Definition Types of pressure VARIATIONS Regulation of BP FACTORS MAINTAINING ARTERIAL BLOOD PRESSURE VASOMOTOR CENTER APPLIED PHYSIOLOGY

1. BLOOD PRESSURE &
IT’S REGULATION
PANDIAN M
DEPT OF PHYSIOLOGY
DYPMCKOP

2. SLO
• DEFINITION
• TYPES OF PRESSURE
• VARIATIONS
• REGULATION OF BP
• FACTORS MAINTAINING ARTERIAL BLOOD PRESSURE
• VASOMOTOR CENTER
• APPLIED PHYSIOLOGY

3. • Definitions
• Arterial blood pressure is defined as the lateral pressure exerted by
the column of blood on wall of arteries. when blood flows
through the arteries.
• Generally, the term ‘blood pressure’ refers to arterial blood pressure.
Arterial blood pressure is expressed in four different terms:
1. Systolic blood pressure - - 120 ± 20 mmHg (ADULTS)
2. Diastolic blood pressure - 74 ± 16 mmHg (ADULTS)
3. Pulse pressure
4. Mean arterial blood pressure.

4. WHAT DO SYSTOLIC AND DIASTOLIC BLOOD
PRESSURE INDICATE? WHAT IS ITS CLINICAL
SIGNIFICANCE?
• Systolic B.P. Indicates cardiac output.
• Diastolic B.P. Indicates peripheral resistance.
• Systolic B.P. Is the maximum pressure the blood vessels
have to withstand.
• Diastolic blood pressure is the measure of work load on
heart.

5. VARIATIONS
•Blood pressure is altered in physiological and
pathological conditions.

6. PHYSIOLOGICAL VARIATIONS
1. Age
2. Sex - in females, up to the period of menopause, arterial pressure is
5 mm Hg, less than in males of same age.
After menopause, the pressure in females becomes equal to that in
males of same age.
3. Body built - pressure is more in obese persons than in lean persons.
4. Diurnal variation - in early morning, the pressure is slightly low. It
gradually increases and reaches the maximum at noon. It becomes low
in evening.

7. 5. After meals
• Arterial blood pressure is increased for few hours after meals due to increase in
cardiac output.
6. During sleep
• Usually, the pressure is reduced up to 15 to 20 mm hg during deep sleep.
However, it increases slightly during sleep associated with dreams.
7. Emotional conditions
• During excitement or anxiety, the blood pressure is increased due to release of
adrenaline.
8. After exercise
• After moderate exercise, systolic pressure increases by 20 to 30 mm hg above the
basal level due to increase in rate and force of contraction and stroke volume.

8. PATHOLOGICAL VARIATIONS
•Pathological variations of arterial blood pressure are
hypertension and hypotension.

9. RAPID BLOOD PRESSURE CONTROL
MECHANISM (NERVOUS REGULATING
MECHANISM)
1. Baroreceptor reflexes
2. Central nervous system ischaemic response
3. Chemoreceptor reflexes

10. INTERMEDIATE BLOOD PRESSURE CONTROL
MECHANISMS
•Renin–angiotensin vasoconstrictor mechanism,
•Stress relaxation and reverse stress relaxation
mechanism.
• Capillary fluid shift mechanism.

11. LONG-TERM BLOOD PRESSURE CONTROL
MECHANISMS
• Kidneys play main role in the long-term control of blood
pressure by the following mechanisms:
1. Direct mechanism, i.e. Renal body fluid feedback mechanism.
2. Indirect mechanisms control kidney functions indirectly via following
hormonal mechanisms:
(I) aldosterone system and
(Ii) renin–angiotensin system.

12. DETERMINANTS OF ARTERIAL BLOOD PRESSURE – FACTORS
MAINTAINING ARTERIAL BLOOD PRESSURE
TYPES OF LOCAL FACTORS
• Local factors are divided into two types:
A. CENTRAL FACTORS, WHICH ARE PERTAINING TO THE
HEART:
1. CARDIAC OUTPUT
2. HEART RATE

13. B. Peripheral factors, which are pertaining to blood and blood
vessels:
3. Peripheral resistance
4. Blood volume
5. Venous return
6. Elasticity of blood vessels
7. Velocity of blood flow
8. Diameter of blood vessels
9. Viscosity of blood.

15. REGULATION OF ARTERIAL
BLOOD PRESSURE
A. Nervous mechanism or short term regulatory
mechanism
B. Renal mechanism or long term regulatory
mechanism
C. Hormonal mechanism
D. Local mechanism.

17. • Nervous regulation is rapid among all the mechanisms
involved in the regulation of arterial blood pressure.
• When the pressure is altered, nervous system brings the
pressure back to normal within few minutes.
• Although nervous mechanism is quick in action, it operates
only
• For a short period and then it adapts to the new pressure.
• Hence, it is called short term regulation.

18. VASOMOTOR CENTER
• Vasomotor center is bilaterally situated in the reticular
formation of medulla oblongata and the lower part of the
pons.
Vasomotor center consists of three areas:
• I. Vasoconstrictor area or pressor area
Ii. Vasodilator area or epressor area.
Iii. Sensory area.

19. Nerve supply to baroreceptors
and chemoreceptors

20. Regulation of blood pressure by baroreceptor mechanism

21. Regulation of blood pressure by reninangiotensin

22. Marey (cardioinhibitory) reflex

23. Bainbridge (cardioaccelerator) reflex

25. APPLIED PHYSIOLOGY
• Pathological variations of arterial blood pressure:
A. Hypertension
B. Hypotension.
Hypertension
Definition
• Hypertension is defined as the persistent high blood pressure.
Clinically, when the systolic pressure remains elevated above 150
mm hg and diastolic pressure remains elevated above 90 mm hg

26. HYPOTENSION
•Definition
•Hypotension is the low blood pressure. When the
systolic pressure is less than 90 mm hg, it is
considered as hypotension.

29. REFERENCES
• TEXT BOOK OF MEDICAL PHYSIOLOGY
• GUYTON & HALL
• TEXT BOOK OF MEDICAL PHYSIOLOGY
• INDUKURANA. A.K.JAIN, SEMBU
• NET SOURCE

30. THANK YOU . . .