RESPIRATORY SYSTEM *Gas exchange between the atmosphere and cells.

FUNCTIONS Obtain O2 Excrete CO2 Filter incoming air Control temperature and water content of air Produce vocal sounds Smell Blood pH

ORGANS Upper respiratory tract Nose Made of bone and cartilage Hairs prevent entry of large particles

Nasal Cavity Hollow space behind nose Septum divides into right and left portions Conchae divide passageway and support mucus membrane Mucus membrane produces mucus that entraps small particles that is then swallowed and digested. Mucus membrane moistens air Blood vessels release heat from blood to warm incoming air

Paranasal Sinuses Pharynx (throat) Air filled sacs Lined by mucus membrane Reduce the weight of the skull Resonant chambers affect sound of voice Pharynx (throat) Air passageway Helps produce sounds of speech

Lower Respiratory Tract Larynx Enlargement below pharynx Conducts air in and out of trachea Prevents foreign objects from entering trachea Houses vocal cords Composed of cartilage and muscle Thyroid is the largest (Adam’s apple) Glottis: opening within vocal cords Epiglottis: flap-like structure that covers larynx

Trachea (windpipe) Bronchial Tree Flexible cylinder tube 2.5 cm in diameter Anterior to esophagus C- shaped pieces of hyaline cartilage rings Lining has ciliated mucous membrane with goblet cells to filter air. Bronchial Tree Branched airways leading from trachea to alveoli in lungs Bronchii bronchioles alveolar ducts alveolar sacs alveoli Alveoli: small sacs where gases diffuse in and out of blood in capillaries

Trachea Bronchioles Bronchii Bronchioles Alveoli ducts Alveoli sacs Alveoli

Lungs Soft, spongy, cone-shaped Suspended in thoracic cavity by bronchus and blood vessels Visceral pleura; parietal pleura; pleural cavity Right lung – larger, 3 lobes Left lung - 2 lobes

Healthy Lung Smokers Lung

BREATHING MECHANISM Inspiration (inhalation) Atmospheric pressure due to the weight of air is the force that moves air into the lungs. Low pressure inside alveoli and lungs-atm pushes outside air in and visa versa Impulses in phrenic nerves stimulate the diaphragm to contract Intercostals muscles contract Surfactant: mixture of lipids and proteins made by alveolar cells that reduces the alveoli’s tendency to collapse. (respiratory distress syndrome in premature infants lack this and may be injected)

Expiration (exhalation) Passive process due to elastic recoil Air volumes and capacities (table pg. 457) Spirometry: measure air volume (spirometer) 1 inspiration + 1 expiration= 1 respiratory cycle Tidal volume: amount of air that enters/leaves in one respiratory cycle (500ml) Inspiration reserve volume: extra volume from forced air (3,000 ml) Expiration reserve volume: 1,100 ml extra with residual volume left over (1,200 ml) Medulla and Pons are the 2 main respiratory centers

Factors affecting breathing Emotional state Hyperventilation: breathing rapidly and deeply lowering blood CO2 levels Physical activity

Problems and Others Nonrespiratory movements: used to clear air passageways Coughing: clear from lungs Sneezing: irritation in nasal cavity that forces air through glottis up to 200mph Laughing Crying Hiccup: sudden inspiration due to a spasmodic contraction in diaphragm (function is not known) Yawn: triggered by low blood O2

Atelectasis: collapsed lung Emphysema: progressive, degenerative disease that destroys alveolar walls Lung cancer: uncontrolled division of abnormal cells that rob normal cells of nutrients and O2 Hypoxia: deficiency of O2 reaching tissues Cystic fibrosis: genetic disorder that causes a formation of extremely thick, sticky mucus, which encourages infections by microorganisms