A&P2 Exam2 Ch16.5

These flashcards cover key terms and concepts related to the lymphatic system and immunity as discussed in the lecture notes.

Adaptive (Specific Defenses)

The immune response that specifically targets pathogens after they have entered the body.

First line of defense

Mechanical barriers such as skin and mucous membranes that prevent pathogen entry.

Second line of defense

Includes chemical barriers, natural killer cells, inflammation, phagocytosis, and fever.

cellular and humoral immune responses

What is the Third line of defense? (2)

Antigens

receptors on the surface of lymphocytes enabling cells to recognize non-self antigens

1. proteins

2. polysaccharides

3. glycoproteins

4. glycolipids

What can antigens be? (4)

large and complex molecules

What are the traits of the most effective antigens? (2)

Haptens

Small molecules that are not antigenic by themselves but can provoke an immune response when attached to a larger molecule.

1. stem cells in red bone marrow give rise to lymphocyte precursors

2. some lymphocyte precursors are processed in the thymus to become T cells

3. some lymphocyte precursors are processed within the bone marrow to become B cells

4. Both T cells and B cells are transported through the blood to lymphatic organs, such as the lymph nodes and spleen`

What are the 4 steps of lymphocyte origination?

T lymphocytes (T cells)

70%-80% of circulating Lymphocytes that are specialized in the thymus and become either helper or cytotoxic T cells

B lymphocytes (B cells)

20% - 30% of circulating Lymphocytes that develop in the bone marrow

cellular immune response (responds to infected cells)

What is the primary function of T cells?

humoral immune response (interacts directly w/ pathogen)

What is the primary function of B cells?

presence of processed fragments of antigen attached to surface of an antigen-processing cell

What is required for T-cell activation?

major histocompatibility complex (MHC) antigens

antigens that help T-cells recognize an antigen is foreign

class 1 MHC antigens

class of MHC antigens that are within the cell membrane of all body cells except RBCs

class 2 MHC antigens

class of MHC antigens that are located on surfaces of antigen-presenting cells, thymus cells, and activated T-cells

Helper T cells

A type of T cell that activates other immune cells by secreting cytokines; stimulate B cells to produce antibodies and stimulate activity of cytotoxic T cells; any harm to them destroys immunity

When its antigen receptor combines with displayed foreign antigens

When do helper T cells become activated?

Cytotoxic T cells

T cells that attack and destroy infected or cancerous cells directly

perforin

What do cytotoxic T cells secrete?

1. macrophage phagocytizes antigen-bearing agent

2. macrophage digests antigen-bearing agent

3. macrophage displays antigen on its surface

4. Cytotoxic & helper T cells contact displayed antigen (helper T cell also contacts proliferates)

5. activated helper T cell interacts with B cell and cytotoxic T cell and releases their chemicals to activate the other of the same kinds

6. Proliferation and differentiation'

7. B cell combines with antigen

8. Activated B cell

What are the steps of the T cells in the cellular immune response? (8)

colony-stimulating factors

cytokine secreted by T cells to produce lymphocytes

Interleukins (IL-1 & IL-2)

cytokine secreted by T cells to control lymphocyte differentiation and proliferation

tumor necrosis factor

cytokine secreted by T cells to stop tumor growth, release growth factors, causing fever that accompanies bacterial infection, stimulates lymphocyte differentiation

interferons

cytokine secreted by T cells to block viral replication, stimulate macrophages to engulf viruses, stimulate B cells to produce antibodies, attack cancer cells

Memory T cells

T cells that provide future immune protection

Regulatory T cells

T cells that suppress immune responses after defeat of pathogens, which lowers chance of developing an autoimmune diseaseand maintain immune homeostasis.

T cell “help”

What do most antigens require to activate B cells?

memory cells and plasma cells

What are the 2 types of cells that B cells can differentiate into?

plasma cells

cells that produce and secrete antibodies for the humoral immune response

polyclonal response

immune response can have several types of antibodies created against a single microbe or virus

1. antigen-bearing agents enter tissues

2. B cell encounters an antigen that fits its antigen receptors

3. Either alone or more often in conjunction with helper T cells, the B cell is activated, The B cell proliferates, enlarging its clone

4. some of the newly formed B cells differentiate further to become plasma cells

5. plasma cells synthesize and secrete antibodies whose molecular structure is similar to the activated B cell’s antigen receptors

B cell steps (5)

1. antigen-bearing agents enter tissues

2. an antigen-presenting cell, such as a macrophage, phagocytizes the antigen-bearing agent, and the macrophage’s lysosomes digest the agent

3. antigens from the digested antigen-bearing agents are displayed on the membrane of the antigen-presenting cell

4. helper T cell becomes activated when it encounters a displayed antigen that fits its antigen receptors

5. activated helper T cell releases cytokines when it encounters a B cell that has previously combined with an identical antigen-bearing agent

6. cytokines stimulate the B cell to proliferate, enlarging its clone

7. some of the newly formed B cells give rise to cells that differentiate into antibody-secreting plasma cells

T cell steps (7)

antibody molecules

soluble, globular proteins; 4 chains of amino acids linked by disulfide bones (Y shaped structure); 2 light chains & 2 heavy chains; end of chains are variable regions (react w/ shape of specific antigen

IgG

The most common type of antibody, accounting for 80% of the total; targets bacteria and viruses, toxins

IgA

Found in exocrine gland secretions, accounts for 13% of total antibodies.

IgM

acts on antigens in foods and bacteria, accounts for 6% of total antibodies.

IgE

found in exocrine gland secretions, accounts for less than 1% of total antibodies.

agglutination, precipitation, neutralization

What 3 effects do the antibody action of direct attack have?

agglutination

antigens clump

precipitation

antigens become insoluble

neutralization

antigens lose toxic properties

opsonization, chemotaxis, agglutination, lysis, neutralization

What 5 effects does the activation of complement antibody action have?

opsonization

alters antigen cell membranes so cells are more susceptible to phagocytosis

chemotaxis

attracts macrophages and neutrophils into the region

lysis

allows rapid movement of water and ions into the foreign cell causing osmotic rupture of the foreign cell

inflammation

What effect does localized changes of antibody action have?

inflammation

helps prevent the spread of antigens

primary immune response

immune response where detectable levels of antibodies appear 5-10 days following exposure; production and release of antibodies continues for several weeks

secondary immune response

antibodies may be produced within a day or two of exposure

Naturally acquired active immunity

Immunity obtained through exposure to live pathogens; stimulates an immune response with symptoms of a disease

Artificially acquired active immunity

Immunity gained through vaccines containing weakened or dead pathogens; stimulates an immune response without symptoms

Naturally acquired passive immunity

Immunity provided to a fetus through maternal antibodies or breast milk; short-term immunity for newborn without stimulating immune response

Artificially acquired passive immunity

Short-term immunity gained through antibody or antitoxin injections; no immune response stimulated

Hypersensitivity reactions

Exaggerated immune responses to nonharmful antigen

Type I hypersensitivity

Immediate reactions, often involving overproduction of IgE antibodies; example: hay fever.

Type II hypersensitivity

Antibody-dependant cytotoxic reaction that leads to phagoctosis and complement-mediated lysis of antigen; example: mismatched blood transfusion.

Type III hypersensitivity

immune complexe reaction; phagocytosis and lysis cannot clear antigen-antibody complexes; example: autoimmunity.

Type IV hypersensitivity

Delayed-reactions; T cells & macrophages release chemical factors into the skin; example: dermatitis.

1. initial B cell contact with allergen

2. plasma cell secretes antibodies

3. antibodies attach to mast cell

4. subsequent contact with allergen

5. mast cell releases allergy mediators

What are the immediate reaction allergy steps? (5)

Transplantation

The process of transferring tissues or organs from one body to another.

Tissue rejection reaction

When the recipient's immune system attacks transplanted tissue.

Graft-versus-host disease (GVHD)

transplanted tissue may produce substances that harm recipient’s tissues.

Isograft

A graft taken from an identical twin.

Autograft

A graft taken from the same individual.

Allograft

A graft taken from a donor of the same species.

Xenograft

A graft taken from a different species.

Autoimmunity

An immune response against the body's own tissues.

a virus that breaks down immune system function; may stay silent for years then produce to AIDs, the infections begin; helper T cell #s decline, B cells can’t produce antibodies; later cytotoxic T cells are also affected; person dies from loss of immune response against pathogens

What are 5 main points about HIV/AIDS (clinical application)

sexual contact, contaminated needles, birth or milk from infected mother, receiving infected blood or tissues form donor

How can HIV be transmitted? (4)