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A&P II > Immune System > Flashcards

Immune System Flashcards

1
Q

What are two defense systems the immune system is made up of?

A
  1. Innate (nonspecific)
  2. Adaptive (specific)

Both are intertwined

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2
Q

What does the innate immune system do?

A
  • First line of defense; external (skin and mucosae)
  • Second line of defense; phagocytes, natural killer cells, inflammation (macrophages, mast, WBCs), antimicrobial proteins (interferons and complement proteins), fever
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3
Q

What does keratin do?

A

Provides resistance against acids, alkalis, and bacterial enzymes

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4
Q

What is mucin?

A

Thick sticky mucus that lines the digestive and respiratory passageways. Traps microorganisms.

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5
Q

What are defensins?

A
  • A broad-spectrum antimicrobial peptide, increases in response to inflammation when surface barriers are breached.
  • Help to control bacterial and fungal colonization in the exposed areas
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6
Q

What does TLR (toll-like receptors) do?

A
  • Plays a central role in triggering immune responses. Allow the cells to recognize invaders and sound an alarm to initiate inflammation.
  • 11 types, each recognizing a particular class of attacking microbe.
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7
Q

What are phagocytes?

A

WBC that ingest and digest foreign invaders

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8
Q

What are neutrophils?

A

Most abundant phagocytes, but die fighting; become phagocytic on exposure to infectious material

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9
Q

What are macrophages?

A

Develop from monocytes and are chief phagocytic cells; most robust phagocytic cell
- Free macrophages: wander through tissues e.g. alveolar macrophages
- Fixed macrophages: permanent residents of some organs, e.g. stellate macrophages in the liver

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10
Q

What’s the process of phagocytosis?

A
  1. Phagocyte adheres to pathogens
  2. Phagocyte forms pseudopods that eventually engulf the particles, forming a phagosome
  3. Lysosome fuses with the phagocytic vesicle, forming a phagolysosome
  4. Toxic compounds and lysosomal enzymes destroy pathogens
  5. Sometimes exocytosis of the vesicle removes indigestible and residual material
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11
Q

What is opsonization?

A

The coating of an antigen or particle (eg, infectious agent) by substances, such as antibodies, complement components, fibronectin, and so forth, that facilitate uptake of the foreign particle into a phagocytic cell.

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12
Q

What are natural killer cells?

A
  • Nonphagocytic, large granular lymphocytes that police blood and lymph
  • Can kill cancer and virus infected cells before adaptive immune system is activated
  • Attack cells that lack self cell surface receptors
  • Kill by inducing apoptosis in cancer cells and virus infected cells
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13
Q

What is inflammation?

A

A nonspecific response to any tissue injury.

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14
Q

What are some causes of inflammation?

A

Triggered whenever body tissues are injured
- Trauma
- Heat
- irritating chemicals
- Infections by microorganisms

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15
Q

What are the benefits of inflammation?

A
  • Prevents spread of damaging agents
  • Disposes of cell debris and pathogens
  • Alerts adaptive immune system
  • Sets the stage for repair
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16
Q

What are 4 cardinal signs of acute inflammation?

A
  • Redness
  • Heat
  • Swelling
  • Pain
  • Impairment of function
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17
Q

What is complement and what does it do?

A

A group of plasma proteins that are activated if pathogens provoke the inflammation; to form potent inflammatory chemicals.

  • Complement system consists of ~20 blood proteins, including C1-C9
  • Nonspecific
  • Enhances both innate and adaptive defenses.
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18
Q

What are the inflammatory chemicals that are released and what are the effects?

A

Histamine, kinins, and prostaglandins.
- Vasodilation of local arterioles
- Leaky capillaries
- Attract phagocytes to the area

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19
Q

What are two stages of inflammation?

A
  1. Inflammatory chemical release
  2. Vasodilation (hyperemia- congestion with blood, redness and heat) and increased vascular permeability (exudate- fluid containing clotting factors and antibodies to leak into tissue)
    - Local swelling (edema)
    - Swelling pushes on nerve endings (pain)
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20
Q

Phagocyte mobilization process

A
  1. Leukocytosis
    - neutrophils multiply and flood the area followed by macrophages
  2. Margination: phagocytes clinging to the inner walls of the capillaries and postcapillary venules
    - endothelial cells project cell adhesion molecules (CAMs) into vessels
  3. Diapedesis
    - Neutrophils flatten and squeeze b/w endothelial cells, moving into interstitial spaces
  4. Chemotaxis
    - inflammatory chemicals act as chemotactic agents to promote positive chemotaxis (the migration of cells toward attractant chemicals or away from repellents)
  5. If attack continues, monocytes arrive later
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21
Q

What are interferons?

A
  • IFN: family of immune modulating proteins
  • Cells infected with viruses secrete IFNs to warn healthy neighboring cells
  • Not virus-specific
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22
Q

What substance raises body temp in fever?

A

Pyrogens are secreted by Leukocytes and macrophages that are exposed to foreign substances
- Acts as body’s thermostat in hypothalamus, raise body temp
- Benefits: Causes liver and spleen to isolate iron and zinc needed by microorganisms. Increases metabolic rate and rate of repair

23
Q

What does the adaptive immune system do?

A
  • Third line of defense attacks particular foreign substances (takes longer than innate)
  • Specific defensive system that eliminates almost any pathogen or abnormal cell in body
24
Q

What are the characteristics of adaptive immunity?

A
  • Specific: recognizes and targets specific antigens
  • Involves B and T lymphocytes
  • Systemic: not restricted to the initial site
  • Has memory: mounts an even stronger attack to known antigens
25
Q

What is a shortcoming in adaptive defenses?

A

Must be primed by initial exposure to specific foreign substance

26
Q

What are two main branches of adaptive defense system?

A
  • Humoral (B cells) immunity: antibody-mediated
  • Cellular (T cells) immunity: cell-mediated
27
Q

What does humoral immunity target?

A
  • Antibodies produced by lymphocytes, circulate freely in body fluids
  • Bacteria, toxins, free viruses in the blood, aka extracellular
28
Q

What does cellular immunity target?

A

Lymphocytes act against target cell directly by killing infected cells and indirectly by releasing chemicals that enhance inflammatory response or activating other lymphocytes or macrophages

Virus-infected and cancer cells, and cells of foreign grafts

29
Q

What are antigens?

A

Substances that can mobilize adaptive defenses and provoke an immune response
- Targets of all adaptive immune responses
- Most are large, complex molecules not normally found in body
- Intruders aka nonself

30
Q

What are the characteristics of antigens?

A
  • Can be complete or
  • incomplete: hapten: small peptides, nucleotides, some hormones)
  • Contain antigentic determinants
  • Can be a self-antigen
31
Q

What are the two functional properties of complete antigens?

A
  • Immunogenicity
  • Reactivity
32
Q

What is immunogenicity?

A

The ability to stimulate specific lymphocytes to proliferate/multiply
- E.g. bacteria, fungi, virus particles (small molecules such as peptides, nucleotides and hormones are NOT)

33
Q

What is reactivity?

A

The ability to react with the activated lymphocytes and the antibodies released by immunogenic reactions

34
Q

What are self-antigens?

A

Cells covered with proteins located on surface that are not antigenic to self, but to others in transfusions or grafts
E.g. MHC proteins

35
Q

What is MHC I?

A

Found in all nucleated cells except RBC.
- Present endogenous antigens to cytotoxic T cells
- Originate inside the cells

36
Q

What is MHC II?

A

Found only on antigen-presenting cells
- Present exogenous antigens to helper T cells

37
Q

What three crucial types of cells are involved in adaptive immune system?

A
  • Two types of lymphocytes: B cells (humoral) and T cells (cellular)
  • APCs (antigen-presenting cells): Do not respond to specific antigens. Play essential supporting roles in immunity
38
Q

What is APCs (antigen-presenting cells)?

A

Engulf foreign antigens and present fragments of antigens on MHC II to helper T cells for recognition

39
Q

What are the major types of APCs?

A
  • Dendritic cells
  • Macrophages
  • B cells (present foreign antigens to helper T cell to assist in their own activation)
40
Q

What is an immunocompetence?

A

The ability to recognize its one specific antigen by binding to it.

41
Q

How does humoral immunity work?

A

When B cell encounters target antigen, it provokes a humoral immune response
- B cells are activated
- Antibodies specific for that particular antigen are produced
- A clone of B cells forms
- Clone B cells become plasma cells, antibody secreting effector cells
- Secrete antibodies at rate of 2000 molecules per sec. for 4-5 days then die

42
Q

Clone cells that do not become plasma cells become _______.

A

Memory cells
- Provide immunological memory
- Mount an immediate response to future exposure to same antigen

43
Q

What is a primary immune response?

A

Cell proliferation and differentiation upon exposure to antigen for the first time
- Lage period 3-6 days
- Peak levels of plasma antibody are reached in 10 days

44
Q

What is a secondary immune response?

A

Re exposure to same antigen gives faster, more prolonged and effective response
- Respond within hours
- Antibody level peak in 2-3 days at much higher levels

45
Q

What is active and passive humoral immunity?

A

Active: When B cells encounter antigens and produce specific antibodies
Passive: When ready-made antibodies are introduced into body

46
Q

Where do B cells mature?

A

In the bone marrow

47
Q

Where do T cells mature?

A

In the thymus

48
Q

Antibodies are also called?

A

Immunoglobulins (Igs): proteins secreted by plasma cells which make up gamma globulin portion of blood
- capable of binding specifically with antigen detected by B cells
- Have light and heavy chains
- Have variable and constant regions
- Grouped into one of five Ig classes

49
Q

What do antibodies do?

A
  • Inactivate and tag antigens
  • Form antigen-antibody (immune) complexes
50
Q

What are the defensive mechanisms used by antibodies?

A
  • Neutralization
  • Agglutination
  • Precipitation
  • Complement fixation
51
Q

What is neutralization?

A
  • Antibodies block specific sites on viruses or bacterial exotoxins
  • The virus or exotoxin cannot bind to receptors on tissue cells
  • Phagocytes destroy the antigen-antibody complexes
52
Q

What is agglutination?

A

The clumping of particles together

53
Q

What is precipitation?

A

Soluble molecules are cross-linked into large complexes that settle out of solution

54
Q

What is complement activation?

A

A system of plasma proteins that can be activated directly by pathogens or indirectly by pathogen-bound antibody, leading to a cascade of reactions that occurs on the surface of pathogens and generates active components with various effector functions.

A&P II (6 decks)

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