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