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Breathing Inhalation Exhalation. Pulmonary Network of Capillaries and Venules. Trachea . Bronchiole. Alveoli. Alveolus. Inspiration (Inhalation) External Intercostals (muscles) contract Internal Intercostals (muscles) relax
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Breathing Inhalation Exhalation
Pulmonary Network of Capillaries and Venules Trachea Bronchiole Alveoli
Inspiration (Inhalation) • External Intercostals (muscles) contract • Internal Intercostals (muscles) relax • This pulls the rib cage upwards and outwards away from the spinal column. • At the same time the diaphragm contracts and flattens downwards • This increases the volume of the chest cavity (thorax) • This increases lung and alveoli volume • There is a drop in air pressure in the lungs and the air flows in to equalise the pressure
Normal Expiration (Exhalation) • Internal Intercostals (muscles)contract • External intercostals (muscles)relax • This pulls the rib cage downwards and backwards towards the spinal column squeezing the lungs. • At the same time the diaphragm relaxes and curves upwards (dome shape) squeezing the lungs from underneath • There is a decrease in the volume of the chest cavity (thorax) • This increases the air pressure in the lungs and alveoli and the air flows out to equalize.
Forced Expiration • The abdominal muscles contract • This pushes the diaphragm upwards squeezing the lungs from underneath • At the same time internal intercostals (muscles) contract pulling the rids downwards and backwards towards the spinal column also squeezing the lungs • This gives a larger and faster expiration as seen when we are exercising
Gaseous Exchange in Humans • Oxygen from the air dissolves in the fluid lining the surfaces of the air sacs • A diffusion gradient is established between the oxygen in the air and that in the blood • Oxygen in solution moves along this gradient from the alveoli to the blood • At the same time carbon dioxide diffuses in the opposite direction
In Lungs Oxygen Diffuses into the Red Blood Cell Carbon Dioxide Diffuses into the alveoli The Opposite Happens in Tissue In Tissue
Common factors to all respiratory systems Large surface area to volume ratio Close to vascular bundles Thin Moist