction) blood flow into ventricles
What is preload?
Ventricular filling is the amount of blood the heart must pump with each beat.
Determined by venous return to heart and accompanying stretch of cardiac muscle fibers.
What is afterload?
Resistance to ejection of blood from heart.
Narrowed arteries or stenotic heart valve increases afterload.
Arterial blood pressure is the main source of afterload on left side heart
Pulmonary arterial pressure main source of afterload in right side heart
What is cardiac contractility?
Ability of heart to change force of contraction without changing resting length (diastole).
What is heart rate?
Frequency when blood is ejected from heart usually specified as beats per minute.
What is the importance of cardiac output? What is the equation for cardiac output?
The heart continuously attempts to maintain adequate cardiac output to provide oxygen and nutrients for all cells.
Cardiac output = heart rate × stroke volume
What is stroke volume? What is the equation of stroke volume?
Stroke volume is the amount of blood ejected with one heart beat.
Stroke volume = cardiac output / heart rate
What does stroke volume include?
Stroke volume includes preload, afterload, and cardiac contractility
What is the Frank-Starling Mechanism or Starling Law of the Heart?
Increased force of contraction that accompanies an increase in the volume of blood in the ventricles.
Tension and force of contraction is related to the degree the muscle fibers are stretched just before ventricles begin to contract.
What is the Frank-Starling Mechanism?
An increase in resting muscle fiber length will produce a more forceful cardiac contraction
What is the tipping point in the Frank-Starling Mechanism? What can it result in?
The heart muscle (myocardium) loses elasticity as it works harder and harder to try to maintain adequate cardiac output.
The result is heart failure.
What object can be related to the Frank-Starling Mechanism?
A rubber band when a pulling action is inhibited.
What is the Right Coronary Artery?
Supplies the right atrium, right ventricle, and part of the wall of left ventricle
What is the Left Coronary Artery (2 branches)?
Left Anterior Descending (LAD)
Left Circumflex Artery (LCA)
What’s a question we’d need to know about the heart?
Is the myocardium (muscle layer) of the heart receiving adequate blood supply?
What are some questions we need to know about the individual?
Is the heart size normal?
Is the heart contracting normally?
Is cardiac output adequate to supply blood throughout the body?
What can occur in the individual with inadequate blood supply to the myocardium?
What does the nurse assess for as indicators of adequate cardiac output?
What assessment findings can occur with decreased cardiac output?
What influences myocardial oxygen supply? (There is 5)
Blood flow through coronary arteries and capillaries to the myocardium
Oxygen intake through the respiratory tract
Red blood cell count
Oxygen content of hemoglobin
Hemoglobin ability to release oxygen
Low level of which electrolyte decreases hemoglobin release of oxygen ?
Phosphorus
What is Myocardial Oxygenation?
Identify conditions that can cause decreased myocardial oxygen supply (MVO2)
Identify factors that can cause increased myocardial oxygen demand