Inflammation – B. Pharma 2nd Semester Pathophysiology notes pdf




At the end of this PDF, student will be able to

         Define “inflammation”

        Classify inflammation 

        Describe the etiology of inflammation

         Identify the signs of inflammation

         Describe the changes involved in acute inflammation


“Local response of living mammalian tissues to injury due to any agent “

     Body defence reaction to eliminate or limit the spread of injurious agent, followed by removal of the necrosed cells and tissues

       Protective response

Etiology of Inflammation

      Infective agents – bacteria, viruses and their toxins, fungi, parasites

     Immunological agents –  cell-mediated and antigen antibody reactions

     Physical agents – heat, cold, radiation, mechanical trauma

      Chemical agents  – organic and inorganic poisons

Signs of inflammation

4 cardinal signs of inflammation

     Rubor (redness)

     Tumor (swelling)

     Calor (heat) and

     Dolor (pain)

Fifth sign – functio laesa (loss of function) – Virchow

Types of inflammation

Depending upon the defense capacity of host and duration of response

       Acute Inflammation

       Chronic inflammation

Acute Inflammation

     Short duration

     Represents early body reaction

     Followed by repair

Main features

     Accumulation of fluid & plasma at the affected site

     Intravascular activation of platelets

     Polymorpho nuclear neutrophills (PMN) – inflammatory cells

Chronic Inflammation

     Longer duration

     If causative agent of acute inflammation persists for long periods

     Recurrent attack of acute inflammation

Main features:

     Presence of lymphocytes, plasma cells & Macrophages as inflammatory cells

Changes in Acute inflammation

Two main events involved

1. Vascular events

     Alteration of microvasculature (arteries, capillaries & venules)

2. Cellular events

      Exudation of leucocytes


Vascular events

     Alteration in the microvasculature – tissue injury

Haemodynamic Changes

Earliest features – vascular flow change,  calibre of small blood vessels

1.  Irrespective of the type of injury –  transient vasoconstriction of arterioles

     Mild form – blood flow –  3-5 seconds

     More severe injury the vasoconstriction –  5 minutes

Vascular changes

2.  Persistent progressive vasodilatation

     Mainly arterioles

     lesser extent –  venules and capillaries

      Increased blood volume  – redness and warmth

3.      Progressive vasodilatation

     Elevate the local hydrostatic pressure – transudation of fluid into the extracellular space – swelling

4. Stasis of microcirculation

     Increased concentration of red cells – blood viscosity

5. Leucocytic margination

     Leucocytes stick to the vascular endothelium

     Move and migrate through the gaps between the endothelial cells into the extravascular space


Triple response


    Appearance of red line

    Local vasodilatation of capillaries and venules


    Bright reddish appearance or flush surrounding the red line  

     Vasodilatation of the adjacent arterioles


    Swelling or oedema of the surrounding

    Transudation of fluid into the extravascular space

Pathogenesis of altered vascular permeability

Normal circumstances – fluid balance – two opposing sets of forces that causes:

Outward movement of fluid from microcirculation

     intravascular hydrostatic pressure

    colloid osmotic pressure of interstitial fluid

Inward movement of interstitial fluid into circulation

    intravascular colloid osmotic pressure

    hydrostatic pressure of interstitial fluid

Contraction of endothelial cells

       Increased leakiness – venules exclusively

       Endothelial cells – temporary gaps – contraction – vascular leakiness – release of histamine, bradykinin and others

       Response – immediately after injury – reversible – short duration (15-30 minutes)

       Example: immediate transient leakage is mild thermal injury of skin of forearm

Retraction of endothelial cells

       structural re-organisation of the cytoskeleton of endothelial cells – reversible retraction – intercellular junctions – venules – cytokines such as interleukin-1 (IL-1) and tumour necrosis factor (TNF)-α – response takes 4-6 hours after injury – lasts for 2-4 hours or more

       The example invitro experimental work only

Direct injury to endothelial cells

       Cell necrosis, physical gaps at the sites of detached endothelial cell – thrombosis at site initiated

       Affects – microvasculature –  immediately after injury  last for several hours or days or  delay of 2-12 hours and last for hours or days


       Inflammation is the local response of living mammalian tissues to injury due to any agent

       The four cardinal signs of inflammation are redness, swelling, heat and pain

       Inflammation is of 2 type acute and chronic inflammation

       Acute inflammation is of Shorter duration , represents early body reaction, followed by repair

       Chronic inflammation is of longer duration and occurs when the agents remains for longer time

       Acute inflammation is characterized by cellular events and vascular events


Q1: What is inflammation, and how is it defined? Inflammation is a complex biological response of the body to harmful stimuli, such as pathogens, injury, or irritants. It is characterized by specific physiological changes and can be either acute or chronic.

Q2: How is inflammation classified? Inflammation is classified into two main types: acute inflammation, which is a short-term and immediate response, and chronic inflammation, which is a prolonged, sustained reaction often associated with tissue damage.

Q3: What is the etiology of inflammation? Inflammation can be triggered by various factors, including infections, physical injuries, chemical irritants, autoimmune disorders, and exposure to foreign materials or allergens.

Q4: What are the signs of inflammation that can be observed? Common signs of inflammation include redness (erythema), heat (calor), swelling (tumor), pain (dolor), and loss of function (functio laesa). These are often referred to as the five cardinal signs of inflammation.

Q5: Could you describe the changes involved in acute inflammation? Acute inflammation is characterized by rapid and short-term changes, including dilation of blood vessels (vasodilation), increased vascular permeability, recruitment of immune cells like neutrophils, and the release of various chemical mediators. These changes collectively help the body respond to and eliminate the source of injury or infection.

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