Chapter 12 Flashcards
how much cc of oxygen does one litre of air contain?
210cc
how much cc of oxygen does one litre of water contain?
10cc
how do fishes obtain a steady flow of oxygen?
a steady, unidirectional flow of water
who is more efficient at oxygen removal, fish or humans?
fish
how does water flow across gills?
unidirectionally, thru the mouth and out the opercular openings
what are the four phases of respiration in fishes?
Phase1: Opercular Suction Pump
Phase2: pressure is reduced
Phase3: Buccal Pressure Pump
Phase4: pressure is reversed
describe the Opercular Suction Pump
both the Buccal and Opercular cavities expand, creating negative pressure in both cavities.
describe phase 2 in respiration
the mouth closes and the Buccal cavity contracts, creating positive pressure in the buccal cavity and causing a reduced pressure differential between the two cavities.
The Buccal Pressure Pump. describe.
the buccal cavity is further compressed, while the opercular cavity is being compressed as well, causing water to be pushed out thru the opercular opening. pressure is positive in both cavities, but the pressure differential between the two is maximized
Phase 4 of respiration. describe.
the buccal cavity expands while the opercular vavity is still being compressed. there is a slight reversed differential pressure between the two cavities, but this lasts for only a v. short time. Gills prevent any backflow of water.
why is it needed to have an always present differential pressure of water along the gills?
because the gills have an appreciable resistance to water flow
in slower swimming fish, does the opercular or buccal pump predomintae?
opercular
what is the accessory pump for truly benthic forms? does this change the way things are done?
Branchiostegal Pump. yeah, the buccal pump plays a relatively minor role. The inspiratory phase is increased. completely eliminates the reverse of differential pressure of phase 4.
what kind of structure do gills form?
a sieve-like structure
each gill arch is made up of what?
gill fillaments/holobranchs. they’re made up into two halves, called hemibranchs. they’re made up of gill lamella
why do holobranchs open and close (adduction and abduction)?
to create resistance
how do elasmobranchs’ and lower bony fish’s gills differ from more derived fish?
the gill septum is complete and there is little freedom for individual filament movement
what happens in regard to gills with increase in activity?
more lamella, larger gill surface area, thickness of the EPITHLIAL LAYER DECREASES
what pathways does blood take as it travells to and from the gills?
arrives by the afferent branchial arteries, passes thru gill lamellae, leaves thru the efferent branchial arteries
how does blood and water pass each other in the gills?
countercurrent flow
accessory air-breathing structures of bony fishes are all modifications of what?
modifications of the epethelium of the alimentary canal, or gill chamber.
where are the respiratory fans and membranes located in a catfish?
the suprabranchial chamber
what is the epithelium often equipped with?
branched, tree like outgrowths to increase the surface area. lying underneath is a rich network of blood capillaries
why are gills not used for out-of-water breathing?
the structures are not strong enough out of water. they collapse and the fish suffocates.
what is the biological significance of air breathing?
- survival in oxygen poor habitats
- utilization of terrestrial food resources
- abandon drying ponds to search for better habitat
- invade new territories and thus enhance distribution
