University:
Glendale Community College
Course:
BIO160 | Introduction to Human Anatomy and Physiology
Academic year:

2019
Views:

199

Pages:

11
Author:

Shea Cuevas

Cardiovascular System Circuit • Cardiovascular System consists of: – heart, arteries, veins and capillaries • 2 major divisions – Pulmonary Circuit right side of heart carries blood to lungs for gas exchange – Systemic Circuit left side of heart supplies blood to all organs of the body Heart Shape and Position • Heart is located in the mediastinum, between lungs • Base of the heart is the broad superior portion of heart • Apex of the heart is the inferior end, tilts to the left, tapers to point Heart Position Pericardium • Pericardium consists of the membranes around the heart that allows the heart to beat with minimal friction, provides room for the heart to expand but resists excessive expansion. • Pericardial Sac (also called the parietal pericardium) is the membrane that loosely surrounds the heart. Pericardial sac has 2 layers: – Fibrous layer: outer, tough, fibrous layer of CT – Serous layer: inner, thin, smooth, moist membrane • Pericardial Cavity is the space between heart and pericardial sac that is filled with pericardial fluid that acts as a lubricant. • Visceral Pericardium (also called the epicardium) is the thin, smooth, moist serous layer that covers heart surface. Figure 19.3 Pericardium and Heart Wall 3 Layers of the Heart Wall • Epicardium (visceral pericardium) – serous membrane covers heart • Myocardium – thick muscular layer – fibrous skeleton - network of collagen fibers and elastic fibers • provides structural support • attachment for cardiac muscle • nonconductor important in coordinating contractile activity • Endocardium – smooth inner lining – equivalent to the lining of blood vessels Figure 19.3 3 layers of the Heart Wall Bacterial Endocarditis Gross pathology of subacute bacterial endocarditis involving mitral valve. Left ventricle of heart has been opened to show mitral valve fibrin vegetations due to infection with Haemophilus parainfluenzae. Autopsy. CDC/Dr. Edwin P. Ewing, Jr. http://pathmicro.med.sc.edu/ghaffar/bord-hemo.htm Cardiac Cycle • One complete contraction (systole) and relaxation (diastole) of all 4 chambers of the heart followed by a brief period of inactivity: Heart Sounds • Heart sounds as heard through a stethoscope are due to turbulent flow of blood as heart valves close. Auscultation - listening to sounds made by body. • First heart sound (S1) is louder and longer, sounds like “LUBB”, occurs when the AV valves close. • Second heart sound (S2), is softer and sharper, sounds like “DUPP”, occurs when the semilunar valves close. • S3 – rarely audible in people older than 30 – known as triple rhythm or gallop. Heart Sounds • S1 and S2 sounds of normal rhythm can be simulated by drumming two fingers on a table. • If there is a third heart sound (S3) it can be simulated by drumming three fingers on a table, and it is described as a “gallop”. • The cause of each heart sound is not known with certainty, but they are correlated with specific phases of the cardiac cycle.