IV.
Heart Anatomy
a.
Located between two lungs
b.
Muscular pump
c.
Four-chambers
d.
Upper chambers - atrium; receive blood returning to heart
e.
Lower chambers - ventricles; thicker, muscular walls that allow them to pump
blood throughout the body
f.
Flaps of tissue in heart called valves (such as tricuspid, mitral/bicuspid,
pulmonary valves) prevent blood from flowing the wrong direction
-->
Heartbeat is the valves opening and closing
a.
Pacemaker sets rate at which heart contracts (located in wall of right atrium)
b.
Pacemaker generates electrical impulses that spread quickly over walls of both
atria, causing the contraction
c.
Impulses spread to AV node, and then to the ventricles, causing them to
contract
d.
Contractions of ventricles causes blood spreading all over the body
e.
Pacemaker creates rhythmic heartbeats
-
Diastole (atria and ventricles relaxed, allowing blood from veins to enter
heart)
-
Systole (atria first contracts, blood forced into ventricles, which are
relaxed. Then the ventricles contract, pumping blood into arteries, while the
atria are relaxed)
f.
Cardiac defibrillator (artificial pacemaker for if the pacemaker stops
functioning)
VI.
Blood Pressure
a.
Systolic pressure - highest recorded pressure in an artery when the ventricles
contract
b.
Diastolic pressure - lowest recorded pressure in an artery during the
relaxation phase of the heartbeat
c.
120/70 is normal for an adult
VII.
Make-up of Blood
a.
Plasma - 55% of blood is plasma, 45% red blood cells. Plasma = 90% water, 10%
dissolved salts, proteins, and other transported substances
b.
Red Blood Cells - carries oxygen from lungs to all tissues of the body.
Contains hemoglobin, protein storing oxygen for delivery to cells (oxygen binds
to iron in hemoglobin). Produced in bone marrow, as they mature, nuclei and
mitochondria lost. Structure provides increased surface area for oxygen
transfer. Average lifespan of 100-120 days
c.
White Blood Cells - leukocytes. Have nuclei and mitochondria and are
responsible for fighting infection and preventing cancer growth. Action takes
place in interstitial fluid.
