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
Adverse effects of menactra The most common adverse reactions to Menactra include headache, fatigue and malaise, in addition to pain, redness and induration at the site of injec

Q. What are the major parts of ferns? Ferns are constituted by small roots that come downwards from the rhizome stem and often horizontalized. The fronds also arise from the rh

What are the characteristic of Soil It is commonly conceived as a plane at right angles to the surface. The upper part of a soil profile above the parent material in which proc

Coronary Arteries The right coronary artery originates form the right aortic valvular cusp, its, SA nodal branch supplies the SA node and AV nodal branch supply the AV nod

How much time is required for a single cell of Detoxivicatium completeium to grown into a population large enough to fill the volume of the earth?

Which of the following terms best describes calcium metals? Check all that apply. Molecule, element, matter, and compound.

Cap site Two usages are given below: 1] In eukaryotes, the cap site is position in the gene at which transcription begins, and really should be called the "transcription initia

Before you solve the problem organize your thoughts on paper in the following manner. A) What will my answer look like? What units will I be using? B) What do I need to know

Determine the purpose of  the study: There must be  a sound  rationale  or justification for every research project.  If  the pui-pose of  the  study is clearly presented and just

TEST CROSS Crossing of F hybrid with its homozygous recessive parent is called test cross and the progeny of test cross is called test cross progeny. A .      Monohybrid Te