CHAPTER 12: THE CARDIOVASCULAR

SYSTEM—THE HEART

Cells depend on interstitial fluid for survival

The circulatory system balances the contents of the interstitial fluid (gas exchange, nutrients, waste, etc…)

The heart provides the mechanical “pumping” necessary for blood to circulate

Two circuits: Pulmonary (b/t heart & lungs) Systemic (b/t heart & body)

FUNCTION OF THE HEART

Size: 5” x 3.5” (~fist)Shape: blunt cone

Apex: pointed end Base: uppermost part

Location: center of thorax, behind the sternum (mediastinum)

4 Chambers Right atrium Right ventricle Left atrium Left ventricle

ANATOMY OF THE HEART

PERICARDIAL CAVITY (FIG. 12-2)

Pericardium encloses the heart (fist in balloon) and has 2 layersVisceral (epicardium): inner layer closest to the surface of the heart

Parietal: outer layerPericardial fluid

fills the cavity (lubricant)

Auricle: outer flap of deflated atriumCoronary Sulcus: groove between atria and ventriclesAnterior/Posterior Interventricular Sulci: boundary b/t

lft. and rt. ventricles

SURFACE ANATOMY OF THE HEART (FIG. 12-3)

Three layers Epicardium: outermost layer (serous) Myocardium: cardiac muscular layer; concentric wrapping Endocardium: innermost layer, continuous with vessel linings

THE HEART WALL (FIG. 12-4)

Interatrial Septum: separates left/right atriaInterventricular septum: separates left/right

ventriclesLeft/Right Atrioventricular (AV) valve

Bicuspid: left AV has 2 cusps, aka mitral valveTricuspid right AV has 3 cusps

Superior Vena Cava: blood from head, neck, upper limbs, and chest

Inferior Vena Cava: blood from rest of the trunk, viscera, and lower limbs

Coronary Sinus: opens into right atrium, receives blood from coronary veins

INTERNAL ANATOMY OF THE HEART

Chordae Tendineae: connects cusps to papillary muscles

Pulmonary semilunar valve: b/t right ventricle and pulmonary arteries

Aortic semilunar valve: b/t left ventricle and aorta

Aorta: start of systemic circuitPulmonary trunk: start of pulmonary circuitLeft/Right Pulmonary veins: receives

deoxygenated blood from lungs

INTERNAL ANATOMY OF THE HEART