The Heart

HEART Main organ that moves blood through the body Pumps around 5 L/minute On average, pumps 75 years continuous It is about the size of a fist Located between the lungs

Heart is 2 pumps in one: 1.Right side— forces blood to lungs and back called pulmonary circulation 2.Left side— forces blood from the heart to the tissues and back to heart called systemic circulation

Heart Anatomy The heart has four chambers right and left atria at the top, and right left ventricles at the bottom septum—large muscle that separates the chambers

-Blood collects in each chamber before that chamber contracts pushing the blood out -Both atria contract at same time and both ventricles contract at same time *The walls around the ventricles have much thicker muscle, why? -The ventricles thrust blood out of heart to body, the atria just thrust it down to ventricles

Heart vessels 1.Pericardium cavity- space surrounding heart (much like a fist in a balloon) -the space contains fluid to protect (absorbs shock) 2.Superior and inferior vena cava- carry blood to the right atrium from the body (deoxygenated blood)

Heart vessels cont… 3. Pulmonary veins- carry blood from lungs to left atrium (oxygenated) 4. Pulmonary trunk- (includes pulmonary arteries)—carries blood to lungs (deoxygenated) 5. Aorta- carries blood from left ventricle to the body

Atrioventricular valve- (AV) located between atrium and ventricle. There are 2 AV valves: a. tricuspid valve — between right atria and right ventricle b. bicuspid valve — (mitral) between left atria and left ventricle Heart valves:

HEART V ALVES CONT… 7. Semilunar valves- shaped like half moon-located at exits of ventricles 2 kinds a. pulmonary valve —b/w right ventricle and pulmonary trunk b. aortic valve — opens b/w left ventricle and aorta

Heart valves looking from bottom of a cross section

Heart Muscle vessels: (Like any muscle, must have oxygen) 1.Coronary arteries- take blood to the walls of the heart -(has oxygen) 1.Cardiac veins - carry blood away from wall of heart -(deoxygenated)

Heart Wall: Made of three layers 1.Epicardium-smooth outer surface of heart (protects) 2.Myocardium- middle thick layer (contracts heart) 3.Endocardium-inner layer (allows blood to move throughout inside of heart)

Cardiac Cycle: 1.Atria systole -refers to contraction of the 2 atria 2.Ventricular systole -contraction of the 2 ventricles 3.Atria diastole -relaxation of the 2 atria 4.Ventricular diastole -relaxation of the 2 ventricles

Blood Pressure Top number is the pressure on the vessels when heart is contracting (systolic pressure) Bottom number is the pressure on vessels when the heart is relaxed (diastolic pressure)

Heart Sounds: When listening to the heart, you will hear 2 sounds 1 st sound—(lub) —is due to the closing of the tricuspid and bicuspid valves b/w atria and ventricles 2 nd sound—(dup) —is due to closing of the semilunar valves

Know passage of blood through heart starting at the vena cava. Tell at which areas it is oxygenated and deoxygenated. Tell the valves it passes.

Superior and inferior vena cava carry oxygen poor blood to the right atria. Right atrium sends blood through the atriventricular or tricuspid valve to the right ventricle. Right ventricle sends blood through the pulmonary semilunar valve into the pulmonary trunk to carry blood to the lungs. pulmonary veins carry oxygen rich blood back to the left atrium. Left atrium sends blood through the atrioventricular valve or bicuspid valve to the left ventricle. Left ventricle sends blood through the aortic semilunar valve into the aorta and out to the body.