Microbiology CH 13 Flashcards
What is the body’s ability to recognize and react to a specific invader?
Specific Immunity
Is specific immunity when the body reacts to the H1N1 influenza virus rather than the H5N8 influenza virus?
Yes
What are the 4 elements of specific immunity?
- It’s a ‘smart’ system
- It’s acquired and developed over time
- A response includes organs
- It’s triggered by specific antigens
What does it mean when the body has a ‘smart’ system?
Has a “memory” to respond rapidly to an infection the second time it happens
What does a response entail?
Includes B and T lymphocytes
What is anything that stimulates a specific immune response called?
Antigen
What is the 3D region of an antigen that is actually recognized by the immune system called?
Epitope
What part of the LPS (lipopolysaccharide) is recognized by the immune system?
Particular set of sugars on polysaccharide
O-Antigen
How many epitopes does an antigen have? What is it recognized by?
Multiple epitopes; recognized by different things
What type of antigens are found on invaders that exist outside host cells?
Exogenous antigens
What are 2 invaders with exogenous antigens?
- Bacterial infections
- Parasitic worms
How does the immune system encounter exogenous antigens/the invaders?
Encounters them directly
What type of antigens are found on invaders that exist inside body cells?
Endogenous antigens
What are 2 “invaders” with endogenous antigens?
- Viruses once they’ve entered the host cell
- Obligate intracellular parasites
Can the immune system detect endogenous antigens directly? Why?
No, because they’re not floating around in the body
What must happen for endogenous antigens to be detected by the immune system?
Antigens must be incorporated into the host cell membrane
What antigens are naturally found on host cells?
Autoantigens
Why do immune cells need to ignore autoantigens?
Because autoantigens label cell as “self”
What happens when immune cells recognize autoantigen cells?
Immune cells that recognize autoantigens are destroyed
What happens if immune cells DON’T destroy autoantigens?
Leads to autoimmunity
What are proteins used by the immune system to identify, bind to, and help attack invading organisms called?
Antibodies
What are antibodies composed of? What types of ‘chains’ are there and how many?
Four polypeptides connected to each other by disulfide bridges
What do antibodies look like?
“Y” shape, stem, hinge, and 2 arms
What part of the antibodies are constant? Which parts are variable?
Constant - Stem, hinge, lower part of arms
Variable - Upper parts of arms
What is another name for antibodies?
How many different types are there?
Immunoglobins
5 different types
What happens when an antibody neutralizes a pathogen?
1000 antibodies bind to a virus, making its surface crowded and makes it unable to attach to target
What happens when an antibody agglutinates a bunch of cells together?
Each antibody can bind to 2 cells, creating a clump
What happens when an antibody oxidizes a target?
Involves recruitment of other proteins
How can antibodies eliminate threats indirectly?
Marks invaders for targeting by immune cells
What is one of the types of leukocytes (WBCs) that is made by stem cells in bone marrow?
Lymphocytes
Which Lymphocytes mature in bone marrow and which ones mature in the thymus?
Bone Marrow - B Lymphocytes
Thymus - T Lymphocytes
Where are B Lymphocytes mainly found? Where do a few circulate?
Mainly found in Lymphatic Organ, few circulate in the blood
How many different B cells does an individual have present at any given time?
10^11
When do B Lymphocytes activate?
Activates when a ‘correct’ antigen has been recognized
When activated, what are B Lymphocytes known as?
Plasma Cells
What 2 things does a plasma cell do?
- Makes lots of copies of itself
- Makes and secretes many copies of specific antibody (the one that recognized the ‘correct’ antigen)
Where do T Lymphocytes (T cells) circulate?
Blood and lymph
How many different types of T cells are present at any given time for any individual?
~10^11
What does different types mean (for T cells)?
Have receptors that recognize different (random) antigens
How are T cells activated?
By binding to an antigen that is presented on an MHC molecule on a host cell
What 2 things do activated T cells do?
- Makes lots of copies of themselves
- Secrete cytokines that affect other cells
What cells are known as T8 or CD8 cells?
Cytotoxic C cells
When Cytotoxic C cells are active, what is secreted? What do they do and what happens?
Secrete cytokines that trigger replication
(Makes more copies of that particular ‘model’ of Tcyt cell)
When Cytotoxic C cells are active, how do they kill bad cells? What type of cells does this include?
Kills bad cells by inducing apoptosis
- Cancerous cells or tumors
- Cells infected by a virus of bacterium
What cells are known as T4 or CD4 cells?
Helper T cells
When Helper T cells are active, what is secreted? What do they do?
Secrete cytokines to help activate B cells and Tcyt cells
When Helper T cells are active, what do they differentiate into? What does each one assist?
Differentiates into:
Type 1 (TH1) assist Tcyt cells
Type 2 (TH2) assist B cells
What is a type of protein that is found on the surface of body cells called?
Major Histocompatibility Complex
What does MHC allow body cells to do?
Allows body cells to alert the immune system that there is an invader present
How does MHC allow the body cells to alert the immune system?
Holds antigens on surface of cell to ‘show’ it to T cells
Where is MHC-I found? This means everything except what kind of cells?
Found on membranes of all nucleated body cells
Everything except RBCs
What kind of antigens does MHC-I display?
Endogenous antigens
What cell does MHC-I “present” to? What’s the message?
- Presented to Cytotoxic T cells
- Message: “Look what I made”
What’s the 2 possible meaning of MHC-I’s presentation? What is the result of each one?
- Meaning: “There is an intracellular pathogen inside the cell”
- Result: Activation of cell-mediated immune response, where T-cell kills the infected body cell
- Meaning: “There isn’t any pathogen, everything is fine”
- Result: No immune response
Where is MHC-I made? What happens while its in the ER?
Made at RER
Stuff from inside cell attached to it while in ER
What packages MHC-I? What is MHC-I carrying and where does it go?
Golgi body packages MHC-I carrying epitopes, and sends it to cell membrane
What happens when the vesicle fuses?
MHC-I/epitope complex is presented to the outside
In what cells is MHC-II present? What are 2 examples of these cells?
Antigen-presenting cells (APCs)
1. Phagocytic cells like macrophages
2. B Lymphocytes
What antigens does it display and to what cells?
Exogenous antigens to helper T cells