Circuits & Location
The heart is located in this region between the lungs.
Mediastinum
This heart-wall layer is also called the visceral layer of the serous pericardium.
epicardium
This valve prevents backflow into the right atrium when the right ventricle contracts.
Right AV (tricuspid) valve
This circulation supplies oxygenated blood directly to the heart muscle.
Coronary circulation
This structure initiates the electrical signal that begins each heartbeat.
SA node
Blood traveling from the left ventricle to body organs is moving through this circuit.
Systemic circuit
These chambers are separated by the interatrial septum and receive returning blood.
Atria
These valves are open while the ventricles contract and close when the ventricles relax.
Semilunar valves
Both major arteries supplying the heart muscle branch directly from this vessel.
aorta
After the SA node fires, excitation first spreads through this type of myocardium.
Atrial myocardium
In this circuit, CO2 is unloaded and oxygen is loaded.
Pulmonary circuit
This chamber has the thickest wall because it pumps blood into the systemic circuit.
Left ventricles
Blood leaving the right ventricle must pass through ___ and then enter ____.
Pulmonary valve, pulmonary trunk
A blockage in a coronary artery can cause this condition, involving death of heart tissue.
Myocardial infarction
This node receives the signal after atrial excitation and fires before ventricular excitation spreads.
AV node
Blood returning from the lungs enters this chamber before passing through the left AV valve.
left atrium
These internal ridges are found in the ventricles
Trabeculae carneae
____ tether the AV valves and help hold them closed during ventricular contraction.
chordae tendineae and papillary muscles
About 80% of venous blood from the cardiac muscle returns to ____ (chamber) through _____.
Right atrium, coronary sinus
The conducting fibers that distribute excitation through the ventricular myocardium.
Purkinje fibers
In the systemic circuit, these gases are unloaded and loaded in the organs.
Oxygen is unloaded, CO2 is loaded
dentify the heart-wall layer that lines the chambers and the type of epithelium forming it.
endocardium, simple squamous epithelium
____ closes when the ventricles contract and ____ close when the ventricles relax.
AV valves, semilunar valves
_____ receives blood from the great, small, posterior interventricular, and left marginal veins.
Coronary sinus
___ connect the cells physically, while ____ allow electrical signals to pass between cells.
Mechanical junctions, gap junctions