Blood Pressure and Its Regulation PDF

Blood pressure and its regulation Sovan Bagchi Professor of Physiology November 3, 2024 www.gmu.ac.ae COLLEGE OF MEDICINE  Learning Objectives Define Blood pres...

Blood pressure and its regulation Sovan Bagchi Professor of Physiology November 3, 2024 www.gmu.ac.ae COLLEGE OF MEDICINE  Learning Objectives Define Blood pressure, its types and normal values List the Determinants of Blood pressure List the factors affecting blood pressure Describe the short term and long-term regulation of Blood pressure Definition of blood pressure Blood pressure is the pressure of blood pushing against the walls of your arteries Healthy and unhealthy blood pressure ranges Determinants of Blood pressure Increased cardiac output Peripheral vascular resistance Blood pressure increases with Volume of blood, Viscosity of blood Rigidity of vessel walls Blood pressure decreases with decreased cardiac output, peripheral vascular resistance, volume of blood, viscosity of blood and elasticity of vessel walls. High Blood Pressure Causes and Risk Factors Age: Blood pressure tends to rise with age.... Family history and genetics: High blood pressure often runs in families Lifestyle habits Medicines Other medical conditions Race or ethnicity Sex Social and economic factors Regulation of BP BP regulation almost sums up It is done in two phases. the CVS regulation. Acute/short term: mainly by Chronic/long term: mainly by reflex mechanisms and neural renal mechanism of Renin control by vasomotor center, angiotensin aldosterone Cardio-Inhibitory Centers and system. cardio-acceleratory centers. Acute or Short-Term regulation of Blood Pressure Baroreceptor reflex Stimulus :  or  BP causes  stretch ,  stretch Receptor : Stretch receptors in wall of carotid sinus and Aortic arch. Afferent nerves: Sinus nerve branch of glossopharyngeal IX center nerve, Vagus nerve from aortic arch. Medulla: 1.Cardio inhibitory center (CIC). 2.Vasomotor center. Efferent nerves: From CIC → vagal fibers to the heart. From vasomotor center the nerves are sympathetic N fibers to arterioles, and Symp.N fibers to the heart. Long term Regulation of Blood Pressure Renin Angiotensin System Kidneys synthesize and store Pro-renin in the Juxtaglomerular cells (JG cells are modified smooth muscle cells.) located in the walls of the afferent arterioles. Renin Angiotensin System WHEN THE ARTERIAL PRESSURE THE PRO-RENIN MOLECULES RENIN ENTERS THE SYSTEMIC FALLS TOO LOW – ARE SPLIT UP TO RELEASE RENIN CIRCULATION Renin Angiotensin System (Angiotensinogen) Dual action of Renin-Angiotensin System Mechanism of salt and water retention: Increases the sodium reabsorption capacity of the tubular cells. Aldosterone secretion by the adrenals – causes further increase in the capacity to reabsorb sodium. Renin-Angiotensin System Mechanism of salt and water retention: Constrict the renal arterioles – blood flow to the kidneys is diminished. Allows greater time for osmotic reabsorption at the pre - tubular capillaries due to the slow moving of blood. Blood Pressure Control By Renin-Angiotensin System Exact opposite changes are seen when salt intake is decreased.  Learning Resources Textbook: John E. Hall and Michael E. Hall. Textbook of Medical Physiology. 14th ed. Elsevier. 2021. ISBN: 978-0- 323-59712-8. Chapter 18, 217-228., Chapter 19, 229-244 https://www-clinicalkey-com.gmulibrary.com/#!/content/book/3-s2.0- B9780323597128000187 https://www-clinicalkey-com.gmulibrary.com/#!/content/book/3-s2.0- B9780323597128000199 Power-point presentation in the moodle November 3, 2024 www.gmu.ac.ae COLLEGE OF MEDICINE