Blood

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Blood Formed Elements
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Blood

• The blood volume in the body varies according to
  size of individual.
• Accounts for about 7 percent of the body weight.
• Intricate part of the Circulatory System.
• Always tries to keep the body in a state of
  equilibrium.
• Major function is to transport all the vital
  substances necessary to maintain life processes.

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Blood composition

• Plasma 55
• Formed elements (hematocrit) 45
• Red blood Cells (Erythrocytes)
• White Blood cells (Leukocytes)
• Platelets (Thrombocytes)

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Blood Transports

• Dissolved gases (e.g. oxygen, carbon dioxide)
• Waste products of metabolism (e.g. water, urea)
• Hormones
• Enzymes
• Nutrients such as glucose, amino acids,
  micro-nutrients (vitamins minerals), fatty
  acids, glycerol
• Plasma proteins
• associated with defense- such as blood-clotting
  and anti-bodies
• Blood cells
• white blood cells 'leucocytes
• red blood cells 'erythrocytes

5
Functions

• Maintains Body Temperature
• Controls pH
• The pH of blood must remain in the range 6.8 to
  7.4, otherwise it begins to damage cells.
• Removes toxins from the body
• The kidneys filter all of the blood in the body
  (approx. 8 pints), 36 times every 24 hours.
• Toxins removed from the blood by the kidneys
  leave the body in the urine.
• Toxins also leave the body in the form of sweat.
• Regulation of Body Fluid Electrolytes
• Excess sodium is removed from the body in urine,
  which may contain around 10g sodium per day
• such as diets containing more salt than the body
  requires.

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Plasma

• Normal blood plasma is 90-92 water.
• The medium in which the blood cells are
  transported around the body (by the blood
  vessels) and are able to operate effectively.
• Helps to maintain body temperature.
• Helps to control the pH of the blood and the body
  tissues
• Helps to maintain an ideal balance of
  electrolytes in the blood and tissues of the
  body.

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Erythrocytes (Red blood cells)

• Immature erythrocytes have a nucleus but mature
  erythrocytes have no nucleus.
• There are approx. 4.5 - 5.8 million erythrocytes
  per micro-liter of healthy blood
• variations between racial groups and men/women
• Hemoglobin
• 4 Peptide Chains
• 4 Hemes
• Each heme has one iron molecule which binds with
  O2
• Heme relies on the presence of iron.

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Erythrocytes
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Erythropoiesis (red blood cell production)

• Stimulated by a reduced level of O2 in the blood
• Regular Catabolism
• High Altitude
• Hemorrhage
• Stimulated by Erythropoietin (EPO)
• Begins in bone marrow
• Life span of 4 months
• Catabolism
• Erythrocytes are eventually broken down by the
  spleen into bilinubin and iron.
• These components are then transported by the
  blood to the liver
• The iron is re-cycled for use by new erythrocytes
• The bilinubin form bile salts. (Bile breaks down
  fats.)

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Erythropoiesis
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Leukocytes (White blood cells)

• There are different types of leucocytes
• Neutrophils
• Eosinophils
• Basophils
• Have a longevity of a few hours to a few days
  (but some can remain for many years).
• There are approx. 5,000 - 10,000 leucocytes per
  micro-liter of blood.
• Major part of the immune system.

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Leukocytes
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Thrombocytes (Platelets)

• They are smallest cellular component of blood.
• Disk-shaped cell fragments
• Have many granules but no nucleus
• Have a longevity of approx. 5-9 days.
• There are approx. 150,000 - 400,000 platelets per
  micro liter of blood.
• Facilitate blood clotting - the purpose of which
  is to prevent loss of body fluids.

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Thrombocytes