blood physiology professor a.m.a abdel gader md, phd, frcp (lond., edin), frsh (london) professor of...

Blood Physiology

Professor A.M.A Abdel GaderMD, PhD, FRCP (Lond., Edin), FRSH (London)

Professor of Physiology, College of Medicine &

King Khalid University Hospital Riyadh

Lecture # 4 & 5

LeucocytesWhite Blood Cells (WBCs)

Granulocytes, The Monocyte-Macrophage

System

Leucocytes (WBCs)

• General Characteristics & types of WBCs• Genesis (Production) of WBCs• Life Span of WBCs• Defense properties of neutrophils &

macrophages– Chemotaxis– Diapedesis– Amaeboid Motion– Phagocytosis

Blood Film

Hematopoiesis

Leucocytes (WBCs) – cont.

General Characteristics & types of WBCs

• Types of WBC1. Granular (polymorphnuclear):

• Neutrophil 62%.– 10-16um, nucleus 2-5 lobes, purple

cytoplasmic granules

• Eosinophil 2.3%.– 12-18um, 2 lobes nucleus, coarse red

granules

• Basophil .4%.– 10-14um, rarely segmented nucleus,

nucleus hidden by large round bluish granules

Leucocytes (WBCs) – cont.

General Characteristics & types of WBCs

• Types of WBC2. Agranular WBC

– Monocytes 5.3%• 15-20um, kidney shape nucleus

– Lymphocyte 30%• round nucleus

– small (5-8um) – large (9-15um)

Formed Elements of Blood• Red blood cells ( erythrocytes )• White blood cells ( leukocytes )

– granular leukocytes• neutrophils• eosinophils• basophils

– agranular leukocytes• lymphocytes = T cells, B cells, and natural killer

cells• monocytes

• Platelets

Leucocytes (WBCs) – cont.

Genesis (Production) of WBCs

Pluripotential stem cell

Committed Stem cell

RBCs WBCs Platelets

Mylocytic Lymphocytic Linage Linage

Hematopoiesis

Leucocytes (WBCs) – cont.

Genesis (Production) of WBCs- leucopoiesis)

Sites of WBC formation• Granulocytes (neutrophil, basophil,

eosinophil):

– bone marrow

• Agranulocytes – lymphocytes- bone marrow,

thymus, lymphoid tissues– monocytes- bone marrow

Life Span of WBCs

Granulocytes:• 4 to 8 hrs (transit time ) in blood circulation• 4 to 5 hrs in tissues

– In infections life span a few hours

Monocytes :– 10 to 20 hrs in blood circulation– Leave capillaries to tissues, increase in size

to become tissue macrphages which live for months

Life Span of WBCs-cont.

Lymphocytes:

• A few hrs in blood circulation >> tissues >> lymph >>> Blood (Recirculation)

?Life span: weeks to months

Leucocytes (WBCs)

• General Characteristics & types of WBCs• Genesis (Production) of WBCs• Life Span of WBCs• Defense properties of neutrophils &

macrophages– Chemotaxis– Diapedesis– Amaeboid Motion– Phagocytosis

Defense properties of neutrophils & macrophages

• Attack and destroy bacteria, viruses

• Sequence of events:– Chemotaxis– Diapedesis– Amaeboid Motion– Phagocytosis

Netrophils function-cont.

Defense properties of neutrophils & macrophages-cont

Phyagocytosis: Engulfing and killing of bacteria or any

invading organism

Steps: Chemotaxis:

– Bacterial & viral toxins• Products of damaged tissues:

attract neutrophil to accumulate at infected site.

– Opsonization: plasma substances (IgG) attached to the bacteria to make them easy to phagocyte

Diapedesis

Diapedesis

http://www.whfreeman.com/immunology/CH01/diapedesis.htm

Defense properties of neutrophils & macrophages

• Attack and destroy bacteria, viruses

• Sequence of events:– Chemotaxis– Diapedesis– Amaeboid Motion– Phagocytosis

Defense properties of neutrophils & macrophages

• Attack and destroy bacteria, viruses

• Sequence of events:– Chemotaxis– Diapedesis– Amaeboid Motion– Phagocytosis

Phagocytosis- cont.

Phagocytosis is selective:Distinguish self from non-self…... How?

– Normal tissues have smooth surface– Normal tissues have protective

protein surface– Antibodies coating bacteria

(Opsonization)

Phagocytosis

Phagocytosis by neutrophils- cont.

Neutrophils attach to bacteria & encircled it with pseudopodia and take it into a vacuole (phagosome).

• One Neutrophil can engulf 3 to 20 bacteria• One Macrophage can engulf up to 100 bacteria

Microbial killing: fusion of neutrophil granules with vacuole,

– Discharge of lysozyme, myeloperoxidase enzymes into the vacuole, killing and digesting the engulfed bacteria.

– Release of Free radicals by oxidizing agents: superoxide, hydrogen peroxide to kill the bacteria

Leucocytes (WBCs) – cont.

• Types of WBC1. Granular (polymorphnuclear):

• Neutrophil 62%.– 10-16um, nucleus 2-5 lobes, purple

cytoplasmic granules

• Eosinophil 2.3%.– 12-18um, 2 lobes nucleus, coarse red

granules

• Basophil .4%.– 10-14um, rarely segmented nucleus,

nucleus hidden by large round bluish granules

Blood Film

Eosinophils

Function: • Phagocytosis: Phagocytosis is same as neutrophil,

but less efficient

• Chemotaxis: eosinophil attracted towards chronic inflammation/allergic tissue (allergic disease of skin & lungs)

By eosinophil chemotactic factor

Phagocytose (& detoxify) antigen/antibody complexes

Eosinophils cont,

•High eosinophil count:– Parasitic (hook worm, ascaris,

bilharzia)– Allergic (asthma, rhinitis, drug

reaction)– Allergic skin diseases

Leucocytes (WBCs) – cont.

• Types of WBC1. Granular (polymorphnuclear):

• Neutrophil 62%.– 10-16um, nucleus 2-5 lobes, purple

cytoplasmic granules

• Eosinophil 2.3%.– 12-18um, 2 lobes nucleus, coarse red

granules

• Basophil .4%.– 10-14um, rarely segmented nucleus,

nucleus hidden by large round bluish granules

Leucocytes (WBCs) – cont.

• Types of WBC1. Granular (polymorphnuclear):

• Neutrophil 62%.– 10-16um, nucleus 2-5 lobes, purple

cytoplasmic granules

• Eosinophil 2.3%.– 12-18um, 2 lobes nucleus, coarse red

granules

• Basophil .4%.– 10-14um, rarely segmented nucleus,

nucleus hidden by large round bluish granules

Blood Film

Basophils

• Similar to tissue mast cells• Non-phagocytic cells• Granules: dark blue color.• Granules contain:

– Heparin– Histamine – Serotonin (5HT).

Released during allergic reactions

Hematopoiesis

Blood Film

Defensive Functions of the Monocytes

• Directly: – phygocytosis of bacteria, dead cells

etc

• Indirectly:– Cooperates with lymphocytes by:

•Recognizing the foreign body •Ingesting the foreign body •Processing the foreign body•Presenting it to lymphocytes

Monocyte-macrophage system

Reticulo-endothelial System

Reticuloendothelial System-RES

Blood Monocyte Tissue macrophage

Attached (fixed) Mobile

Function is phagocytosis of:• Bacteria• Viruses• Dead tissues• Foriegn particles

Immune function

Reticuloendothelial System-RES

• RES is widespread in the body

Cells of the RES:– Monocytes (blood macrophages)– Mobile and fixed tissue Macrophages – Specialiazed endothelial cells in bone

marrow, lymph nodes and spleen– Reticular cells of lymph nodes spleen &

bone marrow.

Reticuloendothelial System-RES

Cells of the RES - Distribution:

• Tissue Macrophages in skin SC tissues

• Tisssue Macrophages of lymph nodes• Tissue macrophages in lungs• Macrphages (kupffer cells) in the

liver• Macrphages in the spleen and

bone marrow

Reticuloendothelial System-RES

Blood Monocyte Tissue macrophage

Attached (fixed) Mobile

Function is phagocytosis of:• Bacteria• Viruses• Dead tissues• Foriegn particles

Immune function