1.3 Cells and tissues of the immune system Flashcards
How do these travel through the blood?
- rbcs
- platelets
- wbcs
- rbcs: gaseous exchange
- platelets: clotting
- wbcs: immunity
The bloodstream:
is just the motorway that WBCs use to get to the site of infection
Macrophage function:
monocytes that have come from blood stream into a tissue carry on phagocytosis
Phagocytosis of bacteria:
Granulocytes:
-neutrophils
Mononuclear cells:
- monocytes > macrophages
Destruction of parasites:
GRANULOCYTES:
- eosinophils
- basophils (tissue mast cells)
Immunity to viruses:
Mononuclear cells:
- lymphocytes
Primary Lymphoid Organs and importance
Develops Lymphocyte:
Organs:
-bone marrow
-thymus
Secondary Lymphoid Organs and function:
Lymphocyte response to infection:
Organs:
– Lymph nodes
– Spleen
– MALT (e.g. Peyer’s patches)
Is the source of all lymphocytes?
Bone marrow
Lymphoid precursors differentiate into?
B & T cells
During lymphocyte development: B cells remain where?
In the bone marrow
During lymphocyte development: T cells do what?
Leave bone marrow and go to the thymus
Where in the Thymus located
In front of heart
T cell development in the Thymus
– Each T cell must generate a unique antigen receptor (TCR).
– Each T cell must decide whether to become a CD4+ or CD8+ cell.
*initially expressed both
T cell receptor (TCR) must engage with ?
MHC
What happens to the TCRs that fail to interact with MHC molecules?
They are useless
TCRs that recognize peptides from self antigens?
Are potentially dangerous
The thymus screens T cells and disposed of those yay are
Unreactive or autoreactive
Thymic Lymphoma (cats):
– Neoplasia of thymic lymphocytes
– Associated with FeLV infection
- Tumor in thymus
Clinical signs:
Anorexia, weight loss, dyspnoea
B cells are located where in Birds?
Bursa of Fabricius
- Primary lymphoid organ for maturation and differentiation of B cells
T cell location in Lymph nodes?
Paracortex
B cell location in lymph nodes?
Follicles
Lymph node function:
- Filters tissue fluid (lymph) and traps foreign organisms
- provides an environment for recognition of antigen by lymphocytes
- provides the right conditions for lymphocyte activation and differentiation
Lymphocytes enter via
blood vessels to inspect the antigens present
Superficial lymphatic drainage (5)
When tissue fluid is produced
It is filtered by the LN and then returned to the circulation
The efferent lymphatics join to form __ and ___
thoracic duct and tracheal ducts
What 2 routes get antigen get into the lymph nodes via?
- Free antigen is swept into LN in afferent lymph and is trapped
- Specialist antigen presenting cells (dendritic cells) in the tissues eat antigen then migrate via the afferent lymph to the LN paracortex
How are dendritic cells formed?
The differentiate from circulating monocytes
Where are immature dendritic cells located?
At epithelial surfaces where they eat antigen
How do dendritic cells migrate?
Via afferent lymphatics to lab during which time they process antigen
Where do dendritic cells take up residency?
In the LN paracortex where they present antigen to naive T cells
Lymphocytes enter LN via?
specialist blood vessels and inspect the antigens trapped there
High Endothelial Venules (HEVs):
are ‘tube stops’ the T cells use to get out of the circulation and into lymph nodes
- where to exit blood in order to get into tissues
Following activation in the lymph node…
Cells multiply, creating thousands of clones:
- B cells differentiate into plasma cells and migrate from follicles to medullary cords and start producing antibody
– Activated T cells leave the LN and go off in search of infection in the tissues
Enlarged lymph nodes (lymphadenopathy) can indicate?
- Infection–Reactivelymphnode
- Neoplasia-Lymphoma
Spleen structure:
- Red pulp for haematological functions
- White pulp for immunological functions
– Periarteriolar Lymphoid Sheaths (PALS)
Spleen function:
- Haematopoietic organ in foetal life
- Removal of particulate material from bloodstream
foreign organisms, old RBCs - Immune responses to blood-borne pathogens • Store of RBCs and platelets
Mucosal-associated lymphoid tissue (MALT)
- Respiratory tract – bronchial-associated
- GIT – gut-associated
- Initiate immune responses to organisms at mucosal surfaces
What is the first point of entry for respiratory pathogens?
Tonsils - located in the pharynx
Where is the Peyer’s patch located?
Found predominantly in the ileum and at the ileocaecal junction
Primary lymphoid tissues __ and ___ are the source of all circulating lymphocytes
Bone marrow and thymus
Lymphocytes visit ___ as part of the immune surveillance
Different secondary lymphoid tissues
Lymph nodes facilitate immune response to?
Infection in tissue fluid
The spleen facilitated immune response to
Infection in blood
MALT facilitates immune response to
Infection at mucosal surfaces
