The document contains feedback from a lecture. The bad points included that some students found the speed too fast, some topics not clearly explained, and less use of the whiteboard. The good points were that most students enjoyed and understood the lecture, and found the diagrams, animations and slides helpful. Some topics were well explained. Overall students felt concepts were cleared and it was a step-wise lecture.

1. Bad Points
1. Should be more animated
videos
2. Some students disturbing the
class by asking irrelevant
questions
3. Speed was a little fast
4. ECG strip should be provided
5. Some things not clearly
explained e.g interpretation,
voltage, X-axis, leads
6. Use of white board was less
7. Did not understand completely
8. Lecture was a little bit lengthy
9. Repeat of LGF demanded
10. Some students ask questions
just to disturb class
Good Points
1. Enjoyed the lecture
2. Understood the lecture
3. Diagrams were good
4. Animations, slides and
images were good
5. Answered the questions
6. Some things were explained
very well e.g leads
7. Way of teaching was liked.
LGF was informative and
well explained; Concepts
were cleared
8. Brief introduction to each
point. Different books were
consulted
9. It was a step-wise lecture
10. I should take more classes

2. Prof. Dr. Rashid
Mahmood

3.  By the end of this lecture, students should be able to know the
physical principles of blood flow peripheral resistance, blood
pressure and change in velocity.
 Specific objectives:
◦ Explain the factors that regulate the volume of blood flow.
◦ Explain how blood pressure changes throughout the cardio
vascular system.
◦ Indicate the factors that determine mean arterial pressure and
systemic vascular resistance.
◦ Outline the relationship between cross sectional area and
velocity of blood flow.
◦ Explain how blood pressure and resistance determine volume of
blood flow.
◦ How is the return of venous blood to the heart accomplished?
◦ Why is velocity of blood faster in arteries than in veins?
Prof. Dr. Rashid Mahmood 3

4.  Interrelationship among pressure flow and
resistance.
 Ohm’s Law and Poieulle’s Law.
 Role of blood Hematocrit and peripheral
resistance.
 Arterial pressure.
 Blood pressure.
Prof. Dr. Rashid Mahmood 4

5. Prof. Dr. Rashid Mahmood 5
Cut here

6. Circulation
Systemic Pulmonary
Prof. Dr. Rashid Mahmood 6

7. Prof. Dr. Rashid Mahmood 7

8. •Arteries
•Arterioles
•Capillaries
•Venules
•Veins
Prof. Dr. Rashid Mahmood 8

9.  Systemic circulation 84 %
◦ Veins 64 %
◦ Arteries 13 %
◦ Arterioles & capillaries 7 %
 Heart & Lungs 16 %
◦ Heart 7 %
◦ Pulmonary vessels 9 %
Prof. Dr. Rashid Mahmood 9

10. More than
64 % of
the blood
is in the
systemic
veins
Prof. Dr. Rashid Mahmood 10

11.  Aorta 2.5 cm 33 cm/sec
 Small arteries 20 cm
 Arterioles 40 cm
 Capillaries 2500 cm 0.3 mm/sec
 Venules 250 cm 3 mm/sec
 Small veins 80 cm
 Venae cavae 8 cm
V = F/A
Prof. Dr. Rashid Mahmood 11

12. Prof. Dr. Rashid Mahmood 12

13. More
pulsatile
closer to
heart
Prof. Dr. Rashid Mahmood 13

14. 1. The rate of blood flow to each tissue is
controlled in relation to the tissue need
2. The cardiac output is controlled mainly by
the sum of all the local tissue flows.
3. Arterial pressure is controlled independently
of either local blood flow control or cardiac
output control
Prof. Dr. Rashid Mahmood 14

15. ◦ Vascular Resistance- Impediment to the flow of the
blood
◦ Pressure gradient, Pressure difference along the
vessel which is absolutely necessary for blood flow
Prof. Dr. Rashid Mahmood 15

16.  F = ΔP/R
◦ (F) =Blood flow (ml/sec)
◦ (R) =Vascular resistance(Peripheral Resistance Units (PRU)
◦ ΔP =Pressure difference (pressure gradient)
between two end of vessels (mm Hg)
 Other forms of equation
◦ ΔP = F x R
◦ R = ΔP/F
Prof. Dr. Rashid Mahmood 16

17.  Enumerate the factors that regulate the blood
flow.
Prof. Dr. Rashid Mahmood 17

18.  LAMINAR or
STREAMLINE FLOW
◦ Steady blood flow
◦ Each layer of blood at
same distance from
the vessel wall
◦ No sound produced
 Turbulent flow
◦ Unsteady flood flow
◦ Blood flowing in all
direction, mixing
different layers
◦ Sounds are produced
◦ Eddy currents
produced
Prof. Dr. Rashid Mahmood 18

19. P2P1
P1 > P2
•Turbulent blood flow
•Eddy currents
•Sound Audible with a Stethoscope
Prof. Dr. Rashid Mahmood 19

20. Reynolds‘ Number is the measure of the
tendency of turbulence
Re =
v. d. ρ
η
Where:
v= mean velocity
d=vessel diameter
ρ =density
η=viscosity
200- 400 Turbulence may occur in some big vessels
>2000 Always turbulent
Prof. Dr. Rashid Mahmood 20

21.  Re rises in big vessels and chances of
Turbulence & sound increase
◦ Base of the aorta
◦ Base of the pulmonary artery
◦ More diameter
◦ Sudden change in the diameter of the blood vessel
◦ Pulsatile blood flow
◦ High velocity of blood
Prof. Dr. Rashid Mahmood 21

22.  How is Peripheral Resistance related to blood
flow.
Prof. Dr. Rashid Mahmood 22

23.  Force exerted by the flowing blood
against per unit area of the vessel
wall
 Usually expressed as mm Hg
 Occasionally expressed as cm H2O
 1 mm Hg = 1.36 cm of H2O
Prof. Dr. Rashid Mahmood 23

24. Recording arterial pressure with a mercury
manometer
Prof. Dr. Rashid Mahmood 24

25.  Volume of blood flow in a vessel for given
pressure difference (ΔP)
 It is inversely proportional to resistance
 Conductance = 1/Resistance
 Conductance is proportional to (diameter)4 of
the blood vessel
 Slight change in vessel diameter →
tremendous change in conductance
Prof. Dr. Rashid Mahmood 25

26. Prof. Dr. Rashid Mahmood 26

27.  Rate of blood flow is determined
◦ Pressure difference
◦ Radius of the blood vessel
◦ Viscosity of the blood
◦ Length of the blood vessel
 Poiseuille’s law
F = ∏ΔP r4 /8ηl
Prof. Dr. Rashid Mahmood 27

28.  Hematocrit = %age
of Formed elements
in blood
◦ 42 % in males
◦ 38 % in females
◦ Less in anemia
◦ More in polycythemia
Prof. Dr. Rashid Mahmood 28

29.  Normal blood viscosity = 3 times H2O
 ↑Hematocrit → ↑ Viscosity → ↑ Resistance
 ↓Hematocrit → ↓ Viscosity → ↓ Resistance
 Polycythemia → Hematocrit 60-70% → ↑(10X)
Viscosity
 Anemia may → ↓ Viscosity (1.5 times H2O)
Prof. Dr. Rashid Mahmood 29

30. Prof. Dr. Rashid Mahmood 30

31.  How does an increase in hematocrit affect the
peripheral resistance.
Prof. Dr. Rashid Mahmood 31

32. •↑ Pressure → ↑ Force to push
•↑ Pressure → ↑ ↑ Blood flow
•At 50 mmHg F = 1
•At 100 mm Hg (x2) F = 4
(NOT 2)
•↑ Pressure → Distension of
blood vessel
•Flow is proportional to
(diameter)4
Prof. Dr. Rashid Mahmood 32

33.  Circulation is described as systemic and
pulmonary circulation
 About 64% of blood is in systemic Veins
 Velocity of blood is inversely proportional
to vascular Cross sectional area (V = F/A)
 Blood Pressure in blood vessels decreases
as the Distance increases from the heart
 Blood flow, as determined by Ohm’s Law, is
directly proportional to pressure gradient,
and inversely proportional to peripheral
vascular resistance (F = ΔP/R)
Prof. Dr. Rashid Mahmood 33

34.  Factors that increase the chances of
turbulent flow (Reynolds‘ Number) include
↑velocity, ↑ vessel diameter,↑ density of
blood, sudden changes in diameter of blood
vessels and pulsatile blood flow while
increased viscosity of blood favors laminar
flow
 Force exerted by the flowing blood against
per unit area of the vessel wall is called
Blood Pressure, and is usually expressed
as mm Hg
Prof. Dr. Rashid Mahmood 34

35.  Volume of blood flow in a vessel for given pressure
difference is called Conductance. It is inversely
proportional to Resistance, and directly
proportional to (diameter)4 of the blood vessel
 Rate of blood flow, as determined by
Poiseuille’s law, is directly proportional to
Pressure difference and Radius of the blood
vessel, and indirectly proportional to Viscosity
of the blood and Length of the blood vessel
 ↑ hematocrit increases blood viscosity, leading
to ↑ Rate of blood flow
Prof. Dr. Rashid Mahmood 35

36. Write your feedback about this presentation
i. Did you enjoy?
ii. Did you understand?
iii. What were the good points?
iv. What were the bad points?
v. Suggestions for improvement
Prof. Dr. Rashid Mahmood 36

37.  Guyton and Hall (Text book of physiology), 13th
Edition
 Ganong (Text book of physiology), 24th Edition
 Berne & Levy Principles of Physiology (Koeppen
BM), 6th Edition
 Human Physiology Stuart Fox, 13th Edition
 Human Physiology : from cells to system with
Power Lecture DVD Lauralee Sherwood, 9th edition
 Internet
Prof .Dr. Rashid Mahmood37

38.  Questions
 Comments
 Criticism
rashid.mahmood@rmi.edu.pk
drrashid62@gmail.com
Prof .Dr. Rashid Mahmood38

39.  Regulation of blood pressure –I
 27.04.2017
Prof. Dr. Rashid Mahmood 39