Host defences against injury Flashcards
What lineage do T cell, B cells and NK cells derive from?
Lymphoid
What lineage do granulocytes derive from?
Myeloid
List some granulocytes associated with the immune response
- Neutrophils
- Eosinophils
- Basophils
- Mast
How do innate cells recognise a pathogen?
Dendritic cells recognise and bind to PAMP’s on bacteria with PRR’s
How do cells present antigens to immune cells?
Dendrites present parts of antigens on their cell surface through MHC
What are the three mechanisms that neutrophils use to kill?
- Phagocytosis
- Degranulation
- NET’s
What are two examples of PRR’s
- Scavenger receptors
2. Toll-like receptors
What are some components of eosinophil granules?
- Peroxidases
- Lysosomal hydrolases
- Lysophospholipase
What are some components of neutrophil granules?
- Peroxides
- Lysozyme
- Lactoferrin phospholipase
- Cytokines (e.g. IL-3)
How do neutrophil NET’s kill?
NET’s are extracellular DNA traps which immobilise pathogens
What are the cells of the adaptive immune response?
B-cells and T-cells
What are the cells of the innate immune response?
- Mast cells
- Basophils
- Eosinophils
- Neutrophils
- Macrophages
What are the cells involved in both the innate and adaptive immune responses?
Dendritic cells and NK cells
What type of T-cells are directly kill pathogens?
Cytotoxic T-cells (CD8). They also induce apoptosis in infected and damaged cells
What type of T-cells interact with B-cells to differentiate into plasma cells and secrete antibodies?
Helper T-cells (CD4)
What are the components of mast cell granules?
- Histamine
- acid hydrolases
- Prostoglandin D2
- Leukotrines
- Platelet-activating factor
- Cytokines (e.g. IL-3)
What does histamine do?
Increases vascular permeability
What does prostaglandin D2 do?
- Vasodilation
- Bronchoconstriction
- Neutrophil chemotaxis
What are the 5 cardinal signs of inflammation?
- Redness
- Pain
- Swelling
- Heat
- Loss of function
What are the inflammatory mediators for acute inflammation called?
Autocoids
What are three characteristics of autocoids?
- Low molecular weight
- Act locally
- Rapidly broken down
What are some mediators of vasodilation?
- Histamine
- PG’s
- NO
- Bradykinin
- Substance P
What are some mediators of pain?
- PG’s
2. Bradykinin
What are three different eicosanoids?
- Prostoglandins
- Thromboxanes
- Leukatrines
What substances cause increased vascular permeability?
- Histamine
- Bradykinin
- Leukatrines
They act by stimulating endothelial cell contraction
What are the characteristics of transudate fluid?
Low protein, few-cells (non-infectious)
What are the characteristics of exudate fluid?
High protein, many cells (potentially infectious)
What are the characteristics of modified transudate fluid?
In-between transudate and exudate (moderate protein)
What are the three steps to leukocyte emigration
- Expression of adhesion molecules on endothelial cells, stimulated by cytokines
- Neutrophils adhere to endothelium by binding
- Neutrophils move through blood vessel walls into damaged tissue down chemokine gradient
What are some mediators of pruritus?
- Histamine
- PG’s
- Serotonin
What are the characteristics of serous inflammation?
Low MW solutes and water (most mild form of inflammation)
What are the characteristics of catarrhal inflammation?
Exudate formed on mucosal surface so serous fluid is mixed with mucous
What are some characteristics of suppurative inflammation?
Purulent inflammation (pus)
What is meant by the term phlegmon?
Spreading diffuse suppurative inflammation within loose connective tissue
What is meant by the term empyema?
Accumulation of pus within a body cavity
Generally speaking, over what time period is it considered chronic inflammation?
Inflammation persisting over 7 days
What are three broad characteristics of chronic inflammation?
- Changes in inflammatory cell population
- Inflammatory tissue damage
- Tissue healing
What is the predominant cell type in granulomatous inflammation
Macrophages
What is another word for lymphocytic inflammation?
non-suppurative inflammation
What is that most common distribution in lymphocytic inflammation?
Perivascular, this is because it consists of predominantly T-cells and B-cells
What are clusters of macrophages called?
Granulomas
What type of inflammation commonly forms discrete or coalescing nodules?
Granulomatous inflammation
What are characteristics of pyogranulomas?
Central foci of neutrophils surrounded by macrophages
What are characteristics of caseating granulomas?
Central foci of necrosis surrounded by macrophages
What type of inflammation grossly appears green?
Eosinophillic inflammation
What are the factors which result in tissue destruction due to chronic inflammation?
- Damage by the original insult
- Release of inflammatory mediators
- Cellular phagocytosis or apoptosis
- Tissue death due to circulatory compromise (thrombosis)
What are the two major processes in tissue healing?
- Regeneration
2. Repair
What is meant by tissue regeneration?
Replacement of the damage tissue with the original cell type, restoring structure and function
What is meant by tissue repair?
Replacement of the damaged tissue by fibrous connective tissue (scar tissue), restoring structure but not function
What types of cells can undergo regeneration?
Liable cells and stable cells
What are the steps involved in tissue repair?
- Clearance of damaged tissue debris by inflammatory cells (neutrophils and macrophages)
- Proliferative phase, involving the formation of granulation tissue through angiogenesis and fibroplasia (type 3 collagen)
- Maturation phase, involving the reorganisation and contraction of collagen (type 1). Regression of vasculature
What are some factors influencing healing?
- Presence of infection
- Presence of foreign material
- Nutritional state
- Degree of movement and pressure
- Vascular and oxygen supply
- Hormones
- Concurrent disease
- Age
What is proud flesh?
Formation of excessive granulation tissue
Will the removal of proud flesh be painful?
No, given that proud flesh is excessive granulation tissue it only consists of connective tissue and blood vessels. No nerves!
What are some consequences of scar tissue formation?
- Strictures (narrowing of a hollow organ)
- Adhesions (attachments between adjacent organs)
- Restricted movement