blood volume
TRANSCRIPT
DR NILESH KATE
MBBS,MD ASSOCIATE PROF
DEPT. OF PHYSIOLOGY
BLOOD VOLUME
OBJECTIVES Definition Physiological variations Pathological variations Measurement of blood
volume Factors regulating
blood volume Applied physiology
Wednesday, May 3, 2023
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
PHYSIOLOGICAL VARIATIONSSex : female < male Muscular exercise : exercise : increases
High altitude : increasesPregnancy : increases Age : infants – more
compared to adultsSurface area of bodyBody weightAtmospheric temperaturePosture Emotion
PATHOLOGICAL VARIATION
PATHOLOGICAL INCREASE
1.Hemorrhage or blood loss
2. Fluid loss3. Haemolysis 4. Anemia5. Obesity6. Hypothyroidism
PATHOLOGICAL DECREASE
1. Hyperthyroidism 2. Hyperaldosteronism 3. Cirrhosis of liver 4. Congestive Cardiac
Failure
NORMOVOLEMIANORMOVOLEMIA HYPOVOLEMIAHYPOVOLEMIA HYPERVOLEMIAHYPERVOLEMIA
Simple Simple normovolemianormovolemia
Simple Simple HypovolemiaHypovolemia
Simple Simple HypervolemiaHypervolemia
Polycythemic Polycythemic normovolemianormovolemia
Polycythemic Polycythemic HypovolemiaHypovolemia
PolycythemicPolycythemic
HypervolemiaHypervolemia
Oligocythemic Oligocythemic normovolemianormovolemia
Oligocythemic Oligocythemic HypovolemiaHypovolemia
OligocythemicOligocythemicHypervolemiaHypervolemia
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
The substance which binds to red cells are used for this method
The substances are radioactive chromium
ESTIMATING THE RBC MASSRADIOACTIVE 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
ESTIMATING THE RBC MASS BY RADIO ISOTOPE METHOD
GEIGERMULLER COUNTER RADIOACTIVITY OF RBC
INTRAVENOUS INJECTION
ESTIMATING THE PLASMA VOLUME
INTRAVENOUS INJECTION
A known quantity of dye is injected into the blood The amount of substance excreted is measured and from this blood volume is measured
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
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
REGULATION OF VOLUME (WATER LEVEL)
1.Capillary fluid shift2.Osmoreceptors3.Volume receptors4.Baroreceptors 5.Renin Angiotensin System
CAPILLARY FLUID SHIFT More fluid filtered
into interstitial space – decreases blood volume
More fluid filtered across glomerulus – GFR increases
Wednesday, May 3, 2023
OSMORECEPTORSRise 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 volumeWhen blood volume decreases reverse changes takes place
ROLE OF VOLUME RECEPTORS
Receptors mainly present in great veins and atria respond to volume changes
ROLE OF VOLUME RECEPTORS
High blood volume
Activation of Activation of volume receptorsvolume receptors
sympathetic.dischargeTo kidney ADH SECRETION
SYMPATHETIC.DISCHARGE TO SYSTEMIC VESSELS
Urine output Water excretion Blood volumeUrine output
ROLE OF BARORECEPTORS High blood volume
High cardiac output
Rise in B.P
Activation of Baroreceptors
ROLE OF BARORECEPTORS
Activation of BaroreceptorsActivation of Baroreceptors
SYMPATHETIC.TONETO KIDNEY ADH SECRETION
SYSTEMIC VASODILATATION
URINE OUTPUT FLUID IN INTERSTITIAL SPACE
INHIBITION OF THIRST
URINE OUTPUT
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.
RENIN-SITE OF PRODUCTION
FORMATION OF RENIN AND IT’S ROLEGlomerular filtrate
Na+ and Cl- concentration in macula
Stimulate the JG cells to secrete Renin
Angiotensinogen Angiotensin Iconverting enzymes in lungs
Angiotensin II
Efferent vasoconstriction
G.F.R
Na+ and Cl- concentration
REGULATION OF RBC MASSLow blood volume
Hypoxia present
Liver Kidney
Erythropoietin
EP Sensitive stem cell
RBC production increases
RBC mass restored
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
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
APPLIED PHYSIOLOGY DECREASED BLOOD VOLUME :1.Haemorrage2.Burns3.Dehydration 4.Myxoedema 5.Addisons disease
APPLIED PHYSIOLOGYINCREASED BLOOD VOLUME DUE TO IN WHOLE BLOOD: 1.Polycythemia Vera 2.Cushings syndrome 3.Thyrotoxicosis
APPLIED PHYSIOLOGY
INCREASED BLOOD VOLUMEDUE TO PLASMA VOLUME
4.Congestive cardiac failure5.Cirrhosis of liver
APPLIED PHYSIOLOGY
RECAP Definition Physiological variations Pathological variations Measurement of blood volume Factors regulating blood volume Applied physiology
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