various Organisms · Part 2

bronchioles and respiratory bronchioles. Bronchi have ‘C’ shaped curved cartilage plates to ensure that the air passage does not collapse or burst as the air pressure changes during breathing. The ­bronchioles are without cartilaginous rings and have rigidity that prevent them from collapsing but are surrounded by smooth muscle which contracts or relaxes to ­adjust the diameter of these airways. The fine respiratory bronchioles ­terminate into highly vascularised thin walled pouch like air sacs called alveoli %URQFKXV &XWHQG RIULE /XQJ +HDUW 'LDSKUDJP %URQFKLROH 3OHXUDOIOXLG $OYHROL 3OHXUDO PHPEUDQHV 7UDFKHD /DU\Q[ (SLJORWWLV Figure . The Human Respiratory System XI Std Biology-Zoology Chapter- The steps involved in respiration are i. The exchange of air between the atmosphere and the lungs. ii. The exchange of O and CO ­ between the lungs and the blood. iii. Transport of O and CO by the blood. iv. Exchange of gases between the blood and the cells. v. Uptake of O by the cells for various activities and the release of CO . Figure . Structure of Alveoli 3XOPRQDU\ DUWHU\EUDQFK GHR[\JHQDWHG EORRG 3XOPRQDU\ YHLQEUDQFK R[\JHQDWHG EORRG &DSLOODULHV VXUURXQGLQJ DOYHROL %URQFKLROH $OYHROXV 7UDFKHD &DUWLODJHULQJV &DUWLODJHSODWHV /HIWSULPDU\EURQFKXV 5RRWRIOXQJ 6HFRQGDU\EURQFKXV 7HUWLDU\ EURQFKL 6PDOOHU EURQFKL %URQFKLROHV 7HUPLQDO EURQFKLROH 5HVSLUDWRU\ EURQFKLROH $OYHROLLQ SXOPRQDU\ OREXOH Figure . The Human Respiratory tract