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Flashcards in The immune system Deck (57):
1

Innate (Nonspecific) Immunity

defenses that are always active
lack ability to target specific invaders over others
-Nonspecific Response

2

Adaptive Immunity

"specific immunity;" defenses that target a specific pathogen; slower to act, but can create immunological memory of an infection for faster attacks in the future

3

Bone Marrow

produces all leukocytes (WBCs) that participate in the immune system through the process of hematopoiesis

4

Spleen

location of blood storage and activation of B-Cells, which turn into plasma cells to produce antibodies for adaptive (specific) immunity

5

Humoral Immunity

subsection of specific immunity; involves antibodies that dissolve and act in the blood (rather than within cells)
-involves B cells
-Production of antibodies that are specific to the antigens. B-cells are lymphocytes that produce antibodies, they mature in the bone marrow and are activated in the spleen and lymph nodes.

6

T-cells

another type of adaptive immune cells that mature in the thymus (right in front of the pericardium)

7

cell-mediated immunity


subsection of specific immunity involving T cells; immunie system is coordinate by T-cells who directly kill virally infected cells

8

lymph nodes


place for immune cells to communicate and mount an attack; B-cells can activate here

9

Gut-Associated Lymphoid Tissue (GALT)

other immune tissue in close proximity to the digestive system (a site of potential invasion); tonsils/adenoids in head, Peyer's Patches in the small intestine, and appendix (contains lymphoid aggregates)

10

Hematopoietic Stem Cells

Produce granulocytes and agranulocytes. precursur cell for all other blood cells including RBCs and WBCs

11

Granulocytes vs aganulocytes

Granulocytes contain granules: neutrophils, eosinophils, and basophils
Agranulocytes: lymphocytes and monocytes

12

Lymphocytes

agranulocytes, responsible for antibody production, immune system modulation, and targeted killing of infected cells.

13

Monocytes

Phagocytic cells in the bloodstream, agranulocytes. They become macrophages in tissues (microglia, langerhans (skin), and osteoclasts).

14

Nonspecific/ innate Immune Response

Cells can carry these out without learning.

15

Specific/Adaptive Immunity

Immune cells learn to recognize and respond to certain antigens. The specific immune system is further divided into the cell-mediated and the humoral immune system

16

Noncellular Nonspecific Defenses

Skin
Defensins
Lysozyme
Mucus
Stomach acid
Normal gastrointestinal flora
Complement

17

Skin

Provides a physical barrier and secretes antimicrobial enzymes

18

Defensins

Example of antibacterial enzymes on the skin

19

Lysozyme

Antimicrobial and is present in tears and saliva

20

Mucus

Is present on mucous membrane and traps incoming pathogens

21

Stomach acid

Antimicrobial mechanism in the digestive system

22

Normal gastrointestinal flora

Provides competition, making it hard for pathogenic bacterial to grow in the gut

23

Complement

Set of proteins in the blood that can create holes in bacteria

24

Professional antigen- presenting cells

Include macrophages, dendrite cells in the skin, some B-cells, and certain activated epithelial cells

25

What are the differences between MHC-I and MHC-II?

MHC-I is found in all nucleated cells and presents proteins created within the cell (endogenous antigens); this can allow for detection of cells infected with intracellular pathogens (especially virus). MHC-II is only found in antigen-presenting cells and presents proteins that result from the digestion of extracellular pathogens that have been brought in by endocytosis (exogenous antigens).

26

Compare and contrast B and T cells:

-Both B and T cells develop in the bone marrow.
-B cells mature in Bone marrow, but are activated by spleen or lymph nodes. T-cells mature in thymus.
-B-cells major function is to produce antibodies
-T-cell's major function is to coordinate immune system and directly kill infected cells
-B and T-cells are specific/adaptive immunity
-B-cells are part of humoral system while T-cells are part of cell-mediated immunity

27

Pattern Recognition Receptors

They recognize the category of the invader for production of appropriate cytokines to recruit the right type of immune cells. TOll like receptors

28

Natural Killer (NK) Cells

A type of nonspecific lymphocyte that are able to detect the down-regulation of MHC and induce apoptosis in these virally infected cells. Cancer cells may also downregulate MHC production, so NK cells also offer protection from the growth of cancer as well.

29

Granulocytes (3 types)

Neutrophils:
Eosinophils:
Basophils:
Mast cells

30

Neutrophils:

Phagocytic, follow bacteria via chemotaxis, they can detect bacteria one they have been opsonized (tagged with antibody from B-cell). They create pus.

31

Eosinophils:

Involved in allergic reactions and invasive parasitic infections, they release histamine, an inflammatory mediator. Causing vasodilation and increased leakiness of blood vessels, allowing additional immune cells to move out of blood stream and into tissues.

32

Basophils:

Involved in allergic responses, least popular leukocyte in the bloodstream under normal conditions.

33

Mast cells

have smaller granules and exist in tissues, mucosa, and epithelium. Like basophils. They also release a lot of histamine in response to allergens, leading to inflammatory responses.

34

Interferons

innate immunity; protect against viruses; cause flue-like symptoms; cells infected with viruses produce interferons that prevent viral replication and dispersion via:
1) cause nearby cells to decrease production of both viral and cellular proteins
2) decrease permeability of these cells, making it harder for a virus to infect them
3) upregulate MHC-I and MHC-II molecules, thus increasing antigen presentation and better detection of infected cells by the immune system

35

Complement System

innate immunity; system of proteins in blood that act nonspecifically on BACTERIA; classical pathway requires binding of an antibody to a pathogen; alternative pathway doesn't require antibodies --> complement proteins punch holes in cell walls of bacteria, rendering them osmotically unstable

36

antibodies

target a particular antigen; they contain two heavy chains and two light chains

37

antigen-binding region

located at the end of what is called the VARIABLE REGION (domain) at the tips of the antibody's Y; these region contains specific polypeptide sequences that will bind only one specific antigenic sequence

38

Hypermutation

part of the reason why it takes so long to initiate the antibody response; B cell undergoes this process at its antigen-binding region, trying to find the best match for the antigen (improve specificity); only the B-cells that can bind the antigen with high affinity survive, providing a mechanism for generating specificity called CLONAL SELECTION

39

constant region

region of antibody molecule for which natural killer cells, macrophages, monocytes and eosinphils have receptors for, and can initiate the complement cascade.

40

isotopes of antibody

even though each B-cell makes only one type of antibody, we have many B-cells in our body that can ISOTOPE SWITCH as needed

41

opsonization

process of marking for destruction by antibodies, which will cause AGGLUTINATION (clumping) into insoluble complexes that are ingested by phagocytes, or neutralize pathogens

42

cell-surface antibodies

can activate immune cells or mediate allergic reactions

43

Plasma Cells

Form from B-cells exposed to antigen and produce antibodies

44

memory B-cell

Also form from B-cells exposed to antigen and lie in wait for a second exposure to a given antigen to be able to mount a rapid, robust response

45

helper T-cells (Th or CD4+)

respond to antigen on MHC-II and coordinate the rest of the immune system; secrete LYMPHOKINES to activate various arms of immune defense; Th1 cells and Th2 cells; loss of helper T-cells occurs in HIV (advanced AIDS); because MHC-II presents exogenous antigens, CD4+ cells are most effective against BACTERIAL, FUNGAL AND PARASITIC infections

46

Th1 Cells

secrete interferon gamma, which activates macrophages

47

Th2 cells

activate B-cells, primarily in parasitic infections

48

Cytotoxic T-Cells (Tc, CTL, CD8+)


respond to antigen on MCH-I and kill VIRALLY infected cells and intracellular bacteria/fungi (by injecting toxic chemicals to promote apoptosis)

49

Supressor (regulatory) T-Cells (Treg)

tone down the immune response after an infection and promote self-tolerance; express FoxP3

50

What are the three main effects of circulating pathogens?

1. Circulating antibodies can mark a pathogen for destruction by phagocytic cells (oponization)
2. Cause agglutination of the pathogen in insoluble complexes that can be taken up by phagocytic cells
3. Neutralize the pathogen by preventing its ability to invade tissue

51

Positive selection of T cell

maturation of t-cells occur in thymus to select for those only capable of reacting to antigen presented on MHC are allowed to survive ( those that do not undergo apoptosis)

52

Negative selection

When T-cells that respond to self-antigens undergo apoptosis before leaving thymus

53

thymosin

peptide hormone promoting t-cell development

54

Active immunity

Refers to the stimulation of the immune system to produce antibodies against pathogen
-natural or vaccination

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Passive Immunity

Refers to the transfer of antibodies to prevent infection without stimulation of the plasma cells that produce these antibodies

56

Lymphatic System

a circulatory system that consists of one-way vessels with intermittent lymph nodes; connects to the cardiovascular system via the THORACIC DUCT; equalizes fluid distribution, transports fats and fat-soluble compounds in CHYLOMICRONS, and provides sites for mounting immune responses (in germinal centers)

57

lacteals

small lymphatic vessels located at the center of each villus in the small intestine where chylomicrons enter to create CHYLE (lymphatic fluid)