T Lymphocytes and Cell-mediated Immunity Flashcards Preview

Biology-5-Cell Recognition and The Immune System > T Lymphocytes and Cell-mediated Immunity > Flashcards

Flashcards in T Lymphocytes and Cell-mediated Immunity Deck (12):
1

What do antigens stimulate

An immune response as it’s recognised as foreign (non self)

2

What does the presence of an antigen trigger

The production of an antibody

3

Where are lymphocytes produced

By stem cells in the bone marrow

4

Why are t lymphocytes called that? What are they associated with ?

Because they mature in the thymus gland


With cell mediated immunity that is immunity involving body cells

5

Why are b lymphocytes called that? What are they associated with ?

Because they mature in the bone marrow

With humoral immunity, immunity involving antibodies that are present in body fluids or humour such as plasma

6

How can t lymphocytes distinguish these invader cells from normal cells

Because :

Phagocytes that have engulfed and hydrolysed a pathogen present some of a pathogens antigens on their own cell surface membrane

Body cells invaded by a virus present some of the viral antigens on their own cell surface membrane

Transplanted cells from individuals of the same species have different antigens on their cell surface membrane

Cancer cells are different from normal body cells and present antigens on their cell surface membrane

7

What is cell mediated immunity

T lymphocytes will only respond to antigens that are presented on a body cell rather than to antigens within the body fluids

8

How do T lymphocytes respond to infection by a pathogen

Pathogens invade body cells or are taken by phagocytes

The phagocyte places antigens from the pathogen on its cell surface membrane

Receptors on a specific helper T cell fit exactly to these antigens

This attachment activates the T cells to divide rapidly by mitosis and form a clone of genetically identical cells

The cloned T cells:

Develop into memory cells that enable a rapid response to future infections by the same pathogen

Stimulate phagocytes to engulf pathogens by phagocytosis

Stimulate B cells to divide and secrete their antibody

Activate cytotoxic T cells

9

What do B memory cells do

Remain in blood so if there is a second exposure to the pathogen the immune response is more rapid

10

How do T killer cells destroy cells ( cytotoxic)

Release perforin which punctures holes in the pathogen cell membrane causing the pathogen to die, cell contents come out and change in water potential

11

Why are T killer cells so effective in viruses

As viruses use living cells in which to replicate, this sacrifice of body cells prevents viruses multiplying and infecting more cells

12

State 2 similarities and 2 differences between B and T cells

Both are types of white blood cells
Both produced from stem cells

T cells mature in thymus gland while B cells mature in bone marrow

T cells are involved in cell mediated immunity while B cells are involved in humoral immunity