Class 1 Flashcards
What is the immune system?
• Bodies system that defends against foreign invaders
• ex. bacteria, viruses, other organisms, foreign bodies/substances, abnormal molecules and cells that develop abnormally in body (cancerous cells).
What is immunity?
Protection from disease and infectious disease based on capacity to recognize foreign invaders (non-self).
What is immune response?
Collective, coordinated response of the cells
and molecules of the immune system.
Problem occurs when the response to invader is …
• excessive = allergies, hypersensitivity or
• when self tissue is perceived as foreign or dangerous = auto-immunity.
What is a microbe?
Type of microorganism that is too small to see with the united eye; ex. bacteria, viruses, fungi.
What is a pathogen?
Microbe that causes disease
What is a antimicrobial substance?
Tends to kill or damage microbes
What is an antigen?
large molecules (usually proteins or polysaccharides) on cell surfaces that elicit specific responses from hosts; can be on self-cells, that are toxic or diseased, and foreign cells, invaders from outside world.
What is an epitope?
Part of an antigen molecule to which an antibody attaches itself which can be used as identifier and binding site by host immune cells.
What is an antibody?
Protein in immune system responsible for binding to an epitope and initiating destruction of associated organism.
What is the lymphocyte?
White blood cells
What is a phagocyte?
Means “to eat”
What is the neutrophil?
WBC’s that help heal tissue and infection by attacking antigens. Circulate in blood, but die after they attack.
What is the macrophage?
Larger WBC’s that attack antigens. Do not die after attacking antigens.
What are natural killer (NK) cells?
Patrol blood and lymph. Can kill your own cells without using an APC.
What are immune responses?
Collected coordinated response of cells and molecules of immune system to protect against infectious disease.
What are the two responses of the immune system?
1) Innate Response
2) Adaptive Response
What is the innate response?
-something that we are born with
-non-specific
-initial line of defence
-effective barrier to microbes
• rapid, early response
• always the same (non-specific)= Inflammation, fever, etc
• primarily reacts to microbes
• relies on phagocytes and antimicrobials
• includes external physical barriers like skin and mucous membranes
• fairly easy for microbes to adapt to it
• stimulates adaptive responses
What is the first line of defense?
Skin and mucus membranes
What is the second line of defense/internal defences (aka natural/native)?
Antimicrobial substances, natural killer (NK) cells, and phagocytes.
What is the adaptive response (aka specific/acquired)?
-specific response
-develops with exposure to various organisms and substances that it finds threatening
-very effective
• slower to kick in
• develops in response to specific attributes of an invader
• works with innate response system to enhance
reactivity
• attacks microbes and antigens
• generates immunologic memory, meaning that
subsequent exposures lead to a more rapid response
What are immune cells?
Primary cells of adaptive immunity are B-Lymphocytes (B-cells), and T-Lymphocytes (T-cells).
What two things do lymphocytes do?
1) Act as regulator cells = assist in controlling and
orchestration of immune response (ie. by activating other cells).
2) Act as effector cells = kill and eliminate microbe or antigen.
What are accessory cells?
Accessory cells are phagocytes (macrophages, neutrophils,
eosinophils) that kill or break apart an invader.
What are dendritic cells?
Present antigens and epitopes to killers.
Humoral Immunity = ____________________________________.
High number of immune cells and other immune materials (like antibodies) circulating in blood and lymph.
Immune cells can be located in various tissues and organs such as?
• Lymph nodes
• Bone marrow
• Thymus
• Tonsils
• Spleen
• Skin
• Mucosa
• Vital organs
When immune cells are signal by presence of microbes or antigens, or by other immune cells, what do they do?
Reproduce to create populations (clones) of targeted cell types.
What are the B-Cells?
-Key players in humoral immunity
-Very good at recognizing microbes and antigens (assisted by T-helper cells).
-Recognizes friend from foe
-Produce antibodies
B-Cells are activated when?
It binds to its associated antigen.
When B-Cell is activated it selects type of clone needed, which are either?
• plasma cell
• memory cell
What are plasma cells?
When fully matured they produce and secrete antibodies (aka immunoglobulins) designed for specific antigen which then bind to epitopes and either kill or neutralize invader, or present them to T-cells or macrophages.
What are memory cells?
Do not participate in initial immune response. Stay in body to respond quickly if a secondary exposure to same antigen occurs.
How many types of antibodies can be passed down from mother to child, and what are they?
• Only 2 types of antibodies that can be passed from mother to child.
• IgG more common
• IgA is only found if child is breastfed
what is IgA antibody?
- Found in mucus, saliva, tears and breastmilk. Protect against pathogens.
• Predominant in saliva, tears, nasal, GI, and respiratory secretions
• Found in breast milk (protects neonates)
• Blocks entry of organisms to eyes, gut, respiratory, and urinary tracts
• Protects mucosa
What is IgD antibody?
*Part of the B cell receptor. Activates, basophils and mast cells.
- Present in small amounts in serum
- Needed for B-cell maturation
What is IgE antibody?
*Protect against parasitic worms. Responsible for allergic reactions.
- Found in tiny amounts in plasma
- Binds to mast cells and liberates histamine and other inflammatory substances
- Attracts eosinophils
- Responds to parasites
- IgE overreaction -> allergic/hypersensitivity reactions, asthma, etc.
- Can be a genetic predisposition to producing excess IgE
What is IgG antibody?
*Secreted by plasma cells in blood. Able to cross placenta into fetus.
• 75% of antibodies are IgG
• Only Ig to cross the placenta (protects neonates) -> passive immunity in newborn
• Diffuses readily out of vascular zone into tissues
• Antiviral, antitoxin, antibacterial actions
• Activates killer cells
• Activates the complement system
What is IgM antibody?
*May be attached to surface of B-Cell or secreted into blood. Responsible for early stages of immunity.
• Doesn’t leave blood or lymph
• Early responder
• First Ig formed after immunization or initial exposure to pathogen
• Activates complement system
• Forms natural ABO antibodies
What are antigen presenting cells?
-Cells bind to and/or break down antigens.
-Present epitopes on their surfaces, or alter antigen to make it more recognizable.
-B-cells, macrophages, and dendritic cells all act as presenting cells.
• Antigen presenting cells present antigens to T-cells. However, sometimes they are presented to phagocytosing cells
What are T-Cells?
-Responsible for cell-mediated/cellular immunity
-Work via cell-to-cell contact or by secreting messenger compounds that communicate with immune system cells
This will:
• Attract cells
• Prevent cells from leaving area
• Amplify effectiveness of cells
• Increase or decrease cell reactions
• Activate and regulate B-cells
• Signal natural killer cells
• Increase local blood flow to facilitate immune cell movement
• Determine if humoral or cellular immunity is needed
T-cells also:
• Activate mast cells and IgE’s in allergen responses
• Involved in rejection of foreign tissue grafts
• Control intracellular (viral) infections
• Kill tumor cells
N.B. T-cells are involved in differentiating between self vs. non-self recognition and reaction.
What are the three types of T-Cells?
• T-Helper Cells (aka CD-4 cells)
• Regulatory T-Cells (aka Tregs)
• T-Cytotoxic Cells (aka CD-8 cells)
What are T-Helper Cells (aka CD-4 cells)?
-upregulate
-key regulatory cells of immune system
-release various T-messenger compounds that activate and regulate activities of the other cell types
-activate B and T cells correctly depending on type of immune challenge
What are Regulatory T-cells (aka Tregs)?
-downregulate
-suppress/modify immune responses
-decrease immune cell production
-control mechanism to help ensure response matches situation, and that healthy self-cells are not killed
T-cytotoxic cells (aka CD-8 cells)
-destroy identified/presented antigens
-kill virus-infected cells by various means
-involved in attacking cellular problems that antibodies cannot influence
