Agranulocyte

20-45% of WBCs

Spherical, dark-staining nucleus

Thin rim of blue staining cytoplasm

Each lymphocyte recognizes and acts against a specific antigen

T lymphocytes can attack foreign cells directly

(17.6)

B lymphocytes transform into plasma cells and secrete antibodies

Hemostasis means prevention of blood loss and this achieved by:

1. Vascular constriction

2. Formation of a platelet plug

3. Formation of blood clot

4. Growth of fibrous tissue into the blood clot

After blood vessel has been cut, the smooth muscle wall contract; this immediately reduces the flow of blood from the ruptured vessel

Platelets or thrombocytes Formed in the bone marrow from megakaryocytes

Do not have nuclei

Function in the clotting process.

Normal value – 150,000 to 300,000/cubic millimeter.

It has a half life in the blood of 8 – 12 days, its functional process run out over several weeks

Formation of platelet plug

1. Contractile protein thrombosthenin that can cause the platelet to contract

2. Endoplasmic reticulum that store Calcium ions

3. Mitochondria capable of forming ATP

4. Enzymes that can synthesize prostaglandins which involves in local tissue reactions

5. Contain fibrin stabilizing factor

6. Growth factors that causes vascular cells to grow and multiply

Platelet begin to swell and assume irregular forms when comes in contact with collagen fibers

They become sticky so that they adhere to collagen in the tissue

They secrete ADP and form thromboxane which activate nearby platelets

The damaged vascular wall activates increasing

numbers of platelets thus forming platelet plug. (In small vessels the platelet plug is all that is necessary to stop the bleeding).

1. Exposed collagen binds and activate platelets

2. Release of platelet factors

3. Attract more platelets4. Aggregate into platelet

plug

Blood coagulation take place in three steps 1. As result of rupture blood vessels, formation of

prothrombin activator (protein manufacture in the liver)

2. Conversion of prothrombin to thrombin in the presence of calcium

3. The thrombin acts as enzyme to convert fibrinogen (blood protein) into fibrin fibers that enmesh platelet, blood cells and plasma to form clot

Note: vitamin K is required by liver for formation of prothrombin

Prothrombin

Prothrombin Ca

Activator

Thrombin

Fibrinogen Fibrinogen monomer

Ca

Fibrin fibers

Activated fibrin

Stabilizing factor

Cross linked fibrin fibers

SEM of a clot with platelet, fibrin mesh, rbc’s

The clot composed of meshwork of fibrin fibers entrapping blood cells, platelets and plasma

Prothrombin activator is generally formed in two ways

1. Extrinsic pathway (begins with trauma to the vascular wall)

2. Intrinsic pathway (begin with the blood)

Preventing blood clotting in vascular system is

1. Smoothness of the endothelial cell surface

2. Layer of glycocalyx on the endothelium

3. Protein bound with the endothelial membrane thrombomodulin which binds thrombin

The most important anticoagulant in the blood

1. Fibrin fibers

2. Antithrombin III or antithrombin-heparin cofactor

Both fibrin fibers and antithrombin acts as antithrombin

About 85-90% of thrombin becomes adsorbed to the fibrin fibers

The thrombin that does not adsorb combines with antithrombin III which block the effect of thrombin

Heparin is anticoagulant, low concentration in the blood

Effectiveness of antithrombin III increases when it combines with heparin

Heparin is formed by basophilic and mast cell

Plasma protein contain euglobulin called plasminogen when activated becomes plasmin

Plasmin resemble trypsin

Plasmin digest fibrin fibers and other protein coagulants

Plasmin caused lysis of a clot

Injured tissue release activator called tissue plasminogen activator (t-PA) which convert plasminogen to plasmin

Red blood cells White blood cells Platelets

1 Site of

formation

formed in bone

marrow,

life-span:

4 months

formed in bone

marrow or thymus

formed in

blood

marrow

2 Shape biconcave discs,

no nucleus,

red colour

phagocytes:

irregular,

lobed nucleus &

granular cytoplasm

irregular

shape,

no nucleus,

tiny pieces

of cell

fragments,

Red blood cells White blood cells Platelets

3 Size small in size some large &

some small

tiny cell

fragments

4 Number 5,000,000 /mm3 7,000 /mm3 250,000/mm3

5

Functioncontain

haemoglobin to

carry oxygen

from lungs to

all parts of

body

phagocytes kill

pathogens &

digest dead cells

lymphocytes

produce

antibodies for

killing pathogens

for blood

clotting

Albumin Helps control osmotic pressure Helps control diffusion of water

Globulin Includes antibodies (Abs) Transport proteins (lipids, iron, copper, etc.)

Fibrinogen Involved in clotting

All the albumin and fibrinogen and 50 – 80% of globulin are formed in the liver

The reminder of the globulin are formed in the lymphoid tissues

Total protein: 4.2 - 5.6 g/dl

Albumin: 2.3 - 3.5 g/dl

Globulin: 1.9 – 2.1 g/dl

66 kDa

ALBUMIN

Accounts for ~50% of the total plasma protein and ~ 50%

of the total liver protein production

Half-life ~ 20 days

Highly polar

At pH 7.4 it is anionic with 20 negative charges per molecule

Functions of albumin

Maintenance of the osmotic pressure of plasma

Transport of free fatty acids

Globulin is made up of different proteins called alpha,beta, and gamma types.

Some globulins are made by the liver, while others aremade by the immune system.

Other globulins transport metals, such as iron, in theblood and help fight infection.