The Heart

Ch. 20

Circulation•Pulmonary

▫Eliminates carbon dioxide and oxygenates blood

▫Involves lungs•Systemic

▫Delivers blood to body cells and carries waste away

▫Involves the body

Heart• About the size of your fist• Rests on the diaphragm,

near the midline of the thoracic cavity▫ Surrounded by

pericardium (protects)• Lies in the mediastinum,

2/3 is to the left of the midline

Pericardium•Surround

s heart

Pericardium• 3 layers

▫Epicardium – external layer Thin, transparent layer;

makes heart smooth and slippery

▫Myocardium – middle layer Cardiac muscle, makes up

bulk of heart Responsible for pumping

action▫Endocardium – inner layer

Thin tissue, covers valves

Chambers of the Heart• Atria – superior chambers (receive blood from veins)• Ventricles – inferior chambers (pump blood out of

arteries)• Septum – separates right and left sides• Auricle – wrinkled, pouch-like structure on each atrium

▫ Increases volume of blood each atrium can hold• Sulci – grooves on surface of heart; contain blood

vessels and fat▫ Separates two chambers▫ Coronary sulcus – divides atria from ventricles▫ Anterior/posterior interventricular sulcus – divides

ventricles

Heart•Double

pump &double circuit

Heart Valves• Valves – allow one way flow of blood• 4 total valves• 2 atrioventricular (AV) valves

▫Left AV valve (bicuspid or mitral valve) – between LA and LV

▫Right AV valve (tricuspid valve) – between RA and RV• 2 semilunar valves

▫Aortic semilunar (aortic valve) – between LV and aorta

▫Pulmonary semilunar (pulmonary) – between RV and pulmonary artery

Heart Valves

Path of Blood Flow•From the body into heart through vena cava•Into RA•Into RV•Out to lungs through pulmonary arteries•Into heart from lungs through pulmonary

veins•Into LA•Into LV•Out to body through aorta

Path of Blood Flow

Path of Blood Flow

Name the Valves

Heart Actions•Cardiac Cycle – one complete heart beat•Contraction of heart chamber – systole•Relaxation of heart chamber – diastole

Contraction Cycle

Valve Control•Cusps (flaps) of

bicuspid and tricuspid valves are anchored to walls of ventricles by “cords” (heart strings) – chordae tendineae

•This prevents valves from being pushed up into the atria during ventricular systole

Heart Sounds•Lub-dup – opening and closing of the

valves•Sound byte

http://www.ilovewavs.com/Effects/People/Sound%20Effect%20-%20Heart%20Beat%2001.wav

Cardiac Conduction•SA node•Right and left

bundle branches

•AV node•AV bundle•Perkinje fibers

Cardiac Conduction

Name the Parts

Review•What are the two circulatory systems? What

do they do?•Where is the heart located?•What is the pericardium? What three layers

does it contain?•Describe the main structures of the heart.•Describe the valves of the heart.•What is the cardiac cycle?•What are the heart strings? What do they do?•Describe cardiac conduction.