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PinkMonkey Online Study Guide-Biology

Functions of plasma: Plasma is the chief transporting medium supplying water, Oxygen and metabolites to all cells and also collects nitrogenous waste products and Carbon Dioxide from them.

(B) Blood corpuscles: These are blood cells suspended in plasma and are of three types, namely, erythrocytes, leucocytes and blood platelets.

Red blood corpuscles

Figure 18.9 Human red blood corpuscles

(1) Red blood cells (corpuscles) or Erythrocytes

Red blood cells or erythrocytes are red in color and are numerous, about five million per cubic millimeter; hence they give the red color to blood. They are circular biconcave, anucleate (without a nucleus) and immobile. Being flexible, they get twisted and can be squeezed through blood capillaries smaller than their diameter. Each red blood cell shows the central spongy mass called stroma containing a red colored substance called hemoglobin which is the respiratory pigment. Hemoglobin readily combines with oxygen to form an unstable compound known as oxyhemoglobin.

Hemoglobin + Oxygen.         Oxyhemoglobin

Hence red blood cells are called oxygen carriers. The red blood cells of human beings are short-lived, having about 100 to 120 days of normal life span, probably because of the absence of a nucleus. They are produced in the red bone marrow and when dead they are constantly disintegrated in the liver and spleen.

Hemoglobin contains iron atoms involved in binding oxygen; thus liver is a good dietary source of iron.

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Table of Contents

Table of Contents

18.0 - Introduction
18.1 - Closed Vascular System
18.2 - Heart
18.3 - Arterial Blood Pressure
18.4 - Blood

Chapter 19


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