RESPIRATORY SYSTEM Chapter 19 FUNCTIONS OF RESPIRATORY SYSTEM Filter incoming air Transport air into lungs Respiration Gas exchange Levels of respiration Ventilation External respiration Internal respiration Cellular respiration WHY WE BREATHE Cellular respiration Cells derive energy from nutrients e g glucose Aerobic respiration Requires oxygen as final electron acceptor Waste products CO2 and H2O Without O2 aerobic respiration cannot proceed Without removal of CO2 blood pH is disrupted ORGANS OF THE RESPIRATORY SYSTEM Upper tract Nose Nasal cavity Sinuses Pharynx Lower tract Larynx Trachea Bronchus Lungs UPPER RESPIRATORY TRACT Nose Muscle bone cartilage External nares nostrils Air enters tract Hairs filter large particles UPPER RESPIRATORY TRACT Nasal cavity Hollow space behind nose Boundaries Ethmoid bone hard palate Nasal conchae Divide cavity into passages Meatuses superior middle inferior Support mucous membranes MUCOUS MEMBRANES Line nasal cavity Pseudostratified ciliated epithelium Goblet cells Secrete mucus Warms and moistens air Traps dust microbes Cilia propel mucus and particles into pharynx to be swallowed UPPER RESPIRATORY TRACT Sinuses Air filled cavities empty into nasal cavity Frontal ethmoid sphenoid maxillary Lined with mucous membranes drain into nasal cavity Inflammation of membranes block drainage accumulate pressure headache UPPER RESPIRATORY TRACT Pharynx Posterior to oral cavity Between nasal cavity and larynx Passage for food and air Divisions Nasopharynx Oropharynx Laryngopharynx LOWER RESPIRATORY TRACT Larynx AKA Voice box Superior to trachea inferior to pharynx Consists of muscle and cartilage Functions Block foreign objects from trachea House vocal cords CARTILAGE OF LARYNX Thyroid Covered by thyroid Protrudes Adam s apple Cricoid Inferior to thyroid cartilage Epiglottic Elastic cartilage Connected to thyroid cartilage Supports epiglottis VOCAL CORDS Two folds within larynx Upper folds Muscle CT False vocal cords Do not produce sound Lower folds Elastic fibers True vocal cords Vocal sounds when fibers vibrate Alter tension change pitch Alter intensity change volume VOCAL CORDS Glottis cords Opening between vocal Open during breathing b Close during swallowing a Epiglottis Flap that closes over larynx to prevent liquids foods from entering larynx LOWER RESPIRATORY TRACT Trachea Windpipe Cylindrical tube Flexible Anterior to esophagus Splits into bronchi TRACHEA Inner wall Ciliated epithelial cells Cilia filter incoming air Mucous membrane Goblet cells mucus Trap debris Outer wall Anterior C shaped cartilaginous rings Prevent collapse Posterior Smooth muscle Allow esophagus to expand LOWER RESPIRATORY TRACT Bronchial tree Airways leading from trachea into lungs Trachea splits into primary bronchi R L Carina cartilage separating each bronchus BRONCHIAL TREE Primary bronchi Secondary bronchi Tertiary bronchi Intralobular bronchioles Terminal bronchioles BRONCHIAL TREE Respiratory bronchioles Alveolar ducts Alveolar sacs Alveoli COMPOSITION OF BRONCHI Similar to trachea Cartilaginous rings replaced by plates in lung Amount of cartilage decreases with diminishing size of passages Smooth muscle and elastic fibers Cell type Pseudostratified ciliated columnar larger tubes Cuboidal epithelium bronchioles Squamous epithelium alveoli ALVEOLI Thin layer of epithelial cells Large surface area for gas exchange O2 diffuses from alveolus into blood in capillary CO2 diffuses from blood in capillary into alveolus LOWER RESPIRATORY TRACT Lungs Soft spongy Right lung 3 lobes Left lung 2 lobes Lobes lobules Terminal bronchioles alveolar ducts alveolar sacs alveoli nerves blood vessels lymphatic vessels BOUNDARIES OF LUNGS Thoracic cage Ribs Sternum Diaphragm Heart PLEURAL MEMBRANES Visceral pleura Parietal pleura Pleural cavity BREATHING Also called ventilation Inspiration Expiration Atmospheric pressure Weight of air is force that moves air into lungs 760 mm Hg or 1 atm Pressure exerted on all surfaces in contact with air Pressure inside lungs is same as on outside VOLUME VS PRESSURE A B Increase volume decrease air pressure inside pushing outside air in Decrease volume increases air pressure forcing air out VOLUME VS PRESSURE Normal inspiration Pressure inside lung decreases outside air pushed into airways INSPIRATION Diaphragm stimulated by phrenic nerve Diaphragm enlarging thoracic cavity Intra alveolar pressure forcing air into lungs INSPIRATION External intercostal muscles raise ribs and elevate sternum Lowers intra alveolar pressure even more causing more air to enter SURFACE TENSION Pleural membranes Help expand lungs via surface tension Alveoli Secrete surfactant to decrease surface tension to prevent alveolar collapse Surfactant Surface active agent EXPIRATION Elastic recoil Elastic tissues of the lungs are stretched during inspiration return to original state during expiration Pressure between alveoli increases forces air out EXPIRATION Passive process Does not require muscle contraction Forceful expiration Increase pressure in lungs abdominal cavity forcing air out of lungs Internal intercostals Internal external obliques Transverse rectus abdominis RESPIRATORY VOLUMES Spirometry Measurement of air volumes in out of lungs Respiratory cycle I E 13 min RESPIRATORY VOLUMES Respiratory volumes Tidal volume Amount of air in out of lungs during respiratory cycle Resting tidal volume 500 ml Inspiratory reserve complemental air 3 6L Expiratory reserve supplemental air 1 2L Residual 1 2L RESPIRATORY CAPACITIES Vital capacity Tidal volume inspiratory reserve expiratory reserve Inspiratory capacity Max volume of air inhaled after resting expiration Tidal volume inspiratory reserve RESPIRATORY CAPACITIES Functional residual capacity Volume of air remaining in lungs after resting expiration Expiratory reserve residual volume Total lung capacity Vital capacity residual volume NONRESPIRATORY AIR MOVEMENT Reflexes Coughing Sneezing Yawning Hiccup Removal of substances caught in respiratory passages Clears upper respiratory passages of debris Deep breath that helps oxygenate alveoli Spasm of diaphragm causes short inspiration RESPIRATORY CENTER Function Controls breathing Adjusts rate and depth of breathing in response to need Components Medulla Rhythmicity area Dorsal respiratory group rhythm of breathing Ventral respiratory group forceful breathing Pons Pneumotaxic area Control dorsal respiratory group Controls rate of breathing FACTORS AFFECTING BREATHING O2 and CO2