Hemodynamics, Circulation Schematic
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The document discusses hemodynamics, focusing on blood circulation and the factors influencing blood flow, such as pressure gradients, resistance, viscosity, diameter of blood vessels, and velocity. It outlines two types of blood flow: streamline and turbulent, as well as the determinants of peripheral resistance and blood viscosity. The overall importance of these factors is emphasized for maintaining proper blood circulation throughout the cardiovascular system.
Hemodynamics, Circulation Schematic
- 1. Prep: Amen Ullah Lecturer Surgical 12/25/18 studyforum911@hotmail.com 1
- 2. Hemodynamics The branch of physiology dealing with the forces involved i n the circulation of the blood. OR The study of the movements of the blood and the forces co ncerned therein. OR The study of movement of blood through circulatory system. cardiovascular system is Responsible for to pump the blood and to circulate it through different parts of the body. It is essential for the maintenance of pressure and other physical factors within the blood vessels. 12/25/18 studyforum911@hotmail.com 2
- 3. Circulation Schematic Lungs Tissues Left Side of Heart Right Side of Heart A V V A Pulmonary Vein Pulmonary Artery Aorta Sup. & Inf. Vena Cava Mitral Valve Pulmonary Valve Aortic Valve Tricuspid Valve 12/25/18 studyforum911@hotmail.com 3
- 4. Mean Volume of Blood Flow 12/25/18 studyforum911@hotmail.com 4
- 5. Types of blood flow • Blood flow through a blood vessel is of two types: • 1. Streamline or laminar flow • 2. Turbulent flow. 12/25/18 studyforum911@hotmail.com 5
- 6. 1. Streamline Flow Streamline flow is a silent flow. Within the blood vessel, a very thin layer of blood is in contact with the vessel wall. It does not move or moves very slowly. This type of flow does not produce any sound within the vessel Streamline flow occurs only at velocities up to a critical level. OR Flow of a fluid in which its velocity at any point is constant or varies in a regular manner. It can be represented by streamlines. 12/25/18 studyforum911@hotmail.com 6
- 7. • 2. Turbulent Flow • Turbulent flow is the noisy flow. When the velocity of blood flow increases above critical level, the flow becomes turbulent. • Turbulent flow creates sounds. 12/25/18 studyforum911@hotmail.com 7
- 8. Factors determining volume of blood flow • Volume of blood flow is determined by fiv factors: – 1. Pressure gradient – 2. Resistance to blood flow – 3. Viscosity of blood – 4. Diameter of blood vessels – 5. Velocity of blood flow. 12/25/18 studyforum911@hotmail.com 8
- 9. • 1. Pressure • Volume of blood flowing through any blood vessel is directly proportional to the pressure gradient. • Pressure gradient is the pressure difference between the two ends of the blood vessel. • Pressure gradient = P1 – P2 Where, • P1 = Pressure at proximal end of the vessel • P2 = Pressure at distal end of the vessel. 12/25/18 studyforum911@hotmail.com 9
- 10. 2. Resistance to Blood Flow •(Peripheral Resistance) •Volume of blood flow is inversel proportional to the resistance. Resistance is the friction, tension or hindrance, against which the blood has to flow. Peripheral resistance means the resistance offered to blood flow in peripheral blood vessels. Though resistance exists in all the blood vessels to some extent, it is remarkable in the peripheral vessels, particularly the arterioles. Determinants of peripheral resistance •i. Radius of blood vessels •ii. Pressure gradient •iii. Viscosity of blood. 12/25/18 studyforum911@hotmail.com 10
- 11. 3. Viscosity of Blood •Volume of blood flow is inversely proportional to the viscosity of blood. Viscosity is the friction of blood against the wall of the blood vessel. •Isaac Newton described viscosity as the internal friction or lack of slipperiness. Viscosity influences the blood flow through resistance. Factors determining viscosity •RBC count is the main factor which determines the viscosity of the blood. •Another factor determining viscosity is plasma protein, mainly albumin. •When hemoconcentration occurs as in case of burns or in polycythemia, the viscosity increases and the velocity of blood flow decreases, so the volume of blood reaching the organ is decreased. 12/25/18 studyforum911@hotmail.com 11
- 12. 4. Diameter of Blood Vessels •Volume of blood flow is directly proportional to the diameter of the blood vessels. •When the diameter of a segment of blood vessel is considered, the aorta has the maximum diameter and capillary has got the minimum diameter. •But, in circulation, the diameter of the vessel is considered in relation to the cross-sectional area through which the blood flows 12/25/18 studyforum911@hotmail.com 12
- 13. 5. Velocity of Blood Flow •Volume of blood flow is directly proportional to the velocity of blood flow. •Velocity of blood flow is the rate at which blood flows through a particular region. 12/25/18 studyforum911@hotmail.com 13
- 14. Velocity of Blood Flow • Velocity of blood flow is the rate at which blood flows through a particular region of the body. • It mainly depends upon the diameter or cross- sectional area of blood vessel. • Velocity of blood flow is the rate at which blood flows through a particular region of the body. • It mainly depends upon the diameter or cross- sectional area of blood vessel. 12/25/18 studyforum911@hotmail.com 14
- 15. FACTORS MAINTAINING VELOCITY •Three factors are responsible for the maintenance of the velocity of blood flow. 1. Cardiac output 2. Cross-sectional area of the blood vessel 3. Viscosity of the blood. 12/25/18 studyforum911@hotmail.com 15