Gas Exchange in Animals

1. Gas Exchange in Animals

2. Rib Muscles and the Diaphragm Help Us Breathe • The diaphragm is a thick sheet of muscle that forms the floor of the chest cavity and, along with the rib muscles, makes inhalation possible

3. Rib Muscles and the Diaphragm Help Us Breathe • During inhalation, the diaphragm and the rib muscles contract, moving the ribcage outward and the diaphragm downward, reducing the pressure in the lungs and thereby drawing oxygen-rich air into the lungs

4. Rib Muscles and the Diaphragm Help Us Breathe • During exhalation, relaxation of the rib muscles and diaphragm compresses the chest cavity, raises the pressure inside the lungs, and forces air out

5. Rib Muscles and the Diaphragm Help Us Breathe

6. The Upper Respiratory System • The upper respiratory system includes the airways in the nose, mouth, pharynx, and larynx • When we inhale, air enters the nasal cavities, where it is heated and moistened by the mucous membranes • From the nasal cavities, air enters the pharynx at the back of the mouth

7. The Upper Respiratory System • The sinuses are hollow spaces in the forehead and cheekbones that act as resonating chambers and are part of the upper respiratory system

8. The Upper Respiratory System • The pharynx is where the mouth and two nasal cavities join • Air moves into the larynx, which houses the cartilaginous structures that project from the wall of the larynx and are called vocal chords • The epiglottis closes when you swallow to prevent food going into your lungs. Note: book has the larynx as both in the lower and upper respiratory system, we will say it is in the upper portion of this system

9. The Lower Respiratory System • The trachea, bronchi, and lungs make up the lower respiratory system • The trachea is the largest breathing tube in our respiratory system and is lined with microscopic hairs called cilia that trap small particles before they can reach the lungs

10. The Lower Respiratory System • The trachea branches into two bronchi, which lead to the lungs

11. The Lower Respiratory System • The bronchi divide into a series of ever-smaller branches called bronchioles

12. The Lower Respiratory System • The bronchiole extensions open into the alveoli,where there is a moist surface of thin epithelial cells that line each alveolar sac

13. The Lower Respiratory System • In the alveoliiswhere gases are exchanged! • At the surface of an alveolus, just like in any other cell, oxygen and carbon dioxide are exchanged through diffusion

14. Principles of Gas Exchange • Oxygen and carbon dioxide diffuse from areas of high concentration to areas of low concentration • The greater the differences in concentration gradient, the larger and more rapid the diffusion of gases from source to destination becomes

15. A Large Surface Area Facilitates Diffusion • The amount of surface area that an organism has available for gas exchange determines the capacity of that organism to absorb oxygen • Alveoli provide a specialized and very large gas exchange surface, which allows us to meet the very high demands of our bodies

16. Which one of these is lung tissue from an emphysema patient? Why?

17. Oxygen Demand • The oxygen demand of an animal depends on its size and its level of activity

18. The Shorter the Diffusion Distance, the Faster a Gas Can Reach Its Destination • The rate of diffusion decreases with distance; therefore, most animals must have either a shape that brings all their cells within a few millimeters of their surroundings or a way of transporting gases quickly within their bodies

19. How Animals Transport Gases to Respiring Cells • All vertebrates have oxygen-binding pigment molecules and specialized blood cells for transporting great quantities of dissolved oxygen • Hemoglobin is bound to red blood cells for efficient oxygen delivery throughout the body • Red blood cells lack nuclei and are shaped like flattened discs that are thinner in the center in order to maximize surface area and facilitate the rapid exchange of oxygen

20. How Animals Transport Gases to Respiring Cells • The oxygen-binding pigment in humans is called hemoglobin • Each red blood cell can carry up to a million molecules of oxygen

21. How Animals Transport Gases to Respiring Cells • Oxygen-binding pigments (ex. Hemoglobin) have the ability to pick up oxygen in regions of high oxygen concentration and release oxygen in regions of relatively low concentration in a process called reversible binding • Why is reversible binding very important here?

22. Other Oxygen Binding Proteins Myoglobin: muscle tissue of many vertebrates, including humans, gives muscle tissue a distinct red or dark gray color. It is very similar to hemoglobin. It is used to store oxygen rather than transport it. Hemocyanin: Found in the blood of many arthropods and mollusks. Uses copper instead of iron, and is blue in color when oxygenated. Other colors of oxygen transporting fluid: Some marine invertebrates: pink/violet when oxygenated, clear when not. Iron. Some annelids: green when deoxygenated and red when oxygenated. Iron. Bivalve molluscPinna squamosa: Brown, Mangaese.