Cardiovascular system Flashcards
How many circuits does the cardiovascular system have? What are their functions?
Two circuits: Pulmonary and systemic.
Pulmonary transports deoxygenated blood to lungs.
Systemic transports oxygenated blood to the rest of the body.
Which system has the highest pressure?
Systemic system - high pressure needed to keep unidirectional flow.
How many chambers does the heart have? Describe the direction of flow through them.
Four chambers: Left atrium, left ventricle, right atrium, right ventricle.
Blood flows from superior & inferior vena cava to right atrium, through to right ventricle and out the pulmonary artery to the lungs. Oxygenated blood flows back through pulmonary veins to left atrium, then to left ventricle and out of the aorta to the rest of the body.
Which chamber of the heart is the most muscular? Why?
Left ventricle - Needs more strength to work against a high pressure.
How many valves does the heart have? Where are they located?
Four valves: Two atrioventricular (AV), two semi-lunar. Right AV valves are tricuspid, left are bicuspid. The two semi-lunar valves are the pulmonary and aortic.
AV valves are between the atriums and ventricles. Semilunar valves are between ventricle and aorta/pulmonary artery.
Why are valves important?
Valves prevent the backflow of blood between chambers, and maintain a unidirectional blood flow.
What is the function of papillary muscles?
They control the opening and closing of valves, and they prevent backflow or prolapse of valves. Only AV valves have chordae tendineae.
Describe the anatomy of the pericardium.
A fluid-filled sack surrounding the heart for protection.
Outer fibrous pericardium: Tough, rigid connective tissue preventing overfilling of heart.
Inner serous pericardium: Within the the fibrous pericardium divided into two layers
Parietal layer: outer wall of serous pericardium
Visceral layer: Inner wall layering on the heart.
The pericardial cavity is between the two serous layers and is filled with fluid
Describe the coronary arteries.
Coronary arteries transport oxygenated blood to the heart muscle, wrapping around the heart
Which valves open during systole and diastole?
During ventricular systole, the AV valves are closed and semilunar valves are open.
During diastole, semilunar valves are closed and AV valves are open.
What is stroke volume?
The amount of blood pumped out by the heart per beat.
How would an increase in venous return increase cardiac output (CO)?
An increase in venous return will increase End Diastolic Volume (EDV), therefore influencing the stroke volume used to calculate cardiac output(CO). CO is a results of heart rate (b/pm) multiplied by stroke volume (blood per beat).
What are the first, second, third, and fourth heart sounds a result of?
First: Two bursts of vibrations (turbulence) due to sequential closure of AV valves.
Second: Vibrations due to closure of aortic & pulmonary valves (SL).
Third: End of rapid filling - recoil of blood from ventricular wall.
Fourth: Coincides with atrial contraction. Normally not heard.
Define EDV and ESV.
EDV=End Diastolic Volume: volume of blood in ventricle before contraction.
ESV=End Systolic Volume: volume of blood in ventricle after contraction.
Stroke volume equation.
Stroke volume (SV)=End Diastolic volume (EDV) - End Systolic volume (ESV)
