what does the lymphoid system include
- Lymphatic system
- Lymphoid organs + tissues
- WBC
- Cytokines
list possible pathogens
- bacteria
- viruses
- fungi
- algae
- toxic products
list the lymphatic system components
- capillaries
- vessels
- lymph
- lymph nodes
functions of the lymphatic system
- circulates body fluids
- removes foreign materials from body fluids
- transports WBC
Lymph
white milky protein containing excess interstitial fluid
lymphatic capillaries
permeable one way flaplike mini valves that permit the entry of interstitial fluid, ions, WBC, foreign materials
Lymphatic Vessels
carry lymph from peripheral tissues through the lymphatic ducts back to the blood
lymphedema
fluid accumulates in the tissue causing swelling due to the blockage of lymphatic drainage
lymph nodes
contain WBC that capture and destroy foreign materials and activate an immune response to destroy
(located along lymphatic vessels)
Primary Lympphoid Organs
sites where stem cells differentiate into the various WBC of the lymphoid system e.g. red bone marrow and thymus
Secondary Lymphoid Organs and Tissues
- contains WBC
- sites where foreign materials become trapped and destroyed or immune response generated
e.g. lymph nodes, spleen, tonsils
White Blood Cells
Found in blood, lymph, lymphoid organs and tissues
protects body from foreign materials
Cytokines
produced and secreted by WBC
chemical messengers that recruit and activates WBC
e.g. interferons, IL1 IL2
What are the 2 main immune defences
- Innate (non specific) defences
2. Adaptive (Specific) defences
What are the 2 different types of innate defences
1st line = surface barriers
2nd line = internal defences
what is a type of adaptive defences
3rd line = immune response
Innate defences
present at birth and provides immediate protection against any type of foreign material entering and spreading
surface barriers
an innate defence which presents foreign material from entering the body including physical and chemical barriers
list physical barriers (surface barriers)
- skin (intact keratinise epithelial membrane = formidable barrier)
- accessory structures e.g. hair and tile
- normal flora (take up space and nutrients required by pathogens)
list chemical barriers (surface barriers)
- sweat
- saliva
- tears
- mucus
- gastric juice
Internal Defences
prevent foreign materials becoming systematic and spreading throughout the body
eg. macrophages, neutrophils, NK cells, Interferons, Complement, Inflammation, Fever
Internal Defences - Macrophages and Neutrophils
phagocytic cells that:
- migrate to cite of infection
- adere to materials
- engulf foreign
- internalise foreign
- destroy
Internal Defences - Natural Killer Cells (NK)
destroy virus infected & cancerous cells
- recognise
- adhere
- destroy
via the release of performs and granzymes
NK CELLS - performs
create pores in target cell membrane, allowing entry of granzymes
