BLOOD COMPOSITION AND FUNCTION//LYMPH AND LYMPH NODE//

 

BODY FLUIDS


·       Blood

·       Lymph

All living cells have to be provided with nutrients, O2 and other essential substances and also have to remove harmful substances continuously for proper functioning.

Complex organism use special fluids to transport these substances.

Blood is the most commonly used body fluid in higher organism for this purpose.

Lymph is another body fluid which helps in transport of certain substances.

Blood

·        Blood is a connective tissue.

·        Its  pH value is 7.4

·        Study of blood is called Serology or Haematology.

·        Male has more blood than female. In male 5.5-6.8 liter and female 4.5 – 5.0 liter.

·        Blood depends on body weight ( up to 7-8% blood of body weight)

·        Blood has two part-

A.   Plasma-

o   It is a straw coloured.

o   It makes about 55% of the blood.

o   90-92% of plasma is water and 6-8%  is proteins ( Fibrinogen, globulins and albumins, prothrombin are major proteins )

o   Plasma without the clotting factors is called Serum.

Function of plasma-

v It helps in transport of nutrients, respiratory gases, metabolic waste, hormones etc.

v It acts as acid base buffer.

v Prothombin and fibrinogen help in blood clotting.

B.  Blood corpuscles or formed elements-

They make 45% of the blood.

There are three types of blood cells-

(i)                Erythrocytes or RBC

(ii)             Leucocytes or WBC

(iii)           Platelets

 

(i)                Erythrocytes or RBC-

Erythrocytes also known as red blood cells or RBC.

RBCs ( Red blood cells) are biconcave , oval  in shape and  red in coloured due to presence of Haemoglobin.

In mammals (except camels and lama), the mature RBC is circular, biconcave and non- nucleated.

RBC is about 7-8 micrometer in diameter.

A healthy man has 5-5.5 millions of RBCs mm-3 of blood.

They are formed in the Red bone Marrow.

RBCs have an average life span of 120 days after which they are destroyed in the Spleen. That is why spleen is called Graveyard of RBCs.

Function of RBC-

·        Haemoglobin (Hb) plays a significant role transport of respiratory gases.

 

(ii)             Leucocytes or WBC-

Leucocytes also known as white blood cells or WBC.

They  are colourless due to absence of haemoglobin.

They are rounded or amoeboid, nucleated.

Size of WBC ranges from 8-15 micro meters.

The number of WBC 6000-8000mm-3 of blood.

WBCs have an average life span of 4 days.

They are formed in the Red bone Marrow.

WBCs are two types-

a.     Granulocytes

b.     Agranulocytes

 

a.     Granulocytes

They have granular cytoplsm

They make about 60 to 65% of the total WBCs.

They formed in Red bone marrow.

They are divided into 3 types-

I.                   Neutrophils

II.                Basophils

III.             Eosinophils

 

I.                  Neturophils-

They make 62% of the total WBC.

Neturophils are the most abundant .

Nucleus is 3to 5 lobed.

They show Phagocytosis.

II.               Basophils-

They make 0.5 to 1% of the total WBC.

Nucleus is bilobed.

Basophils secrete histamine, serotonin, heparin, etc.

III.           Eosinophils-

They make 2-3% of the  total  WBC.

Nucleus is bilobed.

They resist infection and are also associated with allergic reactions.

Their number increases in allergic reaction like Asthma and Hey fever.

b.    Agranulocytes

Cytoplasm is non- granular.

Make about 35% of WBC.

They are two types-

I.                   Monocytes

II.                Lymphocytes

I.                  Monocytes -

The nucleus is oval or kidney shaped.

They are phagocytic .

They act as a scavenger cells or macrophages which remove dead cellsfrom the body.

They make 6-8% of total leucocytes.

II.               Lymphocytes –

They make 20- 25% of total WBC

Nucleus in large and round.

They produced antibodies.

Cytoplasm is less.

They are two types-

(i)    T- Lymphocytes – they formed in bone marrow but mature in thymus.

(ii) B- Lymphocytes- they formed in bone marrow.

Both are responsible for immune responses of the body.

(iii)                       Platelets-

Platelets are also called Thrombocytes.

It is not a complete cell it is a part of Megakarocytes.

They small in size, colorless, non-nucleated.

The number ranges from 1.5 to 3.5 x 105/mm3 of blood.

Life span is 7-10 days.

They help in blood clotting.

Reduction in their number cause clotting disorders which will lead to excessive loss of blood from the body.

Functions of Blood-

·        Maintain body temperature.

·        Help in gaseous (CO2 and O2) transportation.

·        Hormones and Nutrients transportation.

·        Remove excretory products.

Lymph (Tissue fluid)

It is white vascular connective tissue that floats inside specialized vessels called Lymph vessels or lymphatics. It acts as a middle-man.

It is an alkaline.

It is present between blood and tissue.

It containing specialized lymphocytes which are responsible for the immune response of the body.

Function of lymph-

·        It helps in exchange of nutrients, gases, etc.

·        It helps in the absorption of fat from the intestinal villi.

·        It also act as carrier for some hormones and larger proteins into the blood.




Blood Cells






































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