The pulmonary artery is the vessel that leaves the right ventricle and enters into the lung tissue to undergo oxygen exchange. The pulmonary artery is known to be the only artery in the body that does not carry oxygen-rich blood. 

An artery is defined as a vessel that leaves the heart and a vein is a vessel that returns to the heart. The pulmonary artery is the vessel carrying deoxygenated blood away from the heart. 

A "p-wave" in an ECG correlated to depolarization and contraction of the atria of the heart. The duration of the "p-wave" is associated with how low it takes an electrical signal to transfer across an atrium from the sinoatrial node to the atrioventricular node. Therefore, a prolonged "p-wave" can be commonly associated with an enlarged atrium because the electrical signal has further to travel across a dilated chamber.

Beta 1 receptors are the adrenergic receptor on the heart muscle that are responsive to epinephrine and norepinephrine released by the sympathetic nervous system.

Beta 2 adrenergic receptors are primarily located within the pulmonary tissue to cause bronchodilation during a sympathetic response.

Muscarinic cholinergic receptors are present on many tissue types, but are the receptors for acetylcholine rather than epinephrine or norepinephrine.

Alpha 1 adrenergic receptors are present on peripheral blood vessels and respond primarily to norepinephrine to cause vasoconstriction during a sympathetic response.

Alpha 2 adrenergic receptors are special receptors present on the preganglionic sympathetic neuron that help to depress a sympathetic response through negative feedback inhibition.

The tricuspid (atrioventricular) valve separates the right atrium from the right ventricle and prevents back-flow during systole (heart contraction). The path of blood in the heart goes as follows: right atrium, tricuspid valve, right ventricle, pulmonary valve, pulmonary artery, lungs, pulmonary vein, left atrium, mitral valve, left ventricle, aortic valve, aorta, systemic circulation.

Lead II is the limb lead that will show the best view of atrial depolarization. Remember, atrial depolarization starts at the sinoatrial node in the right atrium and spreads through the right and left atria. If you were to draw this on a heart, the net vector would be down (inferiorly) and to the left side of the heart. Also remember, lead II is the lead configuration that runs from the right arm to the left leg. aVR would show a good view of atrial depolarization (although it would be a negative deflection), but it is an augmented lead, not a limb lead. aVL is also an augmented lead.

The diameter of the vessels is the primary determinant of resistance. Our three factors affecting resistance of a vessel are length, viscosity, and diameter. Length of the vessel and viscosity of the blood are relatively constant, so that just leaves diameter. Hematocrit is percentage of blood as red blood cells and would represent viscosity.

Cardiac output is directly proportion to both heart rate and stroke volume. Decreasing ejection fraction decreases stroke volume, which would decrease cardiac output, not increase it.

The pulmonary veins carry oxygenated blood form the lungs to the left atrium of the heart. The pulmonary arteries carry deoxygenated blood from the right ventricle to the lungs. 

When blood needs to leave the heart to become oxygenated, it leaves the right ventricle through the pulmonary trunk, which then splits into the right and left pulmonary arteries. This blood goes to the lungs, becomes oxygenated, and comes back to the heart via the right and left pulmonary veins, which empty into the left atrium. The newly oxygenated blood travels through the left atrium and ventricle of the heart before it exits through the aorta to deliver freshly oxygenated blood to the rest of the body.

The heart has four chambers and only two interact with deoxygenated blood. The right atrium receives deoxygenated blood from the superior and inferior vena cava which then passes through the tricuspid valve into the right ventricle where it is pumped towards the lungs to be oxygenated.