The Respiratory System

THE FUNCTION OF THE RESPIRA- TORY SYSTEM IS TO CONDUCT AIR IN AND OUT OF THE LUNGS FOR GAS EXCHANGE. 2. EACH LUNG LIES WITHIN A PLEURAL SAC.

3. AIR ENTERS THROUGH THE NASAL CAVITIES. CILIA AND HAIR FILTER DUST AND PARTICLES. BLOOD VESSELS WARM THE AIR AND MUCUS MOISTENS THE AIR.

                                                                                                                                                                                                  

4. AIR MOVES THROUGH THE PHARYNX, LARYNX, VOCAL CORDS, TRACHEA, BRONCHIAL TUBES, BRONCHI, BRONCHIOLES AND INTO THE ALVEOLI.

5. EACH BRONCHIOLE BREAKS INTO ALVEOLAR SACS. THE ALVEOLI PRO- VIDE A TREMENDOUS SURFACE AREA FOR GAS EXCHANGE WITH THE BLOOD LOCATED IN THE DENSE CAPILLARY NETWORK THAT SURROUNDS EACH ALVEOLAR SAC.

LE 42-23 Branch from Branch pulmonary from artery pulmonary (oxygen-poor blood) Branch from pulmonary vein (oxygen-rich blood) Terminal bronchiole Nasal cavity Pharynx Alveoli Larynx Left lung Esophagus 50 µm Trachea Right lung 50 µm Bronchus Bronchiole Diaphragm Heart SEM Colorized SEM

6. TO INHALE, THE DIAPHRAGM CONTRACTS AND FLATTENS. THE RIB CAGE MOVES UP AND OUT, THE CHEST CAVITY VOLUME INCREASES, INTERNAL PRESSURE DECREASES AND AIR RUSHES IN. 7. EXHALE – REVERSE OF INHALE. *How Stuff Works – Animation http://health.howstuffworks.com/adam-200020.htm

Rib cage gets smaller as rib muscles relax Rib cage expands as rib muscles contract Air inhaled Air exhaled Lung Diaphragm INHALATION Diaphragm contracts (moves down) EXHALATION Diaphragm relaxes (moves up)

8. GAS EXCHANGE – IN THE ALVEOLI, OXYGEN DIFFUSES DOWN A PRESSURE GRADIENT INTO THE BLOOD PLASMA AND BINDS TO THE HEMOGLOBIN OF THE RED BLOOD CELLS. THIS OCCURS ONLY IF THE MEMBRANE IS PERMEABLE AND MOIST.

-THE BLOOD CARRIES THE OXYGEN TO THE TISSUES AND GIVES IT UP WHERE OXYGEN PRESSURE IS LOW AND PH IS LOW. -CO2 IS HIGHER IN THE BODY TISSUES SO IT DIFFUSES INTO THE BLOOD. -CO2 IS RETURNED TO THE LUNGS AND RELEASED DURING AN EXHALE.

Inhaled air Exhaled air Alveolar spaces O2 CO2 O2 CO2 Alveolar 160 0.2 120 27 Alveolar spaces O2 CO2 O2 CO2 104 40 Alveolar epithelial cells O2 CO2 CO2 O2 Blood entering alveolar capillaries Blood leaving alveolar capillaries CO2 O2 Alveolar capillaries of lung 40 45 104 40 O2 CO2 O2 CO2 Pulmonary arteries Pulmonary veins Systemic veins Systemic arteries Heart Tissue capillaries CO2 O2 Blood leaving tissue capillaries Blood entering tissue capillaries 40 45 CO2 O2 100 40 O2 CO2 O2 CO2 Tissue cells < 40 > 45 O2 CO2

                                                                                                                                                                                                                                           

9. BESIDES SIMPLE DIFFUSION, GAS EXCHANGE RATES ARE AFFECTED BY METABOLIC ACTIVITY AND THE PH OF THE BLOOD. MORE METABOLISM = MORE ACIDITY = HEMOGLOBIN WITH LESS AFFINITY FOR O2 10. BREATHING IS CONTROLLED BY SEVERAL DIFFERENT PARTS OF THE BODY: CONSCIOUS BREATHING IS BELIEVED TO BE CONTROLLED IN THE CORTEX OF THE BRAIN.

B. UNCONCIOUS BREATHING IS CONTROLLED BY THE PONS AND MEDULLA OF THE BRAIN. C. CHEMORECEPTORS MONITOR THE BLOODS OXYGEN, CARBON DIOXIDE AND PH LEVELS.

Cerebrospinal fluid Pons Breathing control centers Medulla oblongata Carotid arteries Aorta Diaphragm Rib muscles