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Chapter 16 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. THE RESPIRATORY SYSTEM Functions: -Obtain oxygen -Remove carbon dioxide -Trap particles from the air -Warm the incoming air - Produce vocal sounds -Smell -Regulate blood pH Respiration - gas exchange between between atmosphere and cells Events of Respiration: -Air in and out of lungs = ventilation -Gas exchange between blood and air -Gas transport in blood -Gas exchange between blood and cells = cellular respiration Upper Respiratory System pharynx and superior Lower Respiratory System - larynx and inferior Upper Respiratory Tract Structures Nasal Conchae - support the mucous membrane & increase it’s surface area Mucous membrane - has pseudostratified ciliated epithelium and is rich in goblet cells that secrete mucus -has extensive blood vessels within so warms air -Sticky mucous traps dust and other small particles SINUSES - air filled spaces in the maxillary, frontal, ethmoid and sphenoid bones of the skull; decrease the weight of the skull and affect voice quality MUCUS MOVEMENT AND CILIA Cilia move mucus and particles toward the pharynx where the mucus is swallowed and digestive juices destroy invaders LARYNX Enlargement in the airway at the top of the trachea below the pharynx Conducts air in and out Prevents foreign objects from entering the trachea Houses the vocal cords Made of: muscles and cartilages bound by elastic tissue Upper folds: false vocal cords Lower folds: true vocal cords VOCAL CORDS Word sounds result from change in shape of the pharynx cavity Increases of tension increases pitch Decreases of tension lowers pitch Stronger blasts of air = louder sounds Lighter blasts of air = quieter sounds The glottis closes when food or drink is swallowed The epiglottis is a flaplike structure that allows air into the larynx and presses downward when food or water enters LARYNGITIS - the mucus membrane of the larynx is inflamed and swollen secondary to infection or irritation preventing vocal cord vibration THE BRONCHIAL TREE TRACHEA - flexible, cylindrical tube anterior to the esophagus and runs into the thoracic cavity -has a ciliated mucous membrane with goblet cells to move particles to the pharynx where they are swallowed -Has “c shaped” cartilages to keep the airway open THE TREE - branched airways from trachea to small air sacs in the lungs THE PASSAGEWAYS OF THE RESPIRATORY SYSTEM Bronchioles have smooth muscle walls Alveoli - have a thin layer of squamous epithelial cells for gas exchange Figure 16.09 GAS EXCHANGE FROM ALVEOLI TO VESSELS THE LUNGS - reside in the thoracic cavity and are separated by the mediastinum; the right lung has 3 lobes and the left has 2 lobes VISCERAL PLEURA - serous membrane that directly attaches to the lungs and folds back to form the parietal pleura PLEURAL CAVITY - not a real cavity - serous fluid resides in this cavity to allow for friction reduction during breathing BREATHING MECHANISMS INSPIRATION = moving air from outside of the body inside the lungs EXPIRATION = moving air from inside the lungs out AIR MOVES INTO THE LUNGS BECAUSE PRESSURE OUTSIDE OF THE LUNGS IS GREATER THAN PRESSURE INSIDE = INSPIRATION WHEN AIR PRESSURE INSIDE THE LUNGS IS GREATER THAN ATMOSPHERIC PRESSURE (AIR OUTSIDE OF THE LUNGS) WE CAN EXHALE = EXPIRATION MAXIMAL INSPIRATION MAXIMAL EXPIRATION SURFACTANT AND ALVEOLI Alveolar cells have surfactant which reduces their tendency to collapse when lung volumes are low Surfactant allows for easier inspiration and inflation of the alveoli If a child is born without surfactant (or is a premie) synthetic surfactant may be injected into the lungs via an endotracheal tube Without the surfactant a newborn is unable to inflate their lungs RESPIRATORY AIR VOLUMES RESPIRATORY AREAS -are groups of neurons in the brainstem that control inspiration and expiration -Scattered throughout the medulla oblongata and pons -medullary respiratory center - aka dorsal respiratory group stimulates muscles of inspiration -Ventral respiratory group controls intercostal and abdominal muscles - pontine respiratory group controls the rhythmicity of breathing EMPHYSEMA AND LUNG CANCER - EMPHYSEMA - progressive, degenerative disease that destroys alveolar walls leading to loss of tissue elasticity and difficulty expelling air from the lungs - LUNG CANCER - uncontrolled division of abnormal cells -may start in another area such as the breast and metastasize to the lungs -PRIMARY PULMONARY CANCERS - start in the lungs -BRONCHOGENIC CARCINOMA - originates from epithelium in a bronchiole secondary to prolonged irritation from a substance like tobacco smoke -Cancer cells eventually form tumor masses that obstruct air passages and decrease gas exchange -These cancers spread easily to the circulation leading to lymph node, liver, bones brain or kidney metastasis. Figure 16.17 FACTORS THAT AFFECT BREATHING -Chemoreceptors in the medulla oblongata detect changes in CSF, CO2 and Hydrogen -If high amounts are detected then increase in breathing occurs to decrease the chemical levels - carotid and aortic bodies sense blood O2 level change -If blood O2 is very low then respiration is triggered to increase -Inflation reflex - prevents overinflation of the lungs with forceful breathing -Hyperventilation - lowers the level of CO2 levels THE RESPIRATORY MEMBRANE Alveoli are lined with simple squamous epithelium and in close association with capillaries The membrane is a layer of fused basement membranes and simple squamous epithelium Gas molecules diffuse from high concentration to low aka high pressure to low pressure GAS EXCHANGE BETWEEN CAPILLARY AND ALVEOLI Partial pressure - the amount of pressure that each gas exerts Movement occurs across the respiratory membrane until equilibrium is reached Soluble gases like alcohol and acetone can diffuse into alveoli OXYGEN TRANSPORAT ACROSS THE RESPIRATORY MEMBRANE Oxygen binds primarily to the iron-containing protein hemoglobin Oxyhemoglobin molecules are unstable and favor release of oxygen when it is in demand (such as in exercise) CARBON DIOXIDE TRANSPORT CO2 readily diffuses into the blood as its concentration is high in the tissues Carbaminohemoglobin - CO2 bound to hemoglobin BICARBONATE AND CARBONIC ANHYDRASE Carbon dioxide is transported in the form of a bicarbonate ion HCO3 to = H2CO3 Carbonic anhydrase speeds the reaction between CO2 and H2O to break the H2CO3 molecule into a hydrogen and bicarbonate Hydrogen ion concentration variances can raise or lower blood pH CYSTIC FIBROSIS AND CARBON MONOXIDE POISIONING CYSTIC FIBROSIS - salty skin is a common symptom -causes thick mucus which leads to infections -Chloride channel is missing an amino acid so it is deformed and chloride stays in the cell -Water moves into the cell via osmosis and has to way to leave thus organs become clogged -There is no effective treatment to date CARBON MONOXIDE POISONING - carbon monoxide binds to hemoglobin preventing oxygen from binding leading to gradual tissue death