Respiratory 1

Question 1

Challenges of breathing water (compared to air)

Answer 1

• lower max O2 content, and decreases as temperature, [salt] increase
• 800x denser than air, so much more difficult to pump

Question 2

Function of respiratory system

Answer 2

Facilitate gas exchange

Question 3

How are gas exchange surfaces, in general, specialized?

Answer 3

• Thin
• Highly vascularized
• High surface area

Question 4

Describe the structure of gills in chondrichthyes

Answer 4

• gill ray extends from branchial arch -> supports interbranchial septum -> lined on both sides by primary lamellae -> lined on both sides by secondary lamellae
• gill rakers extend into pharyngeal cavity & block off entry to parabranchial chambers
• flap valve on outside closes off entry to parabranchial chambers

Question 5

How is diffusion rate calculated?

Answer 5

Fick’s equation: dV/dt = A/dx * D * (P1-P2)

Question 6

Advantages of breathing water

Answer 6

• Density supports gas exchange surfaces (which are thin)

- Keeps surfaces moist (required for efficient exchange)

Question 7

What kinds of factors affect P1-P2, the partial pressure difference in Fick’s equation?

Answer 7

Environmental (change P_O2, P_CO2 in air/water)

Internal (change P_O2, P_CO2 in tissues)