VPB 121: Veterinary Physiology - II (2+1)

AIRSACS

• These large thin-walled airsacs arise from some secondary bronchi. They lie outside the lungs in the body cavity. They function as airways. Since they are avascular, no gasesous exchange occurs.
• There are 9 airsacs ; (5 anterior and 4 posterior ) unpaired inter clavicular sac, paired cervical and anterior thoracic airsacs) are anterior air sacs. Paired posterior thoracic and large abdominal sacs are the posterior air sacs.
• Diverticula from some of the airsacs are connected to many of the bones. Hence, many of the bones in birds are pneumatic and the humerus is an important pneumatic bone.
• The humerus a bone is connected to interclavicular air sac. Lungs can be ventilated via humerus and birds can suck air through broken and opened humerus.
• Gas volume of the airsacs is approximately 10 times more than lungs.