Medical Concepts

 PNEUMONIA Definition: "Pneumonia is an infection of pulmonary parenchyma". (Harrison)                                                    OR "Pneumonia is defined as an acute respiratory illness associated with recently developed radiological pulmonary shadowing which may be segmental, lobar or multilobar". (Davidson) Etiology: Microorganisms gain excess to the lower respiratory tract in several ways: Aspiration from the oropharynx (most common). Inhalation of contaminated droplets. Hematogenous spread. Contiguous extension. Pathophysiology of Pneumonia: Pneumonia results from proliferation of microbial pathogens at the alveolar level and the hosts response to these microorganisms.  Defensive Mechanisms against Pneumonia: The defensive mechanism against pneumonia involve: Branching architecture of tracheobronchial tree. Muco-ciliary clearance. Local antibacterial factors. Gag Reflex. Cough mechanism. Normal flora adhering to mucosal cells of oropharynx. Alveolar mac

 PORTAL HYPERTENSION Definition: "Portal Hyperension is present when the hepatic venous pressure gradient exceeds 10mmHg and risk of variceal bleeding increases beyond a gradient of 12mmHg." Classification: According to The Site of Action: 1. Pre-Hepatic, Pre-Sinusoidal:     Caused by;          Portal vein thrombosis due to sepsis          Abdominal trauma including surgery. 2. Intra-hepatic pre-sinusoidal:    Caused by;          Schistosomiasis         Congenital hepatic fibrosis         Drugs         Sarcoidosis 3. Sinusoidal:     Caused by;          Cirrhosis         Polycystic liver disease        Nodular regenerative hyperplasia        Metastatic malignant disease 4. Intrahepatic Post-sinusoidal:     Caused by;        Veno-occlusive disease 5. Post-hepatic post-sinusoidal:   Caused by;       Budd-Chiari syndrome Etiology: Cirrhosis Schistosomiasis Portal vein thrombosis Drugs Fibrosis Clinical Features: Variceal bleeding Congestive gastropathy Renal failure Iron deficien