Two Circulations, One Vital Organ

Today I am looking at the bloody supply to our lungs

The lungs have a unique dual blood supply. One circulation makes gas exchange possible, while the other nourishes the lung tissue itself. Together, they keep oxygen moving into the bloodstream and carbon dioxide moving out.

Deoxygenated blood leaves the right ventricle through the pulmonary trunk, which divides into the right and left pulmonary arteries. These arteries follow the branching airways and form capillary networks around the alveoli. Across the thin alveolar–capillary membrane, carbon dioxide diffuses from the blood into the air spaces, while oxygen diffuses into the blood. Oxygenated blood then returns to the left atrium through the pulmonary veins.

The bronchial arteries arise from the systemic circulation, usually from the thoracic aorta or nearby branches. They deliver oxygenated blood to the bronchi, connective tissue, visceral pleura and supporting structures of the lungs. Some bronchial venous blood drains through the bronchial veins, while some enters the pulmonary veins, creating a small normal contribution to the physiological shunt.

The pulmonary circulation is a low-pressure, high-flow system designed for efficient gas exchange. The bronchial circulation operates at systemic pressure and supports the metabolic needs of the lung tissue. Connections between the two systems can provide some backup blood flow, but they can also become clinically important in conditions involving inflammation, obstruction or bleeding.

Let’s look at what happens if there is a blockage a blockage in a pulmonary artery, most often caused by a blood clot that has travelled from a deep vein in the leg or pelvis, is called a pulmonary embolism. It reduces or stops blood flow to part of the lung, so that area may still receive air but cannot exchange gases effectively with the blood. This can lower oxygen levels, increase pressure on the right side of the heart and, if the blockage is large or there are multiple clots, cause haemodynamic collapse or death. Possible symptoms include sudden shortness of breath, chest pain that may worsen with breathing, a rapid heart rate, coughing up blood, dizziness or fainting. A suspected pulmonary embolism requires urgent medical assessment.

Today I am looking at Emphysema which is a long-term lung condition and a form of chronic obstructive pulmonary disease (COPD). It damages the tiny air sacs in the lungs, reducing the surface area available for oxygen exchange and making it difficult to breathe out fully. The damage cannot be reversed, but treatment can relieve symptoms, slow further decline and improve quality of life.

What causes it are things like

Smoking: Cigarette smoking is the leading cause. Cigars, pipes and repeated exposure to second-hand smoke can also contribute.

Airborne irritants: Long-term exposure to dust, chemical fumes, smoke or air pollution—especially in some workplaces—may damage the lungs.

Alpha-1 antitrypsin deficiency: This uncommon inherited condition can cause emphysema, sometimes at a younger age or in people who have never smoked.

Age and susceptibility: Risk rises with age and may be influenced by genetics, childhood lung development, recurrent respiratory illness and other individual factors.

Most people with emphysema are diagnosed after age 40, commonly in their 50s, 60s or later, because lung damage usually develops slowly and symptoms may be present for years before diagnosis. People with inherited alpha-1 antitrypsin deficiency can develop emphysema earlier, sometimes in their 30s or 40s, especially if they smoke or are exposed to lung irritants. Age alone does not confirm emphysema; diagnosis usually involves breathing tests such as spirometry and sometimes chest imaging.

Symptoms often develop gradually and may include shortness of breath, reduced exercise tolerance, persistent cough, wheezing, chest tightness, tiredness and unintended weight loss in advanced disease. A clinician may use a medical history, examination, breathing tests such as spirometry, oxygen measurements and chest imaging. Blood testing may be recommended when alpha-1 antitrypsin deficiency is suspected.

How does someone treat this condition well here is what I found.

Stop smoking: Quitting is the most important step for people who smoke. A GP or pharmacist can discuss counselling, nicotine replacement therapy and prescription medicines.

Inhaled medicines: Bronchodilators relax the airway muscles; some people may also benefit from inhaled corticosteroids, particularly when exacerbations are frequent or asthma features are present.

Pulmonary rehabilitation: Supervised exercise, breathing techniques, education and nutritional support can improve stamina and confidence.

Vaccination and infection management: Recommended influenza, COVID-19 and pneumococcal vaccination may reduce complications. Respiratory infections should be assessed promptly.

Oxygen therapy: Long-term oxygen may help selected people with persistently low blood oxygen levels, but it must be prescribed after proper testing.

Specialist procedures: For severe disease, selected patients may be considered for lung-volume-reduction surgery, bronchoscopy valve procedures or lung transplantation.

Alpha-1 antitrypsin deficiency care: Management includes avoiding smoke, specialist monitoring and, in some settings, disease-specific augmentation therapy.