Intro Flashcards
what is Phagocytosis
ingestion of foreign matter by white blood cell
what is an Antigen (Ag)
Any substance that is recognised as foreign (non-self ) by the immune system so provokes an immune response.
Two important characteristics
Immunogenicity - ability to provoke an immune response
Reactivity - ability to react with antibodies or T cell
Examples
- Bacterial components (flagella, capsules, cell wall, toxins)
- Egg white, peanuts, pollen, incompatible blood cells (blood transfusion)
- Transplanted tissues and organs, drugs
What do the primary organs of the lymphatic system do and where are they made?
Where immune cells are formed/mature. They get made in the bone marrow and T lymphocytes mature in the thymus
Describe what the secondary organs of the lymphatic system does?
Where immune cells do their work. They do that in places like the lymph nodes/lymphatic system or the spleen.
Infections come from outside your body get fought in the lymphatic system
Blood borne diseases get fought in the spleen. Spleen and lymphatic system have similar structures.
Red pulp in spleen is where red blood cells go to die
White pulp is where you fight blood borne infections.
What is Hematopoiesis?
Blood cell production. Your body continually makes new blood cells to replace old blood cells so you have a steady blood supply. Hematopoiesis starts before birth and continues as a cycle throughout life.
In adults, hematopoiesis of red blood cells and platelets occurs primarily in the bone marrow, most blood cells are made in your bone marrow. This process is called haemopoiesis.
In children, haemopoiesis takes place in the long bones, like the thighbone (femur). In adults, it’s mostly in the spine (vertebrae) and hips, ribs, skull and breastbone (sternum)
Cells of the immune system
Natural immunity
Granulocytes:
- neurtrophils
- Eosinophils
- Basophils
Monocytes
Natural Killer cells
Specific Immunity
Lymphocytes
- T lymphocytes
- B lymphocytes
What are the cells of the innate immune system?
Effector cells of innate immunity
Neutrophils - immflamatory cells - first on the scene: phagocytes
Monocytes - Macrophages -
wound healing: opsonisation, antigen-presenting cells: phagocytosis
Eosinophils - raiaed in allergy, produce major basic protein that is toxic to helminths
Basophils - mast cells : Allergy
raised in allergy, inflammatory
Describe the complement system (part of innate immune system)
It is a cascade of proteins - activated complement proteins engage in a range of different activities:
- inflammatory reactions
-adhering to microbial surfaces to attract phagocytes
-puncture holes in cell membranes - water floods in and the cell bursts - helps to clear antibody -antigen complexes that could otherwise cause inflammatory damage to tissues
The 2 types of Immunity - Innate (natural) and Adaptive (specific)
Innamte Immune - epithelial barriers, anti-microbial peptides, phagocytes, complement system, accute phase reactants and natural killer NK cells
Adaptive Immunity - relies on the functions of T and B lymphocytes.
B cells produce antibodies
T cells can be either killer (cytotoxic), helper or suppressor
What do Cytokines (immunological hormones) do?
-Stimulate, regulate and activate the immune system.
- Stimulate production of different blood cell types in bone marrow
- anti-viral activity
-inhibit certain cell types, e.g. tumours
What are the 2 types of immunity?
Active - where you have recognised and responded to that disease (immunity following the disease or vaccine)
This is done so by the B and T lymphocytes
Passive - taken all the cells and put them from one person into another (immunity donated from another individual)
e.g. mum to fetus/ neonate.
This gives immediate immunity rather than Active which takes some time. However passive immunity only lasts about 4 months
What are the 4 properties of specific Immunity?
Recognition, Response, Remembers,, Regulates
Recognition - of the foreign antigen
Response - then mounted for its elimination provoked by specific antigens
Remembers - immunological memory response via multiple exposure to the same antigen aka memory
Regulates - once infection load has reduced, the immune response diminishes
What are the 3 phases of the Immune response to initial infection
Innate immunity , Early induced response , Adaptive immune response.
The effector mechanisms that remove the infectious agent (for example, phagocytes and complement) are similar or identical in each phase, but the first two phases rely on recognition of pathogens by receptors of the innate immune system, whereas adaptive immunity uses variable antigen-specific receptors.
Adaptive immunity occurs late, because the rare B and T cells specific for the invading pathogen must undergo clonal expansion before they differentiate into effector cells that can clear the infection.
What is the difference between the primary and secondary Immune response
The primary immune response occurs during the first exposure to an antigen and is relatively slow and less effective. In contrast, the secondary immune response occurs upon subsequent encounters with the same antigen and is faster, stronger, and more effective due to the presence of memory cells from the primary response.
Secondary immune response is a second, third or fourth etc. (normally the second exposure) exposure to a specific pathogen. Since your body already has antibodies and memory cells against the specific pathogen, your immune response will be much faster and antibodies will be produced (by B memory cells differentiating to plasma cells) immediately.
Example of primary and secondary Immune responses
Let’s say little Johnny contracts the influenza virus (commonly called flu) for the first time. When the influenza virus enters his body, it will successfully pass the first and second line of defence. However since Johnny as never contracted the virus before, he has no antibodies ready against the virus. Therefore he has to wait some time before any antibodies are produced. This time is known as the ‘time/phase’ can last to 2–3 days or even weeks. This takes some time as clonal selection of T and B cells, clonal expansion and differentiation has to occur. Finally, after some time, antibodies are produced and the influenza virus is removed. This is known as the primary response (first exposure to the pathogen).
At the same time, memory cells are produced (B and T memory cells). Memory cells are involved in the immunological memory of pathogens so that when a secondary immune response occurs, these memory cells can quickly differentiate into B and T cells. The B cells then can differentiate into plasma cells, which in turn produce more antibodies (quicker than the secondary response) than the primary response. Therefore the secondary response is more effective against the influenza virus than the primary response.
