Chapter 12

Question 1

how much cc of oxygen does one litre of air contain?

Answer 1

210cc

Question 2

how much cc of oxygen does one litre of water contain?

Answer 2

10cc

Question 3

how do fishes obtain a steady flow of oxygen?

Answer 3

a steady, unidirectional flow of water

Question 4

who is more efficient at oxygen removal, fish or humans?

Answer 4

fish

Question 5

how does water flow across gills?

Answer 5

unidirectionally, thru the mouth and out the opercular openings

Question 6

what are the four phases of respiration in fishes?

Answer 6

Phase1: Opercular Suction Pump
Phase2: pressure is reduced
Phase3: Buccal Pressure Pump
Phase4: pressure is reversed

Question 7

describe the Opercular Suction Pump

Answer 7

both the Buccal and Opercular cavities expand, creating negative pressure in both cavities.

Question 8

describe phase 2 in respiration

Answer 8

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.

Question 9

The Buccal Pressure Pump. describe.

Answer 9

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

Question 10

Phase 4 of respiration. describe.

Answer 10

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.

Question 11

why is it needed to have an always present differential pressure of water along the gills?

Answer 11

because the gills have an appreciable resistance to water flow

Question 12

in slower swimming fish, does the opercular or buccal pump predomintae?

Answer 12

opercular

Question 13

what is the accessory pump for truly benthic forms? does this change the way things are done?

Answer 13

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.

Question 14

what kind of structure do gills form?

Answer 14

a sieve-like structure

Question 15

each gill arch is made up of what?

Answer 15

gill fillaments/holobranchs. they’re made up into two halves, called hemibranchs. they’re made up of gill lamella

Question 16

why do holobranchs open and close (adduction and abduction)?

Answer 16

to create resistance

Question 17

how do elasmobranchs’ and lower bony fish’s gills differ from more derived fish?

Answer 17

the gill septum is complete and there is little freedom for individual filament movement

Question 18

what happens in regard to gills with increase in activity?

Answer 18

more lamella, larger gill surface area, thickness of the EPITHLIAL LAYER DECREASES

Question 19

what pathways does blood take as it travells to and from the gills?

Answer 19

arrives by the afferent branchial arteries, passes thru gill lamellae, leaves thru the efferent branchial arteries

Question 20

how does blood and water pass each other in the gills?

Answer 20

countercurrent flow

Question 21

accessory air-breathing structures of bony fishes are all modifications of what?

Answer 21

modifications of the epethelium of the alimentary canal, or gill chamber.

Question 22

where are the respiratory fans and membranes located in a catfish?

Answer 22

the suprabranchial chamber

Question 23

what is the epithelium often equipped with?

Answer 23

branched, tree like outgrowths to increase the surface area. lying underneath is a rich network of blood capillaries

Question 24

why are gills not used for out-of-water breathing?

Answer 24

the structures are not strong enough out of water. they collapse and the fish suffocates.

Question 25

what is the biological significance of air breathing?

Answer 25

• 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