The Heart Chapter

The Heart Is a Double Pump Delivers Oxygen and nutrients to the tissues Removes carbon dioxide and waste from the tissues

Location and Design Hollow muscular organ located within the center of the chest in the mediastinum. 60% is located to the left of midline 5”X3.5” approximately the size of a clenched fist.

Shape Oval type shape Base - is the top of the heart Apex - is the bottom of the heart

Organ Layers The heart moves freely and can change its stroke volume (SV) and twist to eject blood friction free. Pericardium Surrounds: Heart Great vessels

3 Layers of the Heart Muscle Epicardium The outer most layer. Is contiguous with the visceral pericardium Myocardium The actual muscle of the heart. It is the thickest. Responsible for contraction (more later) Endocardium The inner lining of the heart, made of epithelial cells In contact with the blood in the chambers.

Myocardial Muscle Specialized found only in the heart Striated like skeletal Electrical properties like smooth muscle

Chambers Double pump. Right and left sides. 4 chambers. 2 atria - upper chambers deliver blood to ventricles. 2 ventricles- lower chambers pump blood out of the heart. The two atria contract together, as do the ventricles The heart sounds (lub dub) are caused by the closing of the valves

Valves of the heart Designed to promote forward flow Valves close to prevent backflow Made of fibrous tissue that has grown out of the walls of the heart 2 types: Atrioventricular (AV) (separate chambers) Semilunar (separate chamber/vessel)

AV Valves The two valves that separate the atrial chambers are called AV or atrioventricular valves. The Bicuspid or Mitral valve is between the left atrium and ventricle Tricuspid is between the right atrium and ventricle

Semilunar valves (half moon) Both arteries that leave the heart have these valves separating them from the ventricles Pulmonary Aortic Are between the two ventricular chambers and the large arteries that carry blood away from the heart. They each have 3 leaflets