Chapter 32 And 33

Question 1

Immune system function

Answer 1

The Immune System and the Lymphatic System work hand-in-hand. Specifically, the Immune System:
protects the body from pathogens
is made up of the Lymphatic System, specialized cells, and ‘free-floating’ molecules

Question 2

Immune system defence

Answer 2

The immune system continuously monitors the body for ‘invaders’ and is ready to spring into action when necessary

Question 3

Antigens

Answer 3

Antigens are unique identifying molecules recognized by the immune system. There are two main types:

Question 4

Self antigens

Answer 4

on the surface of cells that are unique to an individual (e.g. antigens on an individual’s red blood cells)

Question 5

Nonself antigens

Answer 5

On the surface of foreign cells (eg. Pathogens, organ transplants)

Question 6

Self antigens have

Answer 6

Self-tolerance: The immune system attacks abnormal or foreign cells but leaves the body’s own cells alone

Question 7

Non self antigens have ______ which is -________

Answer 7

Immunocompetence: the ability of the immune system to activate an effective response to a nonself antigen

Question 8

Innate (non-specific) immunity

Answer 8

always present and ‘in place’
general defense against ‘nonself’ antigens
quick, initial response

Question 9

Adaptive (specific) immunity

Answer 9

develops through exposure to ‘nonself’ antigens
response is specific, that is, unique to particular antigens
slower, developed response (especially if it is the body’s first exposure to the antigen)

Question 10

Innate immunity and adpative immunity are

Answer 10

complementary strategies that work together to defend the body against ‘invaders’ of all types.

Question 11

Examples of innate cells

Answer 11

Epithelial barrier cells (skin, mucosa)
Phagocytic cells
Neutrophils (most numerous  pus)
Monocytes
become large phagocytes = macrophages
Macrophages
Kupffer’s cells (liver)
Dust cells (lung)
Natural Killer (NK cells)  apoptosis (see Figure in Textbook)

Question 12

Example of adaptive cells

Answer 12

Lymphocytes
B-cells
T-cells

Question 13

Substances that contribute to immune response

Answer 13

Cytokines
Complement
Antibodies
Interferon

Question 14

Cytokines

Answer 14

Chemicals released from cells to trigger or regulate immune responses
Examples include: interleukins (ILs), leukotrines, interferons (IFNs

Question 15

Complement

Answer 15

A group of about 20 inactive enzymes (plasma proteins)
Produce a domino effect of reactions  formation of a membrane attack complex (MAC)
End results is lysis of ‘foreign’ cell

Question 16

Antibodies

Answer 16

a plasma protein made by B-lymphocytes (B cells) to destroy or inactive antigens

Question 17

Interferon

Answer 17

a protein made by certain cells when they are invaded by a virus
interferes with virus replication

Question 18

First line of defense

Answer 18

Innate

Skin/secretions
Mucosa
Tears, saliva, HCL

Question 19

Second line of defence

Answer 19

Innate

Inflammation (heat, redness, swelling)

Phagocytosis

Question 20

Third line of defence

Answer 20

Adaptive
Phagocytes
Specific immune response
Natural killer cells

Question 21

Inflamatory response

Answer 21

A generalized response to pathogens that are causing tissue damage (signs = heat, redness, pain, swelling; fever)
Triggers release of immune factors from immune system cells
attracts WBCs
causes increased blood flow (site becomes warm and reddened) and increased vascular permeability (site swells with associated discomfort)
These changes help phagocytic WBCs reach the site and enter the affected tissue (See Figure in Textbook

Question 22

Adaptive/specific immunity

Answer 22

Protection against invaders due to the ability of the body to recognize, respond to, and remember specific harmful substances or bacteria – aka nonself antigens.

Third line of defense
Antigen-specific ‘customized’ response
Response is systemic (not restricted to initial area of ‘invasion’)
Has memory - if the body is ever exposed to the same antigen, the immune response will be even stronger than it was to previous exposures
Involves B-lymphocytes (B cells) & T-lymphocytes (T cells

Question 23

B and T cells

Answer 23

Both originate from immature hematopoietic cells in the red bone marrow
Once formed, both circulate to lymph nodes and spleen
T cells make a ‘pit-stop’ in the thymus as part of their development
Both become activated by exposure to antigens/chemical signals; however, they have very different immune mechanisms once activated!

Question 24

B cell development

Answer 24

Activated B cells undergo repeated and rapid mitosis to form two different ‘cloned’ populations of cells:

Plasma cells - secrete antibodies into blood to form an ‘army’ of protection against an antigen (up to 2,000 antibody molecules per second!)
Memory cells - are stored in lymph nodes as an ‘emergency supply’ and then if subsequent exposure to the same antigen occurs, memory cells quickly become plasma cells and secrete antibodies

Question 25

B cells

Answer 25

B cells Do not directly attack antigens Launch attack by making antibodies that either: attack antigens; or direct other cells to attack antigens Referred to as: Antibody-mediated immunity; or Humoral immunity

Question 26

Antibodies

Answer 26

Are types of immunoglobulins (Igs) G, A, M, E, D (see Figure in Textbook) IgG – most abundant circulating Ig (makes up 75% of all antibodies in the blood) IgM –immature B-cells make it and insert it into their plasma membrane; most predominant one made after initial antigen contact Protein compounds with specific combining sites Combining sites attach antibodies to specific antigens, forming an antigen–antibody complex Inactivation of antigens in this way is called humoral or antibody-mediated

Question 27

Antibodies aka

Answer 27

Immunoglobins or lgs

Question 28

Antigen

Answer 28

``` Antigen–antibody complexes have various modes of action. They may: Neutralize toxins Clump or agglutinate enemy cells Promote phagocytosis Complement fixation ```

Question 29

Complement fixation

Answer 29

A group of about 20 inactive enzymes (plasma proteins) Complement fixation Important mechanism of action for antibodies Causes cell lysis by permitting entry of sodium and then water through ‘holes’ (MACs = membrane attack complexes) created in the plasma membrane by complement molecules  cell bursts due to an increase in internal osmotic pressure (cytolysis

Question 30

T cells

Answer 30

Like B cells, T cells must be activated by an antigen; however note that T cells: Don’t make antibodies React to cells that are already infected or have engulfed antigen Can only react to protein fragments on the surface of APCs or infected cells (recall antibodies made by B plasma cells can react to soluble antigens in blood plasma) Carry out cell-to-cell ‘direct contact’ combat by: Killing APCs or infected cells by ‘poisoning’ them Releasing chemicals that attract and activate macrophages to destroy APCs and infected cells by phagocytosis Referred to as: cell-mediated immunity or cellular immunity

Question 31

T cell development

Answer 31

Similar to a B cell, once a T cell is activated by/sensitized to an antigen, it forms two types of cloned populations of the original T-cell: Effector T cells Memory T cells

Question 32

Memory T cells

Answer 32

Remain in red bone marrow until needed Produce more active T cells if necessary

Question 33

Effector T cells

Answer 33

Use ‘contact’ to kill APCs/infected cells Release cytokines to orchestrate killing of APCs/infected cells, e.g. Interleukins (ILs) are a class of cytokines involved in a wide variety of immune functions in different cell types Lymphotoxins are powerful poisons that act more directly, quickly killing any cell it attacks

Question 34

Cytotoxic T cells

Answer 34

aka ‘killer T cells’ Release lymphotoxins Cause contact killing of a target cell (APC or infected cell)

Question 35

Helper T cells and suppressor T cells

Answer 35

Help to regulate adaptive immunity by regulating B and T cells

Question 36

Helper T cells

Answer 36

Secrete cytokines that stimulate B cells and cytotoxic T cells as well as phagocytes and other leukocytes Activated TH form cloned populations of TH cells & memory TH cells

Question 37

Suppressor T cells

Answer 37

aka or Regulator cells (T-regs) Suppress B cell differentiation into plasma cells (allows fine tuning of antibody-mediated response) Regulate other T cells, including reducing T-cell reactions to self-antigens ( self-tolerance  autoimmune diseases, organ transplants)

Question 38

Humoral immunity

Answer 38

Immunity conferred by the action of antibodies | Activated B cells  plasma cells and memory cells

Question 39

Cell- mediated immunity

Answer 39

Immunity conferred by the action of cells Activated/Sensitized T cells kill APCs and infected cells directly by: releasing toxins that kill APCs/infected cells Releasing cytokines to attract and activate macrophages to kill APCs/infected cells by phagocytosis

Question 40

Natural immuity

Answer 40

Exposure to pathogen is not deliberate

Question 41

Artificial/ acquired immunity

Answer 41

Exposure to pathogen is deliberate

Question 42

There are both _____ and _____ forms of natrual and artificial immunity

Answer 42

Active and passive

Question 43

Natural immunity

Answer 43

Inherited immunity to certain diseases from birth Exposure to pathogen is not deliberate Can be active or passive Active – active disease promotes immunity (production of antibodies) Passive – mother passes immunity (antibodies) to fetus through placenta or breast milk

Question 44

Artificial/ acquired immunity

Answer 44

Exposure to pathogen is deliberate (immunization) Can be active or passive Active – vaccination ‘stimulates’ antibody production leading to immunity (typically longer lasting) Passive – immune ‘material’ (antibodies) developed in another individual is given to a non-immune person via an injection (typically shorter lasting)