() Identify all five types of leukocytes shown here.
(ii) Mention two differences between Fig. B and C.
(iii) Mention a difference between Fig. A and E.
(iv) Define phagocytosis.
(v) Where are these cells produced?
(vi) What is the lifespan of these cells and their
count in a healthy person?
(vii) Name the other two types of cells found in
blood and also mention its main functions.
Answers
Answer:
(i) Fig.,A, - Neutrophils ( First to respond to bacteria or a virus )
Fig.,B, - Eosinophils ( Known for their role in allergy symptoms )
Fig.,C, - Basophils ( Known for their role in asthma )
Fig.,D, - Monocytes ( Clean up dead cells )
Fig.,E, - Lymphocytes ( Fight infections by producing antibodies )
(ii) Neutrophils have a two-lobed or bilobed nucleus, while eosinophils have bean-shaped nucleus.
The lifespan of neutrophils is 5-90 hours, whereas eosinophils lifespan is 8-12 hours.
(iii) Neutrophils which make up 50 to 70 % of all circulating WBCs. Their cytoplasm is packed with pale granules containing lysosomal enzymes and bacteria-killing compounds.
Lymphocytes , slightly larger than RBCs, make up 20 to 30% of circulating WBCs. They migrate in and out of the blood.
(iv) The ingestion of bacteria or other material by phagocytes and amoeboid protozoans is known as phagocytosis.
(v) Phagocytes are constantly produced throughout a human's lifespan in the bone marrow and are stored there before being transported in the blood. Their function is to remove any dead cells or invasive microbes.
(vi) The life-span of tissue macrophages has been estimated to range from four to fifteen days. Macrophages can be activated to perform functions that a resting monocyte cannot. T helper cells (also known as effector T cells or Th cells), a sub-group of lymphocytes, are responsible for the activation of macrophages.
Phagocytes are important throughout the animal kingdom and are highly developed within vertebrates. One litre of human blood contains about six billion phagocytes.
(vii) They are RBC's and Platelets.
Red blood cells carry oxygen from our lungs to the rest of our bodies. Then they make the return trip, taking carbon dioxide back to our lungs to be exhaled.
Platelets are only about 20% of the diameter of red blood cells. The normal platelet count is 150,000-350,000 per microliter of blood, but since platelets are so small, they make up just a tiny fraction of the blood volume. The principal function of platelets is to prevent bleeding.