Chapter 8 - Immune System Flashcards Preview

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Flashcards in Chapter 8 - Immune System Deck (61)
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What do superantigens do?

(Proteins) cause the immune system to become nonspecifically over activated.

Leaves the body open to SUPERINFECTION (infection with other pathogens)


Innate versus adaptive immunity

Innate: defenses that are always present, non-specific

Adaptive: target a specific pathogen, specific. SLOWER but can mount a faster attack in subsequent infections


What are B-cells?

Where are they produces?

Where do they mature?

Produced in the bone marrow (leave bone marrow mature but naive)

Stored and activated in the SPLEEN

B cells turn into plasma cells to produce antibodies as part of adaptive immunity. Dissolve and act in the blood --> HUMORAL immunity


What are T-cells?

Where are they produced?

Where do they mature?

Produced in the bone marrow (immature)

Mature in the THYMUS, a small gland in front of the pericardium

The main agent of CELL-MEDIATED immunity because they coordinate the immune system and directly kill infected cells


What do lymph nodes do?

Filter lymph. Provide a place for immune cells to communicate and mount an attack.

B-calls can be activated in the LN as well


What is gut-associated lymphoid tissue?

Immune tissue located in proximity to the digestive system, which is a site of potential invasion by pathogens.

Peyer's patches (small intestine)
Lymphoid aggregates (appendix)


What happens in the spleen?

Storage for blood (good for use in case of hemorrhagic shock)
Filter for blood and lymph
Recycle iron
Site where immune responses can be mounted


What is hematopoiesis? Where does it take place?

The production of leukocytes (and red blood cells and platelets)
Takes place in the bone marrow

Hematopoietic stem cells gives rise to both granulocytes and agranulocytes


What do granulocytes have that agranulocytes don't?

Granules in the cytoplasm
These contain toxic enzymes and chemicals that can be release via exocytosis


What are three types of granulocytes?



What are some agranulocytes?
What does each do?

Antibody production
Immune system modulation
Targeted killing of infected cells
Phagocytic cells in the blood
Monocytes when in tissue!
->Microglia in CNS
->Langerhan's cells in skin
->osteoclasts in bone


What is a complete blood count (CBC)?

What does high # of neutrophils mean?

What does high # if eosinophils mean?

CBC is a blood test that counts the number of red blood cells, platelets, and white blood cells.

When ordered WITH A DIFFERENTIAL each type of blood cell is counted.

90% neutrophil means maybe bacterial infection (normally 40-80%)

20% eosinophils might mean parasitic infection (normally 1-6%)


What are defensins?

What other secretion from this organ?

An antibacterial enzyme found on the skin

Sweat is anti microbial


What are lines of defense in the respiratory system?

Cilia and mucus (cilia push particles up the oropharynx; mucus traps particles)


What is lysozyme?

A nonspecific antibacterial enzyme
Secreted in tears and saliva


Innate immunity in the GI tract
(2 ways)

Stomach secretes ACIDS (kills most pathogens)

Gut is COLONIZED by bacteria already (potential invaders can't compete)


What is complement?
What are the two pathways?

Consists of proteins in the blood that can have a nonspecific defense AGAINST BACTERIA

Complement proteins punch a hole in bacterial cell wall, makes them osmotically unstable.

Classical pathway (binding of antibody to a pathogen)
Alternate pathway (doesn't require antibody)


What are interferons?

Protein that prevents viral replication and dispersion.

Produced by cells that have been infected with VIRUSES.

Makes nearby cells less permeable: harder for virus to infect them, and has them reduce production of proteins (both viral and cellular)

Upregulate MHC class 1 and 2, aka increased antigen presentation and better detection of infected cells.

INTERFERONS = flu-like symptoms of viral infection


What 3 things does an activated macrophage do?

1. Phagocytizes the invader via endocytosis (eats it)

2. Digests the invader using enzymes

3. Presents little pieces (mostly peptides - aka antigen) using MHC


What do MHC molecules do?

Bind with the antigen and carries it to the cell surface

By holding out the antigen, the cells of the ADAPTIVE immune system can recognize it and act accordingly.


MHC class 1 versus MHC class 2

MHC class 1:
All nucleated cells
Can present any protein, but useful to detect presence of pathogen (because then unfamiliar protein is presented)
ENDOGENOUS PATHWAY - antigen comes from inside the cell

MHC class 2:
Antigen-presenting cells
(macrophages, dendritic cells, some b-cells, some activated epithelial cells)
EXOGENOUS PATHWAY - bc the antigens originated outside the cell


What is a pattern recognition receptor?

Toll-like receptors

Macrophages and dendritic cells have them

Can recognize the category (bacteria, virus, etc) of the invader and recruit the right immune cells.


What is a natural killer cell?

A nonspecific lymphocyte

Detect the downregulation of MHC
Induce apoptosis

*eg: cancer cells down regulate MHC expression


What is a neutrophil?

Most populous, short-lived (5 days)
Phagocytes that target BACTERIA (like macrophages)
Track bacteria using Chemotaxis
Can also detect bacteria once they have been opsonized

Pus = dead neutrophils


What does it mean when an invader is opsonized?

It means that it has been marked with an antibody from a B-cell

(Antibody in the blood binds to the antigen, and attracts leukocytes to phagocytize it)


What is an eosinophil?

Red-orange granules

Involved in allergic reactions and parasites
Releases large amounts of HISTAMINE (an inflammatory mediator)

Release of histamine results in blood vessel dilation and increased leakiness of blood vessels


What is a basophil?

Large purple granules
Least populous

Involved in allergic responses
Also releases HISTAMINE and initiates inflammation


What is a mast cell?

Similar to basophil

Smaller granules
Exist in tissues, mucosa, and epithelium


What is humoral immunity?

Involves B cells

Involves the production of ANTIBODIES
May take up to a week to become fully effective

Antibodies are produced by by the B cells


Tell me about antibodies

Where are they found (3)

What do they do?

Aka immunoglobulins
They can be found on the surface of cells or can float freely in blood/chyle/air

Free floating antibodies:
1. Opsonization
(attach to antigen and attract leukocytes)
2. Agglutinate
(cause pathogen to clump together to be phagocytized)
3. Neutralize (block pathogens ability to invade tissue)

For cell surface antibodies:
1. Pathogen bind to b-cell to activate it
2. Formation of plasma and memory cells

For mast-cell antibodies:
1. Degranulation
(Exocytosis of granules, incl histamine, causing inflammatory allergic reaction)