Flashcards in Chapter 8 - Immune System Deck (61)
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
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?
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
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:
(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?
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
*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?
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
Involved in allergic responses
Also releases HISTAMINE and initiates inflammation
What is a mast cell?
Similar to basophil
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