Easily Forgotten Pieces of Information Flashcards
What happens when a T cell becomes activated
Colonial Expansion
Some activated T-cells are formed
Some memory cells are formed
What CD number is expressed by killer T cells?
CD8
What CD number is expressed by helper T cells?
CD4
CD 4 cells produce cytokines: what do these do?
5
Activate macrophages
Activate killer T cells
Cause activation of B-cells
Cause antibody class switching (IgM to other type other than D)
Activate eosinophils
How do CD4 cells (helper T cells) activate other cells?
They secrete cytokines
What are the four ways antibodies deal with antigens?
Precipitation/agglutination
Lysis
Neutralisation
Opsonisation
How do antibodies being about lysis?
Antibodies bind to bacterium which activated complement system - forms MAC
How do antibodies interfere with viruses?
They can interfere with viral entry into host cell
How exactly do antibodies act as opsins?
3
Antibodies bind to pathogens
A phagocyte has antibody receptors which bind to the pathogen
Phagocyte phagocytoses the cell
What are the two ways of classifying immunity in separate ways?
Natural or artificial
Active or passive
What are the four types of immunity?
Natural active
Artificial active
Natural passive
Artificial passive
What are the functions of the lymphatic system?
Fluid balance
Fat absorption
Defence
What does the lymphatic system consist of?
4
Lymph
Lymph vessels
Lymphatic tissue
Lymphoid organs
What makes up the lymph vessels?
Lymphatic capillaries
Lymph collecting vessels
Lymphatic trunks
Lymphatic ducts
What factors promote lymph flow?
4
Active skeletal muscles
Active skeletal muscles
Respiratory pump - pressure changes in the thorax during breathing
Pulsations of nearby arteries
Rhythmic smooth muscle contractions in the walls of the lymphatic trunks & thoracic duct
What are the two types of lymphoid tissue?
Diffuse lymphatic tissue
Lymphoid follicles
Describe the structure of the thymus.
5
Flat, bi-lobed organ situated above the heart
Lobes surrounded by a capsule and divided into lobules which are separated by trabeculae (ct)
Lobule has a cortex and medulla
Cortex = densely packed with thymocytes
Medulla = sparsely populated with mature cells
What happens in bone marrow?
B cell maturation
Immature B cells proliferate and differentiate here
List the secondary lymphoid organs.
Lymph nodes
Spleen
Tonsils
Appendix
Write a note on lymph node function
3
Filter lymph – Antigens that enter tissue spaces are trapped in lymph nodes
Reticular fibres support the resident dendritic cells, macrophages and lymphocytes
Receive lymph from afferent lymphatic vessels and drain from efferent
lymphatic vessel
Write a note on lymph node structure.
Cortex
Paracortex
Medulla
Describe a lymph node cortex.
4
Outermost layer
Has a subcapsular sinus
Diffuse lymphatic tissue
Lymphatic follicles - mainly B cells - primary and secondary
Describe a lymph node paracortex.
3
Beneath the cortex
Populated largely by T cells
Initial T & B cell activation occurs here
Describe a lymph node medulla.
Innermost layer
Medullary cords (diffuse lymphatic tissue – many plasma cells)
List the secondary lymphoid organs.
3
Spleen
Tonsils
Peyer’s patches
What are the three characteristics of the adaptive immune system?
Produced target-specific receptors e.g. antibodies and T-cell receptors
Memory
Improvement upon re-exposure
What does lysozyme do exactly?
It attacks the cell walls of bacteria especially gram +
What are the physical barriers of the body?
Skin and mucosae
What are the physiological mechanisms of the innate immune system?
(5)
Body fluids which can wash away pathogens
pH
Body temperature
Commensals
Proteins such as lysozyme
What cells are phagocytes?
5
Neutrophils Eosinophils Monocyte Dendritic Cell Macrophage
What cells are antigen presenters?
3
Monocyte
Dendritic Cell
Macrophage
List some ways the phagolysosome kills pathogens.
6
Acidification
Toxic oxygen-derived products e.g. hydrogen peroxide
Toxic nitrogen oxides e.g. nitric oxide
Antimicrobial peptides e.g. defensins
Enzymes -> lysosome (cell wall)
Competitors ->lactoferrin binds iron
What two things can be used as opsins?
Activated complement components (innate system)
Antibodies (adaptive immune system)
Name a pro-inflammatory molecule.
Prostaglandins
How do interferons (cytokines) interfere with virus infected cells?
(4)
Cells activate factors that interfere with viral replication
Cells produce RNase enzymes
Cells downregulate protein translation
Cells upregulate pro-apoptotic proteins
What can activate complement?
Antigen-antibody complexes
Pathogens themselves
How does complement cause inflammation?
It causes swelling
Vascular permeability
Contraction of smooth muscle
Degranulation of basophils and mast cells
