Foundations in Immunology 2 Flashcards
Functions of the Lymphoid Organs + The Roles of T Lymphocytes
<p>What are functions of the lymphatic system?</p>
<p>Drainage of tissues</p>
<p>Absorption and transport of fatty acids and fat</p>
<p>Immunity</p>
<p>What is the lymphatic system?</p>
<p>Network of tubes that carry clear fluid called lymph</p>
<p>How does lymph move through the lymphatic system?</p>
<p>By contraction of skeletel muscles</p>
<p>What eventually happens to the fluid in the lymphatic system?</p>
<p>Enters the blood after entering the right lymphatic duct or thoracic duct</p>
<p>What happens to molecules in the interstitual space that are too big to pass through cappilary walls?</p>
<p>They pass into the lymphatic system which has more permeable walls</p>
<p>What are some lymph nodes?</p>
<p>Cervical</p>
<p>Axillary</p>
<p>Bronchial</p>
<p>Abdominal</p>
<p>Inguinal</p>
<p>What are the two kinds of lymph vessels?</p>
<p>Afferent</p>
<p>Efferent</p>
<p>What prevents backflow in lymph vessels?</p>
<p>Valves</p>
<p>What are the two lymphatic ducts?</p>
<p>Right lymphatic duct</p>
<p>Thoracic duct</p>
<p>What is the path that lymph being drained from interstitual space takes?</p>
<ol> <li>Lymph</li> <li>Afferent vessel</li> <li>Lymph node</li> <li>Efferent vessel (filtered lymph)</li> <li>Lymphatic duct</li> <li>Venous system</li> <li>Blood</li></ol>
<p>What are the 3 phases of immune defence?</p>
<ol> <li>Recognition of danger</li> <li>Production of specific weapon</li> <li>Transport of weapon to the site</li></ol>
<p>Where are white blood cells produced and recieve their early training?</p>
<p>Primary lymphoid organs</p>
<p>What are some primary lymphoid organs?</p>
<p>Bone marrow</p>
<p>Thymus</p>
<p>What happens to bone marrow as you get older?</p>
<p>You have less because long bones get filled with fat</p>
<p>What is the site of maturation of T cells?</p>
<p>Thymus</p>
<p>What kinds of cells are found in the thymus?</p>
<p>Macrophages</p>
<p>Dendritic cells</p>
<p>Numerous thyrocytes (T cell precurders)</p>
<p>What is a secondary lymphoid organ?</p>
<p>Site of lymphocyte activation by antigen</p>
<p>What are examples of secondary lymphoid organs?</p>
<p>Lymph nodes and lymphatic system</p>
<p>Spleen</p>
<p>Tonsil</p>
<p>Cutaneous immune system</p>
<p>Mucosal immune system</p>
<p>What is the spleen composed of?</p>
<p>Red pulp</p>
<p>White pulp (lymphocytes)</p>
<p>What are functions of the spleen?</p>
<p>Filter blood</p>
<p>APLs, B cells and T cells promote interactions for development of humoral immune response</p>
<p>What are functions of lymph nodes?</p>
<p>Filter and purify lymph</p>
<p>99% of antigens are removed here</p>
<p>In response to antigen detection T and B cells are stimulated and adaptive immune response initiated</p>
<p>Maintain and produce B cells and house T cells</p>
What does the structure of a lymph node look like?
<p>Where are payer's patches found and what do they do?</p>
<p>Small intestine, prevents the gorwth of pathogenic bacteria</p>
<p>What are payer's patches covered by?</p>
<p>A layer of M cells</p>
What are M cells?
Transport antigens from the lumen of the intestine to the payer's patch, then carried to lymph then lymph node
What are tonsils involved in?
Defence from infection of the upper respitory tract
What is lymphoma?
Caner of the lymphatic system
What is one of the most common pathways for the spread of cancer?
Lymphatic system
What are T cells derived from?
Bone marrow
What are MHC1 and MHC2?
Proteins that express antigens on their surface (antigen presenting cells)
Where is MHC1 found?
On every cell
Where is MHC2 found?
On macrophages and dendritic cells
What are T cells responsible for?
Cell mediated immunity and assisting B cells
What do cell surface receptors in the T cell receptors (TCR) recognise?
Antibodies when bound to MHC
What are different T cells?
Helper of CD4+ T cells
Cytotoxic or CD8+ T cells
What do helper T cells do?
Stimulate B cells to produce antibodies
What do cytotoxic T cells do?
Work similar to natural killer cells, destroying the pathogen
What is the process of the origin of T cells?
- Immature in bone marrow and head to thymus
- Mature in thymus, where receptor markers are given to them
- Head to secondary lymphoid organ
What is T cell selection?
T cells must learn not to recognise out own self antigens, restricted to recognise antigen in association with out own MHC
What does T cell selection happen?
Thymus
What are the two types of T cell seleciton?
Positive selection
Negative selection
What happens during positive selection?
T cells are presented with self MHC on epithelial cells (if they recognise they survive = positive selection ) strength not too strong or too weak
If they do not recognise it they are destroyed by apoptosis
(tests immature)
What happens during negative selection?
T cells are presented with dendritic cells, if they recognise self antigens very STRONGLY they are destroyed by apoptosis
(tests mature)
What does MHC1 do?
Presents virally induced peptides to killer T cells to triger cytotoxic response
What does MHC2 do?
Found on macrophages, B cells, T cells and presents exogenously produced antigen to helper T cells to activate macrophages and B cells
What do helper T cells do?
They cannot kill, they activate and direct other immune cells
What do cytotoxic T cells do?
Release perforin when exposed to infected cells
Creates a pore
Releases granzyme B that enters pores and enduces apoptosis
What do memory T cells arise from?
Memory T cells arise from both differentiated and partially differentiated T cells
What do memory T cells allow?
Potential for further differentiation on reexposure to antigen
What is the difference between Th1 and Th2 cells?
Th1 cells are a cellular response and produce memory cells
Th2 cells are a humoral response and result in antibodies
What can a Th1/Th2 imbalance be caused by?
Genetic factor
Environmental factor
What can an imbalance between Th1 and Th2 cells cause?
Asthma
