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Immune System Concept Map, Types of T-Cells, Adaptive/Specific Defense…
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Types of T-Cells
Cytotoxic T-Cells:
- cells that can kill its target by inducing apoptosis similar to how NK cells can induce it. (21.3)
- More Cytotoxic cells can develop, overwhelming a virus' ability to cause anything. (21.3)
Helper T-Cells:
- secretes cytokines that enhance other immune responses. (21.3)
- Th 1 cells secrete cytokines that help regulate immunological activity and development of different cells. (21.3)
- Th 2 cells, act on B cells to drive their differentiation into plasma cells that make antibody (21.3)
Memory T-Cells:
- long lived immune cell reserved for future exposure to a pathogen (Key term)
- they act fast so a pathogen is often too overwhelmed to do anything (21.3)
Regulatory T-cells:
- suppress other T cell immune response; this is important because if clonal expansion during an immune response becomes uncontrolled, it can lead to an autoimmune disease (21.3)
Adaptive/Specific Defense System:
- specifically recognizes and makes a response against a wide variety of pathogen (21.3)
Two Main Branches:
- Cellular relates to how pathogen is dealt with On an intracellular level. The humoral relates to how pathogens are fought against on an extracellular level. ( T-Cell System Notes)
Cellular (T lymphocytes):
- T cells directly fight intracellular pathogens and cancer cells (T-Cell System Notes)
- T cells can enhance other immune responses by secreting cytokines, or kill target cells by inducing apoptosis. (21.3)
Humoral (B lymphocytes):
- B cells secrete antibodies to target extracellular pathogen (T-Cell system Notes)
- activate by binding to an antigen, differentiating into a plasma cells and spending most of their energy making antibodies. (21.4)
Immunoglobulin are secreted by B-Cells, which are antigen-specific proteins protecting the body by binding to foreign objects (Key terms)
3 important cell types
APCs:
- antigen-presenting cells perform antigen processing, enzymatically cleaving an antigen into smaller pieces. This fragment is brought to the cells surface and interacts with a MHC protein. This molecule causes a recognition of an antigen by a t-cell (21.3)
B-Cells:
- Mature in bone marrow and will become a plasma cell, devoting most of its time making antibodies until death (21.4)
- recognizes native, unprocessed antigens and does not require the participation of MHC molecules and antigen-presenting cells (21.4)
T-Cells:
- Mature in the thymus, These cells secrete molecules that regulate the immune system and can kill foreign cells, viruses, and cancer cells (Key terms)
- These cells often control a B-cell's immune response (21.3)
Target Antigens:
- molecules on a pathogen that the immune system does not recognize as one of its own. APCs can detect this and cleave the antigen and present it to other cells (21.3)
Primary Immune Response:
- the initial response to a pathogen (21.3)
- usually severe because it can take time for an initial adaptive immune response to a pathogen to be effective (21.3)
Secondary immune Response:
- immune response observed upon re-exposure to a pathogen, which is stronger and faster than a primary response (Key term)
- eliminates a pathogen before any damage can be done (21.3)
The Immune system:
A complex collection of cells and organs that destroy or neutralize pathogen (21.1)
Innate/Non-Specific Defense system:
- Rapid but non-specific, not always effective (21.2)
- It serves as our body's basic defense, not responding to specific infections, rather, they respond to broad ranges of pathogens (21.2)
1st line of defense:
-physical barriers of the body such as our skin, or mucosal surfaces; this includes our skin, stomach, and oral cavity (21.2)
- these barriers often destroy, prevent entrances, and can flush pathogens out before they establish themselves in a hospitable environment (21.2)
2nd Line of defense:
- The line of defense including Phagocytic cells and NK cells (21.2)
- Relates to Inflammatory Response, Mast cells release Histamine when detecting an injured cite, increasing blood flow and bringing immune cells to the site to kill pathogen (21.2)
Adaptive/Specific Defense System:
- Slow, but highly specific and effective in attacking a variety of pathogens (21.2)
- Antigens are recognized by receptors on B and T lymphocytes; the adaptive immune response to these antigens are so versatile they can respond to nearly any pathogen (21.3)
3rd line of Defense:
- Primary adaptive response, the immune system's response to the first exposure of a pathogen. Secondary adaptive response happens when there is re-exposure to the same pathogen, becoming stronger and faster (21.3)
- the cells that control the adaptive Immune responses are T & B lymphocytes. T cells tend to make the decisions, controlling immune responses and what the B cell responds to sometimes as well. (21.3)
Innate/Non-specific Defense System:
- relates to our barrier defense, one of the most basic defense mechanisms (21.2)
- the external surface our body, for example, works to keep out pathogens. Our saliva helps destroy bacteria by digesting their cell wall; these are the few examples of our innate defense (21.2)
First Line of Defense:
- physical and chemical barriers including our skin and mucosa (21.2)
- These barrier work to keep pathogens from entering our body (21.2)
Skin:
- Skin has keratinized cells that are too dry for bacteria to grow on (21.2)
- defends against abrasive activity due to contact with grit, microbes, or harmful chemicals (5.3)
- Sweat excreted from the skin as well as other skin secretions can contain toxic lipids and physically wash microbes away. (21.2)
Mucous Membranes:
- membranes that cover and line tissue exposed to the outside environment to protect it (key terms)
- our gastrointestinal tract, respiratory tract, eyes, ears, and nose have mucus layers to trap microbe and debris; they also facilitate their removal (21.2)
Second Line of Defense:
- includes the phagocytic cells and NK cells (21.2)
- If pathogens pass the first barrier, the body responds with phagocytes acting as a fast defense and other antimicrobial responses (21.2)
Phagocytes (Macrophages & Neutrophils):
- These cells are able to engulf a cell/particle via Phagocytosis (21.2)
- Phagocytes take an organism inside itself as a phagosome, fusing with a lysosome and its digestive enzyme and killing pathogens (21.2)
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Inflammatory Response:
- does not have to be started via infection, can be caused by tissue injury (21.2)
- Mast cells detect an injury, releasing histamine which initiates an inflammatory response (21.2)
- Histamine increase blood flow to the site, phagocytes and immune cells come to neutral pathogens. The immune cells and phagocytes also help limit the spread of a pathogen (21.2)
Natural Killer (NK) Cells:
- a lymphocyte able to induce apoptosis, programmed cell death, in cells infected with intracellular pathogens (21.2)
- NK cells respond to chemical signals and expresses the Fas Ligand; a surface molecule that can bind to an infected cell and send it apoptotic signals, killing the cell and pathogen. (21.2)
- They can induce apoptosis intracellularly. They release perforin, forming pores in an infected cell's membrane, and granzyme, which can enter the cell via the pores and digest proteins. (21.2)
Antimicrobial Proteins:
- made when needed early in innate immune response; they are not constitutively present in the body (21.2)
Interferons:
- a protein made in virally infected cells, causing nearby cells to produce antiviral proteins (Key Terms)
- The initial Cell is sacrificed, but the surrounding cells are protected (21.2)
Complement Proteins:
- found in blood plasma; made in the liver (21.2)
- These proteins alter and fragment later proteins in a series, causing an irreversible series of reactions and a release of fragments (21.2)
- binds to the cell membrane of a pathogen to label it for phagocytosis (21.2)
- diffuses away from a pathogen and acts as a chemotactic agent to attract phagocytic cells to the site (21.2)
Antibodies:
- antigenic-specific proteins produced by specialized B-cells that protect the body by binding to foreign objects such as bacteria and viruses (Key terms)
- Plasma cells can secrete soluble antibodies (21.1)
Defense Mechanisms Used
Neutralization:
- inactivation of a virus by the binding of specific antibody (Key term)
- a pathogen is coated with antibodies, making it impossible for the pathogen to bind to receptors (21.5)
- constantly protecting the body, occurring in blood, lymph, and other body fluids / secretions (21.5)
Agglutination:
- cells cluster into masses linked by antibodies (Key terms)
- caused my immunoglobulin, binds to foreign objects like bacteria and viruses (Key Terms, 21.4)
Complement fixation & activation:
- The complement system, series of proteins found in blood plasma. They bind to the cell membrane of a pathogen, labeling it for phagocytosis (fixation). It diffuses away from the pathogen, and attracts phagocytic cells by chemicals. Damaged pores in the plasma membrane are then formed on the pathogen (activation). (21.2)
Types of Antibodies:
- antibodies serve 2 function; act as a B cell antigen receptor, or be secreted, circulate and bind to a pathogen (21.4)
- They fall into five classes
IgA:
- 2 forms: four chain monomer in blood, eight chain/dimer structure in exocrine gland secretions of mucous membranes (21.4)
- effective against digestive and respiratory pathogen and can pass immunity to an infant via breastfeeding (Key term)
IgD:
- serves as a receptor on naive B cells; important for B cell activation (Key terms)
IgE:
- associated with allergies and anaphylaxis
- It can make mast cell degranulation specific, causing the mast cells to degranulate and cause an allergic reaction (21.4)
IgG:
- A monomeric antibody that clears pathogen from the blood and can activate complement proteins (21.4)
- the antibody that crosses the placenta to protect a developing fetus (21.4)
IgM:
- five four chain structures, deeming it the largest antibody. They are also usually the first antibody made during a primary response. (21.4)
- can bind well to any bacterial surface (21.4)
-its monomer is a surface receptor for naive B cells (Key terms)
Humoral Immune Response:
- heavily relates to B cells, Antibodies are made plasma cells and memory cells help with a stronger and faster response when re-encountering a pathogen (21.4)
Active Immunity:
- developed from an individual's own immune system (Key Terms)
- the resistance to pathogens acquired during an adaptive immune response within an individual (21.4)
Naturally acquired:
- the response to a pathogen, leading to your body to make an immune response (21.4)
Passively Acquired:
- acquired artificially through using vaccines (21.4)
- Vaccines cause a weakened primary immune response, causing a person to have protection without the "damages" (21.4)
Passive Immunity:
- Arises from the transfer of antibodies to an individual without requiring them to mount their own active immune response (21.4)
Naturally Acquired:
- seen during fetal development, IgP is transferred to the fetus and protects it from infection. (21.4)
- newborns/fetuses benefit from the immunological memory based on the pathogens of which the pregnant person has been exposed to. (21.4)
Passively Acquired:
- can be acquired with injections of immunoglobulins, temporarily protecting an individual who was exposed to a pathogen (21.4)