Serous Inflammation


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Serous Inflammation

  1. 1. Serous inflammation: Is a type of acute inflammation which is characterised by the copious effusion of non-viscous serous fluid, commonly produced by mesothelial cells of serous membranes, but may be derived from blood plasma. The exudation of this inflammation is clear fluid with no WBCs or PMNs. The serous fluid which is produced by these mesothelial membranes is pink in color and defined as plasma derived from blood or a thin clear watery fluid from secretions of mesothelial cells lining the peritoneal, pleural and pericardial cavities (called effusion). Biologic purpose of serous exudation: Immediate dilution of the noxious agent at the site of inflammation. Etiologic factors include: 1) Hypersensitive reactions. 2) Bacterial and viral tissue injury. 3) Physical and chemical tissue injury. Morphology: According to tissue: - Serosa: Erythema (Hyperemia) and inflammatory swelling from effusion with large numbers of displaced serosal covering cells and few macrophages in the exudate. - Skin: Erythema and swelling that varies according to epidermal involvement. - Mucus membrane: Erythema and swelling lead to mucosal edema with risk of stenosis. - Parenchyma: Erythema and swelling are present with sparse leukocytic infiltrate. This expands the organ capsule, which is tender to palpation due to its sensory innervation. Here the exudate takes the form of an edema.
  2. 2. Examples of this type of Inflammation: 1) Skin blisters. 2) Inflammation of body cavities: Serous pericarditis, Pleuritis (Pleurisy), Peritonitis. 3) Rheumatoid arthritis (serous fluid in joints). 4) Seromucous Otitis. 5) Acute Rhinitis. 6) Serous Pulmonary alveolitis. 7) Organ inflammation such as serous hepatitis, nephritis (acute interstitial nephritis), myocarditis and encephalitis. 8) Vesicular skin infections. 9) Sero-mucosal inflammations can lead to acute glottal and laryngeal edema with risk of asphyxia.
  3. 3. 1) Skin Blisters: The skin blisters result from a burn or viral infection and they represent a large accumulation of serous fluid, either within or immediately beneath the epidermis of the skin. The picture shows an illustration of a skin blister filled with serous fluid. A blister is basically a patch of raised skin that is filled with fluid called serum. This serum is excreted by tissues and blood vessels that go through trauma, such as intense force or friction. The liquid then collects between the gap of the epidermis and dermis. When the area heals, the serum is reabsorbed back into the body. The blister then crusts over and the scab peels off after a few days. Blisters are usually itchy, painful. The area around them may feel warm and swollen. Patients with blisters will definitely experience discomfort to some extent. Blisters are commonly found on the hands and the feet, but they may also manifest on the other parts of your body, depending on the cause.
  4. 4. (A) (B) The previous are microscopic pictures of normal skin (A) and a skin blister (B) Causes: 1) Burns. 2) Rashes. 3) Chicken Pox. 4) Diabetes. 5) Gangrene. 6) Various viral infections. 7) Pressure ulcer. 2) Seromucous inflammation: acute inflammation that occurs exclusively on the mucus membranes of the respiratory and gastrointestinal tracts and produces a watery exudate of serum and mucus. Examples of Seromucous inflammations: A) Acute rhinitis common cold B) Acute catarrhal bronchitis C) Enteritis
  5. 5. Acute rhinitis / common cold: Viral serous catarrhal inflammation of the nasal mucosa. Causes: 1) Upper respiratory tract infection. 2) Flu. 3) Hay fever. 4) Bacterial infections. 5) Certain medication. Pathogenesis and morphology: The disorder is caused by droplet infection by rhinoviruses. The viruses penetrate the epithelium of the upper respiratory tract, triggering inflammation with hyperemia of the mucus membrane and serous exudation. This leads to obstruction of the nasal passage creating optimum conditions for proliferation of the virus. The cytopathic effect of the viruses leads to epithelial necrosis which in turn releases viruses. Inflammatory irritation of the mucous glands and goblet cell hyperplasia (cause hypersecretion of mucus). Result in a runny nose which is a sign of serous catarrhal inflammation. This triggers the sneezing reflex. Sneezing releases both the pathogen and exudate and completes the cycle of droplet infection by which the virus spreads. Gross Picture of Acute rhinitis
  6. 6. A microscopic picture of acute rhinitis An Illustration of acute rhinitis
  7. 7. 3) Serous pulmonary alveolitis Acute inflammation of the pulmonary alveoli resulting in necrosis and hemorrhage into the lungs. It involves the occurrence of exudate into the pulmonary alveoli. It leads to toxic pulmonary edema with exudation into the interstitium of the alveolar wall, causing expansion of the alveolar wall and impaired diffusion. Causes: 1) Inhaling chemical-laden dust particles in an industrial setting 2) Inhaling fungal, bacterial and other naturally occurring spores. Microscopic pictures of a normal lung (C) and a lung tissue with serous alveolitis (D)