Study Guide for Exam 4 The Respiratory System 1 Mechanics of breathing Two separate zones o Conducting zone nose mouth pharynx larynx trachea bronchi and Humidifies and cleans air of impurities o Respiratory zone respiratory bronchioles alveolar sacs alveolar ducts bronchioles alveoli Exchange gases with the body through the respiratory membrane Composed of fused basal lamina from capillary walls and alveolar walls Uses simple diffusion Ventilation what occurs inside the lungs breathing o Pulmonary ventilation Inspiration expiration Inspiration air moves into the lungs At rest Labored inhalation o Diaphragm and external intercostal muscles contract o Sternocleidomastoid scalene muscles and pectoralis major contract with diaphragm and external intercostal muscles Expiration air moves out of the lungs At rest o Diaphragm and external intercostal muscles relax Labored exhalation o Abdominal and internal intercostal muscles contract Expiration cannot occur if alveolar pressure is below 760mmHg Respiration what occurs between the lungs and the body o External respiration Gas exchange between lungs and blood o Internal respiration gas exchange between blood and tissues Transport of respiratory gases 2 Pressure relationships in the thoracic cavity Relative to atmospheric pressure 760mmHg 1 atm o Negative respiratory pressure when respiratory pressure is less than o Positive respiratory pressure when respiratory pressure is greater than atmospheric pressure During inspiration atmospheric pressure During expiration Inspiration diaphragm contracts and becomes smaller giving lungs more space to fill up so pressure DECREASES Expiration diaphragm relaxes and becomes bigger giving lungs less space to hold larger amounts of air so pressure INCREASES Essentially the space of the thoracic cavity changes depending on whether or not the diaphragm is contracted or relaxed which changes the alveolar pressure within the lungs 3 Pulmonary ventilation What occurs inside the lungs is ventilation what occurs between the lungs and tissues is respiration Pressure changes induce inspiration and expiration o Pressure must increase over 760mmHg or 1 atm for air to be expelled from the lungs expiration exhalation 4 Physical factors influencing pulmonary ventilation Size of the thoracic cavity determined by respiratory muscles and change in pressures in the lungs Airway Resistance o The smaller the diameter the larger the resistance o The greatest resistance is found in medium sized bronchioles o Friction is the major NONELASTIC source of airway resistance Friction change in pressure resistance o Inflammation and bronchoconstriction are two ELASTIC forms of airway resistance Inflammation inside the bronchiole swells causing the diameter to shrink Bronchoconstriction the muscles surrounding the bronchiole contract causing the diameter to shrink 5 Dead space and alveolar ventilation Tidal volume total amount of air that enters body o Around 500 600mL depending on the person 150ml is anatomical dead space body 350ml is alveolar air Actual air used to oxygenate body Alveolar ventilation rate the number of breaths you take x 350 o Frequency of breaths x tidal volume dead space Never reaches the respiratory zone and never does anything in the 6 Gas exchange between blood lungs and tissues partial pressures of O2 and CO2 in atmospheric air alveolus pulmonary circulation systemic circulation and cells External respiration partial pressure gradients Air is composed of three gases o CO2 carbon dioxide o O2 oxygen o N2 nitrogen Gas exchange occurs at the respiratory membrane o Between capillaries and alveoli o Uses simple diffusion across a fused basal membrane where the capillary walls and alveolar walls meet Partial pressures o Oxygen Venous blood pressure 40mmHg Alveolar pressure around 100mmHg Pressure gradient 60mmHg 100 40 o CO2 Venous blood pressure 45mmHg Alveolar pressure 40mmHg Pressure gradient 5mmHg o Venous blood pressure is equal to cellular pressure o Alveolar pressure is equal to capillary pressure o What does this mean CO2 has a lower pressure gradient than O2 this makes it 20x more soluble CO2 and O2 diffuse equally But CO2 requires lower pressure 8 Transport of respiratory gases by blood Oxy Hb dissociation curve CO2 transport o CO2 diffuses into red blood cells and is turned into H2CO3 by the addition of water and carbonic anhydrase H2CO3 is then broken apart into H and HCO3 ions H ions change the blood pH CO2 enters the blood and is converted into ions in three ways 10 enters through plasma 70 uses carbonic anhydrase 20 binds to hemoglobin and is converted into oxygen o Haldane effect the lower the saturation level of oxygen in the blood the more CO2 can be carried in the blood O2 transport o Uses hemoglobin protein that carries oxygen through the blood 4 oxygen molecules per 1 hb A hb molecule is considered saturated if all 4 hemes are bonded to an oxygen o Only 20 25 of oxygen is released from hb during one systemic circulation of blood o If oxygen levels decrease hemoglobin releases more oxygen No need for respiratory or cardiac levels to increase o Hb hemoglobin oxygen saturation dissociation curve 98 saturated blood 20mL of oxygen for every 100mL of blood 20 total blood volume Only 5 of blood is released in capillaries during circulation 9 Control of respiration Role of peripheral and central chemoreceptors Peripheral chemoreceptors 30 o Directly stimulated by increase of CO2 If CO2 increases that means O2 decreases which is called hypoxia o Peripheral chemoreceptors are indirectly stimulated by hypoxia Central chemoreceptors 70 o Directly stimulated by increase of H ions H ions are found in the blood when CO2 is being broken down o Central chemoreceptors are indirectly stimulated by an increase in CO2 The urinary System 1 Nephrons capillary beds peritubular capillaries vascular resistance in the microcirculation the JG apparatus 85 in cortex cortical nephrons 15 are in between cortex and medulla juxtamedullary nephrons o Produce concentrated or diluted urine Super yellow or super clear Inside the nephron o Glomerulus High blood pressure Forces fluids solids out of blood into renal corpuscle to be filtered o Proximal convoluted tubule Not water soluble Largest amount of mitochondria Necessary for primary active transport Majority of reabsorption done here o Distal convoluted tubule Water soluble Second chance for reabsorption Main function is secretion into collecting ducts o Collecting ducts
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