Immune system Flashcards

1
Q

Assaults on the body

A
  • external: microorganisms, protozoans, bacteria, and viruses
  • internal: include abnormal cells that reproduce and form tumors that may become cancerous and spread
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2
Q

Immune system organization

A
  1. Antigens
  2. Self vs no self
  3. Innate immunity / non specific
  4. Adaptive immunity / specific
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3
Q

QAntigens

A

q- a protein marker on the surface of cells to identify them

  • stimulate the production of antibodies
  • immunocompetence: the ability to activate an effective response to a foreign antigen
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4
Q

Self markers

A

Molecules on the surface of human cells that are unique to an individual, thus identifying the cells as self to the immune system
- MHC: major histocompatibility complex

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5
Q

Non-self markers

A

Molecules on the surface of foreign or abnormal cells or particles that identify the particle as “non-self” to the immune system

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6
Q

Self-tolerance

A

The ability of our immune system to attack abnormal or foreign cells, but spare our own normal cells

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7
Q

Innate immunity / nonspecific

A

Present at birth

- built in and ready for action providing the initial defense mechanism

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8
Q

Adaptive immunity / specific

A

Mechanisms that develop in response to specific threatening agents or specific abnormal cells

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9
Q

Cytokines

A

Broad and loose category of small proteins that are important in cell signaling

  • they are released by cells and affect the behavior of their cells or the cells that release them
  • regulate or initiate innate and adaptive immunity
  • ex: interleukins, leukotrienes, and interferons, growth factors
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10
Q

Pic

A

Pic

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11
Q

Innate immunity: mechanical and chemical barriers

A

First line of defense is the skin and mucous membranes

- sebum, mucus, enzymes, and hydrophobic acid in the stomach

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12
Q

Innate immunity: inflammatory response

A

Provides a second line of defense

  • tissue damage - release of inflammation mediators (histamine, kinins, prostaglandins, leukotrienes, and interleukins)
  • many of these mediators are chemotactic factors: substances that attract WBCs to area (chemotaxis)
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13
Q

Innate immunity: inflammation

A

Due to increased blood flow and vascular permeability in the affected region, which help phagocytosis WBCs reac the general area and enter the affected tissue
- redness - warmth - pain - edema

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14
Q

Pic

A

Pic

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15
Q

Innate immunity: phagocytosis

A
  • a major component of second line of defense (but also plays role in adaptive immunity)
  • the ingestion and destruction of microorganisms or their small particles by phagocytes
  • cells that perform this funciton are called antigen-presenting cells
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16
Q

APC

A

Antigen-presenting cells

  • phagocytes that ingest foreign particles, isolate protein segments (peptides), and display them as antigens on their surfaces
  • these peptides are then recognized by cells of the adaptive immune response by a specific (adaptive) immune cell
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17
Q

Neutrophils

A

Most numerous; first responder

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18
Q

Macrophages

A

Large eaters

- phagocytes monocytes that have grown to several times their original size after migrating out of the blood stream

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19
Q

Dendritic cells

A

Cells with many extensions

- found in many body tissues that are in contact with the external environment, such as the skin and mucous membranes

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20
Q

Innate immunity: natural killer cells

A
  • lymphocytes (not T or B) that kill tumor cells and cells infected by viruses
  • chemically triggers cell death and destruction
  • must have direct contract with target cell
  • NK cell recognize abnormal cells by using two different recognition receptors (killer-activating and killer-inhibiting receptor)
21
Q

Killer-activating cells

A

Binds to any of several common surface molecules found in cells

22
Q

Killer-inhibiting cells

A

If the NK cell also binds to protein found on the surface of normal cells, then the killing action is stopped
- only abnormal and foreign cells fail to bind to the killer-inhibiting centers, so they are destroyed

23
Q

Pic

24
Q

Innate immunity: Interferon

A

IFN

  • a protein synthesized by lymphocytes, macrophages, and fibroblasts that have been invaded by viruses
  • interferon diffuses into the circulation and to nearby cells
  • interferon proteins interfere with the ability of viruses to cause disease by preventing replication
25
Innate immunity: Complement
A group of enzymes that produce a cascade of reactions resulting in a variety of immune responses - lyes cells when activated by either adaptive or innate mechanism - enhances inflammation and phagocytosis
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Innate immunity: Toll-like receptors
In the membranes of the host cells - they are pattern-recognition receptors - they do not identify specific antigens - they identify a large variety of different bacterial molecules such as toxins and flagell proteins, viral RNA and glycoproteins, and fungal molecules - when triggered, they facilitate the nonspecific/innate immune mechanisms
28
Adaptive immunity
Third line of defense - these mechanisms attach specific agents that the body recognizes as abnormal or non-self - consists of two different classes of lymphocytes (B and T cells)
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Adaptive immunity: Lymphocytes
Adaptive immunity requires activation of lymphocytes populations, which then begin their immune attack of specific antigens - each lymphocyte has receptors for both an antigen and for signaling chemicals - requires two stimuli 1. A specific antigen 2. Activating chemicals
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B lymphocytes
B cells - do not attack pathogens themselves by instead produce molecules called antibodies that attack the pathogens - B cell mechanisms are classified as antibody-mediated immunity or humoral-mediated immunity
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Activation of B cells
Develop in two stages - pre B cells (naive cells) develop by a few months of age - the second stage occurs in lymph nodes and spleen with activation of a naive B cell after it binds to a specific antigen - activated B cells become antibody-secreting plasma cells (effector B cells) - inactive B cells are Memory B cells - when exposed to the antigen that triggered their formation, they rapidly prude more plasma cells and memory cells
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Functions of antibodies
The function of antibody molecules is to produce antibody-mediated immunity (humoral immunity) by disabling antigens - antigen-antibody reactions - complement activation - primary and secondary responses
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Antigen antibody reactions
The binding of the antigen to antibody forms an antigen-antibody complex that may produce one or more effects - transforms toxins into harmless substance - clumps antigens together (agglutination), making it possible for macrophages to dispose of them more rapidly
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T lymphocytes
T cells - attack pathogens more directly - T cell mechanisms are classified as cell- mediated immunity or cellular immunity
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Function of T cells
- T cells funciton to produce cell-mediated immunity and help to regulate adaptive immunity in general 1. Helper T cells 2. Cytotoxic T cells 3. Suppressor T cells 4. Memory T cells
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Helper T cells
Regulate the function of B cells, T cels, phagocytes, and other WBCs
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Cytotoxic T cells
An effector T cell that causes contact killing of a target cell
40
Suppressor T cells
Regulatory T cells that suppress lymphocyte fucntion, thus regulating immunity and promoting self-tolerance
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Memory T cells
Inactive T cells that stay in the circulation - if the same antigen entes the body again, these cells can be activated and proliferate to respond to the antigen quickly
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Adaptive complement
- a component of blood plasma consisting of several protein compounds - complement kills foreign cells by cytolysis or apoptosis - complement causes vasodilation, enhances phagocytosis, and other functions - complement activity can also be initiated by innate immune mechanisms
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Primary response
Initial encounter with a specific antigen triggers the formation and release of specific antibodies that reaches its peak in a few days
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Secondary response
A later encounter with the same antigen triggers a much quicker response - B memory cells rapidly divide, producing more plasma cells and thus more antibodies
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Adaptive immunity review
Adaptive immunity is a specific immunity targeting specific antigens - adaptive immunity involves two classes of lymphocyte: B and T cells - B cells: antibody-mediated (humoral) immunity - T cells: cell-mediated (cellular) immunity
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Adaptive immunity types
1. Natural immunity: results form non-deliberate exposure to antigens - occurs in the course of everyday living 2. Artificial immunity: results from deliberate exposure to antigens, called immunization
48
Immunity
Natural and artificial immunity may be active or passive 1. Active immunity: when the immune system responds to a harmful agent; lasts longer than passive 2. Passive immunity: developed when immunity from another individual is transferred to an individual who was not previously immune; it is temporary but provides immediate protection