oxygen diffusion - way for gases to get across plasma membranes
- levels needed for metabolism can’t be obtained by diffusion over 0.5 mm
- respiratory organs increase surface area and decrease distance over which oxygen must move
gills - tissue that projects out into the water
- has no support, would collapse w/o water
- loses lots of water to evaporation when exposed to air
- external gills - not enclosed within the body
- must be constantly moved
- easily damaged
- branchial chambers - pumps water past nonmoving gills
- bony fish gills - found between mouth and opercular cavity
- most efficient of all respiratory organs
- operculum (gill cover) - moves to open/close opercular cavity
- water moves in through mouth, leaves through operculum
- ram ventilation - forces water over gills through body mov’t, not pumping
- gill arches - 4 on each side of head, each contains 2 rows of gill filaments and lamellae
- blood flows opposite to the water mov’t (coutercurrent)
air-breathing - different organs for terrestrial organisms
- tracheae - network of air passages in insects
- oxygen diffuses directly into different cells
- spiracles - openings of tracheae, close to prevent water loss
- lung - saturates air w/ water vapor before gas exchange
- air moves in/out through same passages
- amphibian respiration - less lung surface area than other vertebrates
- positive pressure breathing - mouth pumps air into lungs
- cutaneous respiration also used (sometimes more than normal respiration)
- reptile respiration - cannot breathe through skin (too dry, tough)
- negative pressure breathing - rib cages, lungs expand through muscular contraction
- mammal respiration - higher metabolic rate than reptiles/amphibians
- alveoli - tiny sacs in lungs, adds to surface area for gas diffusion
- passage of air - mouth >> pharynx >> larynx (voice box) >> glottis (opening in vocal cords) >> trachea (windpipe) >> bronchi >> bronchioles >> alveoli
- external respiration - between lungs, capillaries
- internal respiration - between capillaries, tissues
- bird respiration - has most efficient respiratory system out of all terrestrial vertebrates
- parabronchi - air vessels w/ unidirectional flow (like fish)
- new/old air not mixed together like in other terrestrial animals
- inspiration - inhaled air goes to posterior air sac, air in lungs goes to anterior air sac
- expiration - air from anterior air sac exhaled, air from posterior air sac goes to lungs
- cross-current flow - blood flows perpendicular to air flow, more efficient than mammals
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