Cardiovascular

Cardiovascular - Cardiovascular System William Harvey:...

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Unformatted text preview: Cardiovascular System William Harvey: Initial discovery of circulation, proved arteries carry blood from the heart, veins towards the heart, and that veins have valves preventing backflow of blood. General Function of CV System : Transport Function 1. Distributes substrates and oxygen to all body cells 2. Collects waste products and carbon dioxide for excretion 3. Controls blood flow to the skin and extremities to enhance or retard heat loss to the environment 4. Distributes hormones to distant sites 5. Aids in body defense mechanism by delivering antibodies, platelets, and leukocytes to affected areas of body. Requirements of CV System : 1. Circulation of blood without interruption 2. Adjustment of blood flow in response to varying demands of the tissues Basic Characteristics of the Circulatory System Figure 1: Blood Circulation 1. Circulation is a Complete Circuit a. Unidirectional Flow i. Pressure Gradients ii.Valves 2. Most Blood Volume is Distributed in the Vein of the Systemic Circulation (Lower Part of Diagram) Arteri es Capillari es Vein s X-Sectional Area Small Large Smal l Velocity of Flow High Low High Pressure High Low Low Table 1: Velocity/Pressure of Blood Flow 3. Velocity of Blood Flow is Inversely Proportional to Vascular Cross-sectional Area (Faster in Arteries and Veins than in Capillaries a. Arteries pressure driven from heart b. Capillaries driven by replacement (very low pressure) c. Veins have no heart pressure, valves prevent backflow, and skeletal muscle contractions collapse veins, squeezing blood forward 4. Pressures in the Pulmonary Circulation are Much Lower than in Systemic Circulation 5. Pressure Varies in Different Parts of the Circulation a. From 4, Left Ventricle can have much higher pressure than left atrium b. For systemic vessels, in order of highest pressure to lowest: Aorta and Arteries, Arterioles, Capillaries, Veins. 6. The Blood Flow to Each Tissue of the Body is Precisely Controlled 7. Any Change in Blood Flow in a Single Part of the Body Will Alter Blood Flow in Other Parts of the Body. Basic Characteristics of the Heart Figure 2: Human Heart 1. Two Pumps In Series a. Right Heart pumps blood through the lungs b. Left Heart pumps blood through the peripheral organs c. In each of these hearts is a pulsatile two chamber pump composed of an atrium and a ventricle i. The atrium is a weak primer pump, moving blood to the ventricle ii.The ventricle supplies the main pumping force that propels the blood either through the pulmonary circulation (right ventricle) or the peripheral circuitry (left ventricle) 2. Pumps controlled by Spontaneous Rhythmic Depolarization generated by Electrical Nodes 3. Blood Flow Within the Heart controlled by Cardiac Valves 4. Frank-Starling Mechanism: Within Physiological limits, the heart pumps all the blood that comes to it without allowing excess accumulation of blood in the veins Electrophysiology of the Heart Membrane Permeability is a measure of the ease with which a substance...
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Cardiovascular - Cardiovascular System William Harvey:...

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