Transport of O >2 by the blood to the tissues: O >2 diffusion from the blood to the tissues.
Removal of CO >2 produced by tissue metabolism occurs via four mechanisms. CO >2 diffusion from the tissues to the blood.
Transport by the blood to the pulmonary capillary—alveolar membrane.
CO >2 diffusion across the capillary—alveolar membrane to the air spaces of the alveoli. Ventilation – the transport of alveolar gas to the air. Functional components: Conducting airways (conducting zone; anatomical dead space).
These airways are concerned only with the transport of gas, not with gas exchange with the blood.
They are thick—walled, branching, cylindrical structures with ciliated epithelial cells, goblet cells, smooth muscle cells. Clara cells, mucous glands, and (sometimes) cartilage.
Alveoli and alveolar septa (respiratory zone; lung parenchyma).
These are the sites of gas exchange.
Cell types include: Type I and II epithelial cells, alveolar macrophages.
The blood—gas barrier (pulmonary capillary—alveolar membrane) is ideal for gas exchange because it is very thin (< 0,5 mm) and has a very large surface area (50 —100 m >2). It consists of alveolar epithelium, basement membrane in—terstitium, and capillary endothelium.
New words
respiratory – дыхательный
air – воздух
bloodstream – кровоток
airways – воздушные пути
alveoli – альвеолы
blood vessels – кровеносные сосуды
lungs – легкие
chest – грудь
diaphragm – диафрагма
the systemic blood vessels – системные кровеносные сосуды
red blood cells – красные кровяные клетки
plasma – плазма
respi ratory control neurons – дыхательные нейроны контроля
brainstem – ствол мозга
sensory – сенсорный
motor connections – моторные связи
ventilation – вентиляция
transport – транспортировка
environment exchange – окружающая среда
surface – поверхность
29. Lung volumes and capacities
Lung volumes – there are four lung volumes, which when added together, equal the maximal volume of the lungs. Tidal volume is the volume of one inspired or expected normal breath (average human = 0,5 L per breath). Inspiratory reserve volume is the volume of air that can be inspired in excess of the tidal volume. Expiratory reserve volume is the extra an that can be expired after a normal tidal expiration.
Residual volume is the volume of gas that re lungs after maximal expiration (average human = 1,2 L).
Total lung capacity is the volume of gas that can be con tained within the maximally inflated lungs (average human = 6 L).
Vital capacity is the maximal volume that can be expelled after maximal inspiration (average human = 4,8 L).