Hemodynamics is how your blood flows through your arteries and veins and the forces that affect your blood flow. Normally, your blood flows in a laminar (streamlined) pattern. It flows fastest in the middle of a blood vessel, where there's no friction with blood vessel walls.

2. HEMODYNAMICS 2
Dr. K. Ambareesha, PhD
Assistant Professor, Department of Physiology, GMC

3. LEARNING OBJECTIVES
Define
Bernoullis Principle
Principle of Siphon
Windkessel effect
Critical closing pressure
Resistance vessel Vs Capacitance vessels
Exchange vessels Vs Impedance
Parallel and series arrangement in vascular system
Law of Lawplace and its applications

4. DEFINE
The flow of blood in vascular system is governed by a group of physical laws

5. BERNOULLI’S PRINCIPLE

6. Total end pressure (TE)
Lateral pressure measures the potential energy (PE)
The difference between EP and LP in a flowing tube is due to kinetic energy (KE)
KE=½ MV2 M=Mass, v= velocity)

7. PRINCIPLE
1. Total energy of blood flow is the sum of PE and KE
2. The PE and KE at a given point in a system is constant

8. APPLICATIONS
1. Increase in one form of energy has to overcome at the expend=se of the
other
Ex: As flow velocity increases, LP must decrease to keep the total energy
Constant.
1. When a vessel is narrowed (atheroscerosis plaque) the velocity in narrowed
portion increases and the detending pressure decreases.

9. 2. PRINCIPLE OF SIPHON

10. 1. Bent tube having short arm and long arm
2. Short arm is placed in liquid to be emptied long arm in lower level
3. Air must be removed from siphon before it is operated
4. When air is removed fluid flows because of different pressures

11. 3. WINDKESSEL EFFECT

12. 1. During systole blood enters the large arteries with great force and can be
accommodate by its distensible nature
2. During diastole fore is absent volume entering is zero they recoil due to
elastic property
3. This recoil effect is the WKE
4. Ex: aorta, pulmonary artery and its branches

13. RESISTANT VESSELS Vs CAPACITANCE VESSELS
1. Contain less elastic tissue and more
smooth muscle
2. Change its diameter by contraction and
relaxation of smooth muscle
3. Change in resistance influences the flow
4. Ex: arterioles, meta arterioles and
precapilary spoincters
1. Thin walled tightly distensible
2. Ability to store lagve amount of blood
3. Ex: Veins

14. EXCHANGE VESSELS Vs IMPEDANCE
1. Thin walled and have fenistarations and
help in exchange of materials between
blood and interstitial fluid
2. Ex: Arteriovenous anastomasis
1. Ratio of resistance to piulsatile flow
2. Friction in vascular compliance and blood
mass
3. Change in compliance of aorta changes
impedance in its blood flow

15. PARALLEL Vs SERIES ARRANGEMENT IN CVS
(VASCULAR COMPARTMENT)

17. SERIES ARRANGEMENT
1. Blood pumped by heart flows from higher pressure to lower pressure
arranged in series and parallel
2. The arteries , arterioles, capillaries, venules and veins are arranged in series
3. In the blood vessels , total resistance of the blood flow (Rtotal)= the sum of
the resitance of each vessel
4. R toral= R1+R2+R3+R4……

18. PARALLEL ARRANGEMENT
1. Blood vessels branch extensively form parallel circuits which supply blood to
many organs or tissue to regulate the blood flow to a great extent
2. Greater amount of blood will flow through this comparing to individual blood
vessels
3. Here resistance is far less comparing as a single blood vessel
4. 1/R1=1/R2+1/R2+1/R3+1/R4………

19. FLOW PRESSURE RELATIONSHIP

20. CRITICAL CLOSING PRESSURE
1. In a rigid tube pressure and flow have linear relationship, but in blood vessels
initial rise in pressure do not cause any flow.
2. Eleven after that it doesnt have any relation but is some what curved,
because blood vessels are distensible elastic tubes, so, the pressure at which
the flow stops is called CRITICAL CLOSING PRESSURE

21. FACTORS AFFECTING
1. Some pressure (minimum pressure): RBC require a little more pressure
than plasma to be forced into movement
2. Tissue pressure: in the body the blood vessels are surrounded by tissues
and tissue fluid producing compression affect on it, the pressure has to be
overcome before the blood flows

22. APPLICATION OF LAW OF LAWPLACE

23. In cylinder
T=Pr/w
T= Tension in the wall of cylinder
P=Pressure
r= radius
w=wall thickness

24. Thin walled viscous
P=2T/R [ Wall thickness is negligible]
CYLINDER LIKE BLOOD VESSEL
P=T/R [Radious is infinitive]

25. APPLICATIONS
1. Capillaries do not rupture although they are thin walled
2. Work done by dilated heart is more than non dilated heart
P=2T/R
1. In ventricular thickness is more wall tension decreases
2. Ex: ventricular hypertrophy
3. Dialted heart in heart failure is required to pump the blood against wall
tension.

26. THANK YOU