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Respiratory System Inhalation and exhalation Ventilation The Respiratory Centers of the Brain • PONS. • The apneustic center causes strong and sustained inspiratory movements. • The pneumotaxic center controls medullary activity – Turns off inspiration – Medulla • Dorsal respiratory group- Inspiratory – Acts as pacemaker, expiration occurs when signal from these nerves stops. • Ventral respiratory group- both inspiratory and expiratory – Inactive during normal breathing, speed up inspiratory activity when demands are high Nervous control of breathing • Chemoreceptors detect changes in pH of blood – Send signal to breathing control centers in pons and medulla oblongata. • Nerve signals tell lungs to inhale Oxygen/CO2 transport in blood • Oxygen – Dissolved in blood 1.5% – Bound to hemoglobin 98.5% • CO2 – Dissolved in blood 10% – Bound to hemoglobin 30% – As bicarbonate 60% carbon dioxide transport in blood • From cells – RBC’s and blood pick up CO2 and transport it as carbonic acid (HCO3) – In lungs (at alveoli) CO2 is released and travels by diffusion to alveoli. Compare PO2 and PCO2 in blood and air • Inhaled air • Blood leaving alveolar capillaries • Blood leaving tissue capillaries • Exhaled air Structures of the respiratory system Pathway of air traveling through the respiratory system mouth/nasal cavity– pharynx– trachea– bronchus– bronchiole– alveoli Tissues of voice production • epiglottis • Vocal folds (chords) • Larynx Larynx • specialized structure atop the windpipe, responsible for – sound production, – air passage during breathing – protecting the airway during swallowing Vocal Folds (aka Vocal Cords) • “Fold-like" soft tissue that is the main vibratory component of the voice box; comprised of a – cover (epithelium and superficial lamina propria), – vocal ligament (intermediate and deep laminae propria), – body (thyroarytenoid muscle) Vocal folds Glottis • Opening between the two vocal folds; – the glottis opens during breathing and – closes during swallowing and sound production How we get voice • voice has three components – Voiced sound: The basic sound produced by vocal fold vibration is called "voiced sound." • This is described as a "buzzy" sound. – Resonance: Voice sound is amplified and modified by the vocal tract resonators (the throat, mouth cavity, and nasal passages). • This produces a person's recognizable voice. – Articulation: The vocal tract articulators (the tongue, soft palate, and lips) modify the voiced sound. • This produces recognizable words. Comparing external and internal respiration • External respiration involves the exchange of gases between the alveolar air and the pulmonary capillaries. • Internal respiration occurs when gas diffuses between peripheral capillaries and the fluid surrounding cells. Decompression Sickness (the bends) • It is the result of diffusion between liquids and gases: – Differences in pressure moves air from one place to another and force gas molecules into solution. • The bends occur when pressure decreases rapidly, and gas molecules leave solution to form bubbles in body fluids. – Nitrogen is usually the gas responsible for the observed symptoms. How “the bends” got its name Pneumothorax • occurs when air leaks from inside of the lung to the space between the lung and the chest wall. • The lung then collapses. • The dark side of the chest (right side of the picture) is filled with air that is outside of the lung tissue. – Can result from • ascent in diving without exhaling • A bone or other object puncturing the lung Tuberculosis • characterized by white lesions or tubercles which replace alveoli with scar tissue. – Creates poor gas exchange in the lungs. – Symptoms: coughing, sputum production, lethargy and breathlessness. • Caused by a bacterial infection – Spread through the air. • Almost impossible to transmit b/w people except with repeated exposure. • Most infected people never develop the disease. Tuberculosis xray Emphysema • Cause – Lung has a balance b/w two chemicals that help maintain elastic fibers around alveoli. – When balance is altered, elastic fibers are destroyed and alveoli are enlarged. – Enlarged alveoli are less efficient at gas exchange. – Patient is left short of breath – Smoking is primary culprit. Asthma • a disease of the bronchial tubes, – During normal breathing, the bands of muscle that surround the airways are relaxed, – with asthma, allergy-causing substances or environmental triggers make the bands of muscle surrounding the airways tighten, and air cannot move freely. • Causes – People have very sensitive airways that react to many environmental "triggers." • Contact with these triggers cause asthma symptoms – Triggers include • Infections (colds, viruses, flu, sinus infection) • Allergens such as pollens, mold spores, pet dander and dust mites • Irritants such as strong odors from perfumes or cleaning solutions, air pollution, • Tobacco smoke • Exercise or exertion • Weather -- changes in temperature and/or humidity, cold air Oxygen unloads from hemoglobin more as pH decreases Carbon Monoxide Poisoning • Most common cause of toxin induced death. • Difficult to detect, it is the great imitator of other conditions. 3 reasons why CO poisoning is toxic • direct binding of CO to hemoglobin; – One molecule of CO blocks a whole hemoglobin from carrying oxygen. • shifting the oxygen-hemoglobin dissociation curve; – Hemoglobin gives up less oxygen to tissue when it is bound to CO • CO binding to myoglobin; – Slow twitch muscle fibers can’t use myoglobin and they starve for oxygen. – Heart muscle tissue suffers the same fate. Symptoms • Headache, dizziness, agitation, stupor, seizures, and coma are the most common neurological symptoms. – In one study with acute CO poisoning, 90% had headache. – physicians should attempt to identify the use of gas stoves and other cohabitants with the same symptoms to determine a correct diagnosis.