05.24.17 What can we do to stop the spread of measles? I will describe how the body exchanges gases.

How do organisms exchange gas?

Parapodium (functions as gill) Fig. 42-21a Figure 42.21 Diversity in the structure of gills, external body surfaces that function in gas exchange Parapodium (functions as gill) (a) Marine worm

Gills (b) Crayfish Fig. 42-21b Figure 42.21 Diversity in the structure of gills, external body surfaces that function in gas exchange Gills (b) Crayfish

Coelom Gills Tube foot (c) Sea star Fig. 42-21c Figure 42.21 Diversity in the structure of gills, external body surfaces that function in gas exchange Gills Tube foot (c) Sea star

Figure 42.22 The structure and function of fish gills Fluid flow through gill filament Oxygen-poor blood Anatomy of gills Oxygen-rich blood Gill arch Lamella Gill arch Gill filament organization Blood vessels Water flow Operculum Water flow between lamellae Blood flow through capillaries in lamella Figure 42.22 The structure and function of fish gills Countercurrent exchange PO2 (mm Hg) in water 150 120 90 60 30 Gill filaments Net diffu- sion of O2 from water to blood 140 110 80 50 20 PO2 (mm Hg) in blood

Air sacs Tracheae External opening Tracheoles Mitochondria Fig. 42-23 Air sacs Tracheae External opening Tracheoles Mitochondria Muscle fiber Body cell Air sac Tracheole Figure 42.23 Tracheal systems Trachea Air Body wall 2.5 µm

Breathe In. Pharynx Larynx Alveoli Trachea Bronchus Bronchiole Fig. 42-24 Branch of Pulmonary vein (oxygen-rich blood) Branch of Pulmonary artery (oxygen-poor blood) Terminal bronchiole Pharynx Nasal cavity Larynx Alveoli Trachea Bronchus Figure 42.24 The mammalian respiratory system Bronchiole Diaphragm Heart SEM Colorized SEM 50 µm 50 µm

Big ideas. Work with a partner or independently to respond the the questions. We will review these tomorrow at the beginning of the period.

Artery v. Vein