Blood Volume - Introduction to Human Physiology - Lecture Slides, Slides of Human Physiology

Download Blood Volume - Introduction to Human Physiology - Lecture Slides and more Slides Human Physiology in PDF only on Docsity! Blood Volume 14-17 Docsity.com Blood Volume • Constitutes small fraction of total body fluid • 2/3 of body H2O is inside cells (intracellular compartment) • 1/3 total body H2O is in extracellular compartment – 80% of this is interstitial fluid; 20% is blood plasma 14-18 Docsity.com Overall Fluid Movement • Is determined by net filtration pressure and forces opposing it (Starling forces) – (Pc + πI)– (Pi + πp) – [fluid out] – [fluid in] • Pc = Hydrostatic pressure in capillary • πi = Colloid osmotic pressure of interstitial fluid • Pi = Hydrostatic pressure in interstitial fluid • πp = Colloid osmotic pressure of blood plasma 14-21 Docsity.com Arterial end of capillary Venous end of capillary (Pym) — (P+ nm) (Fluid ut) (Fluid in) ‘Where P, = hydrostatic pressure in the capillary 1, = colloid osmotic pressure of interstitial fluid P, = hydrostatic pressure of interstitial fluid 7, = colloid osmotic pressure of blood plasma Docsity.¢qm2 Edema • Normally filtration, osmotic reuptake, and lymphatic drainage maintain proper ECF levels • Edema is excessive accumulation of fluid resulting from: – High arterial blood pressure – Venous obstruction – Leakage of plasma proteins into interstitial fluid – Myxedema (excess production of glycoproteins in extracellular matrix) from hypothyroidism – Low plasma protein levels resulting from liver disease – Obstruction of lymphatic drainage 14-23 Docsity.com Aldosterone • Is steroid hormone secreted by adrenal cortex • Helps maintain blood volume and pressure through reabsorption and retention of salt and water • Release stimulated by salt deprivation, low blood volume, and pressure 14-26 Docsity.com Renin-Angiotension-Aldosterone System • When there is a salt deficit, low blood volume, or pressure, angiotensin II is produced – Angio II causes a number of effects all aimed at increasing blood pressure: • Vasoconstriction, aldosterone secretion, thirst 14-27 Docsity.com Angiotensin II • Fig 14.12 shows when and how Angio II is produced, and its effects 14-28 Docsity.com