how does the heart work
forces blood through arteries which connect to smaller diameter vessels called arterioles. arterioles branch into the tiniest tubes, the capillaries, the sites of nutrient, electrolyte, gas, and waste exchange. Capillaries converge into venules which in turn converge into veins that return blood to the heart, completing the closed system of blood circulation
what does the pulmonary circuit do
sends oxygen-depleted (deoxygenated) blood to the lungs to pick up oxygen and unload carbon dioxide
what does the systemic circuit do
sends oxygenated rich blood and nutrients to all body cells and removes wastes.
what would happen without circulation
the tissues would lack a supply of oxygen and nutrients and wastes would accumulate. such deprived cells soon begin irreversible changes which quickly leads to death
describe the heart
the heart is a hollow cone shaped pump in the mediastinum of the thorax and rests upon the diaphragm
how is heart size determined
an average adult heart is generally about 14 centimeters long and 9 centimeters side
what borders the heart laterally
the heart is bordered laterally by the lungs , posteriorly by the vertebral column and anteriorly by the sternum.
where does the base of the heart located
the base of the heart, which attaches to several large blood vessels, lies beneath the second rib.
where does the heart's distal end extend
the heart's distal end extends downward to the left terminating as a bluntly pointed apex at the level of the fifth intercoastal space.
how do you sense the apical heartbeat
it is possible to sense the apical heartbeat by feeling or listening to the chest wall between the fifth and sixth ribs about 7.5 centimeters to the left of midline
what is the pericardium
or pericardial sac is a covering that encloses the heart and the proximal ends of the large blood vessels to which it attaches.
what does the pericardium consist of
an outer fibrous bag (the fibrous pericardium) that surrounds a more delicate double layered serious membrane.