1. U NIT 16 (C H. 22) G AS E XCHANGE & E XCRETION How do organisms: Obtain oxygen and eliminate carbon dioxide? (or vice versa…in plants?) Maintain osmotic balance? Excrete nitrogenous waste products? 300

2. G AS E XCHANGE ( CH 22.1) ♦ What gases are exchanged ? ♦O2♦O2 ♦ CO 2 ♦ By which process are gases exchanged? ♦ diffusion

3. G AS E XCHANGE ♦ What conditions are required for gas exchanged? ♦ gas must be dissolved in a liquid ♦ large surface area ♦ Why? ♦ to maximize exchange ♦ protection of structures ♦ Which system does the respiratory system often work with in animals? ♦ circulatory (transport) system

4. G AS E XCHANGE IN U NICELLULAR & S IMPLE M ULTICELLULAR O RGANISMS ♦ How is gas exchange carried out in simple organisms? ♦ diffusion directly with moist environment

5. G AS E XCHANGE IN P LANTS ♦ Where does gas exchange occur in plants? ♦ no specialized gas transport system b/c occurs @ different locations ♦ roots ♦ root hairs ♦ stems ♦ lenticels ♦ leaves ♦ gases enter/exit through stomata & move into air spaces of spongy layer ♦ exchange occurs at moist surface of cells surrounding air spaces

7. G AS E XCHANGE IN M ORE C OMPLEX A NIMALS ♦ Usually carried out by respiratory system. ♦ acquire O 2 from environment, distribute it through body, & discharge CO 2 ♦ “respiration”

8. G AS E XCHANGE IN A NIMALS ♦3♦3 “types” of respiration: ♦e♦external respiration: ♦b♦breathing ♦i♦internal respiration: ♦e♦exchange of O 2 & CO 2 between air sacs & capillaries (or cells) ♦c♦cellular respiration: ♦C♦C 6 H 12 O 6 + 6O 2 → 6H 2 O + 6CO 2 + energy (ATP)

9. E ARTHWORM ♦ gases diffuse through moist skin

10. G RASSHOPPER ♦ air enters spiracle s (openings) ♦ lead to tracheae (tubes) ♦ tracheae branch repeatedly ♦ ending in moist tracheoles (air sacs) ♦ gas exchange (diffusion) – aided by muscle mvmt

11. F ISH ♦ operculum or gill cover ♦ protection ♦ H 2 O enters mouth & flows over gills ♦ CO 2 diffuses blood  H 2 O ♦ O 2 diffuses H 2 O  blood countercurrent exchange = deoxygenated blood moves thru gill in one direction & oxygenated H 2 0 moves thru gill in opposite direction

12. ♦ How does the amount of O 2 dissolved in water change in relation to water temp.? F ISH ♦ Which of these descriptions best explains the decrease in the breathing rate of the goldfish? a) The demand for O 2 increased. b) The rate of metabolic activity decreased. c) The demand for CO 2 decreased. d) The fish's activity levels increased. Virtual Fish Respiration Lab

13. R ESPIRATION IN H UMANS ♦ What path does air follow when inhaling? ♦ nose → pharynx → larynx → trachea → bronchi → bronchioles → alveoli ♦ gas exchange: alveoli ↔ capillaries capillaries How are alveoli an adaptation? Gas Exchange Animation 1 Respiration Animation Epiglottis prevents food from entering trachea. What is the function of the cartilaginous rings around the trachea?

14. H UMAN R ESPIRATORY S YSTEM capillaries

15. ♦ What happens in the lungs during gas exchange? ♦ alveoli have high level of O 2 & low level CO 2 ♦ O 2 diffuses from alveoli  blood in capillaries (combines w/ hemoglobin in red blood cells) ♦ blood in capillaries has high level of CO 2 & low level of O 2 ♦ CO 2 diffuses from blood  alveoli ♦ & is exhaled RESPIRATION IN HUMANS

16. ♦ What happens in the cells/ tissues during gas exchange? ♦ cells/tissues have high level of CO 2 & low level of O 2 ♦ CO 2 diffuses from cells/tissues  blood in capillaries ♦ blood in capillaries has high level of O 2 & low level of CO 2 ♦ O 2 diffuses from blood in capillaries  cells/tissues RESPIRATION IN HUMANS

17. Gas Exchange Animation 3 Gas Exchange Animation 2 Gas Exchange Animation 1

19. ♦ Do you have to remember to breathe? ♦ No, medulla (brain stem) controls breathing. ♦ responds to blood’s CO 2 levels ♦ CO 2 too high  breathe faster R ESPIRATION IN H UMANS

20. ♦ What happens to your breathing rate when you exercise? Why? ♦ increases to adjust rate of gas exchange to needs of cells ♦ b/c CO 2 levels increase & O 2 decrease R ESPIRATION IN H UMANS

21. ♦ What happens to the diaphragm and ribs during inhalation? ♦ diaphragm contracts (pulls down/flattens) ♦ ribs raised (move up/out) ♦ Does the chest cavity gets bigger or smaller? ♦ bigger (expands) ♦ What happens to air pressure in the lungs? ♦ becomes lower inside than outside ♦ Which way does air move? ♦ air rushes in R ESPIRATION IN H UMANS

22. ♦ What happens to the diaphragm and ribs during exhalation? ♦ diaphragm is relaxed ( pushes up/arches) ♦ ribs lowered (move down/in) ♦ Does the chest cavity gets bigger or smaller? ♦ smaller (compresses) ♦ What happens to air pressure in the lungs? ♦ becomes higher inside than outside ♦ Which way does air move? ♦ air rushes out R ESPIRATION IN H UMANS

23. RESPIRATION IN HUMANS: CONTROL OF BREATHING Pressure higher inside, lower outside Pressure higher outside, lower inside Remember… “High, low…”

24. RESPIRATION IN HUMANS: CONTROL OF BREATHING Kid's Health Respiratory System & Breathing