This document summarizes a presentation on the local control of blood flow. It discusses various factors that regulate blood flow both acutely and long-term at the local tissue level. Some key points include: - Blood flow is regulated by local, humoral and nervous mechanisms. Multiple factors like metabolites, ions, hormones, and endothelium-derived factors control blood flow. - Acute control is mediated by changes in local tissue metabolism, oxygen levels, and nutrients. Long-term control involves changing vascularity and the growth of new blood vessels (angiogenesis). - Specific organs like the kidney, brain, skin and muscles have special blood flow control needs. Humoral control involves hormones from endocrine glands

1. Local control of blood flow-II
Prof. Dr. Rashid Mahmood

2. 05/02/19 Presentation Title | Presented By: Name 2
Local control of blood flow-II
Prof. Dr. Rashid Mahmood

3. 05/02/19 Presentation Title | Presented By: Name 3
Recap

4. Control of Blood Flow
Local Humoral Nervous
Acute
Long-
term
Special Areas
1.Kidney
2.Brain
3.Skin
4.Muscles
Endocrines
1.Epinephrine
2.Norepinephrine
3.Angiotensin I
4.ADH
Chemical factors
1.Prostaglandins
2.Bradykinin
3.Histamine
4.CO2
5.Osmolarity
Ions
1.H+
2.K+
3.Ca++
4.Mg++
5.Na+
© Prof. Dr. Rashid Mahmood 4
Endothelium-
Derived Factors
Sympathetic
Para-sympathetic

5. Acute Control of Blood Flow
↑ metabolism
1.Adenosine
compounds
2.Lactic acid
3.CO2
4.K+
5.H+
↓ O2
1.Adenosine
2.↑ demand
↓ nutrition
1.Glucose
2.Amino
acids
Autoregulation of blood Flow
during Changes in BP
Metabolic
theory
Myogenic
theory
© Prof. Dr. Rashid Mahmood 5
1. vasodilator theory
2. Oxygen lack theory
Roll of other nutrients
(Nutrient lack theory)
Metabolic Requirements
Endothelium-Derived
Factors

6. Summary of Mechanisms of
vasodilation in acute local control
Small vessels
Vasomotion
(pre-capillary
sphincter)
Metabolic
factors (micro
vessels)
Large vessels
EDRF(endothelial
derived relaxing
factor)
(nitric oxide)
© Prof. Dr. Rashid Mahmood 6

7. Objectives
Goal/Aim: To understand the importance and
mechanism of Mechanism of Blood Flow Control
Specific Objectives: At the end of the lesson
student will be able to :
 List the regulatory mechanisms of local control of
blood flow
 Describe different factors involved in Acute control
of blood flow
3. Describe different factors involved in Long term of
control of blood flow
4. Describe the Humoral & Nervous control of local
circulation
© Prof. Dr. Rashid Mahmood 7

8. Long-term control
Collateral Blood Vessels
↑Tissue Vascularity
Angiogenesis
Angiogenesis factors
released FROM
1.Ischemic tissues
2.Growing tissues
3.↑ Metabolism
Angiogenesis factors
include
1.VEGF (Vasculo-
Endothelial Growth
Factor)
2.Platelet-Derived Growth
Factor (PDGF)
3.FGF (Fibroblast Growth
Factor)
4.Angiogenin
© Prof. Dr. Rashid Mahmood 8
Vascular Remodeling

9. Angiogenesis
Within days
© Prof. Dr. Rashid Mahmood 9
Oxygen deficiency (a strong stimulant)
Rapid in new growth tissues, like neonates
Physical reconstruction of tissue vasculature

10. Angiogenesis
© Prof. Dr. Rashid Mahmood 10

11. Roll of O2 in long term
High altitude
Angiogenesis
Retrolental fibroplasia
© Prof. Dr. Rashid Mahmood 11

12. © Prof. Dr. Rashid Mahmood 12
Disappearance of blood
vessels when not in use
AngiostatinEndostatin
Steroid hormones (Clinical use)

13. © Prof. Dr. Rashid Mahmood 13
Vascular
Remodeling
Laplace's Equation:
T=r×P
T=tension
r= radius
P=pressure

14. Special phenomena of Long-Term
Local Blood Flow Regulation
© Prof. Dr. Rashid Mahmood 14
Vascularity Is Determined by Maximum
Blood Flow Need, Not by Average Need
after extra vascularity does develop, the extra blood vessels
normally remain mainly vasoconstricted unless required
Development of Collateral Circulation

15. Assessment Q. 5
Name any TWO Angiogenesis
factors.
© Prof. Dr. Rashid Mahmood 15
1. VEGF (Vasculo-Endothelial Growth Factor)
2. Platelet-Derived Growth Factor (PDGF)
3. FGF (Fibroblast Growth Factor)
4. Angiogenin

16. Objectives
Goal/Aim: To understand the importance and
mechanism of Mechanism of Blood Flow Control
Specific Objectives: At the end of the lesson
student will be able to :
 List the regulatory mechanisms of local control of
blood flow
 Describe different factors involved in Acute control
of blood flow
 Describe different factors involved in Long term of
control of blood flow
4. Describe the Humoral & Nervous control of local
circulation
© Prof. Dr. Rashid Mahmood 16

17. Humoral Control of the
Circulation
Vasoconstrictor
Agents
Norepinephrine
and Epinephrine
Angiotensin II, &
Vasopressin
Vasodilator
Agents
Bradykinin,
Histamine
Effects:
arteriolar dilation
↑ capillary
permeability
– Edema
© Prof. Dr. Rashid Mahmood 17

18. Bradykinin (a Kinin)
© Prof. Dr. Rashid Mahmood 18
inactive kallikrein
kallikrein
1. maceration of the blood
2. tissue inflammation
3. chemical or physical effects
alpha2-globulin
Releases
kallidin bradykinin
tissue enzymes

19. Inactivation of bradykinin
In few minutes
By carboxypeptidase or by
Converting Enzyme
© Prof. Dr. Rashid Mahmood 19

20. Histamine
© Prof. Dr. Rashid Mahmood 20
Basophils
Mast cells
Damage
Inflammation,
Allergic
reaction
Produced in almost every tissue

21. Nervous Control of Local Blood
Flow
Sympathetic:
Vasoconstriction
Exceptions:
– Coronary vessels
– Some vasodilator fibers to skeletal
muscles
Parasympathetic Stimulation:
Vasodilation
Indirect effect© Prof. Dr. Rashid Mahmood 21

22. Core knowledge Points (1/2)
1. local blood flow in an exact way, the
tissues almost never suffer from
oxygen and nutritional deficiency
2. Blood flow is directly proportional to
metabolic rate
3. Blood flow to the tissues is
automatically regulated in spite of
changes in blood pressure, within
physiological limits (Autoregulation)
4. Regulatory mechanisms include Local,
Humoral, & Nervous mechanisms© Prof. Dr. Rashid Mahmood 22

23. Core knowledge Points (2/2)
5. Different multiple factors are involved in
Acute control of blood flow, and Long term
control
6. Endothelium-Derived Relaxing and
contracting Factors play a key role in
autoregulation
7. Humoral control of local circulation
involves certain Endocrines , Ions, and
Chemical factors
8. Nervous control of blood flow involves
Sympathetic, and to some extent Para-
sympathetic nervous system
© Prof. Dr. Rashid Mahmood 23

24. Control of Blood Flow (Take Home Points)
1. Local
i. Acute
a. Control by tissue metabolism
I. Vasodilator theory
II. Oxygen lack theory (Nutrient lack theory)
III. Special Examples of Acute metabolic Control
a. Reactive Hyperemia
b. Active Hyperemia
b. Autoregulation of blood flow during changes in arterial Pressure
I. Metabolic mechanism
II. Myogenic mechanism
ii. Endothelium-Derived Factors
iii. Long-term
a. Change in Tissue vascularity
b. Collateral Circulation
c. Vascular Remodeling
iv. Special Areas (Kidney, Brain, Skin, Muscles)
2. Humoral
i. Endocrines
ii. Ions
iii. Chemical factors
3. Nervous
i. Sympathetic
ii. Para-sympathetic
24

25. Learning Resources
Guyton and Hall (Text book of physiology), 13th
Edition
Ganong (Text book of physiology), 25th 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 Mahmood
25

26. Next topic:
Regulation of blood pressure –I
Prior knowledge required for next lecture
Overview of the Circulation; Medical Physics
of Pressure, Flow, and Resistance
Vascular Distensibility and Functions of the
Arterial and Venous Systems
Local and Humoral Control of Blood Flow by
the Tissues
Nervous Regulation of the Circulation
Basic Physiology of autonomic nervous
system © Prof. Dr. Rashid Mahmood
26

27. World Book and Copyright Day (also known
as International Day of the Book)
(April 23rd
)
The things I want to know are in books; my
best friend is the man who’ll get me a book
to read (Abraham Lincoln)
The book you don’t read won’t help (Jim
Rohn)
I read a lot of obscure books and it is nice
to open a book (Bill Gates)
Finishing a good book is like leaving a
good friend (William Feather)
© Prof. Dr. Rashid Mahmood 27

28. Assessment Q. 6-8
6. What is the effect of Bradykinin and
Histamine on blood vessels in addition
to arteriolar dilation?
7. When the World Book and Copyright
Day is celebrated each year?
8. Feedback
© Prof. Dr. Rashid Mahmood 28

29. ThankYou
Questions/ Comments/Feedback
rashid.mahmood@rmi.edu.pk,
drrashid62@gmail.com