Friday, March 7, 2008.

Lecture 2. – Respiration

1. Source of O2 and its requirement for most life forms.

2. 4 main types of respiratory surfaces

- properties, advantages, & limitations of each.

3. Concurrent vs. Counter Current exchange mechanisms

4. Basic properties of the mammalian lung.

5. Crazy Bird lungs.

I-clicker Question #1

What is the source of oxygen in the environment?

a) O2 is a by-product of geochemical processes.

b) O2 is a by-product of respiration.

c) O2 is a by-product of photosynthesis.

d) b and c

e) all of the above

I-clicker Question #2

Why do animals need oxygen?

a) It is necessary for the physical digestion of food.

b) It is needed in order to get rid of CO2

c) It is the endpoint of glycolysis.

d) It is the endpoint for electron transport.

I-clicker Question #3

Why do animals need CO2?

a) CO2 is necessary for the physical digestion of food.

b) CO2 is needed in order to get rid of O2 in the muscles.

c) CO2 is made into sugar by plants which animals eat.

d) CO2 is the endpoint for electron transport.

I-clicker Question #4

What happens in metabolism?

a) CO2 is produced and O2 is consumed.

b) CO2 is consumed and O2 is produced.

c) both a and b.

d) none of the above.

I-clicker Question #5

What is the purpose of gas exchange in animals?

a) Remove O2 and acquire CO2

b) Acquire O2 and remove CO2

c) both a and b.

d) none of the above.

Respiratory Surfaces = sites for gas exchange.

1. Skin

2. Gills

3. Trachea

4. Lungs

Respiration Through Skin

salmon fry

Rivulus marmoratus, mangrove killifish lungless salamander

Fish gills are clumping together on exposure to air.

gill micrograph

--gills have lots of tiny folds to increase surface area for respiration

Respiration Through Gills

Whale Shark - 20 m (59 ft), 90,000 lbs.! Large Sturgeon

Counter Current ExchangeConcurrent Exchange

Trachea System

http://www.youtube.com/watch?v=DoSTehS7iq8

step 1 step 2

step 3 step 4

Bird Respiration

Questions To Review. 1. Explain the environmental pathways of O2 and CO2. Where does O2 come from? Where does CO2 come from? Why is CO2 a requirement for life on earth? Why is it a potential problem for animals?

2. Describe the 4 types of respiratory surfaces discussed in class. Under what scenarios is respiration through the skin effective? Under what scenarios is respiration through gills effective? Under what scenarios is respiration through lungs effective? Under what scenarios is respiration through a trachea effective? What are the limitations of each type of respiratory surface? Do all of these respiratory surfaces rely on diffusion? In what sense?

3. In the gills of fish, the blood flows in the opposite direction of the water. This called a counter current exchange mechanism. What is the advantage of a counter-current exchange mechanism over a concurrent exchange mechanism? Do human lungs have a counter-current exchange mechanism in the alveoli of the lungs? Be able to draw the graphs showing the difference between counter-exchange mechanism and a concurrent exchange mechanism.

4. Lungless salamanders typically live in moist or humid habitats and can die if their skin dries out. Explain why it is critical for the skin of a lungless salamander to remain moist.

5. In fish, there is a positive correlation between whole-animal metabolic rate and the surface area of the gill. What might explain this relationship?

Review Questions cont’d.

6. Describe the anatomy of the human respiratory system. Know the definitions of the following words: alveoli, bronchus, bronchiole, trachea, lung. Where does gas exchange occur in the lung? What is the relationship between surface area in the human lung versus surface area of the body? List 2 important properties of the alveolus that allow for gas exchange to take place.

7. What are surfactants? Why do lungs rely on surfactants over pure H2O?

8. How do the movements of the diaphragm control the direction of air flow in the lungs? (Note we didn’t cover this in class, but this is well covered in your book.)

9. Describe respiration in the bird lung. Explain the difference between bird respiration and mammalian respiration.

10. Very few animals that use water as the respiratory medium have lungs. Instead, most water breathers use gills for gas exchange. What functional disadvantages do lungs have in water?

11. A woman gets a disease that makes her unable to produce surfactant in her lungs. If she has a normal tidal volume (i.e. amount of air moving in and out of her lungs), what can you say about the intrapleural pressure (pressure exerted via the diaphragm) during respiration?

I-Clicker Question:

Lungless salamanders typically live in moist or humid habitats and can die if their skin dries out.

Why is it critical for the skin of a lungless salamander to remain moist?

a) So that diffusion of CO2 occurs.

b) So that the counter-current exchange mechanism works.

c) So that they don’t dry out.

d) Both b and c.