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Blood

Overview of Anatomy and Physiology:
Hematopoietic system includes:
►Blood
►Blood vessels

► Blood-forming organs

►Spleen

►Bone marrow

►Liver

►Thymus

►Lymph nodes

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 Blood

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Properties of blood

Color: Blood is red in color. Arterial blood is scarlet
red because it contains more oxygen and venous
blood is purple red because of more carbon
dioxide.
Blood
2. Volume: Average volume of blood in a normal adult
is 5 L. In a newborn baby, the volume is 450 ml. It
increases during growth and reaches 5 L at the time
of puberty. In females, it is slightly less and is about
4.5 L. It is about 8% of the body weight in a normal
young healthy adult, weighing about 70 kg.
3. Reaction and pH: Blood is slightly alkaline and its
pH in normal conditions is 7.4.
4. Specific gravity:
Specific gravity of total blood : 1.052 to 1.061
Specific gravity blood cells : 1.092 to 1.101
Specific gravity of plasma : 1.022 to 1.026
5. Viscosity: Blood is five times more viscous than
water. It is mainly due to red blood cells and plasma
proteins.

 

Major function of Blood

•  Carry O2 and nutrients to cells
•  Remove CO2 (carbon dioxide) and metabolic waste products.
• Hormone transport
•  Inflammatory and Immune responses
•  Temperature regulation
•  Fluid-electrolyte balance
• Acid-base balance
• „ FUNCTIONS OF BLOOD
  „ 1. NUTRITIVE FUNCTION
  Nutritive substances like glucose, amino acids, lipids and
  vitamins derived from digested food are absorbed from
  gastrointestinal tract and carried by blood to different
  parts of the body for growth and production of energy.
  „ 2. RESPIRATORY FUNCTION
  Transport of respiratory gases is done by the blood. It
  carries oxygen from alveoli of lungs to different tissues
  and carbon dioxide from tissues to alveoli.
• 3. EXCRETORY FUNCTION
  Waste products formed in the tissues during various
  metabolic activities are removed by blood and carriedto the excretory organs like kidney, skin, liver, etc. for
  excretion.
  „ 4. TRANSPORT OF HORMONES AND ENZYMES
  Hormones which are secreted by ductless (endocrine)
  glands are released directly into the blood. The blood
  transports these hormones to their target organs/tissues.
  Blood also transports enzymes.
  „ 5. REGULATION OF WATER BALANCE
  Water content of the blood is freely interchangeable
  with interstitial fluid. This helps in the regulation of water
  content of the body.
  „ 6. REGULATION OF ACID-BASE BALANCE
  Plasma proteins and hemoglobin act as buffers and help
  in the regulation of acid-base balance (Chapter 5).
  „ 7. REGULATION OF BODY TEMPERATURE
  Because of the high specific heat of blood, it is responsible
  for maintaining the thermoregulatory mechanism in the
  body, i.e. the balance between heat loss and heat gain
  in the body.

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Bone Marrow:

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•  Contained inside all bones
•  Occupies interior of spongy bones and center of long bones
•  4-5 % of total body weight
•  Primary function is hematopoiesis
•  Two kinds of Bone marrow:

1. Red (functioning) marrow:

• Carries out hematopoiesis
•  Production site of:
•  Erythroid
•  Myeloid
•  Thrombocytic
•  Found in ribs, vertebrae, other flat bones.

2. Yellow marrow-

• Yellow marrow is red marrow that has changed to fat.
• Found in long bones
• All blood cells start as stem cells in the bone marrow.

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Hematocrit:

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The hematocrit (Ht or HCT)
 Packed cell volume (PCV)
 Erythrocyte volume fraction (EVF)
 The proportion of blood volume that is occupied by red blood cells.

Normal Value-

Male-39%-54% Female-34%-47%

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Plasma

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Liquid portion of the blood. Serum (liquid portion of plasma)
 Fibrinogen
 Proteins

Albumin: Regulate intravascular volume. Maintains osmotic pressure
 Globulins: Alpha globulins transport: Steroids Lipids Bilirubin
Beta globulins transport: Iron and copper
Gamma globulins: Immune response Antibody function
 Fibrinogen play role in Clot formation Produces in the liver
 Prothrombin play role Normal coagulation Produced in the liver Depends on vitamin K.

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Cellular Components

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RBC

Responsible for O2 transport via Hgb.
 male 4.6-6.2 millions/mm³
 female 4.2-5.4 millions/mm³
 Hemoglobin (Hgb):
 male adult 13-18 g/dl
 female 12-16 g/dl
 Average life spans 120 days
 Matured cells removed by liver and spleen.
 Normal Erythrocytes Sedimentation Rate (ESR) 0-10 mm/hr

WBC

Normal Value Leukocytes
 Total leukocytes: 4.00-11.0 x 10 9/L
 Neutrophils: 2.5–7.5 x 10 9/L
 Lymphocytes: 1.5–3.5 x 10 9/L
 Monocytes: 0.2–0.8 x 10 9/L
 Eosinophils: 0.04-0.4 x 10 9/L
 Basophils: 0.01-0.1 x 10 9/L

Platelates-

Essential factor in coagulation via:
 Adhesion
 Aggregation
 Plug formation
Normal value:
150,000-400,000 cells/µ/l

ABO BLOOD GROUPS
Determination of ABO blood groups depends upon the
immunological reaction between antigen and antibody.
Landsteiner found two antigens on the surface of RBCs
and named them as A antigen and B antigen. These
antigens are also called agglutinogens because of their
capacity to cause agglutination of RBCs. He noticed the
corresponding antibodies or agglutinins in the plasmaand named them anti-A or α-antibody and anti-B or
β-antibody. However, a particular agglutinogen and the
corresponding agglutinin cannot be present together. If
present, it causes clumping of the blood. Based on this,
Karl Landsteiner classified the blood groups. Later it
became the ‘Landsteiner Law’ for grouping the blood.
„ LANDSTEINER LAW
Landsteiner law states that:
1. If a particular agglutinogen (antigen) is present in
the RBCs, corresponding agglutinin (antibody) must
be absent in the serum.
2. If a particular agglutinogen is absent in the RBCs,
the corresponding agglutinin must be present in the
serum.
Though the second part of Landsteiner law is a fact, it is
not applicable to Rh factor.

ABO SYSTEM
Based on the presence or absence of antigen A and
antigen B, blood is divided into four groups:
1. ‘A’ group
2. ‘B’ group
3. ‘AB’ group
4. ‘O’ group.
Blood having antigen A belongs to ‘A’ group. This
blood has β-antibody in the serum. Blood with antigen B
and α-antibody belongs to ‘B’ group. If both the antigens
are present, blood group is called ‘AB’ group and serum
of this group does not contain any antibody. If both
antigens are absent, the blood group is called ‘O’ group
and both α and β antibodies are present in the serum.
Antigens and antibodies present in different groups of
ABO system are given in Table 21.1. Percentage of
people among Asian and European population belonging
to different blood group is given in Table 21.2.
‘A’ group has two subgroups namely ‘A1’ and ‘A2’.
Similarly ‘AB’ group has two subgroups namely ‘A1B’
and ‘A2B’.