

Study with the several resources on Docsity
Earn points by helping other students or get them with a premium plan
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Community
Ask the community for help and clear up your study doubts
Discover the best universities in your country according to Docsity users
Free resources
Download our free guides on studying techniques, anxiety management strategies, and thesis advice from Docsity tutors
respiratory system human physiology ventilation
Typology: Essays (university)
1 / 2
This page cannot be seen from the preview
Don't miss anything!
During inspiration the pressure inside the lungs (the intrapulmonary pressure ) decreases to -1 to -3 mmHg compared to the atmosphere. The variation is related to the forcefulness and depth of inspiration. During expiration the intrapulmonary pressure increases to +1 to +3 mmHg compared to the atmosphere.
The pressure oscillates around zero or atmospheric pressure.
The intrapleural pressure is always negative compared to the atmosphere. This is necessary in order to exert a pulling action on the lungs. The pressure varies from about -4 mmHg at the end of expiration, to -8 mmHg and the end of inspiration.
Respiratory output is determined by the minute volume , calculated by multiplying the respiratory rate time the tidal volume.
Rate of respiration at rest varies from about 12 to 15 bpm. Tidal volume averages 500 ml •Assuming a rate of 12 breaths per minute and a tidal volume of 500, the restful minute volume is 6000 ml. Rates can, with strenuous exercise, increase to 30 to 40 bpm and volumes can increase to around half the vital capacity.
Not all of this ventilates the alveoli, even under maximal conditions. The volume air in conducting zone is about 150 ml (dead space) and does not extend into the respiratory zone.
cm H2O 2.Compliance of lungs only:0.22 litre/cm H2O
Compliance increases in: Emphysema,old age Compliance decreases in: pulmonary congestion (lungs filled with blood), pulmonary fibrosis, pulmonary edema
The opposite tendency is called elasticity or recoil , and is the process by which the lungs return to their original or resting volume.
In emphysema compliance increases and elasticity decreases, In this buildup of toxins from cigarette smoke and resulting mucus production leads to destruction of the alveolar and capillary walls and fibrosis of the tissue.
This produces large thick-walled chambers replacing the normal small thin-walled alveoli. It results in a larger volume in the lungs but impaired gas transport and reduced ability to expire the trapped air.
Many emphysema sufferers have the characteristic "barrel chest" as a result. Carbon dioxide tends to increase in alveolar air and in the blood, in some individuals interfering with normal respiratory stimuli and responses.