Lung has two main vascular systems that include pulmonary circulation and bronchial circulation. There are multiple anastomoses between pulmonary and bronchial arteries which create physiologic right to left shunts. Blood in the<unk>  is mostly originated from the Lung. However, it could be from the gastrointestinal system as well. Primary origin of the blood comes from bronchial arteries. However, other sources of bleeding might be pulmonary vessels, aorta, intercostal, coronary, thoracic, and phrenic arteries.<unk>  is an important symptom that has different etiologies and pathogenesis mechanisms.<unk>  may happen following infarction and ischemia of pulmonary parenchyma as seen in pulmonary embolism, vasculitis, and infections. Another mechanism of<unk>  is vascular engorgement with erosion as seen in bronchitis, bronchiectasis, and toxic exposure to cigarette and other irritants. In some cases underlying cause can not be identified and they are considered as idiopathic. However, they might present with massive<unk> . There are multiple conditions that are associated with<unk>  which include granulomatosis with polyangiitis, sarcoidosis, immunodeficiency, and indoor ice hockey play.
Hemoptysis pathophysiology
Lung mass pathophysiology
Pleural effusion pathophysiology
Solitary pulmonary nodule causes
Lung cancer differential diagnosis
Bronchitis differential diagnosis
Farmer's lung differential diagnosis
Hemoptysis causes