THE RESPIRATORY SYSTEM 1.THE FUNCTION OF THE RESPIRA- TORY SYSTEM IS TO CONDUCT AIR IN AND OUT OF THE LUNGS FOR GAS EXCHANGE. 2. AIR ENTERS THROUGH THE NASAL CAVITIES. CILIA AND HAIR FILTER DUST AND PARTICLES. BLOOD VESSELS THAT ARE WARM AND MUCUS MOISTENS THE AIR.

3. AIR MOVES THROUGH THE PHARYNX, LARYNX, VOCAL CORDS, TRACHEA, BRONCHIAL TUBES, BRONCHI, BRONCHIOLES AND INTO THE ALVEOLI. 4. EACH LUNG LIES WITHIN A PLEURAL SAC.

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

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

Rib cage expands as rib muscles contract Air inhaled Lung Diaphragm INHALATION Diaphragm contracts (moves down) Rib cage gets smaller as rib muscles relax Air exhaled 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 Blood entering alveolar capillaries Alveolar epithelial cells Alveolar spaces Alveolar capillaries of lung Exhaled air Blood leaving alveolar capillaries Pulmonary veins Pulmonary arteries Tissue capillaries Heart Systemic veins Systemic arteries Blood leaving tissue capillaries Blood entering tissue capillaries Tissue cells CO 2 O2O2 O2O2 O2O2 O2O2 < 40> CO 2 O2O CO 2 O2O2 O2O CO 2 O2O O2O2 CO 2 O2O2 O2O2 O2O

9. BESIDES SIMPLE DIFFUSION, GAS EXCHANGE RATES ARE AFFECTED BY METABOLIC ACTIVITY AND THE PH OF THE BLOOD. MORE METABOLISM = MORE ACIDITY = HEMOGLOBIN W/LESS AFFINITY FOR O BREATHING IS CONTROLLED BY SEVERAL DIFFERENT PARTS OF THE BODY: A.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.

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