1. The Living World George B. Johnson Jonathan B. Losos Chapter 30
Fifth Edition
George B. Johnson
Jonathan B. Losos
Chapter 30
Respiration
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2. 30.1 Types of Respiratory Systems
Respiration is the uptake of oxygen and the simultaneous release of carbon dioxide
most primitive animal phyla obtain oxygen directly from their environments through diffusion
more advanced phyla have specific respiratory organs
gills, tracheae, and lungs

3. Figure 30.1 Gas exchange in animals

4. 30.2 Respiration in Aquatic Vertebrates
Water always moves past a fish’s gills in one direction
moving the water past the gills in the same direction permits countercurrent flow
this process is an extremely efficient way of extracting oxygen
blood flows through a gill filament in an opposite direction to the movement of water
the blood in the blood vessels always encounters water with a higher oxygen concentration, resulting in the diffusion of oxygen into the blood vessels

5. Figure 30.2 Structure of a fish gill

6. Figure 30.3 Countercurrent flow

7. 30.3 Respiration in Terrestrial Vertebrates
Lungs are less efficient than gills because new air that is inhaled mixes with old air already in the lung
but there is so much more oxygen in air than in water
the lungs of mammals possess on their inner surface many small chambers called alveoli, which greatly increases surface area for the diffusion of oxygen

8. Figure 30.4 Evolution of the vertebrate lung

9. 30.3 Respiration in Terrestrial Vertebrates
Flying creates a respiratory demand for oxygen that exceeds the capacity of the saclike lungs of even the most active mammal
birds have evolved the most efficient lung
an avian lung is connected to a series of air sacs outside of the lung
birds have unidirectional flow of air through the lungs
blood flow and air flow are not opposite but flow at perpendicular angles in crosscurrent flow

10. Figure 30.5 How a bird breathes

11. 30.4 The Mammalian Respiratory System
The mammal respiratory apparatus is simple in structure and function as a one-cycle pump
a diaphragm muscle separates the thoracic cavity from the abdominal cavity
each lung is covered by a thin, smooth membrane called the pleural membrane
this membrane adheres to another pleural membrane lining the walls of the thoracic cavity, basically coupling the lungs to the thoracic cavity
air is drawn into the lungs by the creation of negative pressure

12. 30.4 The Mammalian Respiratory System
The active pumping of air in and out is called breathing
during inhalation, muscular contraction causes chest cavity to expand
during exhalation, the ribs and diaphragm return to their original position

13. Figure 30.7 How breathing works

14. 30.4 The Mammalian Respiratory System
In a human a typical breath at rest moves about 0.5 L of air, called the tidal volume
The extra amount that can be forced into and out of the lung is called the vital capacity and is about 4.5 L in men and 3.1 L in women
The air remaining in the lung after such a maximal expiration is the residual volume, or dead volume, typically about 1.2 L

15. 30.5 How Respiration Works: Gas Exchange
Oxygen moves through the circulatory system piggyback on the protein hemoglobin
hemoglobin molecules contain iron and oxygen binds in a reversible way
Figure 30.8 The hemoglobin molecule

16. 30.5 How Respiration Works: Gas Exchange
hemoglobin molecules act like little sponges for oxygen
at the high O2 levels that occur in the blood supply at the lung, most hemoglobin carry a full load of O2
in the tissues, the O2 levels are much lower so that hemoglobin gives up its bound oxygen
in the presence of CO2, the hemoglobin assumes a different shape that give up its oxygen more readily

17. 30.5 How Respiration Works: Gas Exchange
CO2 must also be transported by the blood
about 8% simply dissolves in the plasma
20% is bound to hemoglobin but at a different site than what O2 binds to
the remaining 72% diffuses into the red blood cells
In order to maintain the gradient for CO2 to leave the tissues and enter the plasma, the CO2 levels in the plasma must be kept low

18. 30.5 How Respiration Works: Gas Exchange
The enzyme carbonic anhydrase combines CO2 with water to form carbonic acid (H2CO3)
this acid dissociates into bicarbonate (HCO3-) and H+
the H+ binds to hemoglobin while the red blood cell moves the bicarbonate out into the plasma
the protein that moves the bicarbonate out exchanges it for a chloride
this exchange is known as the chloride shift

19. Figure 30.9 How respiratory gas exchange works

20. 30.5 How Respiration Works: Gas Exchange
Hemoglobin has the ability to hold and release the gas nitric oxide (NO)
NO has an important physiological role in the body, acting on many kinds of cells to change their shape and function
for example, NO causes blood vessels to expand because it relaxes the surround muscle cells

21. 30.6 The Nature of Lung Cancer
Smoking causes lung cancer
it causes mutations to certain tumor-suppressing genes
Rb codes for Rb protein, which acts as a brake on cell division
p53 codes for p53 protein, which detects damaged or foreign DNA and prevents it replication

22. Figure 30.11 Incidence of lung cancer in men and women

23. Inquiry & Analysis
At an elevation of 5000 feet, the partial pressure of O2 is 50mm Hg. At this elevation, how much of human hemoglobin has succeeded in binding? of llama? of vicuna?
Graphs