Immune System Flashcards
What do Microbes do for our immune system?
- Protect us from diseases
- Occupy space, inhibiting bacteria occupancy
- Train bodily systems to differentiate from good and bad bacteria
How do viruses help our immune system?
Vaccines - Activation of immune system by exposure to “Dead” viruses (Smallpox, Polio)
Explain the equilibrium between Infection and Immunity.
Increased amount of pathogens will force immune system to increase host defenses and “balance out” the system.
What occurs when there is a decreased immune response in the presence of Pathogens? What circumstances could provide this decreased response.
Increased risk of infection
Caused by:
Radiation
Chemotherapy
HIV
What occurs when there is an immune response without the presence of pathogens?
Imbalance of immunity and infection and immunity cells can target host cells. (Autoimmune disease)
Differentiate between Innate and Adaptive Immunological response.
Innate - (Non-specific), generalized and expressed as a process of inflammation. Response within hours, Ø memory, and responses to many pathogens
Adaptive - Reacts to specific pathogens, and has a memory. Typical response within a few days. One cell can only recognize one pathogen.
What is the intrinsic immune system? What is it comprised of?
It is the anatomical and physiological barrier against pathogens. Made from:
Skin
GI Tract
Nasopharynx & Eyes
Explain how the GI tract provides immunity to pathogens.
Peristalsis - removal of wastes
Low pH of stomach - Kills pathogens
Bile salts
Explain how to Nasopharynx & Eyes are a protective against pathogens.
Saliva, Mucous and tears - wash away pathogens and contains Lysozymes - destroy bacterial cells.
How does lysozyme destroy Pathogenic cells?
Cuts between NAG and NAM in petidoglycan layers
Adaptive Immunity has five distinct attributes:
Explain each.
[S.I.C.U.M.] (Sick em’)
Specificity: acts only against specific pathogen of specific molecular shape
Inducibility: Adaptive immunity cells are activated in response to pathogen
Clonality: Adaptive immunity cells proliferate to form multiple generations of almost identical cells (Clones)
Unresponsiveness to Self: Does not act against cells of the host
Memory: Remembers specific pathogens and adapts faster and more effectively to subsequent exposures.
What are the two types of lymphocytes of the adaptive immune system and where do they mature?
B and T lymphocytes
B cells are created and mature in Bone Marrow and reside in the Spleen, in MALT (Mucosa associated lymphoid tissue), and lymph nodes
T Cells are made in Red bone marrow then travel to the Thymus in the chest for maturation
(T = Thymus, B = Bone)
What are antigens?
Substances that are toxic and induce a specific immune response
What are antibodies? What do they do?
Protein molecules produced by plasma cells in response to an antigen and can bind specifically to that antigen.
What does every B Cell have that allows the cell to identify a specific pathogen?
Antibodies
What is Neutralization?
When antibodies neutralize toxins by binding to their attachment molecules
What is Agglutination?
When antigens complete a complex of pathogens to be phagocytized by phagocytes
What is Precipitation?
When antigens attach to molecules and creates a complex to be phagocytized by phagocytes
What is clonal selection?
When an antigen triggers an immune response from specific immunological cell, the cell then divides and becomes multiple plasma cells which release antibodies to free float and fight the same antigen in the future.
Differentiate between the 1st and 2nd exposure and how it affects clonal selection.
During the 1st exposure to pathogen - immune response is small
During the 2nd exposure - secondary immune response is much faster and larger than the 1st. Due to immunological memory, and many antibodies acting rapidly. Initiated from memory cells
What is IgM and IgG?
IgM are memory cells that were triggered from an initial infection.
IgG are antibodies that typically remain in lymph nodes until infection of the same antigen
Who Was Jenner and what did he do?
English Physician who created first safe small-pox vaccine. Did this by exposing people to similar virus that was transmitted by cows; this virus was much less harmful but exposure provided immunization against smallpox.
What is Herd Immunity?
A type of immunity that occurs when the vaccinated population provides protection to unvaccinated people.
Done by reducing the amount of people the virus can spread to - reducing hosts. (Smallpox)
What is a live-attenuated vaccine?
Weakened pathogen that lacks the ability to infect the host, but has the ability to replicate. Typically the pathogen is adapted to another species and is no longer affective at causing disease in humans, but still acts as immunization against human-pathogenic strains.
Explain the attenuation process of the rabies vaccine for humans and dogs.
Rabies was attenuated in rabbits, decreasing the virulence of rabies against humans and canines. This adapted pathogen provides immunity against rabies and is no longer virulent to dogs or humans.
What is the “Rule” of pathogenic attenuation?
Alive: Virus must be alive and able to replicate to initiate a response in the host
What are some examples of attenuated vaccines?
MMR
Influenza (since 2003)
Polio
Varicella Zoster (Chicken Pox-Shingles)
WHat are Killed/subcellular vaccines?
Pathogens inactivated by chemical procedures. They are no longer pathogenic or have the ability to replicate.
What are some examples of Killed/subcellular vaccines?
Influenza
Polio (Salk)
Hep A
Modern rabies Vaccine
Why can the rabies vaccine be used post-exposure to virus?
Rabies has a long incubation period, which can prolong immune response. Vaccination after exposure can increase the systemic antibody production and fight the infection more effectively.
What are Toxoids?
Inactivated toxins used as a vaccine.
Diphtheria, Tetanus
What are small fragments in vaccines?
Taking proteins from a virus by “Fractionation” and creating vaccines from subunit.
(Hep B, HPV)
What is natural Passive immunity?
Systemic transfer of IgG (antibodies) from natural sources. (I.e. Breast feeding, placental transfer).
WHat are the advantages and disadvantages of Passive immunization?
Advantages:
Immediate protection against pathogens
Disadvantages:
Ø memory cells (no long term protection)
Risk of infections from host with unknown pathogens (HIV, HEP B & C)
Serum Sickness (allergic reactions)
Phagocytes of the epidermis are called: A/ Dendritic cell B/ Goblet Cell C/ Capsulated Macrophage D/ Microglial Cell
A/ Dendritic Cell
The complement system involves:
A/ The production of antigens and antibodies
B/ Serum proteins involved in nonspecific defences
C/ A set of genes that distinguishes foreign cells from bodily cells
D/ The elimination of undigested remnants of microorganisms
B/ Serum proteins - non-specific defenses
Interferons A/ Do not protect the cell that secretes them B/ Stimulate the activity of macrophages C/ Cause muscle acts, chills, and fever D/ B and C E/ All the above
E/ All the above
What are interferons and what do they do?
Protein molecules that inhibit the spread of viral infections by inhibiting their growth.
Which are initiated last? A/ Gamma Interferons B/ Alpha interferons C/ Omega interferons D/ Beta Interferons
A/ Gamma interferons - days after infection, they stimulate macrophages and neutrophils
The body recognizes antigens by their three-dimensional shaped regions known as:
Epitopes
What is the significance of major histocompatibility antigens (MHA)?
MHAs can distinguish the difference between host cells and non-host cells
What is the function of Cytotoxic T cells (CD8)?
Directly kill other cells
What is the function of Helper T Lymphocytes?
A/ They Attach to cytokines which trigger cellular apoptosis
B/ They release cytokines which triggers Apoptosis
C/ They release Cytokines that regulate immune functioning
D/ They are derivatives of cytokines that trigger immune responses
C/ Release cytokines that regulate immune functioning
What is the function of regulatory T cells?
Repress immune responses and prevent autoimmune diseases
What is the Single-most major function of B Cells?
Secretion of Antibodies
What is a B Cell Receptor (BCR)?
A receptor on a B cell that contains specific polypeptide chains that only respond to a specific antigen
What occurs when a BCR encounters an antigenic epitope?
The B cell undergoes division, giving rise to identical offspring that secrete immunoglobulins (Antibodies) into the blood or lymph.
How do Plasma cells come into being?
Plasma cells are the Offspring of an activated B cell that secrete antigens (immunoglobulins)
Define Neutralization.
IgA molecules neutralize a toxin by binding to a critical portion of the toxin so that it can no longer harm to body (Blocking system = Neutralization).
What happens during Opsonization?
Antibodies stimulate phagocytosis, by binding to a pathogen then signalling phagocytes which phagocytize the antibody along with the antigen.
Imagine the 0 in opsinization is a mouth swallowing the pathogen and antigen
What is Agglutination?
When multiple antibodies bind to multiple antigens and create a large cluster of antigens. This clustering can inhibit pathogenic activity and become phagocytized or filtered out by the spleen.
This Immunoglobulin is secreted during the initial stages of an immune response.
IgM
This is the most common and longest-lasting Immunoglobulin in the body, accounting for 80% of all immunoglobulins.
IgG
Explain what occurs after a Dendritic cell encounters an antigen and travels to the lymphatic system?
Travels to the lymph node where Helper T Cells who have matching epitopes to the antigen attach to each other. Helper T cells need further stimulation to prevent accidental inducement of an immune response. The original Dendritic cell then sends a second signal to initiate proliferation of the Helper T Cell into clones.
After the Helper T Cell divides in response to presentation of the antigen, it does this…
Binds to B cells that have matching epitopes. B Cell activation then occurs, causing the B Cell to proliferate into two types of cells: Memory and Antibody-secreting plasma cells. Most daughter cells become plasma cells.
What is the purpose of memory cells?
Memory cells retain their BCR (B cell receptor) and wait in lymphatic tissues until a future exposure of the compatible epitope occurs again.
Antibodies function to: A/ Directly destroy foreign organ grafts B/ Mark invading organisms for destruction C/ Kill intracellular viruses D/ Directly promote cytokine synthesis
B/ Mark for destruction
Which of the following lymphocytes predominates in the blood? A/ T Cells B/ B Cells C/ Plasma Cells D/ Memory Cells E/ All are equal
A/ T Cells
This major antibody is found on the surfaces of of walls of the intestines and airways and is secretory. A/ IgG B/ IgA C/ IgG D/ IgE
B/ IgA
In Which of the Following sites can B Cells be found? A/ Spleen B/ Lymph Nodes C/ Red Bone Marrow D/ Intestinal Wall E/ All the above
E/ All the above
