1. The Respiratory System

2. Respiration Cellular respiration-occurs in the mitochondria, and releases energy from the breakdown of food molecules (ch. 9) Respiration-process of gas exchange; blood carries oxygen from lungs to tissues and carries carbon dioxide in the opposite direction

3. Human respiratory system Includes Nose pharynx Larynx Trachea Bronchi Lungs

4. To return to the chapter summary click escape or close this document. Air Into Lungs

5. Path of air Air enters nose and moves to the pharynx (passageway for food and air) From pharynx, air moves to the trachea or windpipe (epiglottis covers trachea when you swallow) At these early places, air is warmed, moistened, and filtered by hairs in nasal cavity and mucus produced in cells in the nasal cavity and trachea to keep air clean

6. Path of air cont. From trachea, air moves to larynx (vocal cords) and then into 2 passageways in the chest called bronchi (each leads to a lung) Each large bronchus subdivides into smaller bronchi and those into bronchioles Bronchioles subdivide into millions of alveoli or air sacs (150 million in each lung) Each alveoli is surrounded by capillaries

7. To return to the chapter summary click escape or close this document. Aveoli

8. Gas exchange Alveoli provide huge surface area for gas exchange Oxygen dissolves in moisture on inner surface of alveoli and diffuses across capillaries into blood Carbon dioxide in blood diffuses in the opposite direction

9. Air Inhaled air is 21% oxygen and.04% carbon dioxide Exhaled air is <15% oxygen and 4% carbon dioxide Lungs remove 1/3 of the oxygen and increase carbon dioxide content 100 times

10. Oxygen in blood Oxygen dissolves easily and moves into blood without difficulty Hemoglobin (oxygen-carrying protein in blood) increase efficiency by increasing oxygen-carrying capacity of blood more than 60 times

11. Breathing structures Lungs sealed in two pleural membranes or sacs in the chest cavity Below the chest cavity is the diaphragm, a large flat muscle

12. Inhaling Diaphragm contracts Rib cage rises up to expand volume of chest cavity Creates a partial vacuum in the chest cavity Atmospheric pressure pushes air into lungs

13. Exhaling Rib cage lowers Diaphragm relaxes Pressure in chest becomes greater than atmospheric pressure Air is pushed back out

14. To return to the chapter summary click escape or close this document. How A Diaphragm Works

15. Control of breathing Controlled by medulla oblongata of brain Cells monitor amount of carbon dioxide in blood As CO 2 levels rise, nerve impulses from breathing center cause diaphragm to contract and fill lungs with air