Circulation 1 Dr.Radmanesh به نام خالق زیبایی ها Circulation 1 Dr.Radmanesh
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Systemic Circulation The oxygen-rich blood from the left side of the heart is pumped to the rest of the body Oxygen-poor blood returns to the right side of the heart This blood is oxygen-poor because the cells absorbed the oxygen and released carbon dioxide into the blood The oxygen-poor blood is ready for another trip to the lungs to get oxygen again
Circulation of Blood Aorta Arteries Arterioles Capillaries Venules Arteries carry blood away from the heart and veins carry blood toward the heart. The capillaries are exchange vessels located between the arterial and venous systems. Veins Vena Cava Chapter 2
Figure 37-5 The Three Types of Blood Vessels Section 37-1 Artery Vein Connective tissue Smooth muscle Endothelium Valve Venule Arteriole Capillary
Arterioles and Capillaries Figure 8.2
Capillary Structure Figure 8.4
Pulmonary Circulation 12 % Pulmonary Circulation 11 % Systemic Arteries 7 % Arterioles and Capillaries 9 % Heart Blood Volume (liter) Systemic Veins and Venules 61 % M. Badavi, Ph.D.
Veins and their Functions Venous valves and the “venous pump” Valves ensure one-way movement of blood Muscle pump - extremity muscle contraction “massages” blood up toward the heart Thoracic pump – breathing action also “massages” blood up toward the heart Venous valve incompetence causes varicose veins in the legs (secondary to pregnancy, or excessive time standing) M. Badavi Ph.D.
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Blood Flow Distribution During Rest and Exercise Brain Heart Liver/Gut Kidneys Skeletal Muscle Skin Skeleton/Fat Rest (5 L/min) Exercise (25 L/min) 13-15% 4-5% 20-25% 20% 15-20% 3-6% 10-15% 3-4% 4-5% 3-5% 2-4% 80-85% 1-2%
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V= Q/A
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Diagram of the velocities of concentric laminas of a viscous fluid flowing in a tube, illustrating the parabolic distribution of velocities (streamline flow).
V d Re = Re > 2000 Turbulent flow
1 cm 2 10 cm 2 A = 2 cm 2 Q=10 ml/s a b c Q=10 ml/s 10 cm/s V = 5 cm/s 1 cm/s Q V = A P P Q = P = Q . R R = R Q
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FACTORS AFFECTING VASCULAR RESISTANCE The quantitative relationship between pressure gradient, ∆P, and flow, Q, in the vascular system is given by Poiseuille’s Law ∆P.π.r4 8hl Flow, Q = r is the radius of the vessel, l is the length of the vessel, h is the viscosity of the fluid (blood). Thus the resistance of fluid flow is given by the term: 8hl πr4 A decrease of radius, r, or an increase of viscosity, h, will increase resistance
Q Pi - Po 1 2 P = gh 4 3 A B A B h2=2h1 h1 Pi Po Pi Po Q = 5 ml/s
5 6 1 Q L 7 Q r 4 r2 =r1 r1 L1 L2 = 2L1 Q = 5 ml/s Q = 10 ml/s
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Relative viscusity Tube diameter (mm) 6 5 4 3 2 1 0.1 0.2 0.3 0.4 0.5 0.6 Tube diameter (mm)
FIGURE 1.1 Blood flow through microvessels in the rat mesentery with inner diameters 7, 12, and 16 μm (top to bottom). Flow is from left to right.
FIGURE 1.3 Human erythrocytes during flow through glass tubes with inner diameters 4, 7, and 17 μm (top to bottom). Flow is from left to right.
P . r 4 Q L Q = . P . r 4 8L
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