The immune system Flashcards
(27 cards)
what are the two forms of the immune system?
innate defence system
adaptive defence system
what is immunology?
the body’s ability to defend itself against pathogens, that is anything that can produce disease
pathogens may be…?
bacterial infection
viral infection
fungal infection
toxin
what is innate immunity?
Non specific
1st line of defence: physical and chemical barriers
2nd line of defence: internal defences
Targets all pathogens
what is adaptive immunity?
Acquired immunity
The body’s ability to recognise specific foreign substances – antigens
Antigens are substances capable of triggering an immune response through the production of antibodies to destroy the pathogens.
This system builds immunological memory
what is Leukopoiesis?
The production of white blood cells to leukocytes
Leukocytes are formed from stem cells in the red bone marrow along with red blood cells (haemopoieses)
what is the lymphatic system?
carries excess interstitial fluid from tissues back to cardiovascular circulation and provides locations for immune cells to monitor the body
how does the lymphatic system work?
porous lymphatic vessels take in fluids from extracellular space and carry them through lymph nodes, where immune cells scan the fluids for foreign particles
why is the lymphatic system needed?
fluid must be returned to circulation via lymphatics to maintain cardiovascular function, and lymph nodes are necessary to monitor the body for infection
name 3 granular cells?
mast cells- Produce histamine
Involved in allergies
basophils
Eosinophils- produce enzymes to break down the histamine and reduce inflammation
what are neutrophils?
Migrate to the site of inflammation Secrete cytokines – which alerts other cells within the immune system Squeeze into the tissue: diapedesis Ingest pathogen Die forming pus largest proportion of blood leukocytes
what are macrophages?
These are the largest phagocytes
Two types:
FREE macrophages: circulate in the blood and lymph systems
FIXED macrophages attached to fibres in specific organs.
Cytoplasmic extensions pulls in pathogen and digests it
Can ingest multiple times
what are monocytes?
Phagocytes Develop in bone marrow Migrate to the area of inflammation Arrive after neutrophils Differentiate into: Macrophages Dendritic cells
what are dendritic cells?
Antigen presenting cells which allows other cells of the immune system to recognise the antigen
Travel to the lymph nodes and present to T-cells
name the three lymphocytes?
B Cells
T Cells
Natural killer cells
explain B- lymphocyte cells ?
Develop immuno-competence in red bone marrow
*Ability to differentiate pathogens from normal cells
Every B -cell has its own antibodies
Travels in blood and lymph
Meet the antigen it has antibodies for binds to it
Clones itself to produce:
Effector cells which produce antibodies to bind to the antigen
Memory cell: secondary immune response
explain T- lymphocyte cells?
Develop in red bone marrow, mature in the thymus.
Acquire antigen specific receptors and differentiate into
HELPER T –CELLS (CD4 cells): produce cytokines which activate B cells, T cells and macrophages
CYTOTOXIC T-CELLS (CD8 cells): destroy foreign cells or body cells with foreign agents. Includes tumour cells and transplant cells.
MEMORY CELLS: versions of helper and cytotoxic T cells which remain in the body and can proliferate if the same antigen invades the body
explain natural killer cells?
Lymphocytes found in blood and lymph
Part of the 2nd line of defence along with phagocytes
All cells have a major histocompatibility complex (MHC1s) protein on the surface membrane. NK cells detect cell where MHC1s are abnormal or reduced.
NK cells bind to the diseased cell and release perforin and granzymes which trigger apoptosis (programmed cell death)
what is the 1st line of innate immunity defence?
physical barrier created by surface membrane=
Skin
Mucous linings (acidic – inhibits bacterial growth)
Mucus traps foreign particles
chemical barriers=
Lysosomes in lacrimal eye fluid
Hydrochloric acid in stomach
Antimicrobial proteins (defensins) eg Genito-urinary tract
Sweat: high salt concentration
what are the 2nd line of defence internal innate
defences ?
phagocytes
natural killer cells
inflammation
fever
explain the process of inflammation?
Triggered by MAST cells in connective tissue, release histamine.
Excess fluid from swelling is absorbed by the lymphatic system and cleaned before being reabsorbed into the blood stream.
Leaky capillaries make it easier for phagocytes and lymphocytes flowing in the blood stream.
explain the process of phagocytosis?
phagocytes engulf pathogen, vesicle merges with lysosome which contains acid, lysosome digest pathogen, exocytosis, antigen presentation
explain process of fever?
Macrophages can release pyrogen chemicals
Target hypothalamus
Raise temperature
Increases metabolism
Causes the Liver/ Spleen to retain iron and zinc – limit bacterial growth
name the two adaptive immunity responses?
humoral responses
cellular defences
