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Transcript
Human Physiology Unit Nine The Respirator y System Oral cavity Larynx Primary bronchus Tertiary bronchus Nasal cavity Pharynx Epiglottis Glottis Trachea Secondary bronchus The Respiratory System Bronchiole Pulmonary arteriole Pulmonary venule Terminal bronchiole Respiratory bronchiole Alveoli Capillary beds Inspiration & Expiration Respiration is divided into three phases: + ventilation + external respiration + internal respiration Inspiration & Expiration Ventilation occurs due to differences in pressure Humans mechanically produce an internal pressure that is less than the atmospheric pressure This is called negative pressure breathing Inspiration & Expiration Intrapulmonary pressure - pressure found inside the lungs (alveoli) Intrapleural pressure - pressure found outside the lungs in the pleural cavity Transplumonary pressure - difference between the two Inspiration & Expiration Inspiration & Expiration Inspiration & Expiration Compliance - the ability of the lungs to stretch and distend Elasticity - lung characteristic produced by large amounts of elastin connective tissues Elastic resistance - the tenancy of elastic fibers to return to original position (elastic recoil) Inspiration & Expiration Muscles of Inspiration & Expiration Sternocleidomastoid Scalenes External intercostals Pectoralis minor Internal intercostals Internal intercostals External abdominal obliques Diaphragm Rectus abdominis Lung Volumes Ventilation Terminology Eupnea - normal, relaxed quiet ventilation Apnea - temporary cessation of ventilation Dyspnea - labored ventilation Ventilation Terminology Hyperventilation - ventilation faster than necessary for metabolic demands Hypoventilation - ventilation slower than necessary for metabolic demands Ventilation Terminology Anoxia - condition in which there is little or no oxygen Pneumothorax - presence of air in the pleural cavity Atelectasis - collapsed lung Pulmonary Disorders COPD - chronic obstructive pulmonary disorder Asthma - obstructive disorder caused by inflammation, mucus secretions & constriction of air passageways Pulmonary Disorders Emphysema - obstructive disorder caused by destruction of alveolar tissue Bronchitis - obstructive disorder caused by inflammation & the mucus it causes Pulmonary Disorders Pneumonia - lower respiratory tract infection that causes the alveoli to fill with fluids Tuberculosis - caused by Mycobacterium tuberculosis - stimulates the lungs to form nodules Pulmonary Disorders Cystic fibrosis - a genetic disorder that clogs air passageways by the production of a thick, heavy mucus Pulmonary Disorders Bronchiogenic carcinoma - lung cancer that arises from the bronchial tubes ~ squamous cell carcinoma ~ small cell carcinoma Lung cancer is the leading cause of cancer death among both men and women Pulmonary Disorders Pulmonary fibrosis - reduced compliance and elasticity due to the accumulation of fibrous connective tissues as a result of lung Blackdamage lung - form of pulmonary fibrosis due to inhalation of carbon dust Major Atmospheric Gases Nitrogen - N2 - 78% Oxygen - O2 - 21% Carbon dioxide - CO2 - 0.04% Dalton’s Law The total pressure of a gas mixture is the sum of the partial pressures that each of the gases in the mixture would exert independently Respiration Remember - respiration is divided into three phases: + ventilation + external respiration + internal respiration Parti al Press ures and Ventilation/P erfusion This ratio indicates the amount Ratio of O2 in alveoli with respect to the blood flow (perfusion) Richly ventilated alveoli have increased perfusion Poorly ventilated alveoli have decreased perfusion Ventilation/P erfusion Ratio Poor ventilation in areas of increased perfusion leads to reduced Po2 Rich ventilation in areas of decreased perfusion leads to reduced Po2 Blood Gas Transportation Oxygen transport: * hemoglobin on RBCs - 98.5% * dissolved in plasma - 1.5% Carbon dioxide transport: * hemoglobin on RBCs - 20% * dissolved in plasma - 10% * converted to HCO3- - 70% Hemoglobin and Blood Gas Transportation Hemoglobin and Blood Gas Transportation Formation of oxyhemoglobin HHb + O2 HbO2 + H+ Carbaminohemoglobin formation CO2 + Hb HbCO2 Hemoglobin and Blood Gas Transportation Hemoglobin and Blood Gas Transportation The Oxyhemoglobin Dissociation Curve Oxyhemoglobin and the Unloading Oxygen pH and temperature will affect the rate and amount of HbO2 dissociation The Bohr effect - the increase in HbO2 dissociation in response to low pH Oxyhemoglobin and the Unloading Oxygen The decrease in pH is the result of glucose metabolism in cells The metabolism results in H+ and CO2 being passed into the capillaries, decreasing the pH and increasing the Pco2 Oxyhemoglobin and the Unloading Oxygen HbO2 is induced to give off O2 for four reasons: ► ambient Po2 ► temperature increase ► pH decrease ► BPG (biphosphoglycerate) The Oxyhemoglobin Dissociation Curve The Effects of Temperature and pH Acidosis vs. Alkalosis Respiratory acidosis - occurs when the blood pH drops below 7.35 - CO2 increases in the blood - caused by trauma, illness, hypoventilation, pulmonary disease or barbiturate overdose Acidosis vs. Alkalosis Metabolic acidosis - occurs when the blood pH drops below 7.35 - increased levels of metabolic acids - caused by starvation, low dietary carbohydrates, diarrhea, strenuous exercise or excessive alcohol Acidosis vs. Alkalosis Respiratory alkalosis - occurs when the blood pH rises above 7.45 - CO2 decreases in the blood - caused by hyperventilation or aspirin overdose Acidosis vs. Alkalosis Metabolic alkalosis - occurs when the blood pH rises above 7.45 - decreased metabolic acids in the blood - caused by constipation, prolonged emesis or overdosing on alkaline drugs Neural Control of Respiration Pontine respiratory center Ventral respiratory group Dorsal respiratory group Neural Control of Respiration Neural Control of Respiration Neural Control of Respiration Since O2 is carried in such high reserves and saturation, it has little effect on the rate of ventilation CO2 concentration and pH do significantly change and have an immediate effect on ventilation Neural Control of Respiration Therefore, ventilation functions to maintain Pco2 within its homeostatic range Neural Control of Respiration The Hering-Breuer reflex inhibits respiratory control centers by way of pulmonary stretch receptors This reflex prevents over distention of the lungs and contributes to the smoothness of ventilation Neural Control of Respiration Cheyne-Stokes ventilation is a condition that exhibits a rhythmic waxing and waning of the depth of ventilation with regular periods of apnea Neural Control of Respiration SIDS (sudden infant death syndrome) is caused by sleep apnea This syndrome typically occurs in infants under the age of two Neural Control of Respiration Causes are being investigated, with failure of respiratory control centers and/or failure of carotid bodies being focused on