A Little Something about Respiration

There is about 500ml of fresh air inhaled with every breath. However, due to our natural anatomy, every individual forfeits 150mL of Oxygen because the conducting zone (trachea and areas before the bronchi) does not engage in gaseous exchange :p

Deep, slow breaths are better for respiratory health than are fast, shallow breaths. With deep slow breaths, your blood vessels are better perfused. This has a little something to do with the total lung capacity that we attain with every deep, slow breath.

Our lungs are not uniform. Many processes are affected by gravity, mostly blood flow.

Gravity affects pulmonary blood pressures by 0.74mmHg/1cm body height. Since pulmonary circulation pressure is much lower, we can expect relatively greater effect on pulmonary circulation than in systemic circulation due to smaller pressures there.

With each cm increase in body height, all the pressures increase, thus the pressure becomes increased and thus the gradient across gets bigger (outside alveolar, pressure is 0) keeping them open (distending/ transmural pressures): these pressures dilate the blood vessels, increasing blood flow. This mechanism is responsible for bigger blood flow at the base of the lungs.