Topic 13: The Body's Defences (part 2) Flashcards
What is the lymphatic system
a part of the immune system involving one way lymph vessels that carry lymph from tissues back to the blood
what is lymph
fluid containing WBCs, plasma, and wastes from blood
What are lymph nodes
receive and filter lymph and interact with immune cells
What is agglutination
Antibodies that bind multiple antigens (clump together) increases chances of phagocytosis & reduces solubility
B-cells
SECRETE ANTIBODIES
mature in bone marrow then concentrate in lymph nodes and spleen
divide into Plasma Cells and Memory B- Cells
What is a vaccination
Provides immunity from a pathogen by forcing the body to make memory B cells and/or T cells
Describe the humoral immune response
B Cells secrete antibodies; antibodies destroy microbe
2 steps of a typical Humoral Response
- Dendritic cell engulfs an antigen; and presents it on its cell surface
- In a Lymph node, a B cell attaches and recognizes the Ag
- B cell is activated and memory cell is made
What are antigens
Specific molecules (usually foreign) recognized by antibodies
What is neutralization
Neutralize a toxin or pathogen
so that it is unable to bind host cells/tissues
What are T-cells and where do they mature
lymphocytes that mature in thymus
what are the four types of T-cells?
Cytotoxic T-Cells, Natural Killer T-Cells, Helper T-Cells, Regulatory T-Cells
Function of cytotoxic T-cells
Kill other cells with specific antigens
Function of Natural killer T-cells
Can recognize and destroy cells infected by viruses
Function of helper T-cells
Secrete messages (cytokines) that regulate/activate other immune cells
Function of regulatory T-cells
Repress and prevent overactivity of immune cells (from attacking self)
What are attenuated vaccines
Uses genetically altered pathogens that are no longer virulent, but can still reproduce
What is the cell-mediated immune response
Does not involve antibodies; is the activation of phagocytes and T Cells
3 steps of a typical Cell-Mediated Response:
- Antigen on infected cell’s surface is recognized by T cell
- T cell gets activated by helper T cell
- T cell clones itself and becomes or recruits cytotoxic T cells
What is an antibody
a molecule which specifically recognizes and binds a particular epitope on an antigen
Describe ELISA
Enzyme-Linked ImmunoSorbent Assay
Used to detect the presence of an antigen or antibody in a sample
Four steps of ELISA
- Bind sample to microplate
- Apply specific antibody
- Apply 2nd antibody with an enzyme linked to it
- Add substrate; colour will develop if substrate is consumed
What is clonal deletion
The body eliminates self-reactive lymphocytes to prevent attack on self. (Failure can lead to auto-immune diseases).
Describe a conjugate vaccine
Vaccine attaches a poor antigen that is easily spotted by the immune system to a strong antigen to elicit a bigger immune response
What does opsonization do
stimulates phagocytosis by neutrophils/macrophages
What are lymphocytes
specific types of Leukocytes (WBC) that include B and T cells
What is a toxoid vaccine
Uses inactivated toxin as the vaccine
Describe the five features of adaptive immunity?
- Specificity
- Recognize a particular molecule (antigen)
- Inducibility
- Cells get activated only in response to specific pathogens
- Clonality
- Active cells duplicate themselves (clones)
- No response to self
- The immune system doesn’t attack its own body
- Memory
- The immune system remembers and reacts faster during a second exposure to pathogen
Describe the five components of adaptive immunity?
- lymphatic system
- antigens
- antibodies
- lymphocytes (B+T cells)
- chemical signals + mediators
- cytokines, interleukins + more chemical messengers that send messages between immune cells
Distinguish between antibody, antigen, and epitope.
antigen - used to recognize foreign things
antibody - bind to antigens
epitope - The specific region of an antigen which is bound by a specific antibody (there may be several per antigen)
Describe four functions of antibodies.
- opsonization
- induces phagocytosis
- antibody- dependent cellular cytokinesis
- non-phagocytotic killing mediated by natural killer cells, neutrophils and eosinophils
- active complement system
- enhances opsonization and lyses some bacteria
- agglutination
- clumping of pathogen creating large complex. increases recognition/phagocytosis
Compare and contrast humoral immunity and cell-mediated immunity.
humoral - small microbes, macromolecules
cell-mediated - large parasites, intercellular pathogens, tumors
Why is there no vaccine for the common cold?
Over 200 know strains!
Many of them mutate from season to season!
Why do we have a new flu vaccine each year?
Virus mutates and new strains arise each year requiring new vaccines
What are the four types of vaccines?
attenuated, killed/inactivated, subunit/conjugate, toxoid
killed/inactivated vaccines
microbe is killed or deactivated and cannot replicate or cause disease but can still train immune system (make memory cells)
Role of memory B cells
Memory B cells remain in the body to speed up the response if the same antigen reappears
