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
