The Immune System

Question 1

Nonspecific: First Line of Defense

Answer 1

A barrier that helps prevent pathogens from entering the body. These include; skin, mucous membranes which release mucus with antimicrobial substances, cilia that sweep out mucus and stomach acid.

Question 2

Nonspecific: Second Line of Defense

Answer 2

Limit the spread of invaders in advance of specific immune responses. It includes inflammatory responses, phagocytes, complement, interferons and natural killer cells.

Question 3

Inflammatory Response

Answer 3

Histamine, released by basophils and mast cells in the connective tissue, trigger vasodilation which increases blood supply to the area and bring more phagocytes. Prostaglandins, chemokines and pyrogens also play a role.

Question 4

Vasodilation

Answer 4

enlargement of blood vessles

Question 5

Basophils

Answer 5

a type of circulating white blood cell

Question 6

Prostaglandins

Answer 6

promote blood flow during an inflammatory response

Question 7

Chemokines

Answer 7

secreted by blood vessel endothelium and monocytes attract phagocytes to the area

Question 8

Pyrogens

Answer 8

released by certain leukocytes; increase body temperature to speed up the immune system and make it more difficult for microbes to function

Question 9

Phagocytes

Answer 9

Ingest invading microbes. Neutrophils and monocytes move to the area in response to chemical attractions called chemotaxis. Neutrophils engulf microbes and die within a few days. Monocytes transform into macrophages, extend pseudopods and engulf huge numbers over a long period of time. They digest with a combination of lysozyme, superoxide anion and nitric oxide.

Question 10

Complement

Answer 10

A group of proteins that lead to the lysis of invading cells.

Question 11

Interferons

Answer 11

block against cell-to-cell viral infections

Question 12

Natural Killer Cells

Answer 12

destroy virus infected body cells or cancerous cells; they attack the cell membrane and cause it to lyse (burst) and die

Question 13

Specific: Third Line of Defense

Answer 13

Relies on B and T lymphocytes. They both originate in the bone marrow and once mature they circulate in blood, lymph and lymphatic tissue. Bothe recognize specific antigens.

Question 14

Antigens

Answer 14

substances that cause the production of antibodies

Question 15

B Lymphocytes

Answer 15

Mature in the bone marrow and produce a humoral response by producing antibodies. They become stimulated by T lymphocytes or be free viruses and bacterial toxins found in the blood.

Question 16

T Lymphocytes

Answer 16

Mature in the thyroid gland and produce a cell-mediate response. They are stimulated by body cells that have been infected and by antigen-presenting cells which display foreign substances on their surface cells. There are two types; cytotoxic T cells and helper T cells. Each responds to a different histocompatibility complex (MHC) molecule.

Question 17

Cytotoxic T Cells

Answer 17

Kill body cells infected with viruses or pathogens or cancer cells. Their antigen receptors bing to protein fragment by class I MHC molecules. After binding, a CD8 surface protein holds the cells together until the T is activated. Then, after activation it differentiates into plasma cells and memory cells. Activated ones kill cells by releasing perforin and infecting microbes are released to the blood and killed by antibodies.

Question 18

Perforin

Answer 18

Released by active cytotoxic T cells; forms pores in the target cell’s membrane

Question 19

Helper T Cells

Answer 19

Announce to the immune system, with macrophages and B cells, that foreign antigens have entered the body. They bind to proteins displayed by Class II MHC molecules. After binding, CD4 holds the cells together until T is activated. After activation, it splits into memory and plasma cells. Helper cells stimulate other helpers, cytotoxic Ts and B cells by releasing cytokines, interleukin-1 and interleukin-2.

Question 20

Major Histocompatibility Complex Molecules

Answer 20

Human Leukocyte Antigen; collection of surface markers that identify the cell. No two people, except twins, have the same markers.

Question 21

Class I MHC Molecules

Answer 21

Found on almost all body cells.

Question 22

Class II MHC Molecules

Answer 22

Found on specialized cells such as macrophages, B cells and activated T cells.

Question 23

Clonal Selection

Answer 23

Mechanism in the development of immunity. Antigenic molecules bind to a B or T lymphocyte and after activation they proliferate into plasma or memory cells.

Question 24

Plasma Cells

Answer 24

Short-lived and fight the antigen immediately in what is called a primary immune response.

Question 25

Memory Cells

Answer 25

Long-lived cells that bear receptors specific to the same antigen as the plasma ells and remain circulating for a lifetime. If the body is attacked again by the same virus, memory cells rapidly reactivate. This is called the secondary immune response, is faster and greater magnitude than the primary one.

Question 26

Immunological Memory

Answer 26

The capacity of the immune system to generate a secondary immune response. It is the basis of vaccinations.

Question 27

How Macrophages Interact with the Immune System

Answer 27

A macrophage acts as an antigen-presenting cell engulfs a bacterium and present a fragment of it to the cell surface by an MHC molecule. A helper T cell is activated by binding to the MHC-antigen complex. The helper T cell proliferates and clones into copies with the same MHC-antigen combination. These clones secrete cytokines. Cytokines stimulate helper T cells, B cells and cytotoxic T cells.

Question 28

Antibodies: Structure

Answer 28

Globular proteins; Y shaped with two identical, heavy polypeptide chains and two identical, light polypeptide chains joined by disulfide bridges; it consists of four constant regions and four variable regions and the tip of the Y are the binding sites for different antigens

Question 29

Five Classes of Imunoglobins

Answer 29

IgM, IgA, IgD, IgE and IgG

Question 30

Antibodies: Function

Answer 30

Antibodies neutralize the antigen by causing them to clump and form an antigen-antibody complex. This complex is then, phagocytosed by macrophages. OR complement fixation occurs and activation of a complement lysis the cells.

Question 31

Antibody Variety

Answer 31

There is no viral disease for which humans cannot produce antibodies. Blueprints for antibodies are made early in life prior to exposure to antigenic agents.

Question 32

Passive Immunity

Answer 32

Temporary; antibodies are transferred to an individual from someone else

Question 33

Active Immunity

Answer 33

Permanent; An individual makes their own antibodies after immunization

Question 34

Blood Donations

Answer 34

If the recipient has antibodies to the donor’s antigens there is a certain danger.

Question 35

Cross-Match

Answer 35

The process by which a donor and recipient are mixed to determine compatibility.

Question 36

Universal Donor

Answer 36

Blood Type O; it has no blood cell antigens to be clumped by the recipient’s blood

Question 37

Universal Recipient

Answer 37

Blood Type AB; there are no antibodies to clump the donor’s blood

Question 38

RH Factor

Answer 38

Antigen located on the surface of red blood cells; 85% of the population is RH+

Question 39

Acquired Immune Deficiency Disorder

Answer 39

AIDS; Causes people to be highly susceptible to diseases, infections and cancers. The human immune deficiency virus causes AIDS and it attacks cells that bear CD4 molecules on their surface. HIV is a retrovirus.

Question 40

Positive Feedback in the Immune System

Answer 40

When helper T cells are activated by class II MHC molecules, it releases cytokines which stimulates more helper T cells as well as B cells and Cytotoxic T cells.

Question 41

Allergies

Answer 41

Hypersensitive responses to antigens. They involve the release of histamines which causes blood vessels to dilate.

Question 42

Anaphylactic Shock

Answer 42

An acute, allergic response that can results in death within minutes.

Question 43

Autoimmune Diseases

Answer 43

Immune systems that cannot distinguish between self and nonself. It perceives cell s in the body as nonself. Examples are lupus, arthritis and juvenile daibates

Question 44

Multiple Sclerosis

Answer 44

Autoimmune Disease: the immune system attacks the myelin sheath surrounding neurons in the CNS

Question 45

Monoclonal Antibodies

Answer 45

Antibody produced by a single B cell that have bee selected for a specific antigen. Important in research.