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Immunology - Coggle Diagram
Immunology
Immune Organs
Thymus
T-cell maturation
Atrophies with age
Bone Marrow
Produces immune cells
B-cells, T-cell precursors
Neutrophils, monocytes, NK cells
Spleen
Filters blood
White pulp
T & B cell maturation
Memory B-cells
Red pulp
Removes old RBCs
Lymph Nodes
Filter lymph
T & B cell activation
Memory B-cell formation
Inflammation & Recruitment
Beginning of Infection
Mast cell activation
Detects damage, antigens, endotoxins
Releases histamine
Inflammation
Vasodilation
Increased permeability
Fluid accumulation
Increased mucus
Recruitment of Immune Cells
Endothelial contraction → gaps
Neutrophils & monocytes adhere
Diapedesis (cross vessel wall)
Chemotaxis towards infection
Systemic Signals
More immune cell recruitment
Liver produces complement proteins
Fever induction
Immune Systems Across Animals
Birds
Bursa of Fabricius (B-cell maturation)
Lymph aggregates (not nodes)
Heterophils instead of neutrophils
Bursa atrophies with age
Reptiles
Slow adaptive immunity
Ectothermic → temperature-dependent
Behavioural fever
Heterophils present
Fish
Weak adaptive immunity
Strong innate immunity
Ectothermic
No bone marrow
Immune cells develop in kidneys
B-cells can phagocytose
Insects
No classical adaptive immunity
Immune priming possible
Immune cells from lymph gland
Haemolymph = blood + lymph
Haemocytes perform phagocytosis
Innate Immune Cells
Phagocytes
Mononuclear
Macrophages
Long-lived
Antigen-presenting
Found in all tissues
Polymorphonuclear (granulocytes)
Neutrophils (main)
Basophils
Eosinophils
Short-lived
Antimicrobial granules
Mast Cells
Release histamine
Increase mucus
Trigger inflammation
Recruit immune cells
Innate Lymphoid Cells (ILCs)
No antigen-specific receptors
Types
NK cells
ILC1
ILC2
ILC3
LTi
Functions
Maintain epithelial barriers
Produce cytokines
Adaptive Immune Cells
T-Cells
Cytotoxic T-cells
Kill infected host cells
Helper T-cells
Activate B-cells
Coordinate immune response
B-Cells
Surface immunoglobulin
Produce antibodies
Form memory B-cells
Natural Killer Cells (bridge innate/adaptive)
Kill virus-infected or cancerous cells
Recognise:
Antibody-coated cells
Missing self-antigen
Stress molecules
Antibodies & Complement
Antibodies
Structure
Variable region
Constant region
Affinity maturation
AID induces mutations
DNA repair introduces errors
Higher-affinity B-cells selected
Functions
Neutralisation
Opsonisation (phagocytosis)
Block infection
Complement activation
Complement System
MAC formation
Pore in bacterial membrane
Water influx
Cell lysis
Role of the Immune System & Exterior Defence
Immune System
Roles
Protects against infectious agents
Recognises pathogens as foreign
Two branches
Innate (non-specific)
Adaptive (specific + memory)
Exterior Defence
Skin
Physical barrier
Platelets seal lesions
Oral
Mucus traps microbes
Stomach acid
Vomiting
Nasal & Respiratory
Mucus + cilia
Sneezing, coughing
Uro-genital
Commensal bacteria
Acidic pH
Urination flush
Eyes
Tears
Antimicrobial peptides
Gut
Microbiome competition
Thick mucus layer
Strong epithelium
Gills
Thick mucus barrier
Epithelium & Immune System Structure
Epithelium
Lines all internal surfaces
Thick mucus layer
Antimicrobial peptides
Immune System Structure
Cells
Phagocytes
Lymphoid cells
Mast cells
Organs
Bone marrow
Lymph nodes
Spleen
Thymus
Fever & Phagocytosis
Fever
Inhibits pathogens
Increases metabolism
Speeds immune response
Phagocytosis
Engulf pathogen
Vesicle formation
Lysosome fusion
Pathogen destruction
Antigen processing
Antigen presentation (macrophages)
Antigen release (neutrophils)
Activation of Adaptive Immunity
T-Cell Activation
APC travels to lymph node/spleen
T-cell receptor binds antigen
T-cell proliferation
Helper T-cells activate B-cells
B-Cell Activation
Free antigen binds B-cell receptor
Helper T-cell signal required
B-cell proliferation
Differentiation
Plasma cells → antibodies
Memory B-cells
NK Cells & Cytotoxic T-Cells
NK Cells & Cytotoxic T-Cells
Recognise infected host cells
Activation signals
Antibody-coated cells
Missing self-antigen
Stress molecules
Mode of Action
Perforins → membrane pores
Granzymes → apoptosis
Same mechanism for NK and cytotoxic T-cells