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
One big difference between pericardium and pleura is that the pericardial sac is surrounded by a distinct fibrous layer called the
fibrous pericardium
There is no division of it into visceral and parietal, just a fibrous layer that helps to contain the serous pericardium
The fibrous pericardial layer is attached inferiorly to the diaphragm by what?
the pericardiacophrenic ligament
Superiorly it blends with the external connective tissue of the great vessels entering and leaving the heart
What is the major consequence of the attachment of the fibrous pericardium to the diaphragm?
the heart moves up and down in the thoracic cavity with inspiration and expiration, and so the heart also changes shape because the great vessels don’t move as much, being anchored by their vessels to or from the neck and arm.
Describe the paricardium of the heart.
Visceral pericardium is a serous layer attached directly to the heart, while the reflection of serous pericardium back onto the inner surface of the fibrous pericardium is called the parietal pericardium
The pericardial cavity is between visceral and parietal layers of serous pericardium and there is normally only a small amount of lubricating fluid within.
What is Cardiac tamponade?
Cardiac tamponade occurs when fluid build-up in the pericardial cavity occurs too quickly. The term tamponade is a general one that refers to a closure or blockage used to stop bleeding. Cardiac tamponade is simply pressure on the heart that is sufficient to stop the flow of blood. An acute accumulation of fluid in the pericardial cavity is dangerous because the pressure can greatly impair heart function. Frequently, there is an acute hemorrhagic source of the fluid and pressure can quickly build up to the point that the heart cannot pump enough blood to keep the individual alive.
NOTE: If the fluid build-up occurs more slowly, over a period of months, the pericardial space can expand gradually, giving time for possible treatment.
What is the most anterior portion of the heart?
the right ventricle. The left atrium is the most posterior
The anterior surface of the heart is called the what?
sternocostal surface
The sternocostal surface is made up primarily of what?
the right ventricle
The tip of the left ventricle is known as what?
the apex of the heart (note that it is inferior, not superior)
The only visible portion of the right atrium is what?
the right auricle (an appendage of the right atrium)
What section of the right is called the base of the heart?
left atrium
If you grabbed the apex of the heart and pulled anteriorly, you would expose what region?
the blind pocket in the pericardial cavity called the oblique sinus
Which portions of the heart move during ventricular systole?
The apex of the heart (tip of left ventricle) and the associated right ventricle are free to move during the cycles of the heart beat.
It is important to note here that because of the way that the venous portion of the so-called great vessels (i.e. SVC, IVC and pulmonary veins) penetrate the pericardium and enter the heart, the base of the heart (i.e. left atrium) is anchored posteriorly. The right atrium is anchored, as well, by the SVC and IVC
What are the Great Vessels?
SVC, IVC, pulmonary veins, aorta and pulmonary trunk
The right margin of the heart is formed by what?
the right atrium
The left margin of the heart is formed by what?
the left ventricle
The left margin of the heart is aka?
the obtuse margin
The inferior margin of the heart is aka?
acute margin (formed mainly by the right ventricle)
What demarcates the division between atria and ventricles?
a coronary sulcus (one for each side)
What demarcates the interventricular septum?
interventricular sulcus
The interventricular sulcus is subdivided into anterior and posterior interventricular sulci, not so for the coronary sulcus.
What originates behind the left semilunar cusp of the ascending aorta?
left coronary artery
What originates behind the right semilunar cusp of the ascending aorta?
right coronary artery
Branching of the left coronary artery
The left coronary artery passes toward the left posterior to the pulmonary trunk and branches into anterior interventricular and circumflex branches. The anterior interventricular artery courses in the anterior interventricular sulcus supplies the left part of the conus arteriosus (conal branches), both ventricles and usually the major part of the interventricular septum.
The circumflex branch gives off one or more left marginal branches along the obtuse border of the heart, and further posteriorly ends as the posterior artery of the left ventricle.
Branching of the right coronary artery
The right coronary artery originates behind the right semilunar cusp and passes toward the right into the coronary sulcus between pulmonary trunk and right auricle.
Some of its first branches are to the conus arteriosus, so both the right and left coronary arteries have conal branches. Another of the first branches of the right coronary artery is the sinoatrial (SA) nodal branch. The SA node is an important part of the conduction system of the heart (the so-called pacemaker) and we will discuss the SA node, as well as the atrioventricular (AV) node, in more detail in the next lecture. The SA nodal artery encircles the base of the SVC and ends in the area of the SA node at the cephalic end of the sulcus terminalis. A right marginal branch is given off along the acute margin of the heart, just before the right coronary artery follows the coronary sulcus around to the posterior, inferior (diaphragmatic) surface of the heart.
On the diaphragmatic surface, the right coronary enters the posterior interventricular sulcus as the posterior interventricular artery. This artery supplies both left and right ventricles and a portion of the interventricular septum. An AV nodal branch is given off the right coronary artery at its junction with the posterior interventricular artery. It branches near the tip of the arrow labeled AV nodal br. and passes deeply into the tissue at the base of the interatrial septum to supply the area of the AV node. So, the arrow is not pointing to the AV nodal branch, but to the approximate point of its origin.
What is Coronary artery dominance?
The artery that gives off the posterior interventricular artery is said to be the dominant artery. 70% of the population is right dominant
That is, the posterior interventricular artery is a branch of the right coronary artery. If the posterior interventricular artery is supplied by the left coronary artery, the coronary circulation is said to be left dominant. If posterior interventricular arteries come from both right and left coronary arteries, then the coronary circulation is said to be co-dominant. Notice that in a left dominant circulation, the whole interventricular septum would be supplied by one artery.
Does the heart have collateral circulation?
No. Collateral circulation is almost non-existent in the case of the heart. The coronary arteries are end arteries, because they are essentially the only source of oxygenated blood to the area served. There are anatomical anastomoses between branches of these arteries, but, for all practical purposes, there are no functional anastomoses that are available acutely. If a blockage develops in the anterior interventricular artery over a long period of time, collaterals may develop and help in delivering O2 to the tissues. But, if the blockage in the anterior interventricular artery develops acutely, the other arterial branches that supply the interventricular septum tend to be incapable of taking over.
Most of the veins drain into what?
the coronary sinus
What veins drain directly into the right atrium?
anterior cardiac veins
Where do the smallest cardiac veins drain?
drain directly into the other chambers of the heart. These drain mainly into the chambers of the right side of the heart, but there are some that drain into the left side of the heart.
Where does the coronary sinus drain?
into the right atrium between the opening of the IVC and the tricuspid valve and it exhibits an incomplete valve of the cardiac sinus.
Describe the route of the great cardiac vein
begins at the apex of the heart and ascends in the anterior interventricular sulcus to reach the coronary sulcus superiorly. There, it turns around to the posterior side of the heart and ends in the leftmost aspect of the coronary sinus. It frequently has a left marginal vein as a tributary.
Describe the route of the middle cardiac vein
begins at the apex of the heart and runs posteriorly in the posterior interventricular sulcus to empty into the rightmost aspect of the coronary sinus
Describe the route of the small cardiac vein
begins along the acute margin of the heart as the right marginal vein and it runs in the coronary sulcus to join the middle cardiac vein before that vein joins the middle cardiac vein.
Describe the route of the anterior cardiac vein
drains the sternocostal surface of the right ventricle. They are the only cardiac veins (other than the smallest cardiac veins) that drain directly into the right atrium, not into the coronary sinus.
The right AV valve is aka?
tricuspid (the left Av valve is called the mitral valve)
Pulmonary veins feed into which portion of the heart?
left atrium
Why does plaque commonly develop in the anterior inter ventricular artery?
The sharp turn of the artery as it branches from the left coronary artery and goes posterior minimizes the surface area of the artery, leading to increase potential of plaque blocking the artery
The majority of people are what coronary artery dominant?
right dominant, balanced
