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Pob 1 > Lecture 21 Immune system > Flashcards

Lecture 21 Immune system Flashcards

1
Q

innative immunity

A

Each of a small set of receptors recognize a molecule absent from animals, but common to a type of pathogen

all animals have innative immunity, a defense active immediately upon infection
innate immuity includes barrier defenses (slide 6)

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2
Q

adaptive immunity

A

a sophisticated and precise defense mechanism in vertebrates, including humans, that provides a tailored response to specific pathogens or antigens. This type of immunity is highly specialized and develops throughout an individual’s life as a response to exposure to various pathogens, vaccines, or environmental factors.
(specificality and memory)

Each of a vast number of receptors is specific for a particular part of a protein in one pathogen, such as a surface protein of the influenza virus

The adaptive immune response is activated after the innate response and develops more slowly. (slide 6)

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3
Q

immune system functions

A

● Protects against pathogens:
○ Bacteria
○ Viruses
○ Parasites

● Protects against foreign molecules (e.g., toxins)

● Removes dead or damaged cells

● Attempts to recognize and remove abnormal cells

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4
Q

nonspecific immunity

A

does not target specific pathogen
-physical barriers
-inflammatory process

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5
Q

specific immunity and what types are there

A

identifies specific pathogen

-natural immunity: (innate) like allergies
recognition of traits shared by broad ranges of pathogens, using a small set of receptors

rapid response

-acquired immunity: active or passive
recognition of traits specific to particular pathogens, using a vast array of receptors

slower response

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6
Q

innate immunity defenses

A

barrier defenses: skin, mucous membranes, secretions

internal defenses: phagocytic cells natural killer cells, antimicrobial proteins, inflammatory response

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7
Q

what are the 2 adaptive immunity responses

A

humoral response: antibodies defend agains infection in body fluids

cell-mediated response: cytotoxic cells defend agains infection in body cells

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8
Q

innate immunity overview

A

● First-line defenses are barriers blocking entry If invaders breach, sensor systems detect
*Physical barriers - Skin and mucous membranes

● Sensor systems –
○ Sentinel cells use PRR (Pattern Recognition
Receptors) in cell membrane and cytoplasm
○ Complement system

● Innate defenses effectors work to destroy invaders
○ Interferons
○ Phagocytosis
○ Fever

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9
Q

Barrier defenses

A

● Skin and mucous membranes of the
respiratory, urinary, and reproductive tracts.

● Mucus traps and allows for the removal of microbes.

● Many body fluids including saliva, mucus, and tears are hostile to many microbes.

● The low pH of skin and the digestive system prevents growth of many bacteria.

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10
Q

Cellular Innate Defenses

A

Innate immune cells in mammals detect, devour, and destroy invading pathogens.

These cells recognize groups of pathogens using TLRs, or Toll-like receptors.

TLRs recognize fragments of molecules characteristic of a set of pathogens.

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11
Q

Hematopoietic stem cells (HSC found in bone marrow)

A

precursors where blood cells originate from

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12
Q

HSC maturing

A

Cytokines induce HSC to mature - Colony-Stimulating Factors (CSFs)
● Move around body, travel through circulatory systems
● Always found in normal blood increase during infections
● Some reside in various tissues

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13
Q

general categories for cells of the immune system

A

● Red blood cells (erythrocytes) carry O2
● Platelets (from megakaryocytes) involved in clotting
● White blood cells (leukocytes) important in host defenses

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14
Q

what are the 4 types of Leukocytes (white blood cells)

A

● Granulocytes
● Mononuclear Phagocytes
● Dendritic Cells
● Lymphocytes

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15
Q

granulocytes

A

contains cytoplasmic granules

● Neutrophils highest numbers, engulf and destroy bacteria,
other material (phagocytes)
● Basophils involved in allergic reactions, inflammation
– Mast cells similar; found in tissues, release histamines
● Eosinophils fight parasitic worms
– Also involved in allergic reactions

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16
Q

Monocytes

A

● Comprise mononuclear phagocyte
system (MPS)
● Monocytes (circulate in blood) and
cell types that develop as they
leave blood stream
● Dendritic cells and Macrophages
differentiate from monocytes

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17
Q

Lymphocytes

A

● Responsible for adaptive immunity
● B cells, T cells - specific in recognition of antigen
● Generally reside in lymph nodes, lymphatic tissues
● Natural killer (NK) destroy certain types of cells

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18
Q

Phagocytosis

A

the ingestion and digestion of foreign
substances including bacteria.

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19
Q

what are the 2 main types of phagocytic cells

A

these cells engulf and destroy pathogens, in mammalian body

  • Neutrophils circulate in the
    blood
  • Macrophages migrate
    through the body or reside
    permanently in organs and
    tissues (slide 19)
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20
Q

Toll-like receptors: TLR

A

TLRs recognize fragments of
molecules characteristic of a set
of pathogens.

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21
Q

Inflammatory response

A

as pain and swelling, is brought
about by molecules released upon
injury or infection.

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22
Q

Mast cells

A

immune cells found tissues, release histamine, which triggers blood vessels to dilate and become more permeable (part of inflammatory response)

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23
Q

Local inflammatory response

A

1.Mast cells release histamines.
Capillaries dilate.

2.Neutrophils and anti- microbial
peptides enter tissue.

3.Neutrophils digest
pathogens and cell debris.
Tissue heals.

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24
Q

Inflammation - Cascade of events

A
  1. Dilation of small blood vessels
    ● Greater blood flow (heat, redness); slower flow rate
    ● Leakage of fluids (swelling, pain)
  2. Migration of leukocytes from bloodstream to tissues
    ● Endothelial cells “grab” phagocytes, slow them down
    ● Phagocytes squeeze between cells of vessel (diapedesis)
  3. Clotting factors wall off site of infection
  4. Dead neutrophils, tissue debris accumulate as pus
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25
Q

what causes inflammation?

A

Tissue damage results in inflammation
● Purpose is to
○ contain site of damage,
○ localize response,
○ eliminate invader
○ restore tissue function

26
Q

what are the 5 signs of inflammation

A

Results in 5 signs
○ swelling,
○ redness,
○ heat,
○ pain,
sometimes loss of function

27
Q

Cardinal signs of inflammation

A
  1. Rubor (redness) - increased blood flow
  2. Tumor (swelling) - exudation of fluid
  3. calor (heat) - increased blood flow, exudation of fluid, release of inflammatory mediators
    4.Dolor(pain) - stretching of pain receptors and nerves by inflammatory exudates, chemical mediators
  4. Functio laesa (loss of function) - pain, disruption of tissue structure, fibroplasia and metaplasia
28
Q

local vs systemic inflammation

A

Acute inflammation
● short term
● mainly neutrophils
● macrophages clean up damage by ingesting dead cells and debris

If acute fails

Chronic inflammation
● macrophages, giant cells accumulate,
● granulomas form

29
Q

Fever - an important host defense mechanism

A

Strong indicator of infectious disease, especially bacterial
● Temperature-regulation center in brain normally holds at 37°C but raises during infection in response to pyrogens (fever inducing substances)
● Growth rates of bacteria optimized for 37°C typically drop sharply above optimum, allows more time for defenses
● Moderate temperature rise increases rates of enzymes
● Enhances inflammatory response, phagocytic killing, multiplication of lymphocytes, release of attractants for neutrophils, production of interferons and antibodies, release of leukocytes from bone marrow
● White blood cells (macrophages) release chemicals that increase body’s temperature
● Divert blood from superficial blood vessels to body core – increase To
● 102-104oF (39-40oC)

30
Q

Adaptations - Evasion of Innate Immunity by Pathogens

A

Modifying their surface to prevent recognition or phagocytosis

  • Streptococcus pneumonia (meningitis) - outer capsule

Resisting breakdown following phagocytosis

  • Mycobacterium tuberculosis -Tuberculosis (TB), another such disease, kills more than a million people a year
31
Q

Adaptive Immunity

A

aka Acquired immune response
● activated later
● slow response
● Relies on lymphocytes

32
Q

Receptors provide pathogen-specific recognition (what cells relate to this)

A

The adaptive response relies on two types of
lymphocytes, or white blood cells:

● T-cells - mature in the thymus, above the heart
● B cells -mature in bone marrow

33
Q

What are antigens?

A

● substances that can elicit a B or T cell response
● T or B cells bind to antigens via antigen receptors specific to part of one molecule of that pathogen.
● The small, accessible part of an antigen that binds to an antigen receptor is called an epitope.

34
Q

Antigen Recognition by B Cells and Antibodies

A

Each B cell antigen receptor is a Y-shaped molecule
● 2 identical heavy chains
● 2 identical light chains.

2 regions
● Constant (C) regions of
the chains vary little
● Variable (V) regions
differ greatly. Provide
antigen specificity.

35
Q

Binding of an antigen activated B cells.

A

● B cell binds to epitope
● This gives rise to cells that secrete a soluble form of the protein called an antibody or immunoglobulin (Ig).
● Different Ab recognize different epitopes

36
Q

T cell antigen receptor

A

T cells bind to antigen fragments
displayed or presented on a host
cell.

These antigen fragments are
bound to cell-surface proteins
called major histocompatibility
complex (MHC) molecules.

MHC molecules are host
proteins that display the antigen
fragments on the cell surface.

37
Q

Adaptive immunity has 2 components

A

the humoral immune response: (b cell) protects blood

the cell-mediated immune response: (t cell) destroy infected host cells

38
Q

Cytotoxic T cells (type of T cell)

A

–TC induces apoptosis: proteases, cytotoxins (perforin)
–Releases cytokines to alert other cells
–Example - CD8

39
Q

Helper T cells (type of T cell)

A

–Activates macrophages – giant cells
–Activate B cells
–Produce cytokines to direct and support T cells
–Example - CD4
CD4 is receptor for HIV, which infects TH
cells

40
Q

Natural killer cells (type of T cell)

A

–Killing of infected cells tagged with antibodies
–Secrete IFN-gamma that stimulates macrophages

41
Q

Cytotxic T cells

A

use toxic proteins to kill cells infected by viruses or other intracellular
pathogens before pathogens fully mature

Activation requires:
● signals from helper T cells
● interaction with an antigen-presenting cell (APC). Fragments of foreign proteins produced in infected host cells associate with class I MHC molecules and are displayed on the cell surface, where they can be recognized by activated cytotoxic T cells.

42
Q

What do T-Helper Cells do (steps)

A

activates humoral and cell-mediated immune responses.
1. a foreign molecule must be present that can bind specifically to the antigen receptor of the helper T cell.
2. this antigen must be displayed on the surface of an antigen-presenting cell (APC) ie dendritic cell, macrophage, or B cell.

43
Q

Activation of B Cells

A

Activation of B cells involves helper
T cells and proteins on the surface
of pathogens.

When an antigen binds a B cell, the
cell takes in a few foreign molecules
by receptor-mediated endocytosis.

The class II MHC protein of the B
cell then presents an antigen
fragment to a helper T cell, a
process that is critical to B cell
activation.

44
Q

Antibody Function

A

● Antibodies do not kill pathogens; instead, they mark pathogens for
inactivation or destruction.
● In neutralization, antibodies bind to viral surface proteins,
preventing infection of a host cell.
● Opsonization - promotion of phagocytosis

45
Q

Activation of B cells

A

slide 46

46
Q

Humoral and Cell-Mediated Immune Responses

A

Both the humoral and cell-mediated responses can include primary and secondary immune responses.
Memory cells enable the secondary response.

47
Q

Immunological Memory

A

Immunological memory is
responsible for long-term protections against
diseases.

48
Q

Primary immune response

A

represents the first exposure to a specific antigen

a clone of lymphocytes

49
Q

Secondary immune response

A

memory cells facilitate a faster, more efficient response

50
Q

types of adaptive immunity

A

slide 54

51
Q

immunization

A

Passive artificial
The projection provided by a second immune
response provided the basis for immunization.

Antigens are artificially introduced into the body to generate adaptive immune response and memory cell formation.

Immunizations are carried out with vaccines,
preparations of antigens from many sources.

Vaccination programs have been successful
against many infectious diseases.

52
Q

Not all cells have the saem genome

A

slide 59 and 60

53
Q

Generation of B and T Cell Diversity

A

● By combining variable elements, the immune
system assembles millions of different antigen
receptors from a small number of parts.
● An immunoglobulin (Ig) gene encodes the light
chain of the B cell receptor.
● Many different chains can be produced from the same gene by rearrangement of the V, J, and C regions.

54
Q

Immunoglobulin (antibody) gene rearrangement

A

slide 62

55
Q

adult stem cells

A

Many early embryos contain stem
cells capable of giving rise to
differentiated embryonic cells of any
type.

Adult stem cells can generate
multiple (but not all) cell types and
are used in the body to replace
nonreproducing cells as needed. (slide 64)

56
Q
  1. Adaptive immunity is blocked or misregulated (allergies)
A

Exaggerated
(hypersensitive)
responses to
certain antigens
called allergens.

57
Q

Adaptive immunity is blocked or misregulated (autoimmune disease)

A

● Immune system is active against particular
molecules of the body
● Loss of self-tolerance has many form
○ Lupus - histones and DNA released by the normal breakdown of body cells. These self-reactive antibodies cause skin rashes, fever, arthritis, and kidney dysfunction.
○ Type 1 diabetes - insulin-producing beta cells of the pancreas
○ Multiple sclerosis - myelin sheaths that encase many neurons

58
Q

Adaptive immunity is blocked or misregualted (HIV Virus)

A

slide 69 ad 70

59
Q

natural immunity:

A

-natural immunity: (innate) like allergies
recognition of traits shared by broad ranges of pathogens, using a small set of receptors

rapid response

60
Q

acquired immunity:

A

active or passive
recognition of traits specific to particular pathogens, using a vast array of receptors

slower response

Pob 1 (10 decks)

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