Biololgy 3.9

Question 1

Antigen

Answer 1

All harmful material that may induce an immune response. There are 3 lines of defence that protect the body against antigens: First line of defence (skin and mucous membranes), Second line of defence (innate immunity) and third line of defence (adaptive immunity)

Question 2

First line of defence (skin and mucous membranes)

Answer 2

• Skin: physical barrier, pH 3-5 due to oil secretions
• Antimicrobial proteins: lysozyme, breaks down bacteria cell walls, in saliva, sweat, tears
• Cilia: in lungs, sweep out harmful bacteria
• Gastric Juice: Acidic juice in stomach that kills microbes
• Symbiotic bacteria: In digestive tract and vagina, outcompete other bacteria that could be harmful

Question 3

Second line of defence (innate immunity)

Answer 3

Includes hormonal factors, interferons, pyrogens, interleukins, complement, inflammatory response, cellular components

Question 4

Hormonal factors

Answer 4

Part of second line of defence (innate immunity). Are dissolvable and transported in fluids

Question 5

Interferons

Answer 5

Part of second line of defence (innate immunity). Secreted by virus-infected cells to tell nearby cells to make virus fighting protein

Question 6

Pyrogens

Answer 6

Part of second line of defence (innate immunity). Released from bacteria, viruses or destroyed cells, raises body temperature

Question 7

Interleukins

Answer 7

Part of second line of defence (innate immunity). Cytokines that regulate inflammatory and immune responses, has anti-tumor properties.

Question 8

Complement

Answer 8

Part of second line of defence (innate immunity). Proteins that “complement” other defences, has 3 major functions.

1) Released in areas of injury to attract phagocytes to the site of interest
2) Forms a network that performs cell lysis on harmful cells
3) Opsonize (coat) bacteria for increased neutrophil action

Question 9

Inflammatory response

Answer 9

Part of second line of defence (innate immunity). Occurs in presence to a pathogen. Consists of histamine, vasodilation and phagocytes.

Question 10

Histamine

Answer 10

Part of inflammatory response in second line of defence (innate immunity). Released by basophils (WBCs) during inflammatory response, histamine increases permeability of capillaries to WBCs to allow them to engage pathogens in infected tissues.

Question 11

Vasodilation

Answer 11

Part of inflammatory response in second line of defence (innate immunity). Dilation of blood vessels in response to histamine, results in increased blood supply, allows WBCs to move easily access where they’re needed. Responsible for redness, swelling, increased temperature.

Question 12

Phagocytes

Answer 12

Part of inflammatory response in second line of defence (innate immunity). Engulfs pathogens via complement proteins. Complements leave chemical gradients, allow phagocytes to move to increasingly concentrated areas to infected area. Complements help engulf pathogens, stimulate release of histamine from basophils, and assist in cell lysis.

Question 13

Cellular Components

Answer 13

Part of second line of defence (innate immunity). Include phagocytic cells that engulf harmful particles via phagocytosis. Includes white blood cells (leukocytes), natural killer cells and dendritic cells

Question 14

White blood cells (leukocytes)

Answer 14

Part of cellular components of second line of defence (innate immunity). Derived from myeloid lineage of blood cells. Consists of neutrophil, eosinophil, basophil, macrophage

Question 15

Neutrophil

Answer 15

Part of white blood cells (leukocytes) which is part of cellular components of second line of defence (innate immunity). Are most abundant, deals with bacterial and fungal infections. Can die and unable to digest several microbes at once, becomes pus when dead

Question 16

Eosinophil

Answer 16

Part of white blood cells (leukocytes) which is part of cellular components of second line of defence (innate immunity). Deals with parasitic infections

Question 17

Basophil

Answer 17

Part of white blood cells (leukocytes) which is part of cellular components of second line of defence (innate immunity). Allergic and inflammatory response, releases histamine for vasodilation

Question 18

Macrophage

Answer 18

Part of white blood cells (leukocytes) which is part of cellular components of second line of defence (innate immunity). Matured form of monocyte, has TOLL-like receptors (TLR) that recognize PAMP (Pathogen associated molecular/membrane patterns) on bacterial surfaces, initiating bacterial phagocytosis

Question 19

Natural killer cells

Answer 19

Part of cellular components of second line of defence (innate immunity). Derived from lymphoid lineage cells, can kill “self” and “non-self” cells. All cells in body have major histocompatibility complex (MHC) class I molecules that turn off killing mechanism of natural killer (NK) cells. NK cell recognizes cancerous or virus-infected cells that lack MHC Class I

Question 20

Dendritic Cells

Answer 20

Part of cellular components of second line of defence (innate immunity). Have dendrites that interact with and phagocytose bacteria. Myeloid and lymphoid lines, link between innate and adaptive immunity

Question 21

Innate immune response

Answer 21

Consists of three steps:
1) Macrophage activity 
2) Neutrophil actiivity 
3) Dendritic cell activation
During this process, basophils become activated and secrete histamine to induce vasodilation, which also causes swelling, redness, heat and pain

Question 22

Macrophage activity

Answer 22

First part of innate immune immune response. Recognizes PAMPs on bacterial surfaces via their TLRs which activates phagocytosis, also produces macrophage derived neutrophil chemotactic factor (MDNF) which recruits neutrophils

Question 23

Neutrophil Activity

Answer 23

Second part of innate immune immune response. Phagocytose bacteria and causes them to undergo cell death producing pus composed of dead bacteria, neutrophil extracellular net (NET), and dead neutrophils. NET is processed chromatin bound to proteins, released by dying neutrophils to slow bacterial invasion

Question 24

Dendritic cell activation

Answer 24

Third part of innate immune immune response. Phagocytoses and digests bacteria, travels to lymph node where it activates the dendritic cell that links the innate and adaptive response

Question 25

Third line of defence (adaptive immunity)

Answer 25

Consists of activation of adaptive immunity, cell-mediated adaptive immunity and humoral adaptive immunity

Question 26

Activation of adaptive immunity

Answer 26

Part of third line of defence (adaptive immunity). Involves immune cells mounting an antigen-specific response, this occurs when B or T cells interact with antigens via MHC Class I or II molecules. The dendritic cell phagocytose bacteria and digest it into smaller peptides, also makes MHC II and travels to the regional lymph node where it activates B or T lymphocytes

Question 27

Major Histocompatibility Complex Molecules

Answer 27

Part of activation of adaptive immunity of third line of defence (adaptive immunity). They are antigen presenting molecules, called HLA in humans. - MHC Class I: On all normal cells, lack of MHC I on "self" cells indicate cancerous or viral infected - MHC Class II: On antigen presenting cells (dendritic cell, macrophage, B cell), main method of activating adaptive immune cell

Question 28

Cell-mediated adaptive immunity

Answer 28

Part of third line of defence (adaptive immunity). Is mediated by the T lymphocyte that originates in bone marrow and matures in the thymus before distributing in lymph nodes. Consists of T cell development, T cell activation and T cell types

Question 29

T cell development

Answer 29

Part of cell-mediated adaptive immunity of third line of defence (adaptive immunity). Body has many T cells with different specific epitome, an antigen receptor specific to one polypeptide sequence. T cells collectively recognize many "non-self" epitopes

Question 30

T cell activation

Answer 30

Part of cell-mediated adaptive immunity of third line of defence (adaptive immunity). At lymph node, dendritic cell finds a T cell carrying a receptor that is specific to the antigen the DC is presenting. Activates T cell in process called clonal selection that causes the specific T-cell to proliferate and make many clones that can identify and eliminate the specific invader.

Question 31

T cell types

Answer 31

Part of cell-mediated adaptive immunity of third line of defence (adaptive immunity). Consists of Helper T cells, Cytotoxic/killer T cells and regulatory T cells

Question 32

Helper T cells

Answer 32

Part of T cell types which is part of cell-mediated adaptive immunity of third line of defence (adaptive immunity). Stimulate proliferation of cytotoxic T and B cells via interleukins. Bind to macrophages that have engulfed pathogens, marking them for destruction

Question 33

Cytotoxic/killer T cells

Answer 33

Part of T cell types which is part of cell-mediated adaptive immunity of third line of defence (adaptive immunity). Recognize and puncture antigens or infected cells presenting antigen via MHC I molecules

Question 34

Regulatory T cells

Answer 34

Part of T cell types which is part of cell-mediated adaptive immunity of third line of defence (adaptive immunity). Down regulates immune response to prevent autoimmunity

Question 35

Hormonal adaptive immunity

Answer 35

Part of third line of defence (adaptive immunity). Is mediated by B lymphocyte that originates and matures in the bone marrow before distribution to lymph node. Consists of B cell development, immunoglobulins/antibodies, B cell activation and B cell types

Question 36

B cell development

Answer 36

Part of hormonal adaptive immunity of third line of defence (adaptive immunity). Can produce one type of receptor molecule that can only recognize one type of epitome, can recognize "self" molecules

Question 37

Immunoglobulins/antibodies

Answer 37

Part of hormonal adaptive immunity of third line of defence (adaptive immunity). Produced and secreted by B cells, can recognize the same epitome as their cell surface receptors which act as a "tag" to allow other components of immune system to destroy antigen or infected cell

Question 38

Antibody structure

Answer 38

2 identical heavy and 2 identical light chains connected with disulphide bonds. - Constant region: Same structure for antibodies in the same class and species, recognized by receptors - Variable region: Varies for each B cell, recognizes epitome (antigen)

Question 39

Antibody Activity

Answer 39

Complement proteins identify antibodies that have bound antigen, inducing cell lysis or activating phagocytosis cells

Question 40

B cell activation

Answer 40

Part of hormonal adaptive immunity of third line of defence (adaptive immunity). When antigen binds to B cell carrying the antigen-specific receptor, the antigen is processed for presentation via MHC II. B cell activated via clonal selection and can proliferate into plasma or memory B cells. For optimal activation, B cells must interact with T cells via MHC II and be stimulated buy interleukins released by activated T cells, causing B cell to make abundance of antibodies and proliferate into 2 daughter cell types

Question 41

B cells types

Answer 41

Part of hormonal adaptive immunity of third line of defence (adaptive immunity). Consists of two types: Plasma B cell and Memory B cell

Question 42

Plasma B cell

Answer 42

Part of B cell types which is part of hormonal adaptive immunity of third line of defence (adaptive immunity). Secretes antibodies to bloodstream, allows them to circulate and bind to antigens

Question 43

Memory B cell

Answer 43

Part of B cell types which is part of hormonal adaptive immunity of third line of defence (adaptive immunity). Remains in body even after identified antigen is cleared to provide body with memory in case of second encounter. Produced in abundance with help of vaccines providing the body with inactivated antigen

Question 44

Types of immunity

Answer 44

Active immunity and passive immunity

Question 45

Active immunity

Answer 45

Involves the 3 lines of immune defence, refers to the mounting of humoral and/or cell-mediated immunity upon first encounter with antigen

Question 46

Passive immunity

Answer 46

Transfer of antibodies from a previously infected individual to a newly infected individual ex. mother to newborns