Pulmonary ventilation, Biology

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.

 

Posted Date: 10/27/2012 7:56:40 AM | Location : United States







Related Discussions:- Pulmonary ventilation, Assignment Help, Ask Question on Pulmonary ventilation, Get Answer, Expert's Help, Pulmonary ventilation Discussions

Write discussion on Pulmonary ventilation
Your posts are moderated
Related Questions
Elaborate the internal vascular circulation of an eye. Retinal vessels are derived from central retinal artery and are distributed within the inner two-third of retina. Outer o

Q. What are the plant cell vacuoles? And what are their functions? And what is the covering membrane of the vacuoles called? Plant cell vacuoles are cell structures delimited b

Q. Of which cells is the nervous tissue constituted? How is the generic function of this tissue related to the characteristics of the main cell type that forms it? The nervous

write two part each in the body where cuboidal epithelia tissue are found in absorption and excretion

Explain the term Tracheostomy ? If the duration of mechanical ventilation is likely to be prolonged, it is wise to do an early tracheostomy. Otherwise, a tracheostomy is usuall

Starch Gelatinisation Starch is insoluble in cold water but in warm water it swells until its gelatinization temperature begins to lose its structure and leaches out its  8con

Explain about the Waist to Hip Ratio (WHR)? Two individuals who have the same BMI and the same total body fat may have different abdominal fat mass. Abdominal fat accumulation

assignment on the topic proteins

Where in eukaryotic cells does mRNA synthesis occur? To where do these molecules migrate? Messenger RNA molecules are synthesized within the nucleus, pass by pores of the nucle

Describe five different types of gateway vectors that are available, what different functions they can perform, and for what purpose. e.g.  (1) Vector pXXX, (2) function - expre