1. The mammalian bones contain along with above written structures, a system of canals called haversian and volkmann's canals. These canals contain an arteriole, a venule, or a nerve fibre. Their structure looks like -

Fig. 1.13 Mammalian bone a portion

–

Fig. 1.14 Mammalian bone an osteon

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• On the basis of their distribution the bone contains following 4 zones which are visualized as

Fig. 1.15 Mammalian bone with zones

–

• These zones can be -

[a]

-

• The haversian canals and their related lamellae (in 4 to 20 concentric layers around them). The haversian canals are present parallel to the bone axis.

[b]

-

• Present in between the haversian zone is certain lamellae called interstitial lamellae. These lamellae along with their lacunae come under this zone as shown below -

Fig. 1.16 Mammalian bone upper view showing interstitial zone

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[c]

-

• The lamellae and lacunae present between haversian zone & periosteum come under this zone.

[d] Inner circumferential zone -

• The lamellae and lacunae present between haversian zone and endosteum come under this zone

• Mesodermal in origin;


• Specific gravity -1.04 - 1.07;


• Viscosity - 4½ to 5½ times more than water.


• pH - 7.3 - 7.5, 7-8% of total body weight.

• Plasma is a crystallo - colloidal mixture, makes 55-60% of blood.


• It contains 90-92% of water.


• Salts make 0.9% of plasma;


• Main inorganic salts include Cl^- & bicarbonates of N_a, K, M_g, and C_a.


• Organic constituents - (a) Proteins - 7% to 8% as colloidal particles contains
  
  
  
  


• Among these prothrombin and fibrinogen are largest blood proteins while Albumins are smallest


• Other constituents of plasma include
  
  
  
  
  
  1. Digested nutrients are also present in plasma.
  
  
  2. Excretory substances
  
  
  3. Defence compounds - Immunoglobulins + Lysozymes + Properdin
  
  
  4. Anticoagulant which is a conjugated Polysaccharide - Heparin.
  
  
  
  
  
  

The

include -

1. RBCs :
   
   
   
   • Count by Haemocytometer;
   
   
   • Seen only in vertebrates [(Except Eel larvae and some fishes);
   
   
   • some invertebrates also have them ex. Glycera, Phoronis, Thynoe (Holothurian)
   
   
   • Described Istby LEEUWENHOCK 1674.
   
   
   • RBCs of Amphibians are largest among vertebrates and among amphibians Proteus and Amphiuma have largest RBCs.
   
   
   • Mammalian RBCs are smallest among veb. and among mammals smallest RBCs are present in musk Deer.
   
   
   • Usually in Mammals the RBCs are circular and non nucleated except those of family camilladae (Camels, Ilmas etc.) which have nucleated RBCs.
   
   
   • In rest of the vertebrates oval and nucleated RBCs are present.
   
   
   • In humans the RBCs are 6.5 mu to 8 mu in diameter and 1-2 mu thick;
   
   
   • Count about 52 Lacks per mm3 (in males) and about 47 Lacks per cubic mm (in females);
   
   
   • Total surface area 1500-2000 times more than that of body;
   
   
   
   

Composition




• 64% water, 20% Haemoglobin, 7% lipids, 3% other substances.



Structure




• The outer membrane is plasma membrane, which contains enzymes, inside it a structural protein is found, called STOMATIN. Which makes it soft clastic & flexible (RBCs can pass through blood with 1/2 of their diameter)


• In one RBCs 24 ½ - 26 ½ crore haemoglobin molecule are present. The blood haemoglobin count is done by Haemoglobinometer.


• Destruction of RBCs produces 250 mg of bite salts/day.



Poikilocytes - Erythrocytes of variable size & shape.

LifeÝ100 -120 days (max. 124 days in Dog)

RBCs Production




• During few early weeks of embryonic life Yolk sac;


• During some later stages Liver. (Main organ) + spleen & Lymph nodes.


• During later part of gestation & after birth RED BONE MARROW Exclusively of all bones until the child ---> 5 yeras old.


• Bone marrow of long bones (except proximal portions of Humerous and Tibia) - up to the age of 20 years.


• After this RBCs production in Membranous bones like vertebrae, Sternum, Ribs etc.)







2.W.B.Cs.




• Colorless, motile and nucleated cells


• Larger than R.B.Cs. But much less in no. (5000 - 9000 /mm³)
  
  
  
  
  
  
  
  
  • Life Span - 1 - 8 hours or days.
  
  
  • These are of following three types
  
  
  
  (1) Eosinophils or Acidophils or Oxyphils
  
  
  
  
  • 1 - 5 % of total WBCs. count (70 - 300 / mm³).
  
  
  • Nucleus BILOBED.
  
  
  • Granules in actual sense are lysosomes contain hydrolytic enz. large
  
  
  • Granules stain by acidic dyes.
  
  
  • Cells play important role in Immunity, allergy and Hypersensitivity.
  
  
  • EOSINOPHILIAIncrease in No. of Eosinophils.
  
  
  
  (2) Basophils
  
  
  
  
  • Least numerous (0.5 - 2.7% of leucocytes i.e., 35 - 150 / mm³of blood)
  
  
  • Nucleus S - shaped, 2 - 3 lobed;
  
  
  • Granules larger and few;
  
  
  • stained with Basic dyes like Methylene Blue.
  
  
  • Can secrete Heparin, Histamine and serotonin. Thus related to Mast cells.
  
  
  
  
  
  (3) Neutrophilsor Heterophils
  
  
  
  
  • Most numerous (60 - 70%) 4000 - 5000 / mm³;
  
  
  • Most active Nucleus 2-5 lobed;
  
  
  • Granules small but most numerous;
  
  
  • stain with netural dyes contain Hydrolytic enz. capable of digesting bact. & other pathogens;
  
  
  • Inside their nucleus a compact rod like structure is also seen in females called DRUMSTICK which can be compared with Barr Body of females.
  
  
  • Agranulocytes
  
  
  • Life span - Some days to months without granules,
  
  
  • These are of 2 types -
  
  
  
  (a) Lymphocytes
  
  
  
  
  • Small, roughly spherical
  
  
  • 20 - 40 % of leucocytes;
  
  
  • Comparatively less motile, Central nucleus and produces ANTIBODIES.
  
  
  
  (b) Monocytes
  
  
  
  • 2 - 7 % of leukocytes largest cells of blood;
  
  
  • With horse shoeshaped Nucleus;
  
  
  • Actively motile and phagocytic
  
  
  • Monocytes [After entry into tissue fluid] become Macrophages.
  
  
  
  
  
  (c).Blood Plalelets(Thrombocytes)
  
  
  
  • Occur only in Mammals 2 - 5 lacks/mm³;
  
  
  • small (2 - 4 mu). Highly contractile, round, oval or biconvex Nucleus absent;
  
  
  • Their 50 % part isProtein and 15 % part isFat.
  
  
  • Among proteins a contractile protein called THROMBOSTHITIN which can be compared with the Actomyosin of muscles.
  
  
  • Formation from certain large cells of bone marrow called Megakaryocytes as buds or pinched vesicles.
  
  
  • Life span - 8 - 10 days.
  
  
  
  (d) Spindle cells
  
  
  
  
  • In all vertebrates except mammals;
  
  
  • Nucleus - spherical or oval;
  
  
  • Cytoplasm - Granular; Function similar to blood plateles.
  
  
  • Show Diapedesis i.e., Movement of WBCs through the walls of the blood vesels in to the surrounding ECF and to the neighbouring blood vessels.
  
  
  • Relation RBCs : WBCs = 600 : 1
  
  
  
  LeucocytosisEnormous increases in WBCs count during abnormal conditions.
  
  Leucopenia If WBCs no. falls below 4000.
  
  
  
  Blood Coagulation
  
  
  
  
  
  
  • The coagulation of blood is a cmplicated phenomenon. Proteins responsible for blood coagulation are called factors. These are -
  
  
  
  
  
  Factor I Fibrinogen
  
  
  
  
  • Given by Virkow 1845
  
  
  • Glycoprotein, mol. wt. 3,40,000.
  
  
  • 3 pairs of Non identical polypeptide chains.
  
  
  • Synthesis - Liver, soluble in plasma converted to fibrin.
  
  
  
  Factor II Prothrombin
  
  
  
  • Given by Schimid, 1863
  
  
  • Glycoprotein, mol. wt. 70,000.
  
  
  • Synthesis - Liver with the help of Vit.k.
  
  
  • Converted to thrombin in the presence of Thromrboplastin.
  
  
  
  
  
  Factor III Thromboplastin or Tissue factor or Schimidt Tissue Thromboplastin -
  
  
  
  
  • Lipoprotein;
  
  
  • Secreted in its inactive from called prothrombo plastin
  
  
  • Converted into thromboplastin under the action of proconvertin of plasma tissues.
  
  
  
  
  
  Factor IVCa⁺⁺ ions –
  
  
  
  
  • Required for the formation of both extrinsic and intrisic thrombo plastin + Conversion of prothrombin to thrombin.
  
  
  
  
  • Apparently involved in all the 3 stages of coagulation.
  
  
  
  
  
  Factor V Proaccelerin or labile factor -
  
  
  
  
  • 1stdescribed by Oweren in 1947.
  
  
  • Plasma glycoprotein of mol. wt. 290,000.