1. Chapter 33 Respiration Chapter 33 Opener
These students say they will quit smoking later. Only about one in three will succeed.

2. Chapter 33 Outline 33.1 Why Exchange Gases?
33.2 What Are Some Evolutionary Adaptations for Gas Exchange?
33.3 How Does the Human Respiratory System Work?

3. Section 33.1 Outline 33.1 Why Exchange Gases?
 Gas exchange supports cellular respiration
Gas exchange in vertebrates
O2 is inhaled into lungs, deposited in blood, and transported to body cells
O2 is used in cellular respiration to convert the energy in nutrients into ATP, generating CO2 as a waste product
Blood transports CO2 from tissues to lungs
CO2 released from lungs during exhalation

4. Section 33.2 Outline
33.2 What Are Some Evolutionary Adaptations for Gas Exchange?
Some Animals in Moist Environments Lack Specialized Respiratory Structures
Respiratory Systems Facilitate Gas Exchange by Diffusion
Terrestrial Animals Have Internal Respiratory Structures

5. Common Respiratory Features
All animal respiratory systems share three features
(1) Respiratory surface must be moist so gases can diffuse across cell membranes
(2) Cells lining respiratory surface are thin to optimizes gas diffusion
(3) The respiratory surface area must be large to allow for adequate gas exchange

6. Animals in Moist Environments
Some animals in moist environments lack specialized respiratory structures
Gases diffuse short distances in smaller animals to reach cells
Gas exchange optimized by long, flat bodies with greater surface area
Examples: flatworms

7. Animals in Moist Environments
Low energy demands translate into larger animals that rely on their moist body surface for gas exchange
Larger size possible because less O2 needed by cells
Example: sea jellies

8. Animals in Moist Environments
Some animals bring the environment close to all their cells
Allows greater exposure of cells to O2
Example: sponges

9. Animals in Moist Environments
Other animals combine large skin surface area with well-developed circulation for delivery to cells
Skin has many capillaries that carry O2 to internal body tissues
This arrangement sustains a favorable O2 concentration gradient between skin and blood
Example: earthworm

10. Gas Exchange
Respiratory systems facilitate more effective exchange of gases between the environment and an animal’s body
Respiratory systems alternate bulk flow of air/water and diffusion of gases
Bulk Flow: describes when fluids or gases move through spaces from high pressure to low pressure

11. Gas Exchange In mammals
Air or water moves past respiratory surface by bulk flow (down pressure gradient)
O2 and CO2 are exchanged by diffusion
Gases transported to/from tissues by bulk flow
Gases exchanged with tissues (cells) by diffusion

12. Gas Exchange in Water
Gills are external projections of the body that exchange gases
Most commonly used in aquatic animals
Can be elaborately folded to maximize their surface area
Have many capillaries to bring blood to body surface for gas exchange

13. Gas Exchange in Water Fish gills are complex structures
Protected by a bony flap (operculum)
Fish controls water flow over gills by swimming with mouth open
Water flows over gills and out of body through opercular openings
Gills are elaborately folded, and cannot support themselves out of water

14. Internal Respiratory Structures
Internal respiratory structures are used by most terrestrial animals to help keep respiratory surfaces moist
Gas exchange is optimized across moist surfaces
Two common terrestrial respiratory structures
Tracheae (insects)
Lungs (most terrestrial vertebrates)

15. Tracheae
Tracheae are elaborately branched internal tubes that deliver air to body cells
Used by insects
Branch into smaller tubes (tracheoles)
Air enters tracheae though abdominal openings (spiracles)
Some insects use abdominal contractions to enhance air movements

16. Lungs
Lungs are internal chambers containing moist respiratory surfaces
Used by most terrestrial vertebrates
Developed to allow ancestral fish to survive in stagnant, O2-poor water

17. Lungs Lungs have differing levels of complexity In amphibians
Many use gills as larvae and simple, sac-like lungs as more terrestrial adults
Many use the skin as a supplemental respiratory surface
Example: tadpoles and a bullfrog

18. Lungs
In reptiles
Scales reduce body water loss and allow for survival in dry environments
Scales reduce gas exchange through skin
Lungs have more respiratory surface area than amphibians
Example: a mangrove
snake

19. Lungs In birds Exclusively lung breathers
Extremely efficient lungs accommodate O2 demands during flight
Air flows through lungs during inhalation and exhalation due to coordination of air sac activity
Bird lungs filled with thin walled tubes (parabronchi)

20. Section 33.3 Outline 33.3 How Does the Human Respiratory System Work?
The Conducting Portion of the Respiratory System Carries Air to the Lungs
Gas Exchange Occurs in the Alveoli
Oxygen and Carbon Dioxide Are Transported Using Different Mechanisms
Air Is Inhaled Actively and Exhaled Passively
Breathing Rate Is Controlled by the Respiratory Center of the Brain

21. The Human Respiratory System
The human respiratory system can be divided into two parts
The conducting portion
The gas-exchange portion

22. The Conducting Portion
The conducting portion is a series of passageways that carry air into the gas-exchange portion of the lungs
Warms and moistens air on way to lungs
Debris in air sticks to mucus that lines respiratory passages
Mucus carried to pharynx by cilia lining respiratory passages

23. The Conducting Portion
Nose and mouth
Nasal cavity and oral cavity
Pharynx(인두): chamber where nasal and oral cavities converge

24. The Conducting Portion
Larynx: opening called the “voice box”
Contain vocal cords: bands of elastic tissue controlled by muscles; vibrate as exhaled air passes over them

25. The Conducting Portion
Larynx covered by epiglottis: flap of tissue that prevents food from entering larynx when swallowing
If food lodges in larynx, choking can occur
Heimlich maneuver can dislodge food

26. Heimlich maneuver FIGURE 33-8 The Heimlich maneuver can save lives
If a person is choking and unable to breathe, use the Heimlich maneuver to push upward on the victim's diaphragm, forcing air out of the lungs and often dislodging the object. Repeat if necessary.

27. The Conducting Portion
Trachea: flexible tube reinforced with cartilage
Bronchi: splitting of trachea into two branches; each leading to a lung

28. The Conducting Portion
Bronchioles: repeated branchings of bronchi
Lined with smooth muscle that can constrict or dilate passageway

29. The Gas Exchange Portion
Where gases are exchanged with the blood
Occurs in the alveoli in the lungs
Alveoli: tiny air sacs where gas exchange occurs
300 million alveoli in both lungs
Arranged in grape-like clusters
Surrounded by dense capillary networks

30. The Gas Exchange Portion
Alveoli in lungs are well adapted for gas exchange
Extensive collective surface area
Are enmeshed in capillaries
Made of a single thin layer of endothelial cells that form the innermost portion of the respiratory membrane, across which gas exchange occurs

31. The Gas Exchange Portion
The respiratory membrane
Consists of the alveolar epithelium and the layer of endothelial cells that forms the innermost wall of each capillary
The alveolar and capillary walls are only one cell thick, minimizing diffusion distance for gases between the blood and the air

32. The Gas Exchange Portion
O2 diffuses from lung air into blood
O2 in freshly inhaled air has higher O2 concentration than O2-poor blood
O2 diffuses down concentration gradient into capillary blood
Oxygenated blood transported to heart, then the rest of body

33. The Gas Exchange Portion
CO2 diffuses from lung blood into alveoli
Metabolically active tissues release CO2 into blood, which transports it to alveolar capillaries
Alveolar capillaries have a higher CO2 concentration than that of alveolar air
CO2 diffuses down concentration gradient into alveolar air, which is then exhaled

34. The Gas Exchange Portion
Surfactant
Oily secretion lining alveolar walls
Reduces surface tension of alveolar walls, preventing collapse during exhalation

35. Oxygen Transport
O2 binds reversibly to hemoglobin molecules in red blood cells
Hemoglobin: iron-containing protein that can bind to four O2 molecules
When bound to O2: cherry-red color
When not bound to O2: maroon-red color

36. Carbon Dioxide Transport
CO2 is transported in the blood in three ways
(1) As bicarbonate ions
(2) Bound to hemoglobin
(3) Dissolved in plasma as CO2

37. Carbon Dioxide Transport
CO2 transport as bicarbonate ions (HCO3-)
70% of CO2 reacts with water to form HCO3-, which is then transported in the plasma
CO2 transported bound to hemoglobin
20% of CO2 binds to and is carried by hemoglobin
CO2 transported dissolved in plasma
10% of CO2 is transported this way

38. Inhalation and Exhalation
Breathing occurs due to volume changes in the airtight chest cavity
Located within rib cage
Bottom of chest cavity defined by dome-shaped diaphragm muscle

39. Inhalation and Exhalation
Breathing occurs in two stages
Inhalation
Exhalation
Air is inhaled actively and exhaled passively

40. Inhalation and Exhalation
Inhalation: when air is drawn into lungs
Chest cavity enlarges when diaphragm and rib muscles contract
Lungs expand with chest cavity, creating a partial vacuum that draws air into lungs

41. Inhalation and Exhalation
Exhalation: when air is passively expelled out of lungs
Chest cavity size decreases when diaphragm and rib muscles relax
Decreasing chest cavity size forces air out of lungs
Additional air can be expelled by actively contracting the abdominal muscles

42. The Respiratory Center
The respiratory center is a cluster of nerve cells located in the medulla(연수) of the brain
Generate cyclic bursts of impulses that cause contraction of respiratory muscles
Sets baseline breathing rate

43. The Respiratory Center
Breathing rate can be modified by
Blood CO2 levels
Blood O2 levels
Activity levels

44. The Respiratory Center
Breathing rate can be modified by blood CO2 levels
Chemoreceptors in medulla detect elevated CO2 levels and stimulate the respiratory center
Respiratory center causes an increase in breathing rate and depth

45. The Respiratory Center
Breathing rate can be modified by blood O2 levels
Chemoreceptors in aorta and carotid arteries detect drastically low O2 levels and stimulate the respiratory center
Respiratory center causes an increase in breathing rate and depth
Little influence on normal breathing

46. The Respiratory Center
Breathing rate can be modified by physical activity
During exercise, higher brain centers activate muscles and stimulate the respiratory center
Causes increased breathing rate and depth
Occurs in advance of significant changes in blood CO2 and O2 concentrations