blood and plasma

Blood and Plasma

Prof. K. Sivapalan

June 2013 Blood and plasma 2

Blood – introduction.

• Blood is a liquid tissue.

• It has different types of cells.

• Intercellular substance is Plasma.

• There are no tight junctions, collagen, and hyaluronic acid.


Composition of the blood.

• Plasma:– Serum + fibrinogen.

• Cells– Red blood cells

(erythrocytes)– White blood cells

(leucocytes).• Neurtophil, eosinophil,

basophil, monocyte, lymphocyte.

– Platelets.


Physical properties.

• Color- red. [hemoglobin]• Osmolality: 290 – 300 m osmol/L.• Osmotic pressure: 5000 mm Hg. [≈7 Atm]• Colloid osmotic pressure [oncotic

pressure] : 25 mm. Hg.• Viscosity: 3 – 4 times that of water.• Specific gravity: 1.050 – 1.060.


Functions of Blood

• Transport of,• Water.• Oxygen.• Nutrients:

• Glucose, amino acids, fatty acids, iron, calcium, etc.

• Wastes:– Urea, carbon dioxide, bilirubin, heat, acid.

• Hormones:– Water soluble, – fat soluble.


FUNCTIONS OF BLOOD-ctd..

• Microcirculation.• Hemostasis.

– Platelets, fibrinogen and clotting factors.• Immunity.

– Antibodies, white blood cells.


BLOOD VOLUME.• Blood : 8 % of the body weight.• 80 ml / Kg ± 10 %• Plasma: 5 % of the body weight.•Males 5-6, females 4-5 liters.Distribution in the vessels:

Lungs- 20 % [1 Liter.]

Veins- 60 % [3 Liters.]

Heart, Arteries, capillaries:

20 % [1 Liter.]


Distribution in Detail.

Structure. Percentage

Aorta 02Arteries 08

Arterioles 01Capillaries. 05

Veins- venules, veins, vena cave

54

Heart 12Pulmonary vessels 18


Measurement.

• Dilution method.• V1C1 = V2C2.

• Plasma volume.• Evans blue, Rose Bengal, Vital Red, Radioactive

Iodine etc.

• Blood volume.– Red Cells labeled with Radio active

Chromium.


Factors that Affect Blood Volume.

• ECF volume- Sodium ions

Dehydration.

Water Balance.

• Blood loss.


Control of Blood Volume.

• Circulatory mechanism• Volume receptor mechanism.• Renin - Angiotensin – Aldesterone

mechanism.• Atrial Natriuretic Peptide.


Circulatory Mechanism

• Blood volume determines cardiac output.• Cardiac output determines blood pressure.• Blood pressure determines Urine

production.• Urine production determines ECF volume

and blood volume.


Volume Receptor Mechanism.Volume receptors in RA and IVC.

[stimulated by stretch which represents blood volume]

Post. Pituitary through Hypothalamus.

Anti Diuretic Hormone. Collecting ducts in Kidney.

Decreased blood volume.

+ [ ↑ impulses in afferents with volume]

- [ ↓secretion.]

- [Reabsorption of water ↓, ↑Urine out put ]

-


Renin - Angiotensin – Aldesterone Mechanism.

• Renin is secreted by the Juxta Glomerular Cells in response to low sodium in tubule and low blood pressure in afferent arterioles.

• It converts angeotensinogen into angeotensin I which in turn gets converted to angeotensin II.

• Angeotensin stimulates secretion of Aldesteron.• Aldesteron stimulates sodium re-absorption in

distal tubule.• Keeps blood volume due to osmotic force.


Atrial Natriuretic Peptide.

• Stretch of the right atrium is determined by venus return which mainly depends on blood volume.

• ANP is secreted by Right Atrium in response to stretch.

• ANP causes Sodium and water loss in urine.


Properties of plasma.

• Straw color.• Volume - 3.5 liters.• High Viscosity.• Osmolality- 290 m Osmols/L• Specific gravity- 1.025.• Coagulability.


Composition of PLASMA.

• Proteins- 7.5 g/100 ml. (dL)– Albumin. 4.5

g.– Globulin. 2.5

g.– Fibrinogen. 0.3 g.– [source: liver, plasma cells.]

• Electrolytes.• Nutrients.• Hormones.• Waste products.


Functions of plasma.

• Fluid exchange.• Maintenance of pH- Buffering.• Transport of substances.• Hemostasis- Clotting.• Immunity.• Reserve of body proteins.


MEASUREMENT OF VISCOSITY.

• Erythrocyte Sedimentation Rate.

• Height of clear plasma at the end of the first hour of standing.

• Determinants of ESR:– VISCOSITY of plasma.– ROULEAUX formation.

• Westegran tube in ESR stand.

• VISCOMETER.

blood and plasma

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