BLOOD VOLUME
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This document discusses blood volume, including its definition as the total amount of blood circulating in the body, normally around 5-6 liters for a 70kg person. Physiological variations in blood volume are described based on factors like sex, exercise, altitude, and pregnancy. Pathological increases and decreases in volume are also outlined. Methods for measuring blood volume directly and indirectly are provided, along with factors that regulate volume, such as osmoreceptors, baroreceptors, and the renin-angiotensin system. Finally, examples of applied physiology involving decreased or increased blood volume are presented.
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BLOOD VOLUME
- 1. DR NILESH KATE MBBS,MD ASSOCIATE PROF DEPT. OF PHYSIOLOGY BLOOD VOLUME
- 2. OBJECTIVES Definition Physiological variations Pathological variations Measurement of blood volume Factors regulating blood volume Applied physiology Thursday, November 10, 2016
- 3. DEFINITION Blood volume is the amount of blood that is circulating inside the circulatory system and stored in certain organs like spleen. It represents the TOTAL BLOOD in the body. NORMAL VALUE = 80 ml/kg = 5 – 6 lit / 70kg body wt
- 4. PHYSIOLOGICAL VARIATIONS Sex : female < male Muscular exercise : exercise : increases High altitude : increases Pregnancy : increases Age : infants – more compared to adults Surface area of body Body weight Atmospheric temperature Posture Emotion
- 5. PATHOLOGICAL VARIATION PATHOLOGICAL INCREASE 1.Hemorrhage or blood loss 2. Fluid loss 3. Haemolysis 4. Anemia 5. Obesity 6. Hypothyroidism PATHOLOGICAL DECREASE 1. Hyperthyroidism 2. Hyperaldosteronism 3. Cirrhosis of liver 4. Congestive Cardiac Failure
- 7. DETERMINATION OF BLOOD VOLUME Direct method : Done only in animals. Indirect method : Blood volume is calculated by two stages. a) Estimating the RBC mass b) Estimating the plasma volume
- 8. The substance which binds to red cells are used for this method The substances are radioactive chromium
- 9. ESTIMATING THE RBC MASS RADIOACTIVE METHOD: VRBC = VD X Ra D Ra R VRBC = Red cell volume VD = Volume of donor cells in ml Ra D = Radioactivity of donor cells / ml Ra R = Radioactivity of recipient cells / ml
- 10. ESTIMATING THE RBC MASS BY RADIO ISOTOPE METHOD GEIGERMULLER COUNTER RADIOACTIVITY OF RBC INTRAVENOUS INJECTION
- 11. ESTIMATING THE PLASMA VOLUME INTRAVENOUS INJECTION
- 12. A known quantity of dye is injected into the blood The amount of substance excreted is measured and from this blood volume is measured
- 13. Estimating the plasma volume 1. Indicator or Dye dilution method 2. Radio isotope method amt. of dye injected - amt. of dye excreted Plasma volume = -------------------------------------------------------- mean conc. of dye / ml Blood volume is determined by taking the Haematocrit and already calculated plasma volume 100 x plasma volume Blood volume = ------------------------------ 100 - pcv
- 15. REGULATION OF BLOOD VOLUME Maintenance of blood volume depends on: Balance between water Adjustment of fluid and intake water loss interchange. 1.Regulation of volume (water level) 2.Regulation of RBC mass 3.Regulation of plasma proteins 4.Regulation of electrolytes
- 16. REGULATION OF VOLUME (WATER LEVEL) 1.Capillary fluid shift 2.Osmoreceptors 3.Volume receptors 4.Baroreceptors 5.Renin Angiotensin System
- 17. CAPILLARY FLUID SHIFT More fluid filtered into interstitial space – decreases blood volume More fluid filtered across glomerulus – GFR increases Thursday, November 10, 2016
- 18. OSMORECEPTORS Rise in blood volume Fall in tonicity Osmoreceptor inhibition ADH release inhibited No absorbtion of water from DCT and CD Rise in urine output Decline in blood volume When blood volume decreases reverse changes takes place
- 19. ROLE OF VOLUME RECEPTORS Receptors mainly present in great veins and atria respond to volume changes
- 20. ROLE OF VOLUME RECEPTORS High blood volume Activation ofActivation of volume receptorsvolume receptors sympathetic.discharge To kidney ADH SECRETION SYMPATHETIC.DISCHARGE TO SYSTEMIC VESSELS Urine output Water excretion Blood volumeUrine output
- 21. ROLE OF BARORECEPTORS High blood volume High cardiac output Rise in B.P Activation of Baroreceptors
- 22. ROLE OF BARORECEPTORS Activation of BaroreceptorsActivation of Baroreceptors SYMPATHETIC.TONE TO KIDNEY ADH SECRETION SYSTEMIC VASODILATATION URINE OUTPUT FLUID IN INTERSTITIAL SPACE INHIBITION OF THIRST URINE OUTPUT
- 23. RENIN-SITE OF PRODUCTION Renin is produced in an inactive form called PRORENIN by the Juxtaglomerular cells of kidney . The inactive renin is converted into active renin by kallikrein.
- 25. FORMATION OF RENIN AND IT’S ROLE Glomerular filtrate Na+ and Cl- concentration in macula Stimulate the JG cells to secrete Renin Angiotensinogen Angiotensin I converting enzymes in lungs Angiotensin II Efferent vasoconstriction G.F.R Na+ and Cl- concentration
- 26. REGULATION OF RBC MASS Low blood volume Hypoxia present Liver Kidney Erythropoietin EP Sensitive stem cell RBC production increases RBC mass restored
- 27. REGULATION OF PLASMA PROTEINS Loss of plasma proteins Restoration of plasma proteins In 4 hours in 24 hours From tissue From liver Factor regulating – High protein diet
- 28. REGULATION OF ELECTROLYTES 1. Na, K, Cl are mainly regulated by : a) Aldosterone b) ADH c) Natriuretic Hormone. 2. Ca, PO4 ,Mg are regulated by: a) Parathyroid Hormone b) Calcitonin c) 1-25 (OH)2 cholecalciferol
- 29. APPLIED PHYSIOLOGY DECREASED BLOOD VOLUME : 1.Haemorrage 2.Burns 3.Dehydration 4.Myxoedema 5.Addisons disease
- 30. APPLIED PHYSIOLOGY INCREASED BLOOD VOLUME DUE TO IN WHOLE BLOOD: 1.Polycythemia Vera 2.Cushings syndrome 3.Thyrotoxicosis
- 31. APPLIED PHYSIOLOGY INCREASED BLOOD VOLUME DUE TO PLASMA VOLUME 4.Congestive cardiac failure 5.Cirrhosis of liver
- 33. RECAP Definition Physiological variations Pathological variations Measurement of blood volume Factors regulating blood volume Applied physiology
- 34. Thank You