Blood pressure by Pandian M, tutor, Dept of Physiology, DYPMCKOP,MH. This PPT for M.Sc

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 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.

14. 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.

15. 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.

16. 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.

17. Nerve supply to baroreceptors and chemoreceptors

18. Regulation of blood pressure by baroreceptor mechanism

19. Regulation of blood pressure by reninangiotensin

20. Marey ( cardioinhibitory ) reflex

21. Bainbridge ( cardioaccelerator ) reflex

22. 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

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

24. References Text book of Medical Physiology Guyton & Hall Text book of Medical Physiology Indukurana . A.K.Jain , Sembu Net source

25. THANK YOU . . .