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Blood & Hemopoiesis
Blood is a tissue of the red blood cells,white blood cells ,and platelets suspended in a liquid matrix, the blood plasma.It circulates in the blood vessels to maintain logistical support and communication between all of the tissues of the body.
erythrocytes(red blood cells)
Blood leukocytes(white blood cells )
platelets
blood plasma:55%--- serum
Erythrocyte ghost
Its volume in the human is about 5 liters.
1. Erythrocyte
1)Shape:
They are the minute corpuscles that impart a red color to the blood,owing to their content of the oxygen-carrying pigment, hemoglobin(Hb) .These are proteins .The number 120~150 g /L in the human male, and 110~140g/L in the female. In the blood ,their form is that of a biconcave disk with a thickness of 1.9um near the periphery and somewhat less in the center.They are 7.5um in diameter.The biconcave shape of erythrocyte is clearly revealed in scanning electron micrographs.
2 )Normal numbers:
Female :3.5-5.0 ×1012/L,
Male : 4.0-5.5×1012/L
3)Structure:
Erythrocyte extrude their nucleus and other organelles and are reduced to membrane-limited corpuscles containing cytoplasm, which consists predominantly of hemoglobin in solution.In blood-smears stained with Wright's or Giemsa's blood -stain,they are pink.
4)Reticulocyte:
In stained blood smears, the great majority of erythrocytes stain a deep pink, but a small number that have recently entered the circulation, from the bone marrow, have a bluish or greenish tint, owing to the basophilic staining of residual ribosomes in their cytoplasm. Such polychromatophilic erythrocytes are commonly called reticulocytes, for when stained with Brilliant Cresyl Blue their ribonucleoprotein is precipitated by the dye as a delicate basophilic network in an otherwise acidophilic cytoplasm.
Within 24 h of entering the blood, the maturing erythrocytes lose their basophilia.The erythrocyte count,the number of erythrocytes are about 0.5-1.5% in the adult human,and 3-6%in the baby.
5)Life time:
The erythrocytes life span in the circulation is about 120 days. It follows from this datum that in excess of 2 million erythrocytes must enter the bloodstream every second, as an equal number are lost. Erythrocytes are taken up and digested by phagocytic Kupffer cells in the liver and by macrophages in the spleen.
Anemia
Anemia is the term applied to any significant reduction in total mass of erythrocytes or in their content of hemoglobin,resulting in a reduced oxygen-carrying capacity of the blood .A deficiency in dietary intake of iron needed for hemoglobin synthesis may result in iron-deficiency anemia. Deficiencies of vitamin B 12or folic acid may lead to megaloblastic anemia in which there is a retarded production of erythrocytes of larger than normal size.
2.Leukocytes : normal number:4-10x109 /L .
The Leukocytes are a group of cell types that are concerned with the defenses of the body against invading foreign mater.They are divided into two categories:granulocytes and agranulocytes,depending on whether their cytoplasm contains specific granules that bind the dyes in Wright's blood stain.
1)Granulocytes
Neutrophil Eosinophil Basophil
diameter 7um(f)10~12um(d) 9um(f)10~15um(d) 9um(f) 10~12um(d)
granules specific&azurophilic larger specific metachromatic (Toluidine Blue)
enzymes peroxidase, aryl sulfatae,
contents acid phosphatase; β-glucuronidase, heparin,
alkaline phosphatase, acid phosphatase, histamine
lysozyme,phagocytins. Ribonuclease
cationic proteins.
nucleus 1~5 lobules bilob U or J shape
life time ( c) 6~8 h 6~8 h 10~15 days
(h) 2~3 days 8~12 days
normal number 50~70% 0.5~3% 0~1%
function
2)Agranulocytes
Lymphocyte Monocyte diameter 6~20um 14~20um
cytoplasm clear blue color pale blue-gray color
contains a few small contains a few small
azurophilic granules azurophilic granules
has no enzymes peroxidase has enzymes peroxidase
nucleus a deeply staining slightly round or kidney-shaped
indented nucleus
life time may be a life span, 1-4days in blood and then
may be several years. enters connective tissue.
normal number 20-30% 3-8%
function
3. Platelet
Platelets or thromboplastids , are minute ,colorless,corpucles found in the blood of all mamals.They are thin ,ovoid ,biconvex disks 2-3um in diameter.When viewed in section ,they are fusiform. In the human, their number ranges100-300×109/Lblood. In the stained blood smears, they exhibit two concentric zones:the hyalomere,and the granulomere. the latter contains small azurophilic granules. Their function in the clotting of blood at sites of injury to blood vessels and thus help to prevent excessive blood loss. The Platelets life span in the circulation is about 14 days.
Hemophilia
Hemophilia is an inherited defect in factor VIII, one of the clottingfactors. The gene involved is located on the X chromosome so this disease usually affects males . Daughters of hemophiliacs are carriersand the sons of such carriers have a 50% chance of inheriting the disease. These patients bleed into muscles,joints,and body cavities for hours or days after an injury.Surgery and even dental extractions must be carried out with extreme care to prevent excess bleeding.
4.Hemopoiesis
1)Definition :
Blood cells are short-lived, and they must be continually
replaced by new cells formed in the generative process called
hemopoisis.
2)Phase:
(1)mesobllastic phase:
The mesobllastic phase of hemopoisis, occure in small islands of cells in the yolk sac and body stalk of the embryo.
(2)Hepatic phase:
At about 6 weeks of gestation, round basophilic precursors of erythrocytes can be found in the primordium of the liver , and the spleen initiating the hepatic phase of hemopoisis .
(3) Myeloid phase:
After medullary cavities develop in the long bones, blood formation is initiated there, establishing the myeloid phase of hemopoisis which continues throughout adult life.
3)Bone marrow: red bone marrow yellow bone marrow
5) Hemopoietic inductive microenviroment(HIM)
Hemopoisis must depend on this microenviroment .It consist of the reticularcells ,macrophages , fibro - blasts , and the sinusoidal endothelium.
6)Hemopoietic stem cells
(1)Their structure is very simple and as a lymphocyte.
(2) Stem cells that are cycling may either undergo self-renewing divisions to maintain the pool of pluri-potential stem cells.
(3) They may undergo differentiating divisions progenitor cells of four kinds.
血细胞发生过程:原始阶段,幼稚阶段和成熟阶段.
规律:
1)红细胞系:
(1)胞体渐小
(2)胞质由嗜碱性 嗜酸性.
(3)细胞核渐小,最后消失.
(4)核仁由有到无.
2)粒细胞系发生规律:
(1)胞体渐小.
(2)颗粒由无到有.
(3)核由大到小,由圆到肾形再到杆状.
(4)核仁由有到无.
3)单核系,淋巴系发生规律
(1)单核系:
原单核 →→ 幼单核 →→单核细胞.
(2)淋巴系:
多能干细胞→→定向干细胞 →→淋巴细胞
4)血小板的发生规律
原巨核细胞 →→ 幼巨核细胞 →→巨核细胞→→胞质脱落(血小板).
Questions
1.What is normal number of the blood
2.How many kinds of cells are there in the blood What are they and their structure,and function
3.What is hemopoisis What is HIM
4.What are characters of the hemopoietic stem cells
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