HAEMATOLOGY AND BLOOD TRANSFUSION


HAEMATOLOGY ANDBLOOD 
TRANSFUSION


BLOOD DONATION 

DEFINITION OF TERMS


ØHematology is the study of morphology and physiology of blood. OR
ØIs the branch of medical science which deal with blood and blood  disorder
ØBlood refers to Specialized fluid tissue circulating through vascular channels which carries compounds to all cells and receives waste products of metabolism for transport to organs of excretion.
ØBlood plasma is the liquid components of ant-coagulated blood that normally holds the blood cell.
ØSerum blood is the liquid component of coagulated blood (without anticoagulant)
Or is the liquid component that is neither contains  blood cells (RBC, WBC) nor clotting factors 
ØBlood transfusion: The transfer of blood together with blood components from one person (the donor) into the blood stream of another person (the recipient).
ØBlood donation is a process by which a blood donor voluntarily has blood drawn for storage in a blood bank for subsequent use in a blood transfusion.

FUNCTIONS OF BLOOD
i.Supply nutrients to cells & tissues such as amino acids, fatty acids and glucose.
ii.Supply of oxygen to & removal of CO2 from tissues & cells
iii.Remove breakdown products, taking them to excretory organs
iv.Transport surplus metabolites to storage organs
v.It has platelets which helps the blood to clot (coagulate) during bleeding.
vii.  Contain body's defenses against foreign substances & pathogenic organisms (WBC)
     
   COMPOSITION OF BLOOD
Blood consists of;
1. Plasma
2. Blood cells; consists of
    i.Thrombocytes (Platelets)
    ii.Erythrocytes(RBC)
    iii.Leukocytes(WBC)
Plasma; aqueous solution of
Proteins (albumin, fibrinogen, globulins) & blood
sugar
Inorganic substances, Na, K, Ca, Mg ions, which
maintain chemico-physical properties of blood.
Bicarbonate & phosphate ions buffer extreme high
or low pH
Final pH of blood is 7.4

BLOOD CELLS
Blood is fluid connective tissue having cells (35
55% of blood) and extracellular fluid intravascular
(blood plasma) (45-65% of blood)
Total amount of blood in man is 5 L (7‑8% body
weight)
Blood cells are;
1. Red blood cells or erythrocytes
2. White blood cells or leukocytes
3. Platelets or thrombocytes.

LEUKOCYTES (WBC)
vLeukocytes also known as WBC are cells of the
immune system  that are involved in protecting the body
against both infectious and foreign invaders.
vAll white blood cells are produced and derived from
bone marrow.
vAll white blood cells have nucleus which distinguishes
them from the other  cells (anucleated  (RBCs) and 
thrombocytes

CLASSIFICATION OF WBC
There are five types of WBC classified as ;
vWBC can be classified based on the presence or
absence of cytoplasmic granules, which are
1.Granular leukocytes
Non granular (Agranular )leukocytes
vGranular leukocytes are also classified based on
three types which are;
i. Neutrophilic
ii. Eosinophilic, &
iii.Basophilic granulocytes
vNon-granular leukocytes comprise of
i. Monocytes and
ii. Lymphocytes
vLeukocytes are also divided on basis of shape of
nucleus as
1. mononuclear (leukocyte with non-lobed nucleus)
2. polymorphonuclear (leukocyte with multi-lobed
nucleus) leukocytes
The main functions of white blood cells is to defend the
body against foreign substances & pathogenic organisms
The number of leukocytes in the BLOOD is often an
indicator of infection or diseases and thus the WBC
count is an important subset of the complete blood
count.  The normal white cell count usually range 
between 4 and 11 × 109/L.
3: Human blood: Nucleus of the neutrophil (a) has not
constricted into distinct lobes. Neutrophils with
more or\less band‑form of nucleus are called band
neutrophils and are more immature than the lobed or
segmented neutrophils.. Blood platelets (b) and a small
lymphocyte (c). 
Human blood: Blood smear showing erythrocytes,
platelets and large lymphocycte

PLATELETS
Platelets are the cells that circulate within our blood
and bind together when they recognize damaged blood
vessels,”
“When you get a cut, for example, the platelets bind to
the site of the damaged vessel, thereby causing a blood
clot. There’s an evolutionary reason why they’re there.
It’s to stop us from bleeding.”
Platelets, the smallest of our blood cells, can only be
seen under a microscope. 
They’re literally shaped like small plates in their non
active form. A blood vessel will send out a signal when it
becomes damaged. When platelets receive that signal,
they’ll respond by traveling to the area and transforming
into their “active” formation. To make contact with the
broken blood vessel, platelets grow long tentacles and
then resemble a spider or an octopus.
A normal platelet count ranges from 150,000 to
450,000 platelets per microliter of blood. Having more
than 450,000 platelets is a condition
called thrombocytosis; having less than 150,000 is
known as thrombocytopenia. You get your platelet
number from a routine blood test called a complete
blood count (CBC).
The medical term for having too many platelets is
thrombocytosis, and there are two types:
Primary or essential thrombocytosis – Abnormal cells
in the bone marrow cause an increase in platelets, but
the reason is unknown
Secondary thrombocytosis – The same condition as
primary thrombocytosis, but may be caused by an
ongoing condition cancer, inflammation, or infection.
When you don’t have enough platelets, it’s called
thrombocytopenia.
Symptoms include easy bruising, and frequent bleeding
from the gums, nose.
Your platelet count drops when something is preventing
your body from producing platelets. There are a wide
range of causes, including:
Medications
An inherited condition
Certain types of cancer, such as leukemia or lymphoma
Chemotherapy treatment for cancer
Kidney infection or dysfunction
Too much alcohol
Platelets are involved in the clotting (coagulation of
blood). When we bleed the platelets clump together to
form a clot.
Platelets have been observed to play a role in coagulation
like in ;
Maintain haemostasis
Provide platelet phospholipid (platelet factor 3), carry
coagulation factors on their surfaces.

RED BLOOD CELLS
Red blood cells (RBC) constitute 99 % of blood cells
They are the smallest cells in the mammalian body
A total red blood count is approximately 5.00 x 1012 / L
Erythrocyte    (Red blood cell) normal range adult ;
ümale 4.6 – 6.5 x 1012 per litre,
üfemale 3.9 – 5.6 x 1012 per litre and
üchildren 3.2 – 5.3 1012 per litre
They function in the transportation of oxygen to cells
and tissues and carbon dioxide from cells and tissues to
the lungs for exchange with O2
Normal  morphology of red  blood cell
Normal red blood cell  have the following features:
Shape : round , biconcave disc
Diameter : 6.7-7.7µm (average 7.2 µm) 
Thickness : 1.7  -2.4 µm   (average  2.1 µm)
The life span of red blood cells has a range of 100 to
120 days
The cytoplasm of erythrocytes is rich in hb an iron
containing molecule that can bind oxygen and is
responsible for the red color of the cells.
Hemoglobin Is the oxygen carrying pigment of the
erythrocytes, formed by developing erythrocyte in the
bone marrow.
Haem is attached to each polypeptide chain ,and it is
this party of the molecule which is principal responsible
for its oxygen carrying capacity.
If the ferrous (Fe2)  ion of  haem is oxidised to the ferric
(Fe3 ) form , then the oxygen carrying capacity of the
haemoglobin is lost
Haemoglobin pigments
In the circulation haemoglobin normally takes the form
of oxyhaemoglobin
Certain other forms can be produced if haemoglobin is
acted upon by other chemicals .eg Carboxyhaemoglobin,
methaemoglobin

FORMS OF HEMOGLOBIN
1. Carboxyhaemoglobin  (Hb CO)
Carbon monoxide  has an affinity  for haemoglobin
many times greater than  that of oxygen. Therefore , even
in low concentration carbon monoxide will rapidly bind
to haemoglobin to form carboxyhaemoglobin.
It is found in high concentration in case of carbon
monoxide poisoning, because these compound can not
carry oxygen may leads to hypoxic death. It is also found
in lower concentration in people who smock tobacco

2. Methaemoglobin 
Methaemoglobin is formed when  the ferrous iron of
haemoglobin is oxidised to ferric form. High levels of
methaemoglobin can be found in individual who are
being treated    with sulphonamide which may cause
oxidation of haemoglobin.
Methaemoglobin  is an inert pigment and does  not
carry oxygen
Methaemoglobin can also occur as a result of an
inherited abnormality  of the haemoglobin molecule
The iron ion may be either in the Fe2+ or in the
Fe3+ state, but ferrihemoglobin (methemoglobin) (Fe3+)
cannot bind oxygen.
In binding, oxygen temporarily and reversibly oxidizes
(Fe2+) to (Fe3+) while oxygen temporarily turns into the
superoxide ion, thus iron must exist in the +2 oxidation
state to bind oxygen. If superoxide ion associated to
Fe3+ is protonated, the hemoglobin iron will remain
oxidized and incapable of binding oxygen. In such cases,
the enzyme methemoglobin reductase will be able to
eventually reactivate methemoglobin by reducing the
iron center.

vErythropoiesis
Is the development process by which new erythrocytes
are produced. Through this process erythrocytes are
continuously produced in the bone marrow, at a rate of
about 2 million per second in a healthy adult
During the early stages of life, erythrocytes are
produced first by the yolk sac and then by the developing
spleen during the third month of gestation, until the bone
marrow is formed in the seventh month and takes over
erythrocyte production exclusively.

REGULATION OF ERYTHROPOIESIS
Thinking logically you might suspect that because the
primary function of erythrocytes is to transport O2 in the
blood, the primary  stimulus  for erythrocyte production
is low O2 levels. You would be correct, but low O2
levels do not stimulate erythropoiesis directly on the
bone marrow.
Instead, it stimulates the kidneys to secrete
the hormone erythropoietin into the blood, and
this hormone in a domino effect stimulates the bone
marrow to produce erythrocytes
Erythropoietin acts on derivatives of
undifferentiated cells that have already been committed
to becoming red blood cells (RBC’s), stimulating the
proliferation and maturation of these cells into mature
RBCs.
This increase in erythropoietin activity elevates the
number of circulating RBCs, thereby raising the O2
carrying capacity of the blood and restoring the delivery
of O2 to the body tissue to normal.
Once the O2 level in the tissues of the kidneys is
brought back to normal, erythropoietin secretion is
turned down until it is needed again. This is an example
of a negative feedback mechanism.

Erythrocyte properties
Red blood cells or erythrocytes contain haemoglobin
(Hb)
Hb gives the red colour of blood
On centrifugation erythrocytes are heavier and settle to
the bottom to form a packed cell pellet, white blood cells
form a layer (buffy coat) on top of the red blood cell
pack, platelets are settled on top of the white blood cells
Erythrocytes are circular biconcave discs in most
mammals
Mammalian erythrocytes have no nuclei (anucleate).
RBC life span 120 days only, short because of the lack
of nuclei
RBC has Hb;
 (1) globin, a protein and
(2) iron containing heme pigment
Blood volume is 6–8 % of body weight, % of blood
volume occupied by RBC is called hematocrit or packed
cell volume (PCV)
PCV depends on number & size of cells and plasma
volume
FUNCTIONS OF RBC
vPrimary function of erythrocytes is to carry Hb, Hb
carries oxygen by being oxidized to O2―Hb (oxy
haemoglobin) then transports O2 to cells, Hb has high
affinity for O2
vHemoglobin is involved in the transport of other gases,
it carries some of the body's respiratory carbon
dioxide as carbaminohemoglobin, in which CO2 is
bound to the globin protein

Common disorders of red blood cell
The following is the abnormal morphology of the red
blood cell
1. Anisocytosis is the variation of the size of the red
blood cell (microcytic , macrocytic)
microcytic means the cell is smaller  than normal  
macrocytic is larger than normal  cell.
2. Polychromasia is the variation of colour in stained
red blood cells
Hypochromasia is the low colour stained to red blood
cells (large central pallor)
3. Poikilocytosis is the variation of red blood cells in
shape
Sickle cells is the red blood cells with a sickle shaped
shape.

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