The cardiovascular system

The cardiovascular system is subdivided into two functional parts
? Blood vascular system
Function
• Transport materials needed by cells Oxygen and Glucose
• Remove waste materials from cells Carbon dioxide and urea
? The blood vascular system consists of three major Components
1. Pump (heart) Continuously circulates blood
2. Network of tubes consist of arteries- blood away from heart and veins- blood back to the heart
3. Blood is Fluid that fills the circulatory system
2. Lymph vascular system
• The lymph vascular system collects tissue fluid from tissues and returns it to the blood vascular system
• The lymph vascular system consists of blind-ended capillaries (lymphatic capillaries) connected to venous vessels (lymphatic vessels) and various lymphoid organs (e.g., lymph nodes).
• The fluid found within the lymph vascular system is lymph. Composition of lymph in smaller lymphatic vessels is very similar to tissue fluid.
The heart
The heart is a four-chambered pump composed of two atria and two ventricles and is surrounded by a fibroserous sac called the pericardium.
Cardiac layers
a. Inner layer = endocardium
b. Middle Layer = myocardium
c. Outer layer = epicardium (also called the pericardium)
? Except for the smallest vessels, blood and lymphatic vessel walls can also be viewed as three-layered structures.
a. Inner layer = tunica intima
b. Middle layer = tunica media
c. Outer layer = tunica adventita


? Cardiac layers
a. Endocardium lines the lumen of the heart and is composed of simple squamous epithelium (endothelium) and a thin layer of loose connective tissue. Subendocardium, a connective tissue layer that contains veins, nerves, and Purkinje fibers, underlies it.
b. Myocardium consists of layers of cardiac muscle cells arranged in a spiral fashion about the heart’s chambers and inserted into the fibrous skeleton. The myocardium contracts to propel blood into arteries for distribution to the body. Specialized cardiac muscle cells in the atria produce several peptides, including atrial natriuretic polypeptide, atriopeptin, cardiodilatin, and cardionatrin, hormones that maintain fluid and electrolyte balance and decrease blood pressure.
c. Epicardium, the outermost layer of the heart, constitutes the visceral layer of the pericardium. It is composed of simple squamous epithelium (mesothelium) on the external surface. Beneath the mesothelium lies fibroelastic connective tissue, containing nerves and the coronary vessels, and adipose tissue.