The pulmonary arteries only supply blood flow and oxygen to the lungs and must have the ability to accept huge blood volumes at times. It is the ability of the blood vessels to distend and be recruited which allows the pressures in the pulmonary system to stay low despite very high blood flow. Once the red blood cells have become oxygenated the capillary bed is drained into venules which then join to form the pulmonary veins. The capillaries have great capability to distend thus enhancing gas exchange and reservoir action. The pulmonary arteries whose walls are very thin in comparison to that of the arteries in the main circulation feed the lung up to the level of the terminal bronchioles and then split into the capillary bed. The blood vessels in the lungs continually branch and get consistently smaller very like the branching of the airways. CO2 is transported in the blood by 3 main routesīlood flow to and around the lung is similar to any other organ but at much lower pressures than the systemic system (see diagram).More oxygen is carried dissolved in blood than CO2.CO2 is carried best by oxygenated haemoglobin.

oxygen CO2 is mainly tranported as carbamino compounds.there is about 15ml of oxygen per 100ml of oxygenated blood.is directly proportional to the thickness.is indirectly proportional to the concentration gradient.is increased with a decrease in surface area.dead space is usually about 45% of tidal volume.anatomical dead space is measured by the Bohr equation.physiological dead space is the same as alveolar dead space.is defined as the volume of gas which does take part in gas exchange.the lungs are lined with transistional epithelium.bifurication of the bronchi occurs at T4.generations 1- 18 are known as the conducting zone of the lungs.The oxyhaemoglobin dissociation curve is shifted to the left by:.The answers can be found at the end of the article, together with an explanation. Before continuing, try to answer the following questions.

Dead space ventilation shunt