Studied by 3 people
What are the different types of organs used for respiration and what organisms are they used by?
Internal gills -- used by most aquatic organisms
External gills -- used by amphibians only
vertebrate lungs -- used by tetrapods
How do positive pressure systems of respiration work? what are the costs of positive pressure systems?
animals actively push air into their lungs via buccal pumping and/or gulping air; cost -- animals canNOT breathe and eat at the same time
what are some examples of positive pressure systems for respiration? (air-breathing fish and Anurans)
air-breathing fish gulp air into their oral cavity and use the pharynx as a suction pump to force air into the pneumatic duct
Anurans use their internal nares and glottis to force air from the buccopharyngeal space into their lungs
Nares open and glottis closes; air is sucked into buccopharyngeal space; Nares close and glottis opens; throat is raised so air is forced into lungs
the subsequent development of axial muscles and ribs has allowed for aspiration (a more efficient form of ventilation that instead uses negative pressure!)
what were the first animals to breathe via aspiration (negative pressure)? what are the benefits of negative pressure systems?
labyrinthodonts; allowed the oral cavity and pharynx to be used more for feeding so that the animal can breathe and eat at the same time
how do negative pressure systems of respiration work?
air is sucked into the lungs by negative pressure (the lungs are expanded to create low pressure inside, so thus air is pulled in)
what are some examples of negative pressure systems for respiration? (reptiles and mammals)
Reptiles use the movement from their sprawling gait to expand or contract one lung at a time
Mammals inflate their lungs via negative pressure by contracting their diaphragm
How do Agnathans (lampeys) respire?
tidal ventilation via gill pouches
how do elasmobranchs (sharks) respire?
they use forward movement / ram ventilation to flow water over their gills on each side of a gill septum; countercurrent exchange
how do bony fish respire?
the ventilate via buccal pumping to flow water over their gills, which are in a single chamber beneath a protective operculum; countercurrent exchange
how do amphibian larvae respire?
they have internal gills within a branchial chamber and some also have external gills; the gills are moved by muscles for gas exchange
what is the vertebrate lung a modification of?
the physostomous (“air gulping”) swim bladder
what is the general evolutionary trend in respiratory surfaces as vertebrates evolve?
increasing surface area via increased surface area of gills or increased compartmentalization of the lungs as body size and/or metabolism increases
what characteristics of lungs do amphibians like Anurans (toads and frogs) have?
large, short lungs and short trachea that divide into two bronchi
what characteristics of lungs do Reptiles have?
many heterogeneously partitioned compartments, long trachea, and long bronchi supported by cartilaginous rings
what characteristics of lungs do mammals have?
very finely compartmentalized lungs, trachea divides into right and left primary bronchi, which divide further into smaller bronchi and respiratory bronchioles (which contain alveoli, where gas exchange occurs)
what characteristics of lungs do avian animals (like birds) have?
avian animals have a very unique respiratory system with lungs and air sacs and unidirectional airflow (NOT tidal)
there are usually 9 air sacs (which help pump air) connected to the lungs (which remain the same volume at all times)
air flows first into the posterior air sacs, then through parabronchi into the lungs, then into the anterior air sacs
crosscurrent exchange of gases occurs across the air and blood capillaries
what are the characteristics of tetrapod lungs (in comparison to fish lungs)?
paired and ventral
higher surface area-to-volume ratio
trachea connects the lung to the pharynx
glottis -- the opening to the trachea
trachea and bronchi are ringed with cartilage to prevent collapse
low-oxygen blood is received via vessels related to the 6th aortic arches
oxygenated blood returns directly to the heart without prior mixing
what are the characteristics of alveolar lungs and where are they found?
alveolar lungs have alveoli (sacs that inflate and deflate to exchange oxygen and co2 with blood); they are found in synapsids like mammals
what are the characteristics of faveolar lungs and where are they found?
Faveolar lungs have faveoli (air flows in only one direction, cross-current to the blood) which are more efficient and allow for a higher metabolic rate; found in sauropsids (birds and reptiles)
why are the kidneys essential to life on land? how do they work, and what is the loop of Henley?
to regulate water content; they work via a negative pressure system called the loop of henley that concentrates ions in urine; the loop of henley increases the surface area where diffusion can take place, which allows birds and mammals to have a higher solute concentration in their urine and thus conserve water
water retention is especially important for endotherms because of their higher metabolic rate, which causes more breathing and water loss
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