11/12/2020

Blood
Composition & Function

Dr Sateesh Belemkar

Blood, when allowed to stand, will

separate into two components:

Liquid Solid

• Plasma, which is a straw- • Cellular -red blood cells

colored fluid comprised components, -white blood cells
mostly of water including: -platelets

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• Originate in the bone marrow

• Resemble the shape of a

doughnut without a hole • Contains an iron-rich
(biconcave) protein molecule called
hemoglobin
• Average lifespan is 120 days
• Responsible for carrying
• Normal value = approximately oxygen and removing
4.5 to 5 million per cubic carbon dioxide from
millimeter of blood every body cell

Normal Hemoglobin Levels

Male = 14–18 grams/100 mL
of blood

Female = 12–16 grams/100

mL of blood Symptoms of Anemia
An abnormally low hemoglobin • Weakness
level and/or decrease in the • Headache
number of red blood cells is called • Pale skin color
anemia.
• Difficulty breathing

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• Also known as white blood cells

Types of White Blood Cells
• Primarily responsible for
destroying foreign substances
such as pathogens
Granulocytes Agranulocytes
• Appear round and white because
• Neutrophils • Monocytes
they lack hemoglobin
• Eosinophils • Lymphocytes
• Normal adult has 5,000 to • Basophils
10,000 white blood cells per
cubic millimeter of blood

Granulocytes

Neutrophils Basophils
• Most numerous of all the WBCs • Least common granulocyte
• Main warriors against infection • Assist with the inflammatory
(phagocytosis) process
• Release histamine and heparin

Eosinophils
• Present in a very small quantity
• Ingest and destroy foreign proteins
• Secrete chemicals to destroy parasites
• Increase during allergic reactions and parasitic infections

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Agranulocytes

Monocytes Lymphocytes
• Largest in size of all the • Assist with the immune
white blood cells system
• Primary function is • Produce antibodies that
phagocytosis destroy pathogens
• Survive for several months • Aid in controlling allergic
• Effective against chronic reactions
infections

Quantities of each type of WBC can be determined

with a blood test known as a differential.

• Also known as platelets

• Smallest of all the cellular
components
• Normal adult has 150,000 to
450,000 per cubic millimeter of
blood
• Average lifespan is 9 to 12 days
• Prevent blood loss following an
injury

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Composition of Plasma
• Water
• Nutrients
• Hormones
• Electrolytes
• Proteins
• Waste
• Protective substances Centrifugation is a
procedure that separates
Serum is the liquid portion blood into liquid and
of clotted blood. cellular components.

Following an injury, four events are available to stop the

bleeding:
1 2
Blood Vessel Spasm Platelet Plug Formation
• Vessels decrease • Inner torn layer of the vessels
in size to stop releases chemical signals that call
bleeding in small platelets to the site of injury
vessels
3 4
Blood Clotting Fibrinolysis
• Requires the presence of certain • Begins the repair
clotting factors to form fibrin process

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The blood group system recognizes four blood types:

• Type A, B, AB, and O

• They are distinguished from each

other in part by their antigens and
antibodies.

• Specific antibodies are found in the

serum based on the type of
antigen on the surface of the RBC.

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Compatibility Chart
Blood Type Can Accept From Can Donate To

A A, O A, AB

B B, O B, AB

AB A, B, AB, O AB

O O O, A, AB, B

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Blood coagulation: factors involved

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Hemostasis:
BV Injury
Tissue
Neural Factor

Blood Vessel Platelet Coagulation

Constriction Activation Activation
Primary hemostatic plug

Reduced
Plt-Fusion Thromibn,
Blood flow
Fibrin

Stable Hemostatic Plug

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Physiological Hemostasis

Mechanism(1) of Platelet in Hemostasis

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Mechanism(2) of Platelet in Hemostasis

HEMOSTATIC SYSTEM
INTRINSIC
PATHWAY EXTRINSIC
PATHWAY

COMMON PATHWAY
Thrombin
Fibrinogen Fibrin

PLATELETS CLOT

COLLAGEN TISSUE FACTOR

VESSEL WALL

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Mechanism of Blood Coagulation

HEMOPOIESIS:
Hemo: Referring to blood cells
Poiesis: “The development or production of”
The word Hemopoiesis refers to the production &
development of all the blood cells:
 Erythrocytes: Erythropoiesis
 Leucocytes: Leucopoiesis
 Thrombocytes: Thrombopoiesis.

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HEMOPOIESIS

Hemopoiesis depends on 3 important

components:
 the bone marrow stroma (Local control)
 the hemopoietic stem and progenitor cells
 the hemopoietic growth factors (Humoral
control)

STEM CELL THEORY

All the blood cells are produced by the bone marrow.
marrow.
They all come from a single class of primitive mother cells
called as:
PLURIPOTENT STEM CELLS. CELLS.
These cells give rise to blood cells of:
 Myeloid series: Cells arising mainly from the bone marrow.
 Lymphoid series: cells arising from lymphoid tissues.

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STEM CELLS
These cells have extensive proliferative capacity and also
the:
 Ability to give rise to new stem cells (Self Renewal)
Renewal)
 Ability to differentiate into any blood cells lines (Pluripotency
Pluripotency))
They grow and develop in the bone marrow.
The bone marrow & spleen form a supporting system, called
the
“hemopoietic microenvironment”

STEM CELLS: Types

Pluripotent Stem cells:
cells:
 Has a diameter of 18 – 23 μ.
 Giving rise to: both Myeloid and Lymphoid series of cells
 Capable of extensive self-
self-renewal.
Myeloid Stem cells:
cells: Generate myeloid cells:
 Erythrocytes
 Granulocytes: PMNs (polymorphonuclear),
( , Eosinophils & Basophils.
 Thrombocytes.
Lymphoid Stem cells:
cells: Giving rise only to:
 Lymphocytes: T type mainly.

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SITES OF HEMOPOIESIS
Yolk sac

Liver and spleen

Bone marrow
–Gradual replacement of active (red) marrow by
inactive (fatty) tissue
–Expansion can occur during increased need for
cell production

SITES OF HEMOPOIESIS
Appendicular
Active Hemopoietic skeleton:
marrow is found, in • Bones of the
children Upper & Lower
throughout the: limbs
 Axial skeleton: In Adults active
Cranium

hemopoietic marrow is
Ribs.
found only in:


 Sternum
 Vertebrae •The axial skeleton
 Pelvis •The proximal ends
of the appendicular
skeleton.

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• In the 3rd to 7th month of fetal life Hemopoietic stem cells

will migrate to the liver and spleen, where hemopoiesis
starts there and hemopoiesis is still mainly erythropoietic
in nature, with minimal granulopoiesis

The bone marrow (BM)

• The stem cells then migrate to the bone marrow (BM)
where hemopoiesis starts and continue all over the life.
In the bone marrow all types of blood cells are formed
which include:
• RBCS
• Granulocytes: Neutrophils, Eosinophils, Basophils
• Lymphocytes
• Monocytes and macrophages
• Platelets

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Cell hierarchy (Haemopoiesis

(Haemopoiesis schematic representation)

What is Sickle Cell Anemia?

 A serious condition in which red blood
cells can become sickle-shaped
 Normal red blood cells are smooth and
round. They move easily through blood
vessels to carry oxygen to all parts of the
body.
 Sickle-shaped cells don’t move easily
through blood. They’re stiff and sticky
and tend to form clumps and get stuck in
blood vessels.
 The clumps of sickle cell block blood
flow in the blood vessels that lead to the
limbs and organs. Blocked blood vessel
can cause pain, serious infection, and
organ damage.

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Normal and Sickled Red Blood Cells

in Blood Vessels
Figure B shows abnormal, sickled red blood cells clumping and
blocking the blood flow in a blood vessel. The inset image shows a
cross-section of a sickled red blood cell with abnormal strands of
hemoglobin.

Figure A shows normal red blood cells flowing freely in a

blood vessel. The inset image shows a cross-section of a
normal red blood cell with normal hemoglobin.

Source from http://www.nhlbi.nih.gov/health/dci/Diseases/Sca/SCA_WhatIs.html

What is Anemia?

• Anemia is defined by reduction in Hg Concentration,

Hct Concentration or RBC count

• WHO criteria is Hg < 13 in men and Hg < 12 in women

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Symptoms
• Exertional dyspnea and Dyspnea at Exertion

• Headaches
• Fatigue

• Bounding pulses and Roaring in the Ears

• Palpitations

Hemophilia
• Hemophilia are bleeding disorders due to deficiency or defect in
one of the factor present in clotting cascade,

• X – linked recessive disorder,

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Hemophilia
• Hemophilia A (classic) : deficiency or dysfunction of factor VIII

• It is a large single chain protein that regulates the activation of

factor X by proteases generated in intrinsic coagulation pathway

• Incidence : 1 in 10,000males

Hemophilia
• Hemophilia B (Christmas) : deficiency or dysfunction of factor
IX

• Incidence : 1 in 25,000-35,000 males

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Clinical features

• Easy bruising & recurrent bleeding in to joints & muscles

• Bleeding occurs hrs or days after injury if untreated continue

for days or weeks
• Large collection of clotted blood putting pressure on adjacent
normal tissue-necrosis of muscle
• Pseudophlebitis : venous congestion

Leukemias
Leukemias are a group of cancers of the blood or bone
marrow and are characterized by an abnormal
proliferation (production by multiplication) of blood
cells, usually white blood cells (leukocytes).
Leukemia is a broad term covering a spectrum of
diseases. Any of various acute or chronic neoplastic
diseases of the bone marrow in which unrestrained
proliferation of white blood cells occurs and which is
usually accompanied by anemia and
thrombocytopenia

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Clinical presentation
Symptoms
• Fatigue, malaise, dyspnea (anemia)
• Bleeding eg after dental procedure
Easy bruisability
• Fever (infections)
• Bone Pain

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