Respiratory Physiology PDF

Module 9: Respiratory Physiology Types of Respiration Cellular Respiration -​ the intracellular metabolic process carried out within the mitochondria, which uses oxygen and produces carbon dioxide while deriving energy from nutrients -​ CO2 and H2O are the waste products -​...

Module 9: Respiratory Physiology Types of Respiration Cellular Respiration -​ the intracellular metabolic process carried out within the mitochondria, which uses oxygen and produces carbon dioxide while deriving energy from nutrients -​ CO2 and H2O are the waste products -​ O2 and Glucose are the fuel made to create ATP External Respiration -​ the entire process of respiration from the external environment and within our internal organ systems What is respiration? -​ obtaining O2 from the atmosphere to be used by the body cells -​ eliminate waste products such as CO2 produced by the body cells back to the atmosphere -​ we produce a lot of CO2 because of our tissues and cellular respiration External Respiration Steps 1.​ Air exchange between the atmosphere and the alveoli within the lungs. This process is called gas exchange or ventilation 2.​ The gas exchange that occurs at the pulmonary capillaries within the alveoli will move via the principles of diffusion. For every inhale, we take in O2, and for every exhale we are releasing CO2 3.​ The blood circulation in our body it’s important for transportation of O2 and CO2. 4.​ The oxygenated blood within the left side of the heart leaves and travels the circulation by giving tissues oxygen in order for them to being cellular respiration, and within that process the CO2 being produced as a waste product travels the bloodstream and back through the right side of the heart in order to get oxygenized Respiratory System Overview -​ nasal cavity -> pharynx -> larynx -> trachea -> left and right primary bronchus -> bronchioles (made out of smooth muscle) -> alveoli  -​ the bronchioles have smooth muscle so they are subject to hormones and external control such as in asthma, when an individual has an asthma attack. When breathing in an inhaler, is has adrenaline, which allows the smooth muscle around the bronchioles to dilate Alveoli ; -​ the end of our respiratory tract -​ they are found at the end of the terminal bronchioles where we find the alveolar sacs, and surrounding the sacs, are the pulmonary capillaries -​ the alveoli are well suited for diffusion because they have very thin walls for gas exchange Zoomed In Alveoli -​ type 1 alveolar cells make up the wall and shape of the sac -​ The alveolus is the sac that contains pulmonary surfactant -​ Alveolar macrophages eat and ingest foreign objects that don’t belong -​ directly surrounding the sacs are the pulmonary capillaries which are a little thicker than an erythrocyte -​ the.5 micrometer distance between the alveolar fluid lining with pulmonary surfactant and the pulmonary capillary is called Respiratory Mechanics -​ air moves down a pressure gradient from a region of higher pressure to a region of lower pressure -​ gas pressure: is the force exerted by gas molecules as they collide, so the more collisions the higher the gas pressure. -​ Boyle’s Law: pressure and volume are inversely proportional -​ As volume increase the pressure in the container will decrease, and as the volume decreases within the container, pressure will increase aka Boyle's Law -​ to apply Boyle's Law to the respiratory system, the lungs become the container, and muscles nearby will help increase/decrease the cavity the lungs are found in. -​ Changes in Lung = Changes in Alveolar Volume -​ the volume of the thoracic cavity will change during ventilation(the actual mechanical part of breathing) -​ pressure gradient: is the difference in pressure of a gas across two areas Important Pressure for Breathing Barometric Pressure -​ the pressure exerted by the weight of air in the atmosphere of the environment  -​ it has a pressure of 760 mmHg at sea level -​ as you go higher in altitude the barometric pressure decreases Intra-alveolar Pressure -​ the pressure within the alveoli -​ alveoli communicate with the atmosphere through the conducting airways -​ air quickly flows down its pressure gradient any time intra alveolar pressure differs from the atmospheric pressure -​ IAP Inspiration -​ when we inspire the goal is to expand the lungs, in order to expand the alveoli, therefore increasing alveolar volume, and decreasing the alveolar pressure -​ even during quiet breathing, or relaxed breathing, muscles are contracting and energy is being used Expiration -​ During quiet breathing, expiration is normally a passive process, accomplished by the elastic recoil of the lungs -​ To produce a forced and active expiration, the contraction of the internal intercostal muscles and abdominal muscles will further reduce the volume of the thoracic cavity and increase IAP greater than the ATM pressure -​ normal expire = elastic recoil Lung Elasticity -​ Also helps with breathing, inspiring and expiring Compliance -​ how much effort is required to stretch the lungs -​ high compliance -> stretches further for smaller increases in thoracic volume -​ low compliance -> Stretches less which requires a bigger increase in thoracic volume Elastic Recoil -​ how ready the lungs rebound after having been stretched -​ also responsible for the lungs returning to their pre-inspiration volume Compliance  -​ How much work do you have to do in order to get a volume change? Such as thin water balloons vs thick party balloons (low compliance) Elastic Recoil -​ a new pair of sock vs an old pair of socks Respiratory Dysfunction Obstructive Lung Diseases -​ difficulty in emptying the lungs, so exhaling impacted. -​ “Air trapping” is common, meaning that there is still a lot of air left over in the lungs -​ elastic recoil can be compromised -​ examples include chronic bronchitis, asthma, and emphysema Restrictive Lung Disease -​ inhaling is compromised -​ difficulty in filling the lungs -​ compliance can be compromised -​ examples: asbestosis, sarcoidosis, pulmonary fibrosis Alveolar Surface Tension -​ a thin liquid film lines each alveolus, filled with water and mostly pulmonary surfactant -​ definition:water molecules are more attracted to each other through bonding, which would create high surface tension, and leading the alveoli to collapsing on itself so those water molecules create this surface tension within the alveoli sacs Surface tension does two things in the alveoli 1.​ It opposes the expansion of the alveolus because the surface water molecules don’t want to be pulled apart 2.​ It can reduce alveolar size due to the attraction of the water molecules to each other. Which allows for the increase of elastic recoil within the alveoli. Pulmonary Surfactant -​ Surfactant: is a soapy liquid that is made up of lipids and proteins which is secreted by the type 2 alveolar cells  -​ the pulmonary surfactant interrupts the hydrogen bonds and decreases alveolar surface tension in the lungs Benefits of Pulmonary Surfactant -​ increases pulmonary compliance, reducing the work of inflating the lungs -​ it reduces the lungs tendency to recoil so that they don’t collapse so easily Gas Exchange Partial Pressure -​ the sum of pressures of the different gas components that make up the total air pressure that we are observing -​ each gas is considered separate and individual from one another -​ PO2 vs PCO2 is how we would denote partial pressure Transport of Oxygen -​ for every single RBC, there are 4 hemoglobin binding sites for O2 to attach to. Fe3+ is the transitional metal that helps to bind the hemoglobin -​ when O2 is ready to bind to the RBC, 90% of the oxygen is bound to hemoglobin -​ Once the RBC reaches our systemic tissues, which will detect the low levels of oxygen, where then oxygen will dissociate from hemoglobin to dissolve to the needed tissue cells. When oxygen is bound to the hemoglobin it is denoted as HbO2 Transport of CO2 -​ most of CO2 is transported to the lungs as bicarbonate ions (HCO3-) dissolved in the blood plasma -​ So when CO2 and H20 are the waste products in cellular respiration and metabolism, then they will dissolve into the bloodstream. Within the blood plasma, there is an enzyme called carbonic anhydrase, which converts carbon dioxide and water into H2CO3 carbonic acid, which is then readily available to dissociate into HCO3- bicarbonate and H+ -​ this reaction is reversible and the conversion process of CO2 and H20 is all done within the RBC -​ This process is done because allows the body to transport CO2 throughout the body and Bicarbonate is a buffer which allows pH equilibrium Steps of Transportation  1.​ CO2 is diffused out of those systemic tissues in our body via glycolysis and cellular respiration because it was a waste product of those processes. 2.​ CO2 dissolves into the RBC, 23% binds to hemoglobin, and 70% will combine with H2O in the present carbonic anhydrase to create H2CO3 carbonic acid, which then dissolves into HCO3- bicarbonate and H+ 3.​ HCO3-gets pushed out into the plasma but is only done so with Cl- ion which allows that process to occur. 4.​ Now we have arrived at the lungs and must reverse the process so we can acquire CO2 from HCO3- bicarbonate. To do so we remove the Cl- from the RBC we are in, Hb and H will dissociate and the H and HCO3- will combine in order to create H2CO3 carbonic acid and carbonic anhydrase will dissociate and form CO2 and H2O Oxygen-Hemoglobin Dissociation Curve -​ Oxygen is transported by being bound to hemoglobin -​ there is a dissociation curve of how readily hemoglobin is available to bind to oxygen, giving us an O2-Hb dissociation curve -​ The availability of oxygen will determine the availability of binding sites on the hemoglobin. -​ The x axis represents how much O2 is available nearby, so as we go further up the scale, meaning that there is more Oxygen available -​ the y axis demonstrates how many binding sites are taken on hemoglobin -​ lower percent saturation, would mean, all binding sites are available. At the 50% saturation mean that half the seats are taken and 100% mean that all four binding seats will be taken by O2 -​ at lower partial pressure,hemoglobin releases oxygen at around 20 or 40mmHg and Hb is almost completely saturated when PO2 is 80 mmHg or above O2-Hb Curve Shift A shift of the curve to the right can be due to a decrease in pH , an increase in CO2, or an increase in temperature. All resulting in a decrease in the ability of hemoglobin to hold oxygen A shift of the curve to the left can be due to an increase in pH, decrease in CO2, or a decrease in temperature. All result in an increase in the ability of hemoglobin to hold oxygen Bohr Effect -​ as pH decreases (more acidic) the curve shifts to the right. This means that at a certain partial pressure of oxygen, hemoglobin is less saturated Adjustment to Tissue Needs Hemoglobin unloads O2 to match metabolic needs of different states of activity of the tissue Three factors that adjust the rate of oxygen unloading from Hb: -​ Ambient PO2: active tissue lower amounts of P O2, meaning O2 is released from Hb -​ Temperature: active tissue has increased temp, promoting O2, unloading -​ Bohr Effet: tissue has excess CO2 resulting in more H+ in the blood plasma, therefore making blood more acidic aka lower pH Blood pH -​ acidosis: blood pH lower than 7.35 -​ alkalosis: blood pH higher than 7.45 How to Normalize pH -​ a combination of pulmonary ventilation and rate of CO2 production Hyperventilation -​ response to respiratory acidosis -​ by reducing the H+ content and pushing the CO2+H2O reversible equilibrium reaction to the left Hypoventilation -​ correcting hypoventilation -​ breathing in very slowly and help with the accumulation of CO2 Spirometry -​ changes in lung volume measure by a scientific apparatus Spirograms -​ a spirogram is used to display changes in lung volume over a period of time and different breathing efforts -​ upwards deflections are known as inspirations -​ downwards inflections are known as expiration Lung Volumes -​ Tidal Volume: aka quiet breathing, the volume of air inspired and expired with each breath under resting conditions which will have an average volume of 500 mL -​ Inspiratory Reserve Volume: the extra volume of air that can be maximally inspired over and above the typical resting tidal volume. The IRV is accomplished by maximal contraction of the diaphragm, external intercostal muscles, and accessory inspiratory muscles. Average volume is 3000 mL in males and 1900 mL in females -​ Inspiratory Capacity: the maximum volume of air that can be inspired at the end of a normal quiet expiration. In other words it would be the sum of IRV and the TV. Average value is 3500mL -​ Expiratory Reserve Volume: the extra volume of air that can actively expired by maximally contracting the expiratory muscles -​ Residual Volume: the minimum volume of air remaining in the lungs even after you maximally expire. Can’t be measure but mathematically derived -​ Functional residual volume: how much air is left over in the lungs at the end of a normal passive expiration. ErV + RV -​ Vital Capacity: maximum amount of air during inhalation or exhalation. It would be the sum of IRV + TV + ERV -​ Total Lung Capacity: the total amount of air that the lungs have including the RV