The Specific Immune System

Question 1

What are the two types of specific immune system?

Answer 1

Cell-mediated response

humoral or antibody-mediated response

Question 2

What is the cell mediated response?

Answer 2

the cellular or cell-mediated
response involves highly-specialized cells that target pathogens inside cells. (Virus)

Question 3

What is the antibody-mediated response?

Answer 3

the humoral or antibody-mediated response targets pathogens in body fluids with antibodies.

Question 4

What are antigens

Answer 4

They are specialised glycolipids and glycoproteins on the surface of cells used by the bodies’ cells to recognise a cell as ‘self’ or ‘foreign’.

Question 5

What is the structure of an antibody like?

Answer 5

They have two light chains and two heavy chains.

These are split into the variable region which is different on each antibody, and the constant region which is the same on each antibody.

They also contain (two) antigen binding sites

Question 6

How do antibodies work?

Answer 6

Directly attack pathogens

Aggltunins

Opsonins

Antitoxins

Question 7

What is Agglutination

Answer 7

It is where one antibody binds to two pathogens, causing them to clump together

This makes pathogens more easily engulfed by phagocytosis

Question 8

What is Neutralization?

Answer 8

Antibodies can act as antitoxins, binding with toxins produced by pathogens. This makes them harmless

Question 9

What are lymphocytes?

Answer 9

Lymphocytes are a type of white blood cell (leukocyte) found in the blood and lymph nodes.

Question 10

What are the two types of lymphocytes?

Answer 10

B Lymphocytes – formed in bone marrow

T lymphocytes – form in the thymus

Question 11

What are T helper cells

Answer 11

These cells produce interleukins, a type of cytokine. This stimulates B cell and antibody production, and attracts other T cells and antibodies.

Question 12

What are T killer cells?

Answer 12

These kill pathogens by producing a chemical called perforin, which makes holes in pathogens cell plasma membranes. They may also produce hydogen peroxide.

Question 13

What are T memory cells?

Answer 13

These act as the immunological memory, as they remain in the blood for long periods of time. When a second infection occurs, they divide rapidly to form many killer T cells.

Question 14

What are T regulator cells?

Answer 14

These prevent an autoimmune response by repressing the immune system after the all the pathogens have been destroyed.

Question 15

What are Plasma cells?

Answer 15

These produce specific antibodies to an invading antigen. These only live for a few days but produce up to 2000 antibodies per second when active.

Question 16

What are B effector cells?

Answer 16

these divide to form plasma cell clones.

Question 17

What are B memory cells?

Answer 17

These remain in the blood for long periods of time, providing immunological memory. If infection occurs these reproduce rapidly and produce the same specific antigen.

Question 18

What is a cytokine

Answer 18

A messenger molecule.

Question 19

What is CD4 and where is it found?

Answer 19

CD4 is a surface receptor and is activated on t helper cells

Question 20

What is an autoimmune disease?

Answer 20

It is where the immune system stops recognizing ‘self’ antigens and attacks healthy body cells.

Question 21

What are the steps for cell mediated immunity?

Answer 21

Macrophages engulf and digest pathogens by phagocytosis. They present the antigens on the
surface (become antigen-presenting cells)

Specific T helper cell with receptor that fits the antigen on the macrophage will bind. The T helper cell will produce interleukins which stimulate more T cell to be produced

Cloned T cells may become, more T helper cells (to produce more interleukins), Killer T cells, or T Memory cells to destroy infected pathogens

Question 22

What are the steps within Humoral Immunity

Answer 22

Antigen Presentation: B-lymphocytes have membrane-bound antibodies specific to one antigen. A B-cell binds to a complementary pathogen antigen and engulfs it via endocytosis, presenting the antigen on its surface (Antigen-Presenting Cell - APC).

T-Helper Cell Activation: An activated T-helper cell, recognizing the specific antigen presented, binds to the B-cell.

Clonal Selection and Activation: The T-helper cell releases interleukins (cytokines), which activate the specific B-cell.

Clonal Expansion and Differentiation: The activated B-cell undergoes rapid mitotic division (clonal expansion) to produce a clone of identical B-cells. These differentiate into:

Plasma Cells: Short-lived cells that secrete large quantities of antibodies specific to the antigen.

Memory B-Cells: Long-lived cells that remain in circulation for a faster secondary response if re-infected.

Antibody Action: Antibodies destroy pathogens through agglutination (clumping), opsonisation (marking for phagocytes), and neutralisation of toxins

Question 23

What is an example of natural active immunity

Answer 23

catching the disease

Question 24

What is an example of natural passive immunity

Answer 24

Breastfeeding

Question 25

What is an example of artificial active immunity

Answer 25

Vaccines

Question 26

What is an example of artificial passive immunity

Answer 26

immunoglobulin injection

Question 27

What differs cell mediated response and the humoral response

Answer 27

The key differences lie in the key players (T cells vs. B cells), the mechanism of action (cell killing vs. antibody production), and the types of threats they defend against (intracellular vs. extracellular pathogen

Question 28

How does a macrophage become an APC

Answer 28

A B-cell is triggered when it encounters its matching antigen The B-cell engulfs the antigen and digests it Then the B-cell displays antigen fragments bound to its unique MHC molecules This combination of antigen and MHC attracts the help of a mature matching T-cell