Pulmonary ventilation, Biology

Assignment Help:

Pulmonary Ventilation:
Pulmonary ventilation is the process by which gasses flow between the atmosphere and lung alveoli. Air moves into the  lungs when air pressure  inside the lungs is less than  the  air pressure in the atmosphere and out of  the lungs when  the pressure inside the lungs is greater than the atmosphere pressure. Breathing  in  is called inhalation or inspiration. Just before each inhalation air pressure inside the  alveoli is equal to the atmospheric pressures, 760 rnmHg,  and the intrapleural pressure is 756 mmHg. With  inspiration, the cavity of the thorax is enlarged as external intercostals muscles  and the diaphragm contract causing a decrease in  the  intrapleural pressure to about 754 mmHg. The parietal pleura lining the cavity is pulled outward in all direction and the visceral pleura and lungs are pulled along with  it. As  the  lung volume increases in this way  the pressure inside the lungs i.e.  760 mmHg drops to 758 mmHg. Thus a pressure difference  is established between the atmosphere and alveoli and air flows into the  lungs from the atmosphere. Breathing out or exhalation (expiration) starts when the  inspiratory muscles and diaphragm relaxes,  the dome of the diaphragm moves up, the ribs are depressed leading  to decrease in the  lung volume and increase in  the lung pressure (763 rnm Hg). Air flows out form the area of higher pressure to the area of lower pressure  in  the atmosphere. The elastic recoil  of the chest wall and the lungs is due to  the recoil of elastic fibers and the inward pull of surface tension due to  the alveolar fluid. A thin  layer of alveolar fluid coats the  surface of the alveoli and exerts a  force known as surface tension. Exhalation is a passive process while inhalation or  inspiration  is an active process.

 


Related Discussions:- Pulmonary ventilation

Why is it necessary to maintain the ph level, Q Coming from the acid pH of ...

Q Coming from the acid pH of the stomach which pH level does the chyme find when it enters the duodenum? Why is it necessary to maintain that pH level in the small intestine? What

Explain zanamivir, Zanamivir  (Relenza) Started within 2 days after on...

Zanamivir  (Relenza) Started within 2 days after onset of symptoms, this orally inhaled neuraminidase inhibitor can shorten the duration of illness and may decrease the incide

Explain polyenes - amphotericin b, Polyenes: amphotericin b Amphoterici...

Polyenes: amphotericin b Amphotericin B products are the only polyenes currently available for systemic treatment of fungal infections.  Nystatin, another polyene, is only avai

Obelia, why is it consideredto have an intermideate grade oforganisation

why is it consideredto have an intermideate grade oforganisation

Carbohydrate distribution in insulin, Q. Carbohydrate distribution in insul...

Q. Carbohydrate distribution in insulin? The carbohydrate distribution varies with the type of insulin prescribed. For example, in case of regular insulin 1/3rd each carbohydra

Gametes, examples of gametes

examples of gametes

Nitrogen cycle, Nitrogen Cycle The nitrogen is an essential constituen...

Nitrogen Cycle The nitrogen is an essential constituent of protein - the building block of all living cells. It is also a major constituent of the atmosphere (79 per cent). Al

Why poriferans and cnidarians do not have excretory systems, Poriferans and...

Poriferans and cnidarians do not have excretory systems. Do platyhelminthes have an excretory system? Platyhelminthes have a primitive excretory system made of flame cells (als

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd