Respiration 2

Question 1

What is a disadvantage of the aspiratory pump for ventilation, in amniotes with sprawled posture?

Answer 1

Lateral undulation requires use of the muscles used for breathing, and causes compression on one side while the other expands -> can’t ventilate while running (when needed most)

Question 2

Describe the gills of amphibians

Answer 2

Branchial arches support external gills

Question 3

What kinds of air breathing organs do fish have? (4 types)

Answer 3

• reinforced gills (supported in air)
• vascularized buccal/pharyngeal cavities (only if soft, smooth food)
• other specialized GIT regions (swallow air)
• labyrinth organ (folded bone dorsal to gills supports highly-vascularized epithelium

Question 4

Who uses a 2-stroke buccal force pump?

Answer 4

most amphibians, air-breathing Sarcopterygii

Question 5

Describe the respiratory pump shared by air-breathing Actinopterygii & some aquatic amphibians

Answer 5

4-stroke buccal force pump:

• Expansion 1: glottis (G) open, mouth/nares (MN) closed -> expand buccal cavity (B) -> suck stale air from lungs to mouth
• Compression 1: G closed, MN open -> compress B -> expel stale air
• Expansion 2: G closed, MN open -> expand B -> suck fresh air in from environment
• Compression 2: G open, MN closed -> compress B -> force fresh air from mouth to lungs

Question 6

Which muscles are involved with the aspiration pump of sauropsids?

Answer 6

Intercostals & other axial

Question 7

What do crocodilians do to aid the axial muscles used in the aspiratory (ventilation) pump?

Answer 7

Use diaphragmaticus, ischiopubis muscles to pull liver towards tail to expand thoracic cavity

Question 8

Describe osteichthyes respiratory pump

Answer 8

Dual pump: buccal & opercular pumps

• Suction: expand buccal & opercular cavities -> water in via mouth (to opercular chamber b/c lowest pressure)
• Pressure: close mouth -> contract buccal & opercular cavities -> expel water out over gills

Question 9

What is an advantage of the aspiratory pump for ventilation, in terms of the buccal cavity?

Answer 9

Buccal cavity not required to pump air/water, so can specialize for specific feeding type (chewing, swallowing large prey, suckling, etc.)

Question 10

What kinds of amphibians have gills?

Answer 10

Larval salamanders & anurans; some adult salamanders (aquatic)

Question 11

Describe the ventilation system used by air-breathing Sarcopterygii & most amphibians

Answer 11

2-stroke buccal force pump:

• Expansion: mouth, nares, glottis open -> suck spent & fresh air into buccal cavity
• Compression: (all still open) force mixed air into lungs, excess into environment

Question 12

Who uses an aspiration pump for ventilation?

Answer 12

amniotes

Question 13

Describe the gills of obligate air-breathing fish, and rationale

Answer 13

• reduced surface area, thicker epithelium

- prevents O2 loss in hypoxic water (higher P_O2 in blood), but still allows ion exchange & CO2 excretion

Question 14

Describe the advantages & disadvantages of external gills. Who has them?

Answer 14

• Advantage: easy to ventilate by flicking around
• Disadvantage: vulnerable to damage (& bleed a lot b/c highly vascularized) & parasite attackes
• Used by amphibians (esp. larvae)

Question 15

Advantages of breathing air

Answer 15

• less dense than water -> easier to pump

- rarely have O2 shortage because lots available in air

Question 16

Which muscles are involved with the aspiration pump of mammals?

Answer 16

Diaphragm (not in others), intercostals, other axial muscles

Question 17

How efficient is the 4-stroke buccal force pump?

Answer 17

Not very - only 1 of 4 stages is used for gas exchange

Question 18

Who has a dual pump for respiration?

Answer 18

Chondrichthyes, osteichthyes

Question 19

Disadvantages of breathing air

Answer 19

• CO2 much less soluble than in water -> can’t just diffuse out through thin skin; regulate ventilation by CO2 levels
• keep gas exchange organs deep in body to retain moisture -> must use less efficient tidal flow

Question 20

Describe teleost gills

Answer 20

• All in opercular chamber, covered by operculum (dermatocranium)
• primary lamellae extend straight from branchial arches (no interbranchial septa)
• secondary lamellae on either side of primary lamellae

Question 21

Why is the 2-stroke buccal force pump as bad as it seems?

Answer 21

• even the spent air returning to lungs still contains O2
• timing of glottis & nares opening minimizes air mixing in buccal cavity
• pump buccal cavity between lung breaths to maintain high amount of fresh air

Question 22

Describe chondrichthyes respiratory pump

Answer 22

Dual pump: buccal & parabranchial pumps

• Suction: expand buccal & parabranchial cavities -> water in via mouth, spiracles (to parabranchial chamber b/c lowest pressure)
• Pressure: close mouth, spiracles -> contract buccal & parabranchial cavities -> expel water out over gills & through flap valves

Question 23

Who uses a 4-stroke buccal force pump?

Answer 23

Air-breathing actinopterygii, some aquatic amphibians