Tag: immunity

White blood cells are an important part of the immune system. Lymphocytes are one of several different types of white blood cells. Lymphocytes are of two types B cells and T cells. When a macrophage engulfs bacteria B cells release antibodies which cause the destruction of bacteria. The T cells destroy the infectious bacteria by killing the body cells that are affected.

Lymphocytes are one of several different types of white blood cells. Lymphocytes are of two types B cells and T cells. When a macrophage engulfs organisms, B cells (humoral immunity) release antibodies which cause the destruction of bacteria. The T cells (cell-mediated immunity) destroy the infectious organisms by killing the body cells that are affected. Hence lymphocytes is a unit of the immune system.

The lymph fluid (P) inside the lymph nodes contains lymphocytes, a type of white blood cell, which continuously recirculates through the lymph nodes and the bloodstream. Molecules found on bacteria cell walls or chemical substances secreted from bacteria, called antigens, are taken up by antigen cells into the lymph system and then into lymph nodes. In response to the antigens, the lymphocytes in the lymph node make antibodies which will go out of the lymph node into circulation, target the pathogens producing the antigens by targeting them for destruction by other cells and complement.

The spleen acts to help keep the blood free of unwanted substances, including wastes and infecting organisms. The blood is delivered to it by the splenic artery and passes through smaller branch arteries into a network of channels lined with leukocytes, known as phagocytes. Red blood cells disintegrate in spleen. 

A) The statement is true as WBCs are called leukocytes because they are colorless and do not possess any pigments.

The blood cells are of three major types they are erythrocytes(RBC), leucocytes(WBC) and platelets. Two main categories of WBCs are granulocytes and agranulocytes. Neutrophils, eosinophils, and basophils are different types of granulocytes, while lymphocytes and monocytes are the agranulocytes.  Lymphocytes are of two major types – ‘B’ and ‘T’ forms. Both B and T lymphocytes are responsible for immune responses of the body.B lymphocytes are responsible for humoral immunity and T lymphocytes in cell-mediated immunity. Hence lymphocytes are not phagocytic.

Smallpox vaccine was introduced by Edward Jenner in 1798. He observed that milkmaids who had previously caught cowpox did not later catch smallpox by showing that inoculated cowpox protected against inoculated smallpox. Smallpox vaccine was the first successful vaccine.

Swine flu and polio can be prevented by giving vaccination at the right time. There are many more diseases which can be prevented by vaccines. Therefore, (c) is the correct answer.

Edward Jenner was an English physician and scientist who was the pioneer of smallpox vaccine, the world's first vaccine. He is often called the father of immunology. Heredity refers to the transfer of biological characteristics from a parent organism to offspring. DNA in the form of large molecules known as chromosomes which is the carrier of genetic instructions for the development and functioning of living organisms. Hydras generally reproduce asexually. They do this through budding.