Unit 2.2 Organs of cell immune system

Immune system

body’s defense system it protects you against harmful substance

primary

where cells of the immune system develop

secondary

where the immune response develop

Lymphoid system

is a collection of tissues, organs, and vessel and helps immune system protect body

and is designed to bring B and T cells in contact with antigens

Lymphoid system includes

1. lymphatic vessels

2. primary lymphoid organs

3. secondary lymphoid organs

Lymphatic vessles

a thin tube sthat collects lymph from tissues in different parts of the body and returns it to the blood stream

its a branch like body tissues and they vary in sizes: larger than blood capillaries and smaller then veins

carry lymphocytes to body tissues

lymph (clear water fluid) formed as result of body’s circulator system and travel through vessels to lymph nodes

high pressure in circulation make some fluid and components to migrate into lymp vessels

Primary lymphoid organs

Bone marrow, thymus and Fetal liver are primary lymphoid organs.

Once mature, cells leave primary lymphoid organs and migrate to secondary lymphoid organs.

B cell mature

Bone marrow mature

T cell mature

Thymus mature

Lymphedma

something blocking lymph and cause build up soft tissue and making them swell

Thymus

The site of T-cell development and maturation

The function of the thymus is to generate and select a repertoire of T cells that will protect the body from infection.

where t lymphocytes mature and learn to distinguish between the body’s own cell and foreign substances

Bone marrow

Bone marrow is in the center of most bones and in the end of spongy bones in body.

Bone marrow store fat and stem cells and produce all blood cells which part of them is the immune cells.

•B-cell origin and development in Bone marrow.

eliminates b cell and that react against body’s own antigen

Secondary lymphoid organs

Sites where lymphocytes gather to encounter antigens.

Secondary lymphoid organs include

•Lymph nodes  

•Spleen.

•Tonsils.

•Appendix.

•Mucosa Associated Lymph tissue (MALT).

•Gut associated lymphoid tissue (GALT).

•Bronchial associated lymphoid tissue (BALT).

•Peyers patches.

Lymph Nodes

Are place where immune cell recognize foreign substance crried in lymph and start immune response

it filters lymph and traps foreign substance

Are encapsulated bean shaped structures containing a reticular network packed with:

lymphocytes, Macrophages, and Dendritic cells.

Lymph nodes (2)

The first organized lymphoid structure to encounter antigens that enter the tissue spaces.

lymph node can be divided into three

cortex, paracortex, medulla

cortex

mostly b cell

paracortex

mainly t cell

medulla

fewer lymphoid lineage cell

Plays a major role in inititing immune responses to antigens in the blood stream

Large, high in the left abdominal cavity.

Specializes in filtering blood and trapping antigens found in bloodstream

two components of spleen

red pulp and white pulp

red pulp

a site where old and defective RBC are destroyed and removed

white pulp

primarily populated by t cell and b cell

Cutaneous - associated lymphoid tissue

skin barrier against external environment

important non specific disease

epithelial cell outer layer called keratinocytes

kertinocytes secrete cytokines

cytokines trigger local inflammation

bone marrow contains:

blood-forming Stem cells,

and makes B cells, innate

cells, and all other blood

cell types, except T cells.

primary lymphoid organs

provide sites where Immune cells originate, mature and become antigenically committed.

Secondary lymphoid organs

capture antigens and provide sites where lymphocytes become activated by interaction with antigens.