Animal Structure & FunctionMaSeleka

BL41 Respiration

Key Concepts• 1. Of all organisms, multicelled animals require the most energy. The energy

comes mainly from aerobic metabolism, which requires O₂ and produces CO₂ wastes. In process called respiration, animals move O₂ into their internal environment and give up CO₂ to the external environment.

• 2. O₂ diffuses into the body as a result of a pressure gradient. The pressure of this gas is higher in air than it is in metabolically active tissues, where cells rapidly use O₂. CO₂ follows a gradient in the other direction. Its pressure is higher in tissues–where it is a byproduct of metabolism–than it is in the air.

• 3. In most respiratory systems, O₂ and CO₂ diffuse across a respiratory surface, such the thin, moist epithelium in the human lungs. Blood flowing through the body’s circulatory system picks up O₂ and gives up CO₂ at this respiratory surface.

• 4. Respiratory systems differ in their adaptations for increasing gas exchange efficiency. They differ also in how they match air flow to blood flow.

Respiration• 1. Animal cells rely mainly on aerobic respiration, a metabolic

pathway that provides enough energy for active life-styles. This pathway requires O₂ and produces CO₂. The process by which the animal body as a whole acquires O₂ and disposes of CO₂ is called respiration.

• 2. Air is a mixture of O₂, CO₂, and other gases, each exerting a partial pressure. Each gas tends to move from areas of higher to lower partial pressure. Respiratory systems make use of this tendency.

• 3. In all respiratory systems, O₂ and CO₂ diffuse across a respiratory surface–a moist, thin layer go epithelium. In vertebrates, airways carry gases to and from one side of the respiratory surface, and blood vessels carry gases to and from the other side.

• 4. The airways of the human respiratory system are the nasal cavities, pharynx, larynx, trachea, bronchi, and bronchioles. Alveoli at the end of the terminal bronchioles are the main sites of gas exchange.

• 5. During inhalation, the chest cavity expands, lung pressure falls below atmospheric pressure, and air flows into the lungs. During normal exhalation, these events are reversed.

• 6. Driven by its partial pressure gradient, O₂ in the lungs diffuses from alveolar air spaces into the lung capillaries. Then it diffuses into red blood cells and binds weakly with hemoglobin. In tissues where cells are metabolically active, hemoglobin gives up O₂, which diffuses out the capillaries, across interstitial fluid, and into the cells.

• 7. Driven by its partial pressure gradient, CO₂ diffuses from cells, across interstitial fluid, and into the bloodstream. Most react with water to form bicarbonate, but the reactions are reversed in the lungs. There, CO₂ diffuses from lung capillaries into the air spaces of the alveoli, then is exhaled.

Key termsalveolus

bronchiole bronchus

carbonic anhydrase countercurrent flow

diaphragm epiglottis

gill glottis

hemoglobin

integumentary exchange

larynx lung

myoglobin oxyhemoglobin

pharynx

respiratory center respiratory surface respiratory system

tracheal respiration vocal cord

Test BT41R• BT41R.1 An O₂ partial pressure gradient exist

between what?

• A. air and lungs

• B. lungs and metabolically active tissues

• C. air at sea level and air at high altitudes

• D. all of the above

• BT41R.2 Which one is an airway that connects the nose and mouth with what?

• A. oral cavity; larynx

• B. pharynx; trachea

• C. trachea; pharynx

• D. pharynx; larynx

• BT41R.3 In human, O₂ in the air must diffuse across what as it follows its partial pressure gradient into the internal environment?

• A. pleural sacs

• B. alveolar sacs

• C. a moist respiratory surface

• D. B and C

• BT41R.4 Each human lung encloses a what?

• A. diaphragm

• B. bronchial tree

• C. pleural sac

• D. B and C

• BT41R.5 Gas exchange occurs at the what?

• A. two bronchi

• B. pleural sacs

• C. alveolar sacs

• D. B and C

• BT41R.6 The Heimlich maneuver may help people:

• A. with altitude sickness

• B. with the bends

• C. choking on food

• D. quit smoking

• BT41R.7 What does breathing do?

• A. ventilates the lungs

• B. draws air into airways

• C. expels air from airways

• D. causes reversals in pressure gradients

• E. all of the above

• BT41R.8 When you inhale, the diaphragm does what?

• A. curves upward

• B. flattens

• C. relaxes

• D. remains stationary

• BT41R.9 After O₂ diffuses into lung capillaries, it diffuses into what and binds with what?

• A. interstitial fluid; red blood cells

• B. interstitial fluid; CO₂

• C. red blood cells; hemoglobin

• D. red blood cells; CO₂

• BT41R.10 Most CO₂ in blood is in the form of what?

• A. CO₂

• B. CO

• C. carbonic acid

• D. hydrogen carbonate

• BT41R.11 Match the components with their descriptions:

• ___ trachea A. airway leading into a lung

• ___ pharynx B. throat

• ___ alveolus C. fine bronchial tree branchings

• ___ hemoglobin D. windpipe

• ___ bronchus E. respiratory pigment

• ___ bronchiole F. site of gas exchange

Assignment BA41R• BA41R.1

• a. If your grade children ask you what insect lungs look like, what would your answer be? [6]

• b. Describe the features of the respiratory surface that are common to all respiratory systems. [7]

• c. People occasionally poison themselves with CO by building a charcoal fire in an enclosed area. Assuming help arrives in time, what would be the most effective treatment: placing the victim outdoors in fresh air or administering pure O₂? Why? [7]

• BA41R.2 Distinguish between:

• a. aerobic respiration and respiration [5]

• b. pharynx and larynx [5]

• c. bronchiole and bronchus [5]

• d. pleural sac and alveolar sac [5]

• BA41R.3

• a. Explain why humans, including the female in the photo, cannot survive on their own for very long in underwater environments. [8]

• b. Label the components of the human respiratory system shown and the structures that enclose it. [12]

• BA41R.4 Some cigarette manufacturers have conducted public relations campaigns urging their customers to ‘smoke responsibly.’

• a. What are some social and biological issues in this controversy? [6]

• b. How do these issues apply to the nonsmoking spouse, children of a smoker, nonsmoking patrons in a restaurant, unborn child of a pregnant smoker? [12]

• c. In your opinion, what behavior would constitute ‘responsible smoking’? [2]

Readings• American Cancer Society: Dangers of Smoking; Benefits of Quitting and Relative

Risks of Reduced Exposure, Revised Edition; New York: American Cancer Society

• Mortality From Smoking in Developed Countries 1950–2000, a 1994 publication by scientists of Britain’s Imperial Cancer Research Fund, the WHO, and the American Cancer Research Fund

• Starr, C., & Taggart R. (1995): Biology: The Unity and Diversity of Life, 7th Edition; Belmont: Wadsworth

• Vander, A., Sherman, J., & Luciano, D. (1990): Human Physiology: The Mechanisms of Body Function, 5th Edition; New York: McGraw-Hill

• West, J. (1989): Respiratory Physiology: The Essentials, 4th Edition; Baltimore: Williams & Wilkins

• Young, J. Z. (1981): The Life of Vertebrates, 3rd Edition; Oxford: Clarendon Press