Week 2 Flashcards
Describe the flow of lymph in the body:
Lymph takes interstitial fluid back to the circulatory system via lamp capillaries, vessels and ducts.
Lymph from the digestive system( chyle) contains milky chylomicrons and drains into lacteals( capillaries) in the SI. Lacteals return chyle to the chyle cistern.
Describe features of primary and secondary lymphoid tissue:
Primary: where lymphocytes are formed and mature into B an T cells. Bone marrow and thymus.
Secondary: where lymphocytes are activated. Spleen, lymph nodes, MALT and payer’s patches.
List 3 functions of the lymphatic system:
1) mechanism for removing excess interstitial fluid.
2) Transportation of fats.
3) Immune defence-at lymph nodes, lymphocytes are added and macrophages act as filters.
Describe some functional features for the thymus, Bursa of Fabricius, Peyer’s patches, lymph nodes, spleen and tonsils.
Thymus- bone marrow derived lymphocytes travel to the cortex where they mature. They either become equipped with the correct receptors to identify self molecules (positive selection). Or, if they recognise MHC/self antigens they are removed by macrophages (negative selection).
- MH11 = CD4+CD8-
- MH1 = CD4-CD8+
Bursa of Fabricius- consists of tall, thick mucosal folds filled with numerous follicles. Surface is covered with pseudo stratified columnar epithelium.
Peter’s patches- part of MALT/GALT, specialised for antigen uptake as have microfilm cells.
Lymph nodes- medulla and cortex surrounded by capsule.
Spleen- consists of red pulp (filters RBCs, removes antibody coated bacteria, retrieves iron from RBC breakdown). White pulp is involved in immune surveillance and respond to blood-born antigens.
Tonsils- part of MALT/GALT, stratified squamous epithelium.
Define neoplasia, mutagenesis and oncogenesis.
Neoplasia- the presence or formation of new abnormal growth of tissue.
Mutagenesis- the process by which genetic info of an organism is changed-mutation.
Oncogenesis- the production/causation of tumours.
What is meant by metastasis and angiogenesis and how are they linked?
Metastasis is the migration of cancer cells to other parts of the body. Angiogenesis is the development of new blood vessels. New blood vessels can provide a new route by which tumour cells can exit the 1’ tumour site and enter circulation.
What are some differences between apoptosis and necrosis?
In apoptosis, organelles still function in blebs. In necrosis, organelles aren’t located in blebs. In necrosis, lysosomal enzymes can harm other cells.
Describe structure and function of B and T cell receptors.
B cell- are secreted in soluble form and can be detected in serum/plasma. B cells can capture antigen directly and then is presented- antigen-antibody complex is completely phagocytosed. Can switch class of Ig they express where the constant region changes. T cell- associates with other membrane molecules to provide stability in antigen presentation. They recognise peptide antigen on surface of APC within MHC. More stable.
State functions of thymus, spleen and lymph nodes.
Thymus- thymus education/central tolerance occurs where lymphocytes are prevented from reacting to ‘self antigen’.
Spleen- screens blood for foreign pathogens, removes defective erythrocytes.
Lymph nodes- monitor lymph for foreign pathogens.
What are the 4 types of ELISA?
Indirect- used to detect specific antibody in sample.
Direct- uses antibodies to detect specific antibody in sample.
Sandwich- uses antibody pair to detect specific antigen.
Competitive- sample antigen competes with labelled antigen for binding site.
How do you perform a qualitative ELISA?
1) Wells are coated with capture antibody.
2) Test sample is added and any antigen can bind to capture antibody.
3) Add primary( detection) antibody.
4) Add 2’ antibody conjugated to substrate specific enzyme such as horse radish peroxidase.
5) Substrate is added and covered bye enzyme.
What are the q’s you should ask about running positive and negative controls?
pos- how do you know they assay is working?
neg- how do you know the assay isn’t contaminated?
What are the 4 main roles of complement in the immune system?
1) Cell lysis: through pore formation in cell membranes.
2) Inflammation: by stimulation of histone release from mast cells.
3) Chemotactic agents: recruitments of neutrophils and macrophages to infection site.
4) Opsonisation: coating of SA leading to increased phagocytosis.
What are the 3 types of complement system?
Classical pathway: antibody dependent, effect of complement strongly amplified in presence of adaptive immune response.
Alternative pathway: antibody independent, pathogen surfaces binding.
Lectin pathway: antibody independent, lectin binding on pathogen surfaces.
Why is C3 and C3 deficiency important?
All 3 pathways converge at C3, has high content of serum complement proteins. C3 breaks down into:
- C3a: acts as chemoattractant.
- C3b: bind to microbe surfaces via carbohydrates and factor H on host cells.
Deficiencies lead to increased susceptibility- trouble making antibodies.
Outline the membrane attack complex:
It is the end point pf all 3 activation pathways. It punches holes in bacterial membranes and kills them( form pores_ and opens cell cytosol.
What are the advantages and disadvantages of contact-dependent and synaptic transmission modes of cell communication?
Contact-dependent:
- Advantages: signalling molecules pass between cells without being secreted in extracellular fluid.
- Disadvantages: communication only between adjacent cells and slow.
Synaptic transmission:
- Advantages: no dilution in general circulation and system can quickly be reactivated.
- Disadvantages: specificity, vulnerability and expensive hardwiring.
How can extracellular signal molecules can act over either short or long distances.
If ligand is bound to cell membrane, then cell-cell contact is required for ligand and receptor to bind. Ligands can be released.
Describe the nature of cytokine cell signalling:
- One cytokine can have different effects on different cells.
- Combined effect of cytokine is vast.
- One cytokine can inhibit the activity of another.
- Can be pro or anti-inflammatory.
What are the role of cytokine receptors?
- Activate enzyme activity in signal domain.
- Allow signal domain to recruit other components.
Discuss effects of inflammation on local vasculative systems:
Tethering and rolling: Inflammatory processes cause local endothelial cells to express new adhesion molecules( Integrin receptors.) These interns slow leukocytes down.
Diapedesis: Leukocytes pass in-between gaps of endothelial cells.
What can occur if inflammation isn’t switched off?
A granuloma can be formed as macrophages have persistent stimulation. Two macrophages fusing form a langharis cell.
