Cell recognition and the immune system

Question 1

types of cells that can stimulate the immune system

Answer 1

-pathogens
-cells from other organisms of the same species
-abnormal body cells
-toxins

Question 2

describe the process of phagocytosis

Answer 2

-antigens binds to specific receptors on the cell surface of the phagocytes

-phagocyte engulfs the pathogen

• phagocytes becomes a phagosome

-lysosome fuses with the phagosome and releases lysozome enzymes hydrolyse the molecule and breaks down the pathogen.

• the pathogen antigens are transported to the phagocyte cell membrane and presented on the cell surface

-antigen-presenting phagocyte is formed

Question 3

define antigen

Answer 3

-foreign protein
-stimulate immune response e.g: antibodies

Question 4

define antibody

Answer 4

-protein
-produced by B-lymphocytes

Question 5

state the difference between the non-specific defence mechanism with the specific defence mechanism

Answer 5

-non-specific defence mechanism : immediate response , same for all pathogens

-specific defence mechanism: slower response, specific to each antigen on pathogens

Question 6

what are the examples of non-specific defence mechanism

Answer 6

physical barrier: e.g : skin, platelets, hydrochloric acid in stomach,epithelia covered in the mucus and moved by the cilia…

phagocytosis

Question 7

what are the examples of specific defence mechanism

Answer 7

-cell mediated response: T lymphocytes
humoral response : B lymphocytes

Question 8

where are B and T lymphocytes formed from

Answer 8

stem cells in the bone marrow

Question 9

what are B lymphocytes associated with

Answer 9

-humoral immunity ( immunity involving antibodies that are present in the body’s fluid

Question 10

what are T-lymphocytes associated with

Answer 10

-cell- mediated immunity ( immunity involving body cells

Question 11

The response of T lymphocytes to a foreign antigen (the cellular response).

Answer 11

-the antigen-presenting phagocytes now have a complementary shape that fits exactly on the receptors of helper T-cells

-this activates a rapid cell division by mitosis to form many cloned helper T-cells.

-cloned helper T-cells differentiate into different cells by:

1) stimulating / activating killer T-cells (or cytotoxic T-cells) that produce perforin that makes holes in the cell-surface membrane so it becomes freely permeable to all substances, so the cell dies

2) stimulating / activating phagocytes to perform more phagocytosis

3) stimulating / activating B-lymphocytes to clone and secrete antibodies

4) some remain as T-helper cells

5) some develop into memory T-cells for that shaped antigen

Question 12

there are ____A___ different B-cells that are complementary to ____B__ different antigens so the antibodies act as receptors to the antigens

Answer 12

A) 10 million
B) 10 million