refers to rupture of an atheromatous plaque in a diseased coronary artery, which rapidly forms an obstructive thrombus.
The amount of blood pumped by each ventricle during a given period. (Resting adult is usually 5L/min of blood.)
How is cardiac output computed?
Multiply Stroke Volume (SV) and Heart rate.
the amount of blood ejected from the heart per heartbeat.
What is the average resting stroke volume?
70 mL, and the heart rate is 60-80 bpm.
What are baroreceptors and their purpose?
Baroreceptors are specialized nerve cells located in the aortic arch and right and left internal carotid arteries. When hypertension occurs the baroreceptors transmit impulses to the cerebral medulla to initiate a parasympathetic response, lowering BP and HR. If hypotension occurs impulses transmit and again to initiate a sympathetic response vasoconstricting and increasing HR to elevate BP.
3 factors that stroke volume is determined?
Preload, Afterload, and contractility.
Preload is the degree of stretch of the ventricular cardiac muscle fibers at the end of diastole. the volume of blood within the ventricle at the end of diastole determines preload.
How can Preload become decreased?
It becomes decreased by a reduction in the volume of blood returning to the ventricles. Diuresis, venodilating agents(nitrates), excessive blood loss, dehydration through vomiting, diarrhea, or diaphoresis.
Resistance to ejection of blood from the ventricle.
the force generated by the contracting myocardium. Contractility is enhanced by circulating catecholamines, sympathetic neuronal activity, and certain medication: digoxin, dopamine, or dobutamine.
the percentage of the end-diastolic blood volume that is ejected with each heartbeat. The ejection fraction of the normal left ventricle is 55-65%. This is used to measure myocardial contractility.