Blood It is fluid which circulates in a closed system of blood vessels and heart and   consists of a variety of c...

BLOOD AND ITS COMPONENTS | FINDYOURSELF

July 16, 2019 2 Comments


          Blood




It is fluid which circulates in a closed
system of blood vessels and heart and 
consists of a variety of cells suspended in a fluid medium called plasma Hematopoiesis.

Begins in early embryonic life and continues
throughout life
§  Yolk sac                 3rd to 10th Week
§   Liver              6th to 32nd Week
§  Spleen           10th to 25th Week
§  Bone marrow      30th to 36th Week and also after
                                birth
 

Bone Marrow

There are three types of bone marrows:

•     Red Bone Marrow also known as Active Bone marrow
•     Yellow Bone Marrow also known as Inactive Bone marrow
•     Extramedullary Hemopoiesis

 Changes that occur when the cell matures:

§     The Size of the cell decreases
§  Cytoplasmic Nuclear Ratio increases
§  Chromatin becomes thick, coarse and  irregular
§  RNA decreases
§  Nucleoli become absent

Stages of Erythropoiesis are:

1.          Proerythroblast.        

•        Size:       20 – 25 Micron
•        Cytoplasm is seen as a thin rim, deep blue homogenous.
•        Nucleus is Large, round or oval.
•        Chromatin forms delicate network give the nucleus retic appearance.
•        N/C Ratio 8:1
•        Hb synthesis starts at this stage but are not seen 

2.  Early (Basophilic) Normoblast

•     Size:                       16 – 18 Micron
•     Cytoplasm is Deep basophilic
•     Nucleus is Rounded or oval, smaller than the previous stage. Chromatin form delicate clumps. Nucleoli absent. 
•     N/C Ratio     6:1

3.  Intermediate (Polychromatic ) Normoblast

•     Size:                       12 – 15 Micron
•     Cytoplasm
 Shows both acidophilic as well as basophilic staining
•     Nucleus is small, very Coarse
•     N/C ratio:  2 : 1 or 4: 1
•     No mitosis is seen after this stage.

4.          Late ( Acidophilic) Normoblast

•     Size:               8 – 10 Micron
•     Cytoplasm
       acidophilic cytoplasm.
       Wide rim of cytoplasm
•     Nucleus is Small, central or eccentric.
    condensation and solidification of     chromatin looks as blackish brown mass.
•     N/C Ratio     1:2 or 1:3

5.  Reticulocyte.

•     Size:                7 – 8 micron
•     Cytoplasm:
    like RBC but  slightly basophilic. (basophilic reticulum)

         Hb synthesis still occurring. some mitochondria and ribosomes seen.
 
•     Nucleus is extruded


Characteristics of RBCs

•        Biconcave discs
•        size : 7.5 Micrometer
•        Membrane flexible
•        No Mitochondria, ribosome or RNA
•        Anaerobic Glycolysis
•        Life Span 120 days
•        4.7-5.2 million/cubic mm3

Factors affecting Erythropoiesis

•     Erythropoietin

•     Protein diet

•     Vitamins  e.g. Vit B12,Folic Acid, Vit C, Vit  E, Riboflavin etc.

•     Metals e.g. Fe, Cu, Co, Mn etc

•     Hormones  e.g. Testosterone, Growth hormone, Cortisol, Adrenaline and nor-adrenaline, estrogen    

Polycythemia

    It is defined as  Increased number of RBCs

1.     Polycythemia Vera

2.     Secondary Polycythemia

§  Physiological

§  Pathological

3.     Relative Polycythemia                               

       









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