Blood Physiology
Professor A.M.A Abdel Gader
MD, PhD, FRCP (Lond., Edin), FRSH (London)
Professor of Physiology,
College of Medicine &
King Khalid University Hospital
Riyadh
Lecture # 4 & 5
Leucocytes
White 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
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–
–
–
Chemotaxis
Diapedesis
Amaeboid Motion
Phagocytosis
Blood Film
Hematopoiesis
Leucocytes (WBCs) – cont.
General Characteristics & types of WBCs
•
Types of WBC
1. 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 WBC
2. 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
Mylocytic
Linage
WBCs
Platelets
Lymphocytic
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:
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–
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,
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–
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 WBC
1. 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 WBC
1. 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 WBC
1. 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
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•
•
•
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:
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•
•
•
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