Oversees gas exchange between blood and external environment Respiratory System Oversees gas exchange between blood and external environment

Anatomy of Respiratory System Nose Purify, humidify, and warms (by veins) incoming air Cilia propel mucus to pharynx Sinuses – lighten skull, act as resonance chamber for speech Pharynx (throat) Muscular passageway Tonsils – lymphatic system Larynx (voice box) Thyroid (Adams apple) Epiglottis (closes when swallow) Trachea (windpipe) Ciliated mucosa propel debris away from lungs Bronchi Subdivisions (bronchioles) branch off and enter lungs Lungs R. lung 3 lobes, L. lung 2 lobes Pleura – surface lining Alveoli – air sacs at terminal ends

Alveoli: Site of gas exchange Simple squamous epithelial tissue Covered in a cobweb of pulmonary capillaries Macrophages move in/out of alveoli Cuboidal cells secrete surfactant lipid coats alveoli Prevents alveoli collapse Begins to function at 28-30 weeks during gestation

Respiration Physiology Pulmonary Ventilation Continuously refreshing the air in the lungs External Respiration Gas exchange between blood and alveoli Respiratory Gas Transport O2 & CO2 transported via blood Internal Respiration Gas exchange between blood and tissues

Mechanics of Breathing Inspiration Diaphragm and external intercostals muscles contracts Size of thoracic cavity increases, lung volume increases (lung pressure decreases below atm pressure) and creates a partial vacuum Air enters lungs Expiration Inspiratory muscles relax, resuming initial size Lungs recoil (effortless) Air is exhaled

Respiratory Volumes and Capacities Spirometer – measures respiratory capacities Vital Capacity Tidal Volume Normal quiet breathing (500mL ea/breath) Inspiratory Reserve Volume Air taken in forcibly (2100-3200mL over TV) Expiratory Reserve Volume Air forcibly expelled (1200mL) Residual Volume Air remaining in lungs that cannot be expelled (1200mL) Allows gas exchange between breaths, keeps alveoli inflated Dead Space Volume Air remains in “passageways” and never reaches alveoli (150mL)

Control of Respiration Neural Regulation Nerve impulses from medulla and pons Maintain a rate of 12-15 breaths/minute Other Influential Factors Physical Factors Talking, coughing, exercising, increase body temp Conscious Control Singing, swallowing, swimming Limited/ignored if O2 levels get low or CO2 levels get too high Emotional Hypothalamus reflex (scared, gasp, etc) Chemical Levels CO2 and decreased blood pH

Interesting Respiratory Topics Smoking and its effect on respiratory system Cleft Palate Rhinitis (Cold) & Sinusitis Atelectasis (lung collapse) Hypoxia (inadequate O2) Hyperventilation & Hypoventilation Apnea Cyanosis COPD (chronic obstructive pulmonary disease) Cystic Fibrosis SIDS (sudden infant death syndrome) Asthma Bronchitis & pneumonia Tuberculosis