This document discusses several intermediate control mechanisms that help regulate blood pressure, including fluid shift between tissues and circulation, stress relaxation of blood vessels, and the renin-angiotensin vasoconstrictor mechanism. The fluid shift mechanism involves absorption or loss of fluid from capillaries into tissues to increase or decrease blood volume and pressure. Stress relaxation occurs as stretched blood vessels relax over time, lowering pressure. The renin-angiotensin mechanism involves the kidneys releasing renin when pressure falls, ultimately leading to vasoconstriction and raised pressure through angiotensin II. Biogenic amines can also cause vasoconstriction or vasodilation as another intermediate control mechanism.

1. ‘’INTERMEDIATE CONTROL MECHANISM’’ Presented by: Burhan Umer

2. MECHANISMS: Fluid shift Stress relaxation Renin-angiotensin vasoconstrictor mechanism Biogenic amines

4. WHEN PRESSURE FALLS TOO LOW, FLUID IS ABSORBED FROM THE TISSUES THROUGH CAPILLARY MEMBRANE AND INTO THE CIRCULATION

5. IT BUILDS UP BLOOD VOLUME AND INCREASES THE PRESSURE IN THE CIRCULATION.

6. WHEN PRESSURE RISES TOO HIGH, FLUID IS LOST OUT FROM CIRCULATION INTO THE TISSUES

7. IT REDUCES BLOOD VOLUME AND DECREASES THE PRESSURE IN THE CIRCULATION.FLUID SHIFT MECHANISM:

9. THIS MECHANISM SERVES AS AN INTERMEDIATE-TERM PRESSURE ‘’BUFFER’’.STRESS-RELAXATION MECHANISM:

11. RENIN ACTS ON A PLASMA PROTIEN ‘’ANGIOTENSINOGEN’’

12. ANGIOTENSINOGEN RELEASES ANGIOTENSIN I

13. ANGIOTENSIN I IS CONVERTED TO ANGIOTENSIN II BY ANGIOTENSIN CONVERTING ENZYME (FOUND MOSTLY IN LUNGS)

14. ANGIOTENSIN II IS A POWERFUL VASOCONSTRICTOR, CONSTRICTON OCCURS IN ARTERIOLES

15. THE CONSTRICTION INCREASES PERIPHERAL RESISTANCE, THEREBY INCREASING THE ARTERIAL PRESSURE.RENIN-ANGIOTENSIN VASOCONSTRICTOR

16. DECREASED ARTERIAL PRESSURE RENIN (KIDNEY) RENIN SUBSTRATE (ANGIOTENSINOGEN) ANGIOTENSIN I ANGIOTENSIN II RENAL RETENSION OF SALT AND WATER VASOCONSTRICTION ANGIOTENSINASE (INACTIVATED) INCREASED ARTERIAL PRESSURE