Regulation of-arterial-blood-pressure

ARTERIAL BLOOD PRESSURE &
REGULATION OF ARTERIAL
BLOOD PRESSURE

1. ARTERIAL BLOOD PRESSURE & REGULATION OF ARTERIAL BLOOD PRESSURE By Dr. Abdul Majid MSc. Medical Physiology

2. Learning objectives Definition of BP and factor affecting BP What are the determinants of BP Mechanism of regulation of BP Applied (Hypertension and hypotension)

3. TERMS SBP DBP PP MAP

4. PHYSIOLOGICAL VARIATIONS AGE SEX BODY BUILT CLIMATE DIURNAL VARIATIONS POSTURE GRVITY AFTER MEALS DURING SLEEP AFTER EXERCISE EMOTIONAL CONDITIONS Sex- In females b efore menopause SBP 4-5 mmHg less as compared to post menopause

5. DETERMINANTS OF ARTERIAL BLOOD PRESSURE ABP = CO x TPR CO = SV x HR SV = EDV ( – ) ESV

6. What factors influence blood pressure? Blood volume Vascular resistance Autoregulation Autonomic influences

7. DETERMINANTS OF ARTERIAL BLOOD PRESSURE

8. REGULATION OF ARTERIAL BLOOD PRESSURE Regulation of Blood Pressure Nervous Mechanism((Rapid Mechanism) Renal Mechanism Hormonal Mechanism Local Mechanism By Vasomotor Center and Impulses from Periphery By Regulation of ECF Volume and renin – angiotensin mechanism By Vasocons- -trictor and Vasodilator Hormones By Local Vasocons- -trictors and Vasodilators

9. REGULATION OF ARTERIAL B.P. SHORT-TERM CONTROL(Rapid Mechanism) (IN SEC – MIN) INTERMEDIATE-TERM CONTROL (30 MIN – HOURS) LONG – TERM CONTROL

10. SHORT-TERM CONTROL OF AP BY CIRCULATORY REFLEXES CNS ISCHAEMIC RESPONSE BARORECEPTOR REFLEX CHEMORECEPTOR REFLEX

11. CUSHING REFLEX Gross hypotension or increased ICP Decreased cerebral blood flow or decreased blood flow to VMC Hypoxia and hypercapnia at VMC Strong stimulation of VMC Intense vasoconstriction Increased pressure in carotid sinus Activation of baroreceptor reflex Reflex bradycardia

12. REGULATION OF BLOOD PRESSURE BY BARORECEPTOR MECHANISM Increase in Blood Pressure Baroreceptors Stimulation Impulses via IX and X Cranial Nerves Normal Blood Pressure Dilatation of blood vessels Bradycardia and reduction in cardiac output Decrease in vasomotor tone Increase in vagal tone Inhibition of vasoconstrictor area Stimulation of vasodilator area Nucleus of tractus solitarius

13. BARORECEPTOR REFLEXES TO RESTORE BLOOD PRESSURE TO NORMAL When blood pressure becomes elevated above normal Carotid sinus and aortic arch receptor potential Rate of firing in afferent nerves Cardiovascular center Sympathetic cardiac nerve activity and Sympathetic vasoconstrictor nerve activity and Parasympathetic nerve activity Heart rate and stroke volume and arteriolar and venous vasodilation Cardiac output And total peripheral resistance Blood pressure decreased toward normal

14. BARORECEPTOR REFLEXES TO RESTORE BLOOD PRESSURE TO NORMAL When blood pressure falls below normal Carotid sinus and aortic arch receptor potential Rate of firing in afferent nerves Cardiovascular center Sympathetic cardiac nerve activity and sympathetic vasoconstrictor nerve activity and parasympathetic nerve activity Heart rate and stroke volume and arteriolar and venous vasoconstriction Cardiac output and total peripheral resistance Blood pressure increased toward normal

15. BARORECEPTOR REFLEX

16. CHEMORECEPTOR REFLEX

17. INTERMEDIATE CONTROL OF Arterial BP RENIN - ANGIOTENSIN – VASOCONSTRICTOR MECH. STRESS RELAXATION OF VASCULATURE FLUID – SHIFT THROUGH THE CAPILLARY WALL

18. REGULATION OF BLOOD PRESSURE BY RENIN-ANGIOTENSIN MECHANISM Decrease in Blood Pressure Stimulation Juxtaglomerular apparatus Renin Angiotensinogen Angiotensin I Converting enzyme Angiotensin II Normal Blood Pressure Vasoconstriction

19. SITES OF PRODUCTION Renin - J.G Cells of Kidney Angiotensinogen - Liver Cells ACE - Lungs

20. LONG – TERM CONTROL OF AP RENAL FLUID SHIFT (THROUGH ADH / VOLUME RECEPTORS) RENIN – ANGIOTENSIN – ALDOSTERONE MECH.

21. RESTORATION OF FLUID VOLUME OF THE BODY BY ADH IN VOLUME DEPLETION STATE. [NTS:

22. Sequential events by which increased salt intake increases the arterial pressure. Increased salt intake Increased extracellular volume Increased arterial pressure Decreased renin and angiotensin Decreased renal retention of salt and water Return of extracellular volume almost to normal Return of arterial pressure almost to normal

23. Summary of Renin-Angiotensin-Aldosterone mechanism

24. LOCAL MECH. FOR CONTROL OF AP A. Vasodilators 1. EDRF 2. Bradykinin 3. Histamine 4. ANP 5. VIP 6. Substance P 7. Prostacyclin 8. Adenosine 9. K + 10. Acidosis [ CO 2 ] 11. Hypercapnia 12. Hypoxia 13. Temperature

25. B. Vasoconstrictors Endothelin-1 Angiotensin II Norepinephrine ADH Serotonin Thromboxane A2 Neuropeptide -Y Cold

26. HORMONAL MECH. FOR CONTROL OF ABP. HORMONES RAISING AP ADRENALINE NORADRENALINE THYROXINE ALDOSTERONE VASOPRESSIN ANGIOTENSIN SEROTONIN

27. HORMONAL MECH. FOR CONTROL OF ARTERIAL BLOOD PRESSURE HORMONES DECREASING ABP VIP BRADY KININ PROSTAGLANDIN HISTAMINE ACETYLCHOLINE ANP

28. PATHOLOGICAL VARIATIONS HYPERTENSION HYPOTENSION