Respiration Section 27.2

What characteristics do the respiratory structures of all animals share? Gas diffusion occurs across thin moist membranes permeable to gasses The larger the surface area, the more diffusion can take place All respiratory structures maintain a difference in the relative concentrations of oxygen and carbon dioxide on either side of the respiratory membrane promoting diffusion

How do fish breathe? Some rely on simple gas exchange by diffusion across the bodys surface Others (most aquatic chordates that are not mammals or reptiles, and even some aquatic invertebrates) exchange gasses through gills A gill is a feathery structure that exposes a large surface area of thin, selectively permeable membrane to water Gill membrane is filled with capillaries Many organisms actively pump water over their gills to maintain differences in oxygen and carbon dioxide concentrations to promote diffusion

For how long can a whale hold it’s breath? For a sperm whale up to 90 minutes Whales, alongside all mammals breathe using lungs

What respiratory structures allow land invertebrates to breathe? Due to the large range of body plans in land invertebrate, there is a large amount of diversity amongst strategies for respiration Respiratory structures include skin, mantle cavities, book lungs and tracheal tubes Key feature is that all must keep their respiratory membranes moist

How do Land vertebrates breathe? Lungs! Lung structure can vary between animals, the process of inhaling and exhaling are similar Inhaling brings in oxygen through the trachea In lungs oxygen diffuses into blood through lung capillaries, and carbon dioxide diffuses out of blood Carbon dioxide is exhaled

How do lungs vary between different invertebrates? Internal surface area of lungs increases from amphibians to reptiles to mammals

How are birds different? Lungs in birds are structured so that the air will flow in only one direction – no stale air gets trapped in the system (as can happen in mammals) Gas exchange surfaces are continually in contact with fresh air Highly efficient – allows birds to obtain oxygen they needs to power flight muscles at high altitudes for long periods of time

Key points questions In what ways are all respiratory structures similar in all animals? Why must respiratory surfaces be moist and selectively permeable? Which aquatic animals breathe with gills? Which breathe will lungs? What is the difference between breathing in land invertebrates and vertebrates? How do lungs vary between reptiles, amphibians, mammals and birds?