Respiration and Gas Exchange

Question 0

Define gas exchange.

Answer 0

The uptake of oxygen and the removal of carbon dioxide.

Question 1

Define respiration.

Answer 1

The sum of the biochemical reactions that provide energy for a living organism.

Question 2

How does body shape and size affect respiration and gas exchange?

Answer 2

To meet metabolic needs, the respiratory gas exchange surface area must scale with the body mass instead of body length. Animals can increase the surface area:volume ration by being long and thin.

Question 3

Why are there no water breathing homeotherms?

Answer 3

Water has a heat capacity 3000x that of air. They would lose too much heat.

Question 4

What are the four main respiratory pigments?

Answer 4

Haemoglobin, haemocyanin, haemerhythrin, chlorocruorin.

Question 5

What is the common structural characteristic of respiratory pigment basic units?

Answer 5

They are a transition metal atom held by organic ligands.

Question 6

How do actively swimming fish ventilate their gills?

Answer 6

Ram ventilation

Question 7

How do teleost fish ventilate their gills?

Answer 7

Buccal pump.

Question 8

What is the size limit for an animal to depend on diffusion?

Answer 8

1mm.

Question 9

What is Fick’s Law?

Answer 9

Rate of diffusion: DxAx(C2-C1)/Path Length.
Where D=fickian diffusional constant
A=area of diffusional surface
C=concentration of solute

Question 10

Which constant is used instead of Fick’s?

Answer 10

Krogh’s diffusional coefficient (K).

Question 11

What is Kleiber’s law?

Answer 11

Rate of metabolism is proportional to (body mass)^0.75

i.e. as mass increases the metabolic rate increases more slowly.

Question 12

What is the relationship between body surface area and body length?

Answer 12

Body surface area increases with the square of the body length, but mass increases with the cube of the body length.

Question 13

What is the relationship between respiratory surface area and body surface area.

Answer 13

Respiratory surface area must increase as body surface area increases.

Question 14

What are metabolically quiescent tissues?

Answer 14

They explain why when an animal gets bigger the proportion of its tissues which are metabolically slower increases.

Question 15

What are the basics of gaseous diffusion?

Answer 15

1) Convention (ventilation or diffusion)
2) Diffusion across epithelium
3) Internal Transport
4) Diffusion into tissues

Question 16

What are open systems?

Answer 16

Where much of the haemolymph goes into empty spaces called sinuses.

Question 17

What is a semi-closed system?

Answer 17

A system which pumps haemolymph to direct organs such as gills in hemichordates.

Question 18

What are closed systems?

Answer 18

Like in polychaetes. Haemolymph is carried by blood vessels.

Question 19

What are polychaete gills like?

Answer 19

They are distributed along the body wall or towards the anterior. Water is forced over the gills by ciliary action or muscular contraction.

Question 20

What are mollusc gills like?

Answer 20

They are highly variable and not necessarily related to metabolic demand for gas exchange. In bivalves they are also the main feeding organ.

Question 21

What is the variation in Arthropod gills like?

Answer 21

Amphipod gills are found at the base of the peropods, which helps irrigate them. In decapods the gills are found in chambers, reducing desiccation.

Question 22

What are gill books?

Answer 22

Found in horseshoe crabs. Five pairs of hinged plate-like gills.

Question 23

What are echinoderms gas exchange systems like?

Answer 23

They perform gas exchange over the epitheliium of their water vascular system. This becomes elaborated into respiratory trees in holothurians.

Question 24

What is unidirectional flow?

Answer 24

Flow in gills which allows for very efficient gas exchange and therefore scope for metabolic activity.

Question 25

How does the buccal pump work?

Answer 25

1) operculum closes, mouth opens. Floor of buccal and opercular cavities lower, drawing water into buccal cavity.
2) mouth closes. Opercular cavity floor lowers.
3) Operculum opens. Floor of opercular and buccal cavities rise, forcing water out through gill slits.

Question 26

Where else are unidirectional lungs found?

Answer 26

Birds and some crocodilians.

Question 27

Why have air breathing fish evolved?

Answer 27

Most likely in response to evolutionary pressures to exploit the margins of coastal and estuary waters that are exposed at high water to to deal with hypoxic conditions, particularly where warm water temps reduce the amount of dissolved oxygen.

Question 28

What is an obligate air breather?

Answer 28

A fish that has to breath air, e.g. the Dipnoi (lungfishes), Electrophorus (electric eel), and the biggest FW fish, Arapaima gigas.

Question 29

What are facultative air breathing fish?

Answer 29

Fish that only breathe air when water oxygen levels are low.