Lecture 1 Flashcards
Stroke volume
volume of blood ejected by the left ventricle after one contraction. SV=EDV-ESV
Pericardium
composed of two layers, the fibrous pericardium and the serous pericardium.
fibrous pericardium
dense, irregular connective tissue that protects and anchors the heart which prevents overstretching.
serous pericardium
thin, delicate membrane that consists of the parietal layer (outer layer), pericardial cavity that’s filled with pericardial fluid and the visceral layer.
Other functions include prevention of displacement, providing physical barrier against infection and inflammation, and having pain and mechanoreceptors to elicit changes.
EDV
volume of blood in the right and/or left ventricle at end load or filling in diastole
Ejection fraction
measurement of the percentage of blood leaving your heart each time it contracts, which is usually 55 to 75%.
EF=SV/EDV
Cardiac index
better indicator of cardiac function.
CI= CO L/min /body surface area
Cardiac output
normally 3.5 to 8 L per min, maximum is 20 to 30 L per min.
CO = HR X SV
Frank Starling’s law
increase in EDV increases stretching (Preload) which increases stroke volume.
Factors that affect stroke volume
preload, contractility, and afterload
Myocardial contractility
increase in strength of contraction that increases stroke volume. Epinephrine and calcium ions increase contractility.
Preload
dependent on EDV and 2 facts effect EDV. First, venous return or venous pressure and second, the duration of diastole.
Afterload
ventricular wall tension
La Place formula
Wall Tension = (Intraventricular pressure x Radius)/ Ventricular wall thickness
How does arterial pressure affect afterload?
Increase in arterial pressure increases resistance to ventricular ejection