The Respiratory System

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Kinesiology & Health Science
KINE 3012
Michael Connor

RESPIRATORY SYSTEM WHAT DOES THE RESPIRATORY SYSTEM DO? 1. Passageway for O2into the body 2. Passageway for CO 2ut of the body 3. Helps regulate pH (7.4) 4. Speech 5. Maintain air quality, dissolve clots LUNG STRUCTURE - Lungs are divided into left and right lobes - Pharynx divides into two o Esophagus o Larynx (vocal cords) - Conducting Zone determines air flow (lined with cilia that secrete mucus) o Trachea, bronchi, bronchioles, terminal bronchioles o Air slows down by terminal bronchioles which allows for effective gas exchange o Low resistance pathway, which warms, humidifies and filters air - Respiratory zone allows for gas exchange o Respiratory bronchioles (lined with cilia that secrete mucus) , alveolar ducts, alveolar sacs - Change the rate of air flow o Increase rate of breathing o Increase the depth o Alter the radius of the airways - Cystic Fibrosis: too much mucus production from the conducting zone down to the respiratory bronchioles. GAS EXCHANGE - Gas exchange occurs in the alveoli, which are lined with epithelial cells. All the alveoli are surrounded by capillaries - The distance between the cells and the lungs is 2 cells which allows for optimal diffusion and gas exchange CELLULAR COMPOSITION OF THE LUNGS - Only one blood cell goes through each capillary each time - The balloon shape of the cell helps air to expand and spread in the alveoli which in turn allows for more surface area - The capillary and the alveoli are almost touching meaning gas exchange occurs really well - Interstitial Fluid around the alveoli allows to keep the cell moist and not dry out - Two types of Alveolar Epithelial Cells o Type 1: allows for gas exchange because of its flat shape o Type 2: Produces surfactant  Breaks up water molecular bonds, allowing us to breath THE LUNGS AND THORAX - Thorax: is the chest cavity which contains the lungs - Boundaries: o Top: muscles and connective tissues o Bottom: Diaphragm o Walls: spine, ribs, intercostal muscles and connective tissue - The only way that air can get into the body is through your larynx and trachea meaning it is airtight and air cannot get into our thorax in any other way - Each lung is surrounded by pleura o Pleura  Visceral Pleura: around the outer surface of the lung  Parietal Pleura: thoracic wall and diaphragm o The two pleura are very close but not attached, there is a thing space where intrapleural fluid o The pressure of the fluid is called hydrostatic pressure and because of the location of the fluid it is called intrapleural pressure RESPIRATION - Ventilation: moving air in and out of our lungs o Bulk Flow: movement of substance (F= P/R) Bulk Flow - Movement of substance needs a pressure gradient, air, blood plasma filtrate - F = Bulk Flow, ΔP= Pressure different (atmosphere and alveolar pressure) , R= resistance (airway diameter) What Determines Delta P - ΔP is determined by P ALVand P IPessures - In order for air to come into our lungs the pressure in the atmosphere has to be greater than the pressure in our lungs - In order for air to come out of our lungs the pressure in the lungs has to be greater than the pressure in the atmosphere - Atmospheric Pressure does not change - Alveolar pressure pushes in and the intrapleural pressures pushes out Boyle’s Law determines the pressure - P1V 1P 2 2 - Breathing In: volume goes up  pressure goes down - Breathing Out: volume goes down  pressure goes up - Overall the independent variable is the volume (container) which affects the pressure Introduction to Air Movement Into and Out of the Lung - Atmospheric pressure never changes - We need to make alveolar pressure go up and down in order for air to move into and out of the lung - Alveolar Pressure pushes out on the alveolar wall, while intrapleural pressure pushes in on the alveolar wall - Intrapleural Pressure is always lower than alveolar pressure - If you have smaller pressure pushing in and larger pressure pushing out causes alveoli to stay open - If the two pressure are equal than the alveoli will collapse TRANSPULMONARY PRESSURE - PTP = PALV - PIP o Example, if the alveolar pressure is 760 and the intrapleural pressure is 756 then the transpulmonary pressure will equal 4mmHG (before inspiration; equilibrium) - Pressure is always measured in ml/mm - At the end of each breath in and out the alveoli pressure is always going to end up being the same as the atmospheric pressure - ΔP only exist if there is air moving in and out of the lung - Transpulmonary pressure is fighting against elastic recoil - Transpulmonary pressure (pressure pushing the lung open) = recoil pressure (pressure keeping the lung closed) INSPIRATION AND EXPIRATION - Recoil: Passive - Transpulmonary: Voluntary Inspiration - In order for the lung to change size, you need to change the balance between elastic recoil and transpulmonary pressure o In order for this to happen the intrapleural space becomes bigger causing the pressure to go down, but since the lung is the same size and only the intrapleural space has changed the pressure of recoil remains the same (4mmHg) o Since the P IPcreased this allow for a ΔP to occur (6mmHg), therefore P TP6mmHg and recoil pressure= 4 mmHg causes the lung to expand and the air gets pushed into the lung due to Boyles Law o Chest and diaphragm allows the intrapleural space to become bigger o The alveoli will get bigger until the recoil pressure = the new transpulmonary pressure Expiration - When we relax the muscles this causes the elastic recoil, making us push the air out of our lungs, which causes the alveoli pressure to be greater and in turn making the air come out - Transpulmonary pressure becomes smaller, and recoil pressure becomes bigger NEGATIVE P IMPORTANT? IP - If IP< PALV that will always keep the alveoli open o P IP always less than P ALV - But if IP= P ALVthen P TPwill equal 0 causing no recoil and the alveoli will collapse WHEN IS P NOT NEIPTIVE? - When the P iIPnot negative then you do not have air tight lung this is also known as Pneumothorax o The lung is open to the atmosphere o Pressure will keep on going into the intrapleural space until P becomes the same as and IP ALV PATMSand recoil will continue to constrict until recoil is also equal o Pneumothorax affects only the lung that has it. - Traumatic Pneumothorax: The lung gets punctured from the outside causing the hole in the lung (in the chest wall) Where the atmospheric pressure matches the intrapleural pressure due to boyles law - Spontaneous Pneumothorax: The lung gets punctured from the inside causing. Where the intrapleural pressure matches the alveolar pressure. CHANGES IN LUNG CHARACTERISTICS COMPLIANCE - Compliance tells us how easy the lung is able to inflate and deflate, it also affects expansion and contraction of the lung - Increased Compliance causes recoil pressure to be less, decreased compliance makes it harder to breath in meaning you will have to generate more transpulmonary pressure because recoil pressure is higher WHAT DETERMINES LUNG COMPLIACNE 1. Stretch ability of the connective tissues a. Meaning if you have thicker connections it makes it less compliant to open up 2. Surface tension of water a. The water molecules of the alveoli want to attract and make a water droplet, meaning every time you breathe in you have to break the water to water interactions b. Alveoli are lined with surfactant which allows us to break apart the water to water interactions i. Made by type II alveolar cells, which makes breathing easier WHY IS SURFACTANT IMPORTANT - Surfactant allows us to counteract the Law of Laplace - No Surfactant o Surface tension is equal in both the alveoli o Only difference is the radius is different o All the alveoli are different sizes  Meaning the air will go towards where the pressure is lower than where the pressure is higher (smaller alveoli)  Meaning A gets bigger and B gets smaller until completely collapses, causing less surface area in the lungs  Cause gas exchange to become insufficient - Surfactant o Equalizes surface tension o More effects on surface tension on alveoli B because smaller area causing more surfactant to be concentrated in alveoli B o In alveoli A more surface tension which allows the pressure not to flow into alveoli B AIR RESISTANCE - If resistance goes up flow goes down vice versa.. - Dependent on variables o Tube length in humans and giraffe is different because giraffe have to move the air at a much greater distance causing less flow o Gas molecules, such as temperature may change, or the makeup of the gas. Meaning if the gas is lighter it will move easier, but if the gas is heavier it is less easier to move o Airway radius is the most important, this changes on a breath to breath basis 1. Physical Factors a. Transpulmonary pressure, mucous accumulation, elastic connective tissue (connects airway to alveoli) all effect air way resistance 2. Neuroendocrine a. Parasympathetic (acetylcholine) constricts the airway b. Epinephrine dilates c. Vasoactive peptide dilates 3. Paracrine a. Histamine constricts (allergic reactions; bee stings) b. Eicosanoids constricts and dilates… DISEASE OF THE AIRWAY - Obstructive Disease o Asthma: smooth muscle contraction, inflammation of the airways o Triggers, exercise, smoke, pollutants o Treat with, anti-inflammatory drugs such as glucocorticoids, leukotriene inhibitors or bronchodilators which mimic epinephrine and inhibit acetylcholine o Relaxes the airs, they mimic epinephrine and inhibit acetylcholine o Chronic Obstructive  Emphysema
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