Bird respiration • Respiratory structures of birds differ from mammals • Birds distinguished by presence of several large thin-walled air sacs • And air spaces
Jan 01, 2016
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 : co2 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
contract
Exhalation expand
expand
Inhalation
see Fig 42.25
step 1 step 2
step 3 step 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 90o 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