The specific immune response

Question 1

Why is a specific immune response necessary in the body?

Answer 1

If the pathogen has not been dealt with by the non-specific immune responses then it becomes important that the pathogen has s response which is specifically targeted against it. This takes the form of antibodies which are made for the shape of the antigens on the pathogen

Question 2

Where are lymphocytes found?

Answer 2

In the lymphatic system as well as the blood stream

Question 3

Where are T lymphocytes made and where do they mature?

Answer 3

-made in the bone marrow
-mature in the thymus gland

Question 4

What are T lymphocytes involved in?

Answer 4

Cell-mediated immunity

Question 5

Where are B lymphocytes made and where do they mature?

Answer 5

Made and mature in the bone marrow

Question 6

What are B lymphocytes involved in?

Answer 6

They make the antibodies and are involved in humoral immunity

Question 7

What does the maturation process involve for both the T lymphocytes and the B lymphocytes?

Answer 7

-the development of the glycoprotein structures on the outside surface membrane
-T cells= receptors
-B cells= antibodies

Question 8

What are the two different classes which T lymphocytes differentiate into in the thymus gland?

Answer 8

-T helper cells
-T killer cells

Question 9

What are T cells known as before they encounter the antigen to which they are complementary?

Answer 9

Naive

Question 10

What is the third and fourth class of T lymphocyte?

Answer 10

T memory cells
T regulatory cells

Question 11

What are the functions of the T helper cells?

Answer 11

-they have CD4 receptors on their plasma membranes which bind to the surface of the antigens of APCs
-they are activated by the cytokine Interleukin 1 (IL-1) produced by the APC
-IL-1 causes T helper cells to undergo mitosis to produce more T helper cells
-T helper cells produce the cytokine Interleukin 2 (IL-2)
-They differentiate T memory cells and T regulatory cells

Question 12

What does interleukin 2 do?

Answer 12

-activates B lymphocytes to bring about antibody production
-stimulate T killer cells
-Attracts and stimulates macrophages to ingest pathogens with antigen-antibody complexes

Question 13

What is the function of T killer cells?

Answer 13

-Destroy the pathogen carrying the antigen
-Produce a chemical called Perforin
-Perforin makes holes in the plasma membrane of the pathogen
-Also kills cells which have been infected with a virus
-has CD8 receptors on its plasma membrane

Question 14

What is the function of T memory cells?

Answer 14

-they are long lived
-part of the immunological memory, which brings about a secondary response
-if an antigen is encountered for a second time these cells divide rapidly to form huge numbers of clones of T killer cells

Question 15

What is the function of T regulatory cells?

Answer 15

-suppress the immune system
-once the pathogen has been eliminated these cells stop the immune response
-this prevents the autoimmune responses
-these are controlled by interleukins

Question 16

What is the cell mediated immunity response for T lymphocytes?

Answer 16

-T lymphocytes respond to processed antigens- they do not respond directly with the pathogen itself but any cell of the host organism which displays processed antigens can activate T cells

Question 17

Give examples of processed antigens which T lymphocytes will respond to.

Answer 17

-a macrophage which has done phagocytosis which is displaying the antigens on its plasma membrane
-a cell infected with a virus
- a cancer cell where a mutation has changed the cell
-a transplanted organ

Question 18

What does it mean when a T helper cell is naive?

Answer 18

These are T cells that have never been encountered with due to the many variations of shaped receptors on the plasma membrane.

Question 19

What is the process of clonal selection?

Answer 19

-When a T helper cell encounters an antigen which is being displayed by an antigen presenting cell, it will bind to it.
-these are specifically the T helper cell clones, with the specific shaped antigen-binding site, different from the others which are not a complementary fit

Question 20

What happens when the T helper cell has bound to the presented antigen on the APC?

Answer 20

The APC release a type of cytokine called interleukin 1 to activate it

Question 21

What is clonal expansion?

Answer 21

-When the T helper cell divides by mitosis to produce many T helper cells
-T memory and T regulatory cells are also made
-clonal= each of the daughter T helper cells have the same antigen specificity
-expansion= result is a much larger number of clones of this variation of T helper cells are made

Question 22

What is the humoral response for B lymphocytes?

Answer 22

-humor=body fluids
-humoral response takes part in blood plasma and tissue fluid, as the B cells attack pathogens found outside the cells

Question 23

Explain what B lymphocytes are covered with

Answer 23

-antibodies
-these are proteins (immunoglobulins) which binds to antigens to form an antigen-antibody complex
-there are many different versions of B cells, each with a different shaped antigen binding site which one will have a COMPLEMENTARY shape

Question 24

Explain how B cells can undergo clonal selection

Answer 24

Only the B lymphocytes with the specifically shaped antigen binding site on its antibody will be able to bind to the antigen

Question 25

What are the B cells activated by?

Answer 25

Cytokines, (interleukins) released by the T helper cells

Question 26

Explain how B cells can undergo clonal expansion

Answer 26

When the activated B lymphocyte then divides by mitosis into plasma cells and B memory cells

Question 27

What is a blood smear?

Answer 27

A sample of blood smeared over a microscope slide, and stains are added to the sample to make the different cells easy to see.

Question 28

What does identifying the numbers of different types of lymphocytes in a blood smear indicate?

Answer 28

If a non-specific or specific immune response is taking place

Question 29

What is a differential white blood cell count?

Answer 29

Where you count the different types of white blood cells seen in the sample

Question 30

What is a decrease in the number of leukocytes called?

Answer 30

Leukopenia

Question 31

What is an increase in the number of leukocytes called?

Answer 31

Leukocytosis

Question 32

How are antibodies produced?

Answer 32

Produced by plasma cells which are clones of the B lymphocyte, they have a binding site which is complementary to the antigen which caused the clonal selection and clonal expansion which led to the plasma cells being made

Question 33

What organelles do plasma cells have lots of due to the mass production of antibodies ?

Answer 33

Ribosomes, RER, golgi, secretory vesicles to enable a high rate of protein synthesis

Question 34

How are antigen-antibody complexes made and what is their function?

Answer 34

-When antibodies bind to the antigens on the surface of the pathogen
-this targets the pathogen for the phagocytes, and is when antibodies act as opsonins

Question 35

Describe and explain the structure of antibodies

Answer 35

-the variable region of the antibody forms the antigen binding site
-shape of variable is complementary to a particular antigen
-the variable region differs between antibodies from other B cells which are not complementary to the antigen
-hinge region which allows flexibility when the antibody binds to the antigen
-the constant region is the same in all antibodies= allows binding to receptors on immune system cells
-polypeptide chain of protein structure are held together by disulphide bonds

Question 36

What is the first role of antibodies in clearing infections?

Answer 36

1. Agglutinating pathogens
   -each antibody has 2 binding sites so can bind to two pathogens at the same time, so they become clumped together

Question 37

What is the second role of antibodies in clearing infections?

Answer 37

2. Neutralising toxins
   -Antibodies called anti toxins can bind to the toxins produced by pathogens. This prevents the toxins from affecting human cells, so the toxins are neutralised

Question 38

What is the third role of antibodies in clearing infections?

Answer 38

3. Preventing the pathogen binding to human cells
   -when antibodies bind to the antigens on pathogens, they make block the cell-surface receptors that the pathogen needs to bind to the host cell.