What allows oxygen to pass into your blood?

Carbon dioxide is excreted from the blood capillaries to alveoli and taken to the air and Oxygen  is absorbed from the air and taken to the blood vessels . A pigment in blood called hemoglobin present in blood combines with oxygen and allows oxygen to pass into blood.


What gives blood it’s color?

A pigment called hemoglobin gives color to blood. It is the coloring material of red blood cell.

What allows oxygen to pass into your blood?



Functions of Blood:-

The Functions of blood are:

  • Respiration:

Firstly, transports oxygen from the lungs to the tissues and carbon dioxide from tissues to the lungs.

  • Excretion:

Secondly, it transports of metabolic wastes to the lungs, kidney, skin and intestine for removal.

  • Nutrition:

Then, it transports & absorbed carbohydrates, Protein and lipid.

  • It maintains normal acid base balance.
  •  Regulation of water balance.
  •  It regulates the body temperature
  •  Transport of hormones, vitamins and salt.
  • Transport of various metabolites (Urine, Body fluid, CSF).
  •  Defense against infection by the WBC
  •  Coagulation of blood by platelets.


Blood is composed of the following factors:


Composition of plasma:

  •  Water: 90-92% of the plasma.
  •  Solids: 8-10% of the plasma

The solids of plasma are:

  •  Plasma proteins: – Albumin, globulin, fibrinogen, prothrombin.
  1. Inorganic salts (Mineral salts):-Sodium, chloride, bicarbonate, potassium, magnesium, phosphorus,iron,calcium,copper,iodine,cobalt,etc.
  2.  Nutrient materials:-Monosaccharide (glucose), amino acids, fatty acids and glycerol, vitamins
  3.  Organic waste materials:Urea, uric acid, cretinine.
  4.  Hormones: – TSH, T3, T4, calcitonin, insuline, glucagon, glucocorticoid.
  5.  Enzyme:Pepsinogen, amylase, lipase, carbonic anhydrase, protease.
  6.  Antibodies:Immunoglobulin, IgG, IgM, IgA, IgD, IgE.
  7. Gases:-Oxygen, carbon dioxide, nitrogen.


Blood Cells:-45%

Composition of blood cells:


Red blood cells (RBC) or  Erythrocytes

Red blood cells are the non-nucleated formed elements in the blood. The red colors of these cells are due to the presence of the coloring matter called hemoglobin. The word erythro means red and cytes means cells.

  • Normal count of red blood cell:

In adult males:5 millions per cubic mm of blood.

In Females:4.5 millions per cubic mm of blood.

  •  Life span: about 120+- 20 days
  • Red blood cell transport oxygen from the lungs to the tissue.
  • Also, red blood cell transport carbon dioxide from the tissue to the lungs.
  • Moreover, hemoglobin in red blood cell also functions as a good buffer.
  • Red   blood   cells   carry   the   blood   group   antigens   like   A Agglutinogen,   B Agglutinogen  and Rh factor.

This helps in determination of blood group and blood transfusion.



White blood cells (WBC) or   Leucocytes

Leukocyte is the colorless and nucleated formed elements of blood.  Also, leukocytes play very important role in defense mechanism of body. It depends upon the presence or absence of granules in the cytoplasm.

Total WBC count (TLC or TC):-4000-11000/cu mm of blood


Classification of WBC

1. Granulocytes

The present of granules

  1.  Neutrophils
  2.  Eosinophils
  3.  Basophils

2. Agranulocytes

The absent of granules

  1.  Monocytes
  2.  Lymphocytes

a. Neutrophils

  • Neutrophils have fine granules or small granules in the cytoplasm.
  • The nucleus is multilobed.

b. Eosinophils

  • Eosinophils have large granules in the cytoplasm.
  • The nucleus is bi lobed.

c. Basophils

  • Basophils have large granules in the cytoplasm.
  • Nucleus is bi lobed.

d. Monocytes

  • The cytoplasm is clear without granules.
  • The nucleus is round, oval horse shoe or kidney shaped.

e. Lymphocytes

  • The lymphocytes have clear cytoplasm without granules.



Life span of white blood cells is constant. It depends upon the demand in the body and their function. However, life span of white blood cells may be as short as half a day or it may be as long as 3-6 months.

Platelets or Thrombocytes

Platelets are small colorless, non nucleated and moderately refractive bodies. These formed elements of blood are considered to be the fragments of cytoplasm.

Normally, spherical or rod shaped and become oval or disc shaped when inactive. Sometimes, the platelets are of dumbell, comma, cigar or any other unusual.

  • The normal range: – 1.5-4 Lakh/cumm of blood.
  • The life span: – 7-14 days.


Hemoglobin is the coloring matter of red blood cells. It is a chromo protein forming.

95% of dry weight of red blood cells and 30 -40% of wet weight

Frequently Asked Questions(FAQs)

How does oxygen pass into the blood?

Oxygen pass into the blood through alveoli.

What happens when oxygen pass into the blood?

When oxygen pass into the blood it binds with a pigment in the blood called hemoglobin which allows oxygen to pass.


What is the main cause of Leukemia?

However the exact cause of leukemia is still unknown but the rise in white blood cell is consider as the cause.


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