Heart Anatomy

Heart AnatomyThe Heart

· cone-shaped muscular organ about the size of your fist· weighs less than a pound· 2/3 lies to the left of the body's midline· apex (tip) tilted to the left

Heart Membranes· pericardium - double-walled sac around the heart

fibrous pericardium - tough and denseprotects the heartanchors it to surrounding structuresprevents overfilling of the heart with blood

serous pericardium - thin and slipperyreduces friction

Layers of the Heart Wall· epicardium - external heart surface

often infiltrated with fat· myocardium - heart muscle

responsible for muscle contraction

arranged in spiral and circular bundles· endocardium - a simple squamous epithelium lining the inner surfaces of the heart and blood vessels

Chambers of the Heart· 4 chambers

R and L atria on top of R and L ventricles· atria - small, thin-walled chambers that receive blood

pumps blood "downstairs" to ventricles· ventricles - large, muscular pumping chambers

pumps blood outside of heart· R and L side of heart divided by a septum

Atria· right atrium - receives deoxygenated blood through superior vena cava and inferior vena cava

passes blood to right ventricles through the tricuspid valve· left atrium - receives oxygenated blood through four pulmonary veins

pulmonary = lungs2 veins from each lungpasses blood to left ventricles through bicuspid

(mitral) valve

Heart Anatomy

Ventricles· papillary muscles and chordea tendinaea play a role in valve function· discharging chambers (pumps) of the heart

walls thicker than atria· right ventricle - pumps deoxygenated blood through pulmonary semilunar valve and pulmonary trunk toward the lungs· left ventricle - pumps oxygenated blood through aortic semilunar valve and aorta to all body parts

thicker wall than R ventricle

Double Pump· R side of heart handles oxygen poor blood ONLY

pulmonary circuitR heart lungs L heart

· L side of heart handles oxygen rich blood ONLY

systemic circulationL heart body R heartharder work = bigger, stronger

structures· blood travels in 2 distinct loops double pump

picks up O2 from lungsdrops off O2 to body cells

· circulates blood to lungs· R atrium R ventricle pulmonary arteries pulmonary arterioles pulmonary capillaries CO2 and O2 exchanged pulmonary venules pulmonary veins L atrium

Pulmonary Circulation· systemic = body systems· circulates blood to body· aorta - largest artery· superior/inferior vena cava - largest veins

superior - collects blood from head, chest, arms

inferior - collects blood from lower body· L ventricles aorta major body regions veins superior/inferior vena cava

Systemic Circulation

Path of Bloodbody superior/inferior vena cava R atrium thru tricuspid valve R ventricle thru pulmonary semilunar valve pulmonary trunk pulmonary arteries lungs pulmonary veins L atrium thru bicuspid valve L ventricle thru aortic semilunar valve aorta body

Coronary Circulation· myocardial cells require a continual supply of oxygenated blood· supplied by the coronary arteries

branch off of aorta· angina - chest pain· blockage of coronary blood vessels can cause a myocardial infarction (heart attack)