2. Why a respiratory system? Need O 2 in – for cellular respiration – make ATP Need CO 2 out – waste product O2O2 food ATP CO 2

3. Passageways and Lungs Respiratory system consists of a pair of lungs & a system of tubes that carry air to them Breathing is just one of the functions that the respiratory system carries out

4. The path air takes Air enters through the nasal cavity – It passes through the pharynx and larynx into the trachea

5. The path air takes – The trachea forks to form two bronchi – Each bronchus branches into numerous bronchioles The bronchioles end in clusters of tiny sacs called alveoli- 1 cell layer thick wall

6. Lungs Structure spongy texture high surface area more absorption of O 2 – alveoli small air sacs – moist lining mucus traps dust, pollen, particles – covered by cilia hair-like extensions of cells move mucus upward to clear out lungs

7. Moving gases into bloodstream Inhale – O 2 passes from alveoli to blood – by diffusion Exhale – CO 2 passes from blood to alveoli – by diffusion capillaries (circulatory system)

8. Gas exchange: Diffusion of gases Gases move by diffusion from high to low concentration – capillaries are thin-walled tubes of circulatory system – alveoli are thin-walled sacs of respiratory system bloodlungs CO 2 O2O2 O2O2 bloodbody CO 2 O2O2 O2O2 capillaries in lungscapillaries in muscle External respiration: exchange of gases between alveoli and blood Internal respiration: exchange of gases between blood and cells

9. The Mechanics of Breathing Breathing ventilates the lungs The action of your diaphragm and the muscles between your ribs enable you to breathe in and breathe out Breathing is the alternation of inhalation (active) and exhalation (passive)

10. Control of Respiration Breathing is usually an involuntary process Partially controlled by an internal feedback mechanism that involves signals being sent to the medulla oblongata about the chemistry of your blood – measure blood pH  CO 2 =  pH (acid)

11. Control of Respiration – coordinate breathing, heart rate & body’s need for energy Will send nerve signals to the rib muscles and diaphragm Nerve signals cause these muscles to contract, and you inhale

12. Breathing and Homeostasis Homeostasis – keeping the internal environment of the body balanced – need to balance O 2 in and CO 2 out – need to balance energy (ATP) production O2O2 ATP CO 2

13. Breathing and Homeostasis Exercise – breathe faster need more ATP bring in more O 2 & remove more CO 2 Disease – poor lung or heart function = breathe faster need to work harder to bring in O 2 & remove CO 2 O2O2 ATP CO 2

14. Cleaning dirty air To prevent foreign material from reaching the respiratory system is lined with ciliated (hair) cells that secrete mucus The cilia constantly beat upward in the direction of your throat, where foreign material can be swallowed or expelled by coughing or sneezing