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Functions Brings oxygen into the bloodstream Removes carbon dioxide from the blood Transfer of gases Pulmonary ventilation breathing in and out External respiration gas molecules diffuse between the air sacs and the tiny capillaries Transfer of gases (cont’d) Internal respiration movement of oxygen and carbon dioxide between the bloodstream and body cells Organs of the Respiratory System Upper respiratory tract Nose Pharynx Larynx Organs of the Respiratory System (cont’d) Lower respiratory tract Trachea Bronchi Bronchioles Alveoli Nose Initial receiving chamber for inhaled air Formed by 2 nasal bones and cartilage External nares = nostrils Nasal septum separates nare and nasal cavity Nose (cont’d) Vestibules – small chambers containing hairs Filter dust and insects Conchae – turbinate bones in nose. Increase surface area – air gets warmed before it goes to the lungs Nose (cont’d) Mucous membrane - warms and moistens inhaled air and traps particles Olfactory receptors located in mucosa in superior part of nasal cavity Ciliated cells in mucosa – move contaminated mucus to throat, where swallowed and digested Nose (cont’d) Nasal cavity separated from oral cavity by palate Cavity surrounded by paranasal sinuses Lacrimal ducts also drain into cavity Pharynx A.K.A. the throat From back of nasal cavity to the larynx Common passageway for food and air Formed by skeletal muscle and lined with mucous membrane Receives air from the nasal cavity via internal nares Pharynx (cont’d) 3 Segments Nasopharynx Superior part Receives air from nasal cavity Two auditory tubes open into here Pharynx (cont’d) 3 Segments (cont’d) Oropharynx What you see when looking in a mirror Laryngopharynx Unites with larynx in neck Pharynx (cont’d) Clusters of lymphatic tissue called tonsils found in pharynx Larynx A.K.A. voicebox Connects the pharynx with the trachea Provides passage to air Prevents solid material from entering the trachea Houses the vocal cords Larynx (cont’d) Walls made up of 9 pieces of cartilage Thyroid cartilage “Adam’s Apple” Cricoid cartilage Larynx (cont’d) Walls (cont’d) Epiglottic cartilage (epiglottis) Spoon-shaped flap of elastic cartilage Protects superior opening of larynx 3 pairs of smaller cartilages attached to vocal cords Larynx (cont’d) Mucous membrane contains 2 pairs of folds False vocal cords True vocal cords Vibrations of the true vocal cords as air rushes past produce sound Trachea A.K.A windpipe Between the larynx and the bronchi Supported by incomplete rings (C- shaped) of cartilage Trachea (cont’d) Internally lined with ciliated mucous membrane Mucus carries particles trapped in sticky mucus toward the pharynx Bronchial Branches Division of trachea Into right and left primary bronchi Right – more vertical (more likely to be blocked) Left – more horizontal because crosses over the heart Bronchial Branches (cont’d) Enter the lungs, subdivide into smaller and smaller branches (secondary , tertiary, etc) Smallest of conducting passageways are bronchioles – no cartilage Bronchial Branches (cont’d) This branching network is called the bronchial or respiratory tree Bronchial Branches (cont’d) Continue into alveolar ducts Terminate in alveoli – air sacs Only site of gas exchange between external environment and bloodstream Occurs at respiratory membrane (air-blood barrier) Via diffusion Bronchial Branches (cont’d) 300-500 million alveoli Enormous surface area Resemble bunches of grapes Each consists of microscopic air space surrounded by thin epithelial wall Interspersed cells produce surfactant. Allows alveoli to inflate Bronchial Branches (cont’d) Alveolar pores connect neighboring air sacs Provide alternative routes for air to reach alveoli Alveoli make up bulk of lungs Lungs are then mostly air space Soft and spongy Lungs Consist of branches of the bronchial tree, alveoli, and supportive tissue Located in thoracic cavity within the rib cage Superior apex located just deep to clavicle Base rests on diaphragm Lungs (cont’d) Serous membranes surround each lung Outer layer - parietal pleura Inner layer - visceral pleura Pulmonary Ventilation Provides an exchange of air between the external environment and the spaces within the alveoli of each lung Sets the stage for gas exchange with the bloodstream 2 events inspiration and expiration Inspiration Initiated by the contraction of the respiratory muscles, diaphragm, and external intercostal muscle Cause the thoracic cavity to expand The pleural cavity volume increases and pressure decreases Inspiration (cont’d) The lung surface is pulled outward, causing the lung volume to increase The alveolar pressure falls below the atmospheric Air rushes into the alveoli Expiration Passive process Relies on the ability of the lungs and thoracic wall to recoil Respiratory muscles relax, causing the thoracic cavity to return to its original volume Expiration (cont’d) The thoracic cavity decreases in size The pleural cavity pressure increases The alveolar pressure becomes greater than the atmospheric pressure Air flows out of the alveoli Expiration ( cont’d) Intrapleural pressure is always negative Major factor preventing collapse of lungs Expiration ( cont’d) If, for any reason, this pressure becomes equal to atmospheric pressure, the lungs recoil completely and collapse (atelectasis). Lung is useless for ventilation Presence of air in pleural space pneumothorax Respiratory Volume Influences activity sex height age weight state of health Respiratory Volume (cont’d) Spirometer - measures respiratory volume under different conditions & compares with average values Tidal volume (TV) Normal quiet breathing moves 500 ml in and out of the lungs each breath Respiratory Volume (cont’d) Inspiratory reserve volume (IRV) Maximum amount of air that can be inhaled forcibly over the tidal volume Between 2100 and 3200 ml Expiratory reserve volume (ERV) Maximum amount of air that can be exhaled forcibly over the tidal volume 1200 ml Respiratory Volume (cont’d) Residual volume (RV) The amount of air remaining in the lungs following a forced expiration 1200 ml Important because allows gas exchange to go on continuously even between breaths and helps keep alveoli open Respiratory Volume (cont’d) Vital capacity (VC) Total amount of exchangeable air The sum of the TV + IRV + ERV 4800 ml Respiratory Volume (cont’d) Total lung capacity Total amount of air contained in the fully inflated respiratory system The sum of the VC + RV 6000 ml Respiratory Volume (cont’d) Dead Space Volume Air that enters respiratory tract and never reaches alveoli Of 500 ml of TV , dead space vol. is 150 ml External Respiration Exchange of gases btwn the alveoli & bloodstream Across the thin respiratory membrane Always more O2 in the alveoli than there is in the blood Causes pressure gradient across the resp. membrane forcing O2 from alveoli into the O2-poor blood of capillaries External Respiration (cont’d) O2 transported in the blood in 2 ways: 98% bound to hemoglobin (oxyhemoglobin or HbO2) Carried thru bloodstream to the tissue capillaries Other 2% carried in a dissolved state within the plasma External Respiration (cont’d) Movement of O2 from alveoli into the bloodstream accompanied by CO2 moving in opposite direction More CO2 in blood than in alveoli Causes a pressure gradient – moves CO2 into alveoli Internal Respiration Exchange of gases btwn capillaries & body cells Includes movement of O2 from the capillaries to interstitial fluid and on to cells Includes the diffusion of CO2 from cells into interstitial fluid on to the capillaries Respiratory Center Located in the medulla & pons Medullary respiratory centers Inspiratory center Sets basic rhythm of breathing Ventral respiratory group Activated when need arises to breathe more forcefully Respiratory Center (cont’d) Pons respiratory centers Appear to smooth out the transitions from inspiration to expiration & vice versa Pneumotaxic center Regulates the breathing rate by inhibiting inspiration Prevents overinflation Apneustic Area Inhibits expiration Respiratory Center (cont’d) Eupnea Normal respiratory rate 12-15 respirations/minute Factors that Affect Breathing Chemicals Chemosensitive area in medulla and chemoreceptors in arteries detect levels of O2, CO2, and H+ in the blood Increased CO2 and decreased blood pH – most impt stimuli leading to increased rate and depth of breathing Stimulate hyperventilation if CO2 levels rise too high Factors that Affect Breathing (cont’d) Stretch Receptors Located in the walls of the lungs Prevent overextension of the lungs during inspiration Factors that Affect Breathing (cont’d) Mental State Breathing & and depth - under both voluntary & involuntary control. Cannot stop breathing completely using conscious thought Certain emotions increase breathing rate Factors that Affect Breathing (cont’d) Physical factors Talking, coughing, exercise Increased body temperature increases rate of breathing Chronic Obstructive Pulmonary Diseases (COPD) Emphysema Alveolar walls break down and enlarge Lungs lose elasticity (compliance) Expiration becomes an active process Chronic Bronchitis Excessive mucus production in lower respiratory passageways Asthma Constriction of bronchioles Restrict airflow Wheezing and shortness of breath Tuberculosis Infectious disease caused by bacterium Mainly affects lungs Fever, weight loss, cough, spitting up blood Lung Cancer 1/3 of all cancer deaths in U.S. Extremely aggressive Metastasizes rapidly Pneumonia Infection of alveoli Fluid build-up within the lungs O2 exchange usually diminishes If not treated, can cause death Cystic Fibrosis Inherited disorder Secretion of thick and sticky mucus and an unusual secretion of sweat and saliva Traps air in smaller airways Progressive lung damage that is fatal Can also affect digestive system Other Disorders Pleurisy Hypoxia – reduced availability of oxygen in blood – become cyanotic CO poisoning – unique type of hypoxia SIDS – crib death Infant respiratory Distress Syndrome – lack of surfactant in premature infants – difficulty in breathing