Heart and cardiovascular system
The heart – an amazing organ! Beats constantly, never rests, about 100,000x per day and
circulates 8000 L blood/day… a big job… but necessary so that all the cells of the body
will have access to nutrients and O2, and a way to get rid of waste.
Organization of the CV system – basically 2 loops, one small (pulmonary) and one large
(systemic), both of which begin and end at the heart.
Blood LEAVING the heart travels in arteries
Blood ARRIVING AT the heart travels in veins… this is regardless of the O
Capillaries aka exchange vessels, where nutrient/gas exchange takes place.
Heart: contains 4 chambers, 2 atria and 2 ventricles, R and L.
From body blood enters R atrium, goes to R ventricle, and is pumped into pulmonary
circuit (lungs); enters L atrium from lungs, enters L ventricle, and is pumped into
Atria: relatively thin muscular walls, highly expandable.
Ventricles, more muscular
Right atrium (RA):
Receives blood from systemic circuit through vena cavae –superior,
from head, neck, upper limbs, and chest; inferior, from the rest of the body.
veins also return blood to RA.
Right ventricle (RV):
Blood leaves RA and travels through the right AV valve, aka the
The three flaps of the AV valve are attached to chordae tendinae, which
originate at the papillary muscles on the inner surface of the right ventricle.
valve closes when the ventricle contracts, keeping blood from backing up into the atrium.
The chordae tendinae keep the flaps from just flapping all the way open the other
Pulmonary semilunar valve – similar to AV valve, valve at entrance to pulmonary trunk
(artery that goes to lungs from RV).
R and L pulmonary arteries go to R and L lungs.
Left atrium (LA):
L and R pulmonary veins bring oxygenated blood from lungs.
AV valve, aka bicuspid valve or mitral valve is between LA and LV.
Left ventricle (LV):
Much larger than RV, has very thick muscular walls.
LV to push blood with a lot of force into the systemic circulation… this requires a lot
more force than sending blood to pulmonary circulation.
Blood leaves through aortic
valve, aka aortic semilunar valve, and goes into ascending aorta.
R and L coronary
arteries branch off from this, and then aortic arch and descending aorta.
supplies blood to the heart, as the tissue of the heart is highly
metabolically active and requires a lot of O