This document discusses various regulatory mechanisms that control cardiovascular function, including intrinsic (local) and extrinsic regulation. Intrinsic regulation involves local mechanisms like myogenic responses, metabolic factors, the endothelium, tissue pressure, and local humoral factors. Extrinsic regulation utilizes neural and humoral pathways through autonomic centers in the spinal cord and medulla that integrate sensory inputs and control sympathetic outflow. Key humoral factors that act as vasodilators or vasoconstrictors are also mentioned.

1. Cardio-vascular
Regulatory
Mechanisms
Dr. Praveen Kumar K

2. Why ??
READJUSTMENT
THERMOREGULATIO
N
THREATS/
ADJUSTMENTS

3. let’s segregate
ROLE OF
TISSUE
PRESSURE
NEURAL
REGULATORY
MECHANISMS
MYOGENIC
MECHANISM OF
AUTOREGULATIO
N
ROLE OF
ENDOTHELIUM
CHEMICAL
&
HUMOARAL
REGULATIO
N
LOCAL HUMORAL
AUTOREGULATIO
N
METABOLIC
FACTORS
MISCELLANEOU
S

4. INTRINSIC (LOCAL)
REGULATION
(OR)
AUTOREGULATION
EXTRINSIC
REGULATION
• MYOGENIC MECHANISM
• METABOLIC FACTORS
• ROLE OF ENDOTHELIUM
• ROLE OF TISSUE
PRESSURE
• LOCAL HUMORAL
AUTOREGULATION
• MISCELLANEOUS
• NEURAL
• CHEMICAL & HUMORAL

5. Myogenic Mechanism of Autoregulation
I
n
t
r
i
n
s
i
c
(
l
o
c
a
l
)
R
e
g
u
l
a
t
i
o
n
o
r
A
u
t
o
r
e
g
u
l
a
t
i
o
n

6. Regulation by Metabolic Factors
I
n
t
r
i
n
s
i
c
(
l
o
c
a
l
)
R
e
g
u
l
a
t
i
o
n
o
r
A
u
t
o
r
e
g
u
l
a
t
i
o
n
Metabolic factors produce local vasodilation and increases
the blood flow
• Change in composition of interstitium
• Liberation of histamine from damaged mast cells (as in
inflammation)
• High local tissue temperature

7. Regulation by Metabolic Factors
I
n
t
r
i
n
s
i
c
(
l
o
c
a
l
)
R
e
g
u
l
a
t
i
o
n
o
r
A
u
t
o
r
e
g
u
l
a
t
i
o
n
The quantum of vasodilatation and resultant increased local
blood flow produced due to the metabolic factors(70 ml/100
gm/min.) in comparison, far higher than that due to the
decreased sympathetic vasoconstrictor effect (2 to 4 ml/100
gm/min.).

8. Regulation by Metabolic Factors
I
n
t
r
i
n
s
i
c
(
l
o
c
a
l
)
R
e
g
u
l
a
t
i
o
n
o
r
A
u
t
o
r
e
g
u
l
a
t
i
o
n
..Adenosine
..Hypoxia
Hypercapnea
Lactate
K+

9. Regulation by Metabolic Factors
I
n
t
r
i
n
s
i
c
(
l
o
c
a
l
)
R
e
g
u
l
a
t
i
o
n
o
r
A
u
t
o
r
e
g
u
l
a
t
i
o
n
What is Reactive Hyperemia ?
What is Active Hyperemia ?

10. Regulation by Metabolic Factors
I
n
t
r
i
n
s
i
c
(
l
o
c
a
l
)
R
e
g
u
l
a
t
i
o
n
o
r
A
u
t
o
r
e
g
u
l
a
t
i
o
n
Metabolic factors produce local vasoconstriction and decreases
the blood flow
• Injury to the artery/arterioles
• Tissue injury resulting in the liberation of serotonin
from platelets
• Low tissue temperatures

11. INTRINSIC (LOCAL)
REGULATION
(OR)
AUTOREGULATION
EXTRINSIC
REGULATION
• MYOGENIC MECHANISM
• METABOLIC FACTORS
• ROLE OF ENDOTHELIUM
• ROLE OF TISSUE
PRESSURE
• LOCAL HUMORAL
AUTOREGULATION
• NEURAL
• CHEMICAL & HUMORAL

12. Role of Endothelium
I
n
t
r
i
n
s
i
c
(
l
o
c
a
l
)
R
e
g
u
l
a
t
i
o
n
o
r
A
u
t
o
r
e
g
u
l
a
t
i
o
n
In response to shear-stress or inflammatory mediators…
• Vasoactive chemicals(e.g., prostaglandins, NO,
Endothelins)
• Growth promoters (for angiogenesis)
• Influencers of platelet aggregation

13. Role of Tissue Pressure
I
n
t
r
i
n
s
i
c
(
l
o
c
a
l
)
R
e
g
u
l
a
t
i
o
n
o
r
A
u
t
o
r
e
g
u
l
a
t
i
o
n
Increase in flow  increase in filteration  

14. Local Humoral Autoregulation
I
n
t
r
i
n
s
i
c
(
l
o
c
a
l
)
R
e
g
u
l
a
t
i
o
n
o
r
A
u
t
o
r
e
g
u
l
a
t
i
o
n
Kinins,
5-HT/Serotonin,
Histamine etc…

15. INTRINSIC (LOCAL)
REGULATION
(OR)
AUTOREGULATION
EXTRINSIC
REGULATION
• MYOGENIC MECHANISM
• METABOLIC FACTORS
• ROLE OF ENDOTHELIUM
• ROLE OF TISSUE
PRESSURE
• LOCAL HUMORAL
AUTOREGULATION
• NEURAL
• CHEMICAL & HUMORAL

16. Extrinsic Regulation
….for quick adaptability of CVS for fast changing situations
(e.g., sudden thermal effects, posture and gravity, threats to
survival like ‘fight or flight’ situation, hemorrhage etc.) or for
chronic threat to circulation(e.g. hypertension) a coordinated
and holistic regulation can only be attended by Extrinsic
Regulation.

17. Extrinsic Regulation
…. Extrinsic Regulation involves both neural and
humoral mechanisms.

18. Neural Regulatory Mechanisms
-
-
-
-
-
-
-
-
E
x
t
r
i
n
s
i
c
R
e
g
u
l
a
t
i
o
n
-
-
-
-
-
-
-
-
Neural innervation of Heart and Blood Vessels
…. Sympathetic & Parasympathetic effects on heart and blood
vessels
 on heart
 on blood vessels
 vasomotor tone
 vascular response in axon reflex

19. Neural Regulatory Mechanisms
-
-
-
-
-
-
-
-
E
x
t
r
i
n
s
i
c
R
e
g
u
l
a
t
i
o
n
-
-
-
-
-
-
-
-
Autonomic Centers
 Spinal centers
 Medullary centers
 Cortico-hypothalamic influences

20. Autonomic Centers
-
-
-
-
-
-
-
-
E
x
t
r
i
n
s
i
c
R
e
g
u
l
a
t
i
o
n
-
-
-
-
-
-
-
-
Spinal Centers
 Located in the lateral horn cells of spinal cord
 Provides sympathetic tone that maintains the resting
vascular tone, heart rate and blood pressure.

21. Autonomic Centers
-
-
-
-
-
-
-
-
E
x
t
r
i
n
s
i
c
R
e
g
u
l
a
t
i
o
n
-
-
-
-
-
-
-
-
Medullary Centers
 Located in the ventrolateral medulla
 Known as Medullary Cardiovascular Center(MCVC)
 Generates and transmit excitatory signals to the
spinal cord
 Integrates all inputs
 Acts as a CVS reflex centre

22. Autonomic Centers
-
-
-
-
-
-
-
-
E
x
t
r
i
n
s
i
c
R
e
g
u
l
a
t
i
o
n
-
-
-
-
-
-
-
-
Medullary Centers
 Named as Vasomotor Center(VMC)
Vasoconstrictor
(Pressor) Area
Vasodilator
(Depressor) Area
Sensory Area

23. Autonomic Centers
-
-
-
-
-
-
-
-
E
x
t
r
i
n
s
i
c
R
e
g
u
l
a
t
i
o
n
-
-
-
-
-
-
-
-
Reflex responses of Vasomotor
Center(VMC)
VMC
 Exercise
 Fight or Flight reaction
 Cerebral ischemic response
 Increased intra-cranial
pressure
 Hypoxia & Hypercapnea
 Cardiopulmonary
baroreflexes
 Cutaneous pain
 Vasovagal syncope
 Deep pain
 Cardiopulmonary
baroreflexes
SYMPATHETIC

24. Autonomic Centers
-
-
-
-
-
-
-
-
E
x
t
r
i
n
s
i
c
R
e
g
u
l
a
t
i
o
n
-
-
-
-
-
-
-
-
Reflex responses of Vasomotor Center(VMC) are elicited
both by mechanoreceptors and chemoreceptors.
Medullary Centers

25. Autonomic Centers
-
-
-
-
-
-
-
-
E
x
t
r
i
n
s
i
c
R
e
g
u
l
a
t
i
o
n
-
-
-
-
-
-
-
-
Reflex responses of Vasomotor Center(VMC) are elicited
both by mechanoreceptors and chemoreceptors.
Medullary Centers

26. Location of chemoreceptors
Location of baroreceptors

28. Chemical and Humoral Regulation
-
-
-
-
-
-
-
-
E
x
t
r
i
n
s
i
c
R
e
g
u
l
a
t
i
o
n
-
-
-
-
-
-
-
-
Vasodilators Vasoconstrictors
Kinins(Bradykinin)
VIP
ANP
Local factors
Metabolites
Prostaglandins
Norepinephrine
Angiotensin – II
Vasopressin
Thyroid hormones