Heart 1 Flashcards
What is the main job of the right atrium?
is to receive deoxygenated blood via superior and inferior vena cavae and the coronary sinus (venous blood from heart) and pump it to the right ventricle
What valves exist to keep blood from entering the atrium?
None. There are no valves to keep blood from entering the atrium
Venous blood begins to accumulate in the atrium as the ventricles contract, during ventricular systole
T or F. The right atrioventricular valve (A-V valve) is closed during ventricular systole
T. However, when ventricular muscles relax at the end of ventricular systole, the A-V valve opens up and roughly 80% of the blood that will enter the ventricle flows in directly even before the atria contract.
What causes the roughly 20% additional increase in the blood volume pumped into the right ventricle?
Atrial systole
What happens if the atriums fail to contract correctly?
The atrium doesn’t have to pump blood very far and the primary pressure that has to be overcome by the right atrium is the stretching of the left ventricular musculature.
Even if the atrium fails to contract, a fair amount of blood will get to the right ventricle and lungs. In fact, the person may not even notice there is a problem until they exercise.
What is the job of the right ventricle?
to pump blood through pulmonary arteries into the lungs and back to the left atrium via pulmonary veins
Which musculature is thicker, the right atrium or the right ventricle?
right ventricle
Still, it is a relatively low pressure system
The right AV valve is also known as what?
the tricuspid valve
What valve closes when the right ventricle contracts? Why?
the right AV valve (tricuspid valve) closes, to prevent ‘back flow’ and to allow the atrium to fill
kept from bulging too far back into the atrium by the papillary muscles and chordae tendinae.
What is the main job of the left atrium?
to receive oxygenated blood from the lungs via pulmonary veins and to pump it to the left ventricle
When does atrial filling occur?
occurs during ventricular systole when the left atrioventricular valve (A-V valve) is closed
Again, at the end of ventricular systole, the A-V valve opens up and most of the blood that will enter the ventricle flows in before the atria contract. Atrial systole again causes an additional increase in the blood volume pumped into the left ventricle
T or F. The musculature of the right atrium is much than the right atrium
F. The left atrium doesn’t have to pump blood very far either, but it has to work a little harder to stretch the left ventricular musculature when filling completely. Even though it has to work harder than the right atrium, you will not see much difference in the thickness of the atrial walls.
What is the main job of the left ventricle?
to pump blood through the ascending aorta to the entire body except the lungs
Which musculature is thicker, the left or the right ventricle?
the left ventricle has much more work to do than the right ventricle (i.e. systematic circulation of blood vs. pulmonary circulation) and, its the muscular wall has to be significantly thicker
The left heart is a high pressure system
What valve closes when the left ventricle contracts?
When the ventricle contracts, the left AV (mitral) valve closes and is kept from bulging too far back into the atrium by the papillary muscles and chordae tendinae
What valves are open during ventricular systole?
Both AV valves are shut and the pulmonary semilunar (PSV) and aortic (ASV) semilunar valves are open.
Ventricular contraction first forces the AV valves closed. Further contraction is required to build up enough pressure to open the pulmonary and aortic valves
Does opening of the semilunar valves happen at the same time as closing of the AV valves? Why?
NO. Further contraction other than the ventricular contraction is required to build up enough pressure to open the pulmonary and aortic valves after AV valves shut
NOTE: both semilunar valves open at the same time
What causes the pulmonary and aortic semilunar valves to snap shut?
After the semilunar valves open, blood then fills the pulmonary trunk and the aorta and all their branches, stretching many miles worth of vessels with smooth muscle and elastic fibers in their walls. This stretching causes a build-up of back pressure. When the ventricular musculature relaxes (diastole), there is no force to overcome the pressure, so the vessels contract and force blood to flow rapidly back toward the ventricles
When is the first heart sound heard?
The first heart sound (i.e. “lub”) is heard when the AV valves shut
What anchors the edges of the AV valves and prevents them from bulging back into the atria and leaking during ventricular systole?
chordae tendinae and papillary muscles
When is second heart sound heard?
heard when the ventricles quit contracting and relax
Back pressure from the pulmonary and systemic vasculature causes the semilunar valves to rapidly snap shut. This causes vibrations in the valves and arteries that is transmitted through surrounding tissues that can also be heard…described as a “dub” sound.
Which heart sound, the first or second, is softer?
AV valve closure is a bit softer than the closure of the semilunar.
The sounds are different because the valve closures are different.
What occupies the middle mediastinum?
The heart, pericardium and great vessels
The heart is surrounded by what?
a pericardial sac, another bursa-like structure to facilitate movements of surfaces against each other
Pericardial friction rub is an audible sign used in diagnosing of what?
pericarditis, when the lubricating system doesn’t work well
the sound(s) of pericarditis can drown out the other heart sounds