Chapter 20 and 21

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1

Innate defense system

  • nonspecific
  • Is more alert in children (covid) adaptive will kick in - to clear the virus (after a few days)
  • Fever and inflammatory response
  • Inflammatory response Is the immune system rushing to clear the infection
  • -Ready to go – will defend immediately
  • Preventing the virus from killing
2

Adaptive defense system

  • specific
  • The older the person the less innate cells they have to protect them
  • Adaptive cells go up in 50+
  • once it kicks in symptoms subside
  • vaccines work because they activate the adaptive immune system.
  • will be ready the second time to recognize the virus. Covid – causes immune reactions.
3

Innate defense has two defeses ?what do they do ?

First/Surface barriers: skin and mucus

second/Internal defenses:

  • fever
  • antimicrobial proteins, phagocytes
  • NK cells
  • Inhibit spread of invaders
  • Inflammation most important mechanism
4

What is the third line of defense a part of ?

Adaptive defense system

5

adaptive defense system

Third line of defense

  • attacks particular foreign substances
  • Takes longer to react than innate system
  • T cells & B cells will recognize the cells
6

Phagocytes

dendritc cell

7

Natural Killar (NK) Cells

Innate form of lymphocyte

-Nonphagocytic large granular lymphocytes

-Attack cells that lack "self" cell-surface receptors

–Induce apoptosis in cancer cells and virus-infected cells

–Soluable factor

–Death reciptors on the surface of each is engaged

    • Secrete potent chemicals that enhance inflammatory response
8

Inflammatory response

INTERFERONS

  • macrophages
  • mast cells
  • WBCs
  • inflammatory chemicals
9

Neutrophils

Most abundant but die fighting

10

Macrophages

  • develop from monocytes
  • chief phagocytic cells
  • robust cells
11

What are the adaptive defenses ?

  • Humoral Immunity
    B CELLS
  • Cellular Immunity
    T CELLS
12

Osmotic Pressure

pushes fluid into blood capillary

13

Hydrostatic Pressure

push fluid out of the blood capillaries

14

Lymphatic system

returns fluids that leaked from blood vessels back to blood

15

Lymphatic system has three parts?

Lymphatic vessels

lymph ( fluid in vessels )

lymph nodes (cleanse lymph)

16

what are the lymphatic organs?

Spleen, thymus, tonsils, lymph nodes and lymphoid tisses

17

Lymphocytes

  • Lymphocytes main warriors of immune system

–Arise in red bone marrow

  • Mature into one of two main varieties

T cells (T lymphocytes) thymis

B cells (B lymphocytes) bone marrow

18

immune cell activation

lymphocytes activated and mount attack against antigens

19

Lymphatic vessel & structure

one way system - lymph flows toward heart.

Lymphatic capillaries

Collecting lymphatic vessels

Lymphatic trunks and ducts

20

Lymphatic capillaries

  • Very permeable (take up proteins, cell debris, pathogens, and cancer cells
  • Endothelial cells overlap loosely to form one-way minivalves
  • Pathogens (and cancer cells) travel throughout body via lymphatics
  • are blind-ended tubes
21

T cells and B cells protect against

antigens - anything that can be recognized by a TCR /BCR

22

Lymphoid follicles

  • malt (the surveillance point for the outside of the body)
  • in mouth , GI Tract, Alimentary canal.
23

lymph node structure

germinal centera

–proliferating/differiantiate B cells

(differentiation not maturing)

–Isolated aggregations of Peyer's patches and in appendix

24

lymph node structure

medulla

central part

25

lymph node structure

cortex

outside

  • Cortex contains follicles with germinal centers, heavy with dividing B cells
26

IgE (monomer)

  • active in some allergies
  • active in parasitic infections
  • causes mast cells & basophiles to release histamine
27

What is the special function of lymph nodes ?

cleanse lymph

specialized lymphatic

28

What is the function of MALT ?

mucosa-associated lymphatic tissue (MALT) and Peyer patches are found in the body. MALT - Lymphoid organs

29

What is the function of SPLEEN?

  • Largest lymphoid organ
  • Spleen is there to filter blood
  • –Cleanses blood of aged cells and platelets, macrophages remove debris
30

Tonsils

  • Simplest lymphoid organs
  • –Palatine tonsils — posterior end of oral cavity –Lingual tonsil— base of tongue –Pharyngeal tonsil— posterior wall of nasopharynx –Tubal tonsils— openings of auditory tubes into pharynx
31

THYMUS What is the function of?

  • a location where T cells can mature
  • Make sure they do not recognize self antigen
  • -positive selection(recognize antigens)
  • -negative selection ( destroy those that cause autoimmunity)
  • Increases in size and most active during childhood
32

Antigens (Ag)

anything lymphocytes can specifically respond to, causing them to proliferate and differentiate into effectors and memory cells

33

Which hypersensitivities are antibody mediated ?

Type I - Type III

34

What hypersensitivities are T-cell mediated?

Type IV

35

Type I - hypersensitivities

immediate example=allergies/anaphylaxis

antibody mediated

36

PASSIVE IMMUNITY

The immunity that is passed along like mother and child through breast milk.

37

Type II - hypersensitivities

complement/cell lysis, example=blood transfusion rejection

antibody mediated

38

Type III - hypersensitivities

immune complexes

example=SLE

antibody mediated

39

Type IV - hypersensitivities

delayed

example=contact dermatitis

T-cell mediated

40

CLONAL SELECTION

-Naive cells first encounter with antigens

-correct signals - lymphocytes complete it differentiation.

Lymphocytes compete for Ag over time: increasing affinity for Ag

The best clone wins

41

WHAT ARE ANTIGEN-PRESENTING CELLS (APCs) ?

  • Dendritic Cells
  • macrophages
  • B Cells
42

B cells

-b cells mature in red bone marrow

-is positively selected once it reaches Ag receptor

-self-reactive :
eliminate by apoptosis (CLONAL DELETION)

43

What is the function of B-Cells ?

  • DO NOT activate naive T cells
  • Presents antigens to helper T cell to assist own activation
44

Dendritic Cells are

(the educators)

found in connective tissues & epidermis.
-Most effective antigen presenter known, they sit in tissue waiting to attack

  • capture antigens and deliver them to lymph nodes

-stay in one location. The first one to recognize bacteria in tissue

45

what are Macrophages ?

-in connective tissue & lympphiod organs
- presents antigens to T cells so they can activate themselves to secrete bactericidal chemicals

-can activate NAIVE T CELLS

46

Lectin Pathway

  • inflammatory response
  • bind to specific kinds of sugars
  • produced by the innagte system to recognize foreign invaders
  • when bound to foreign invaders they bind & activiatr complement.
47

Alternative pathway

  • activated by C3, B, D & P interact on surface of microorganisms
  • parasite/Bacteria
48

Classical pathway

  • Antibodies (adaptive B cells) bind to invading organisms and to complement components
  • Called complement fixation

First step in activation;

49

What are compliment activation pathways?

  • classical pathway
  • lectin pathway
  • Alternative pathway
50

How do TH cells replicate in HIV?

HIV attach/attack TH cells to replicate

51

Classes of Antibodies

IgM(pentamer)

  • Larger than others
  • the first antibody that is released
  • Potent agglutinating agent
  • fixes & activates complement
  • 5 y's
52

Classes of Antibodies

IgA (dimer)

  • Secretory (mucus)
  • Monomer ; in mucus and other secretions
  • helps prevent entry of pathogens
  • 2 y's
53

Classes of Antibodies

IgD (monomer)

  • attaches to surface of B cells
  • Functions as B cell receptor
54

Classes of Antibodies

IgG(Monomer)

  • 75-85% of AB in plasma
  • secondary / late primary responses
  • crosses placental barrier
55

Classes of Antibodies

IgE (monomer)

  • active in some allergies
  • active in parasitic infections
  • causes mast cells & basophiles to release histamine
56

B cells

  • can switch antibody classes
  • retain antigen specificity
  • IgM at first, then IgG
  • almost all secondary responses are IgG
57

T cells

TH (CD4)

  • Play central role in adaptive immune response
  • Ag fragments bind to MHC 2
  • activate both humoral and cellular arms
  • activates T & B cells
  • Induce T & B cell proliferation
  • HIV Target -
58

Subsets of TH Cells

TH1

  • Mediate most aspects of cellular immunity
59

Subsets of TH Cells

TH2

  • Defend against parasitic worms
  • mobilize eosinophils
  • promote allergies
  • humoral immunity
60

Subsets of TH Cells

TH17

  • link adaptive & innate
  • by releasing IL-17
  • may play a role in auto immune disease
61

Cytotoxic TC cells

  • bind to self - NONSELF complex
  • can destroy all infected abnormal cells
  • Directly attack and kill other cells
62

Regulatory T ( T Reg ) cells

  • dampen immune response
  • prevents autoimmune reactions
  • surpress self-reactive lmphocytes

Ex. used in research tp induce tolerance to transplanted tissue

63

T cell Activation

  • 2 step process
  • Antigen binding
  • Co-Stimulation
  • Both occur on surface of same APC
  • Both required for clonal selection
64

Antigen Binding

  • TCRs bind to Ag - MHC complex on APC surface
  • TCR recognizes nonself self complex
  • T cell surface proteins involved in T cell activation.
  • ex. CD4 & CD8 help maintain coupling during antigen recognition
65

Co-stimulation

Requires T cell binding to other surface receptors on an APC

Co- Stimulatory signals

-dendritic cells & macrophages produce surface B7 proteins when innate defenses mobilized

- B7 binding crucial for co-stimulatory signal

66

T cells

Positive Selection

  • Selects T cells capable of recognizing self-MHC proteins (MHC restriction)
  • failures destroyed by apoptosis
67

Subsets of TH Cells

TH17

  • link adaptive & innate
  • by releasing IL-17
  • may play a role in auto immune disease
68

Mucosa-associated Lymphoid Tissue (MALT)

  • Lymphoid tissues in mucous membranes throughout body
  • Protects from pathogens trying to enter body
  • Largest collections of MALT in tonsils , Peyer's patches , appendix
69

Cytokines

  • Chemical messengers of immune system
  • Include interferons and interleukins
  • (IL-1) & (IL-2)
70

Interleukin 1 (IL-1)

macrophages co-stimulates bound T cells to

–Release interleukin 2 (IL-2)

–Synthesize more IL-2 receptors

71

Interleukin 2 (IL-2)

  • key growth factor,
  • acting on cells that release it and other T cells

–Encourages activated T cells to divide rapidly