Gas Exchange I. Introduction

A. Why?

B. Forces & Factors 1. What forces drive gas exchange?

Figure 42.23

2. What factors help to maximize exchange?

C. Transport

II. Strategies A. Direct

Poriferans, Cnidarians, and Platyhelminthes

Figure 33.4

Constant water movement

Simple thin structure

What would be required to lead this life style?

B. Gills 1. Structure

Mollusca to Vertebrata

Figure 42.22

Fish Gills

2. Forces

Ram ventilation vs. Gulping Advantages vs. Disadvantages

a. Passive to b. Active

Circulation of water coupled with perfusion of blood

Figure 42.23

swim bladder in bony fishes via the gas gland

Figure 34.16

C. Tracheal Systems 1. Insecta

Figure 42.24

direct oxygen delivery system to the

muscle fibers

2. Chordata a. Amphibians

Circulate air to lungs from mouth

and skin ==PP breathers

b. Reptilians PP breathers

c. Avians Negative pressure breathers move air into

their lungs and air sacs

Figure 42.27

d. Mammalians

i. Air tubes Negative breathers use

muscle contractions to

move air

Figure 42.25

pseudostratified ciliated columnar with goblet cells

ii. Lungs

alveoli for gas exchange Type I, Type II cells,

and Dust cells

Figure 42.25

Lung expansion == muscle contraction

Quiet versus Forced Inhalation vs. Exhalation

Figure 42.28

iii. Control

Pons, Medulla Oblongata, and the Hypothalamus

Figure 42.29

iv. Transport O2 partial gas pressures

Figure 42.30

Figure 42.31a & b

Respiratory pigments transport oxygen and also buffer

CO2 is transported via other mechanisms

Dissolved in plasma about 7%

Bound to globin about 23%

Travels via the bicarbonate shuttle about 70%

Figure 42.32

iv. Transport CO2

Quantity doesnt mean Quality.