Module 12 - Immune System Flashcards
What is immunity? What are the two types of immunity?
Immunity is the ability to ward off damage or disease caused by disease producing organisms (pathogens) and tumor cells
- innate immunity: in-born (hereditary) non-specific
- adaptive immunity: acquired during life, very specific to particular antigens
Which 2 lines of defense does innate immunity comprise of?
- first line of defense: physical barriers
- skin and mucous membranes, vomiting, tears, gastric juice - second line of defense
- natural killer cells, phagocytes
- fever
- antimicrobial substances
- the inflammatory response
In the second line of defense Natural killer cells and phagocytes…
natural killer cells (type of lymphocyte)
- kill infected body cells and tumour cells
- release toxic chemicals that perforate the cell membranes of target cells > lysis
Phagocytes:
- major types are macrophages, neutrophils, and dendritic cells
- perform phagocytosis (eat cells) = ingestion of microbes and other particles
Innate immunity fever refers to
an abnormally high body temperature due to resetting of the hypothalamic thermostat
it is a non-specific response that:
- speeds up body reactions
- increases the effects of endogenous antimicrobials (e.g., compliment, interferon)
- sequesters (holds back) nutrients from microbes
In innate immunity, antimicrobial substances refer to
chemicals and proteins produced by the body that discourage microbial growth
Interferons:
- chemical early warning system
- released by virus infected cells
- detected by neighbouring body cells that “arm” against virus replication
Compliment system:
-enhances other immune reactions e.g. phagocytosis, inflammation, cell lysis
In innate immunity, an inflammatory response refers to ____
what are the 4 characteristics and signs and symptoms of inflammation?
a non-specific defence response to tissue damage, e.g. pathogens, abrasions, chemical irritants, burns, freezing…
4 characteristics and signs and symptoms of inflammation include:
- redness
- pain
- heat
- swelling
What are the 3 stages of inflammatory response?
3 stages: vasodilation, increased capillary permeability, emigration of phagocytes
- VASODILATION - allows more blood to flow to the damaged area which helps remove bacterial toxins and debris, produces the redness and heat at the site of inflammation
- INCREASED PERMEABILITY of capillaries permits movement of fluids, antibodies and clotting factors into tissues at site of injury, produces swelling (also called edema)
- EMIGRATION
- of phagocytes, depends on chemotaxis (chemical attraction) of released chemicals
- neutrophils predominate in early stages but die off quickly
- macrophages dominate in later stages and initate new tissue growth and repair
- pus is a mass of dead phagocytes, damaged tissue and dead microbes, the end result of inflammation that also includes infection
What is edema? What is pain?
Edema (swelling) results from increased permeability of blood vessels and accumulation of fluid in the tissues
Pain is a symptom of inflammation which results from sensitization of nerve endings by the inflammatory chemicals as well as pressure from the swelling
What is ADAPTIVE immunity? What are the 2 key properties of adaptive immunity?
=defense against SPECIFIC bacteria, viruses, toxins that invade the body
- specificity for foreign molecules called antigens
- memory for previously encountered antigens so that a second exposure provokes a strong immune response
Adaptive immunity involves two types of immune cells called lymphocytes, what are they?
- B lymphocytes (B cells)
- produce antibodies when activated as plasma cells
- called humoral immunity - T lymphocytes (T cells)
- attack invading antigens directly
- called cell-mediated immunity
What are antigen presenting cells?
adaptive immunity requires an antigen presenting cell (APC) to “kick-start” the process
these are phagocytic cells of the innate immune response, e.g., macrophages, dendritic cells
APCs activate ______ cells
APC’s activate helper T cells
activated helper T cells activate other lymphocytes:
-T CYTOTOXIC CELLS which directly kill foreign invaders
-B CELLS which turn into PLASMA CELLS and make ANTIBODIES that kill or help kill foreign invaders
What is clonal selection?
a clone is a population of identical cells, all recognizing the same antigen as the original cell
-activated lymphocytes undergo rapid clonal selection to produce:
EFFECTOR CELLS: active helper T cells, active cytotoxic T cells and plasma cells
MEMORY CELLS: do not participate in the initial immune response but respond rapidly on subsequent exposure
What are antibodies?
antibodies are specialized proteins that bind to specific portions of an antigen called EPITOPES
What is the role of the lymphatic system?
Thymus: site where T-cells mature after migrating from red bone marrow, T-cells develop immunological tolerance in the thymus = do not (usually) react to and attack the body’s own proteins and tissues
Lymph nodes: rich in lymphocytes (T cells and B cells), function in immunity –> filter lymph and remove foreign substances, B-cells develop immunological tolerance in lymphatic tissues such as lymph nodes
