Bird respiration Respiratory structures of birds differ from mammals Birds distinguished by presence of several large thin- walled air sacs And air spaces

This intricate system may be an adaptation for flight – What about Bats!!! More typical mammalian lungs, and some bat species can migrate long distances.

-What about oxygen consumption : -Similar to mammals at rest -And during flight similar to bats -In both an increasing about 8-10

So what is the rule if air sac and air spaces Lighter !!!! Air sacs hasn ’ t any effect on: weight : two test nor gas exchange : co 2 test May its correct ( by very limited effect) with air spaces.

What air sacs do Sacs connect lungs ( is a volume). For similar weight animals( 1Kg)

For a given size, birds have smaller lungs, but greater respiratory surfaces than mammals Birds have greater tidal volumes than mammals, but lower respiratory frequency

1- So air sacs increases the tidal volume ( total respiratory system volume ) It ’ s the first function what else !!!!!!

Lung structure Is a bird like mammals !!!! mammals tracheae end by alveoli Birds tracheae end by what ? the finest branches of bronchial system (parabronchi) permit rapid air exchange

Mammals move air in and out through alveoli lung. Birds unidirectional through lungs But in and out through respiratory system ( as all) Who do this rule ( in and out ) 2- Air sacs act as bellows. Is the second function

Diagram of the lungs Two gropes of air sacs - caudal / posterior : large abdominal - cranial / anterior : several smaller Tracheae divided into two bronchi Each for lung and terminate in large abdominal sacs

Stages: (1) Inspiration: Air flows directly to caudal sacs (2) Exhalation: Air from caudal sacs flows into the lung instead of out the main bronchus (3) Inspiration: Air from lung flows to cranial sacs (4) Exhalation: Air from the cranial sacs flows to outside

contract Exhalation expand Inhalation see Fig 42.25

step 1step 2 step 3step 4 Bird Respiration

Bird Ventilation No diaphragm –Ventilate lungs using bellows action of air sacs site of gas exchange: parabronchus –open tube with unidirectional flow and cross current blood flow unidirectional air flow throw lung –cross current exchange

Cross current exchange blood flow at 90 o to air flow Parabronchus Unidirectional air flow Pul. artery Pul. vein

Allows oxygenated blood that leaves the lung to have a higher oxygen tension than the oxygen partial pressure in exhaled air

Blood about to leave lung (low oxygen content) is in exchange with air that has just entered the lung (high oxygen content) As air flows through lung, it loses oxygen and takes up carbon dioxide Thus, the blood rapidly becomes saturated with oxygen

Birds are better-suited for extracting oxygen from the pulmonary air (and deliver carbon dioxide) than mammals.

Mice and sparrows ( 360 mm.hg) 6100m Compare Mountain climbers

Canary song How does the canary sing continuously without taking a breath? The canary song is always produced during expiratory air flow in the trachea The song consists of single notes that are repeated at high rates, with each note lasting between 11 to 280 ms Between the notes are brief silent intervals, lasting from 20 to235 ms, during which inspiration takes place