Hemodynamics

1. Hemodynamics
Dr. Sara Sadiq

3. Objectives
• Components of vasculature
• Arteries
• Arterioles
• Capillaries
• Veins
• Velocity of blood flow
• Blood flow
• MCQs at the end of the lecture

4. FUNCTION OF CARDIOVASCULAR SYSTEM
Transport nutrients, hormones
Remove waste products
Gaseous exchange
Immunity
 Blood vessels transport blood
◦ Carries oxygen and carbon dioxide
◦ Also carries nutrients and wastes
Heart pumps blood through blood vessels

6. Components of
circulatory system
• Arteries
• Arterioles
• Capillaries
• Venules
• Veins

7. Arteries
• Blood vessels that carry blood
away from the heart are called
arteries.
• Deliver oxygenated blood to the
tissues.
• are thick-walled, with extensive
elastic tissue and smooth muscle.
• are under high pressure.
• The blood volume contained in the
arteries is called the stressed
volume.
• No valves

8. Arteries
• Elastic (conducting) arteries
• Larger arteries
• Muscular ( distributing) arteries
• Medium arterties
• Arterioles
• Tiny , tiny arteries
• Metarteriole

9. Arterioles
• are the smallest branches of the arteries.
• are the site of highest resistance in the cardiovascular
system
• Alpha and beta receptors

10. Capillaries
• Have the highest cross sectional Area

11. VEINS
• Blood vessels that
carry blood back to
the heart are called
veins.
• Thin Walled
• Large irregular lumen
• Have valves

13. Hemodynamics
• is the dynamics of blood flow.
• Hemodynamics explains
the physical laws that govern
the flow of blood in the blood
vessels.

14. Factors Affecting Hemodynamics
1. Velocity of blood flow (Viscosity)
2. Size of blood vessel
3. Resistance
4. Elasticity of muscular layer (tunica media)

15. Blood Flow
• Blood flow - is the amount of blood
flowing through a tissue in a given
period of time
• Velocity of blood flow is inversely
related to the diameter of the
blood vessel
• Blood flows most slowly in areas of
greatest width

16. Velocity of blood flow
• can be expressed by the following equation:
V=Q/A
• where:
• v = velocity (cm/sec)
• Q = blood flow (mL/min)
• A = cross-sectional area (cm2)

17. Blood Flow
•can be expressed by the following equation:
• where:
• Q = flow or cardiac output (mL/min)
• ΔP = pressure gradient (mm Hg)
• R = resistance or total peripheral resistance (mm
Hg/mL/min)

20. MCQs
• Which one of the following has the highest
cross sectional are

22. • Just write them and let me know I will answer
in my next class
• Thanks

23. Resistance

24. Vascular Resistance
• Friction between blood and the walls of blood
vessels: resists to blood flow

25. • Vascular resistance depends on three
factors:
(1) Size of the blood vessels
(2) Blood viscosity
(3) Total blood vessels length

26. What Determines Resistance in the
Vessels?
• Poiseuille’s Law relates these factors to resistance:
• R  Lη/r4
• if the tube length increases, resistance
increases
• if the viscosity increases, resistance increases
• if the tube’s radius increases, resistance
decreases