Biology Today - February 2018

Agranulocytes

Lymphocyte – It has a large rounded nucleus and its cytoplasm lacks granules.

• It is motile, non-phagocytic and produces antibodies; helps in healing.


• It is responsible for immune responses.


• It is of two main types : B cells and T cells.

Monocyte – It is the largest of all types of leucocytes.

• It is somewhat amoeboid in shape.


• Nucleus is bean shaped, has enough cytoplasm.


• It is motile, phagocytic in nature, LH., engulfs germs and cell debris, often changes
  into macrophages.


• This can change into macrophages after entering tissue spaces.

3. Thrombocytes (Platelets) – They are colourless, rounded or oval, non-nucleated fragments of the cells.

• They help in blood clotting by promoting blood clotting mechanisms.


• These are formed in the bone marrow.

Lymph

It is a mobile connective tissue made up of plasma and lymph corpuscles. Lymph plasma is similar to that of blood but has fewer
blood proteins, less calcium and phosphorus and high glucose concentration. Main proteins are globulins which are actually
antibodies. Lymph corpuscles are floating amoeboid cells, mostly lymphocyte. RBCs and platelets are absent in lymph.

Functions of Connective Tissue

Attachment Storage Transport Defence and scavenging Shock-proof cushions Formation of blood corpuscles Packing material

New MCQs

1. Match the column I with column II and select the correct
   option.
   Column I Column II
   Type of leucocyte Shape of nucleus
   A. Lymphocytes (i) Two lobed nucleus
   B. Monocytes (ii) Three lobed nucleus
   C. Eosinophils (iii) Many lobed nucleus
   D. Basophils (iv) Large rounded nucleus
   E. Neutrophils (v) Bean-shaped nucleus
   (a) A-(iv); B-(v); C-(ii); D-(i); E-(iii)
   (b) A-(v); B-(ii); C-(v); D-(iii); E-(i)
   (c) A-(iv); B-(v); C-(i); D-(ii); E-(iii)
   (d) A-(v); B-(iv); C-(iii); D-(i); E-(ii)
   2. An example of holocrine glands is
   (a) mammary glands (b) sebaceous glands
   (c) salivary glands (d) goblet cells.
   3. A epithelium is present in the alveoli of lungs, B epithelium
   is present in pancreatic ducts, C epithelium is present in bile
   duct.
   A B C
   (a) Simple cuboidal Simple squamous Simple columnar
   (b) Simple columnar Simple cuboidal Simple squamous
   (c) Simple squamous Simple cuboidal Simple columnar
   (d) Simple squamous Simple columnar Simple cuboidal
   4. Type of junctions which have intercellular proteins are
   (a) tight junctions (b) gap junctions
   (c) interdigitations (d) desmosomes.
   5. Which of the following statements about spongy bone is
   incorrect?