2 acute inflammation Flashcards
What is inflammation?
A local accumulation of fluid into tissue containing plasma proteins and WBCs.
Often a non-specific (innate) response.
A local physiological tissue response to injury, infection, and cell death
What are the main aims of inflammation?
Restrict damage or infection to a localised area.
Remove the causative agent and damaged tissue.
Promote immune cell and molecule access to initiate repair.
What are the three main causes of inflammation?
Physical (e.g., trauma, burns, radiation).
Biological (e.g., bacteria, viruses, fungi).
Chemical (e.g., toxins, acids, irritants).
How does the immune system combat pathogens?
Recognises and responds to invading organisms.
Avoids overreacting to harmless material or self.
Links innate and adaptive immune responses.
How is inflammation classified?
Acute inflammation: Immediate, transient response.
Chronic inflammation: Prolonged response following acute stages.
What are the cardinal signs of acute inflammation?
Heat
Redness (erythema)
Swelling (oedema)
Pain
Loss of function
Who first described the cardinal signs of inflammation?
Roman physician Aulus Celsus, over 2000 years ago.
What are the four main stages of acute inflammation?
Tissue damage.
Initial vasoconstriction followed by vasodilation.
Cell recruitment (phagocyte migration and margination).
Tissue repair.
What happens during vasodilation?
Small blood vessels dilate, increasing blood flow.
Nitric oxide (NO) relaxes smooth muscle.
Endothelial cells swell and retract, making blood vessels leaky.
What is cell recruitment in inflammation?
Circulating phagocytes adhere to swollen endothelial cells (margination).
They migrate through the endothelial cells (emigration) to the damaged tissue.
Phagocytosis of pathogens occurs.
What happens during tissue repair?
Example: Scab formation and regeneration of epidermis and dermis.
What are the benefits of acute inflammation?
Dilutes toxins.
Increases immune cell entry.
Delivers nutrients and oxygen to the site.
Forms fibrin to impede micro-organism movement.
Activates the adaptive immune response.
What are the downsides of acute inflammation?
Release of proteolytic enzymes damages healthy tissue.
Swelling can be harmful (e.g., airway obstruction, brain swelling in meningitis).
Inappropriate inflammatory responses (e.g., allergic reactions).
What is the role of mast cells in acute inflammation?
Key in inducing inflammation.
Activated by pathogen/damage signals (PAMPs/DAMPs) binding to pattern recognition receptors (PRRs).
Release inflammatory mediators upon activation.
Which innate immune cells are crucial in acute inflammation?
Mast cells
Neutrophils
Macrophages
Dendritic cells (DCs)
What mediators induce vascular dilation?
Histamine
Prostaglandins
Complement components (C3a, C5a)
What mediators increase vascular permeability?
Histamine
Kinins
Prostaglandins
What mediators promote leukocyte emigration?
C5a
Leukotrienes
IL-8/CXCL 8
What is normal fluid movement across capillaries?
Fluid moves out at the arteriolar end and back in at the venous end due to osmotic pressure.
What is oedema?
Swelling due to fluid leakage from capillaries.
What are examples of non-inflammatory oedema?
Pulmonary oedema (high-altitude sickness).
Ankle oedema (long-haul flights).
What causes inflammatory oedema?
Increased vascular permeability following tissue injury.
Mediator-induced endothelial cell retraction.
Which mediators are preformed in mast cells?
Histamine
Serotonin
Tryptase
What does histamine do?
Causes transient arteriolar dilation.
Increases vascular permeability in venules.
