Gas Exchange I (2023-2024) PDF

Block 1.3 (2023-2024) GAS EXCHANGE Done by : Writer 1: Hesham Alrashed Writer 2: Maryam Alfayez Gas Exchange Dr. Arif Mohyuddin Associate Professor Department of Biomedical sciences Physiology Section College of Medicine, in Al Hassa King F...

Block 1.3 (2023-2024) GAS EXCHANGE Done by : Writer 1: Hesham Alrashed Writer 2: Maryam Alfayez Gas Exchange Dr. Arif Mohyuddin Associate Professor Department of Biomedical sciences Physiology Section College of Medicine, in Al Hassa King Faisal University, KSA n< um be 01/29/24 >r  Spirometer gives spirogram in paper Floating drum Air inspiration Recording paper advancing Expiration with time Water Spirogram Spirometer: recording the volume of movement of air into and out of the lung From the volumes we have it. We can determine the lung capacity. First, a person blows into the spirometer. Then, there is a recording, the floating drum is moving up and down because air is going into and out of the drum.Then , a pen is attached to the pap and it records. 220 notes  This recording is called Spirogram From this recording, we are able to record different parameters. Like the volumes and capacity Capacity is the addition of volumes. 220 note There are four volumes of the air in the lung : 1- TV = Tidal volume (500ml) You can not empty your 2- IRV = Inspiratory reserve volume (3,000 ml) lungs because of residual volume ‫بعد الزفير الطبيعي‬ 3-ERV = Expiratory reserve volume (1,000 ml) 4- RV = Residual volume (1,200 ml) And four capacity: 1- IC = Inspiratory capacity (3,500 ml) 2- FRC = Functional residual capacity (2,200 ml) 3-VC = Vital capacity (4,500 ml) 4- TLC = Total lung capacity (5,700 ml) Helping video : tps://youtu.be/mNadr6bGEMU  Conducting = No exchange Terminal bronchiole Smooth Contraction of smooth muscle muscle lead to asthma Branch of Branch of pulmonary pulmonary Air comes to the alveoli and on the surface artery vein of alveoli there is elastic fibers and these fibers help the alveoli in exhaling the air(it helps the lung to get rid off the air) which makes exhalation passive process. On the other hand, Inhalation is an active process Exchange of gases There are also a lot of pulmonary capillaries and these capillaries help in the Respiratory exchange of gasses between veins and bronchiole arteries. We have pulmonary artery which contains venous blood and it comes from right ventricle. 220 notes Pulmonary ‫ الشریان الرئوي یحمل دم غیر مؤكسد‬:‫معلومھ اثرائیھ‬ Alveolus ‫بعكس باقي الشرایین الموجوده في الجسم وبما ان‬ capillaries ‫الشریان یحمل دم غیر مؤكسد فالورید راح یحمل الدم‬ ‫المؤكسد )بمعنى اصح الوضع ھنا عكس(تمام ھذا‬ ‫یفسر ایش؟ یفسر لون الشریان الرئوي اللي ھو ازرق‬ Alveolar ‫طیب‬,‫ویفسر ایضا لون الورید الرئوي اللي لونھ احمر‬ Pores of Kohn sac ‫دام الشریان الرئوي ازرق ویحمل دم غیر مؤكسد لیش‬ ‫مانسمیھ ورید ونفك عمرنا؟ الن بكل بساطھ یحمل‬ ‫الدم بعیدًا عن القلب وھذا اللي خالھم یسموه شریان‬ 1. What is the definition of partial pressure & fractional concentration of a gas in a mixture of gases? n< um be 01/29/24 >r The exchange of oxygen and carbon dioxide at the pulmonary and tissue capillaries is by simple diffusion. Air is a mixture of gases. The partial pressure of each gas depends on its percentage in the total atmospheric pressure. For example, nitrogen is 79% of the air. Its partial pressure is 0.79 x 760 = 600.4 the doctor skipped it  ‫‪Composition and‬‬ ‫‪partial pressure in‬‬ ‫‪atmospheric air‬‬ ‫‪N₂ 79%‬‬ ‫‪Partial pressure of Partial pressure of N₂‬‬ ‫‪If we go up in the mountains the‬‬ ‫‪N₂ = 600 mm Hg :in atmospheric air‬‬ ‫‪partial pressure will reduce‬‬ ‫‪PN2 = 760 mm Hg X 0.79‬‬ ‫= ‪mm Hg 600‬‬ ‫ھنا بس یبي یوضح لنا معنى مصطلح )‪partial‬‬ ‫‪ ( pressure‬المأخوذ اساسًا من كلمة )‪ (part‬او جزء‬ ‫بالعربي ف یقول ان الھواء كما نعرف ھو عباره عن‬ ‫‪partial pressure of‬‬ ‫‪Total‬‬ ‫خلیط من الغازات ‪ ،‬بكمیات ونسب متفاوتھ ‪.‬ف‬ ‫‪each gas depends on‬‬ ‫احنا اذا جینا نتكلم عن ضغط الھواء او الضغط الجوي‬ ‫‪atmospheric‬‬ ‫‪its percentage in air‬‬ ‫)‪ ( atmospheric pressure‬ف احنا في االساس‬ ‫‪pressure‬‬ ‫قاعدین نتكلم عن مجموع الضغوط اللي سببھا‬ ‫= ‪mm Hg 760‬‬ ‫ھالخلیط من الغازات ‪.‬‬ ‫طیب یا دكتور انا ش ابي في ھالمجموع ؟! مو كل‬ ‫الغازات بحتاجھا في التنفس ‪ ،‬انا اللي یھمني ھو‬ ‫ضغط االكسجین وحده ف قالوا وال یھمك بنطلع لك‬ ‫الضغط الخاص باالكسجین ‪ ،‬عن طریق تجزیئ ال‬ ‫‪atmospheric partial pressure of O2‬‬ ‫وبنسمیھ ‪ pressure‬الن االكسجین جزء من خلیط‬ ‫‪Partial pressure of O₂‬‬ ‫الغازات حقت الھواء و ذلك عن طریق معادلة بسیطة‬ ‫‪O₂ 21%‬‬ ‫‪:in‬‬ ‫‪atmospheric‬‬ ‫‪air‬‬ ‫جً دا ‪ :‬نسبة الغاز في الھواء ضرب الضغط الجوي‬ ‫الضغط الجوي ‪760:‬‬ ‫‪PO2 = 760 mm Hg X 0.21‬‬ ‫‪Partial pressure of‬‬ ‫= ‪mm Hg 160‬‬ ‫‪O₂ = 160 mm Hg‬‬ Oxygen and carbon dioxide exchange across pulmonary and systemic capillaries caused by partial pressure gradient n< um be 01/29/24 >r  Atmospheric air Net diffusion gradients Inspiration Expiration for O₂ and CO₂ between the lungs and tissues Alveoli PO2 = 100 in alveoli 1/The oxygenated blood and 40 in venous goes to the cells Pulmonary circulation Systemic circulation 3/ After the exchange the PO2 will be 40 in the blood 2/ PO2 is low in the cells so it will diffuse to them Tissue cell  CO2 story: O2 story It starts from down the figure to the top , from tissues It start from top the figure to down , from atmosphere which has higher Pco2 (46) to atmosphere which has which has higher Po2 (160) to tissues which has lower lower (0.03), As a result of metabolism or cellular function Po2 (less than 40) the Pco2 in the tissue is more than other place which In the atmosphere, the PCO2 is 0.3 and PO2 is 160 equals to 46 and in the arterial blood Pco2 is equal to 40 When the air enters the alveoli, the PO2 becomes down So based on the gas law it will diffuse from higher pressure into 100 ( in the tissue) to lower pressure ( blood ) by simple diffusion , as a result the blood pressure will increase in So why the Po2 reduced? venous blood (46) then venous vessels will take CO2 to the Because CO2 is their and water vapors, so then the O2 lung. will leave the lung and enter the blood vessels ( the PO2 will not change (100) ) to the Left atrium of the heart , In the alveoli the Pco2 is (40) , which is less than Pco2 then to the tissue ( he re the PO2 will drop to less than 40 of the venous blood,as a result, CO2 will enter the alveoli ) this reduction is because: O2 is continuously being used Finally , In the atmosphere the Pco2 is 0.03 which is less for the cellular functions such as metabolism than Pco2 of the alveoli As a result we will exhale CO2 Factor Influence… Comments Rate of Thickness normally 1. Thickness transfer remains constant. of the decreases as Thickness increases respiratory the thickness with conditions like, membrane. increases. pulmonary fibrosis. n< um be respiratory‫المرض هذا الـ‬ ‫>في‬r Thicker ‫ يصير‬membrane decrease the diffusion lead to less O2 in the body  Influenc Factor Comments e When you exercise you need more O2 so surface area Rate of increase to more gas Surface area remains exchange transfer constant under resting increase 2. Surface conditions s as the Area of the Surface area increases during surface Alveolar exercise. area Membrane Surface area decreases with increase It decreases in lung collapse pathological conditions such s as lung collapse.  ‫ مثال النيتروجين‬: ‫ثابت اإلنتشار يعتمد عىل نوع الغاز‬ ‫ضغطه عالي في الغالف الجوي بس ما يقدر ينتقل للدم‬ Factor Influence… Comments 3. Diffusion Rate of Constant transfer Diffusion constant (Related to the increases as for carbon dioxide Gas’s Solubility the diffusion is 20 times that of & Molecular constant oxygen. Weight) increases  Influence on Factor the rate of Gas Comments MED220 transfer We know that: PAO2 is 100 and PvO2.is 40 So, the difference is 60 Whereas PACO2 is 40 and PvCO2 is 46. So, the difference is 6 4. Partial This means that the partial pressure difference of O2 is 10 times more than Rate of transfer.the partial pressure difference of CO2 pressure Major HOWEVER,The solubility of CO2 is 20 increases as the times more than O2 (Previous difference of determinant slide). As a result of these factors, both O2 and CO2 diffuse through the partial pressure membrane at nearly the same rate Oxygen & of the rate of (very gradients quickly). 219 Carbon transfer increases dioxide 01/29/24  Humidified Alveolar Atmospheric Air Expired Air Air Air 78.62% 74.9% 74.5% N2 (597mmHg) 74% decreases absorbed increase 19.67% 13.6% 20.84% (159 O2 (149 (104 15.7% mmHg) mmHg) mmHg) Composition & Partial.04% (0.3 pressures.04%(0.3 5.3% N2: Remains constant O2: CO2 mmHg) mmHg) (40 mmHg) 3.6% Decreases CO2: Increases H2O: Increases 0.5% (3.7 6.2% 6.2% n< that is why the expired air H2O 6.2% um is wet mmHg) (47 mmHg) (47 01/29/24 mmHg) be >r  Alveolar air is renewed There are hundred molecules of the gas of the alveolar that even after 16 breaths there will be few of them And they are 5%-10% This is called slow renewal of the alveolar ‫ يتم تجديد الهواء في‬،‫عند التنفس‬ ،‫ ومع ذلك‬.‫الحويصالت الهوائية‬ ‫هناك بعض الجزيئات من الغازات‬ ‫في الحويصالت تبقى هناك رغم‬ ‫ قد‬،‫ نفًس ا‬16 ‫ حتى بعد‬.‫التنفس‬ ‫ وتكون‬،‫يبقى بعض هذه الجزيئات‬.%10-%5 ‫نسبتها تتراوح بين‬ MED220 Guyton & Hall 14th edition This picture shows us the expiration of gas Page 513 from an alveolus through successive Figure 40-2 shows this SLOW RATE of renewal of breaths. the alveolar air. In the first Top left corner has the maximum alveolus of the figure, excess gas is present in concentration of a gas inside an alveoli and the alveoli, but it decreases after breathing. The importance here is to see that breathing successively note that even at the end of 16 breaths, the lowers the concentration and the alveolar excess gas still has air is replaced and renewed very slowly. not been completely removed from the alveoli.  ‫كلما كان التنفس ابطئ يحتاج‬ if we increase the alveolar ‫الشخص لوقت اطول‬ pressure ventilation the normal alveolar 1/2 ‫ف مثال في‬ partial pressure of the ventilation oxygen will increase ‫ عشان‬seconds 40 ‫يحتاج تقريبا‬ ‫ من تركيز الغاز‬%50 ‫يتخلص من‬ x2 normal alveolar ‫بينما في‬ ventilation ‫ عشان‬seconds 8 ‫يحتاج فقط‬ ‫يتخلص من نفس النسبة‬.Figure 39-3 Rate of removal of excess gas from alveoli Guyton & Hall 14th edition 1- The middle curve (RED) is normal ventilation (or Page 513 breathing) and RR=12/min Figure 40-3 demonstrates graphically the rate at which excess 2- The upper curve is when normal ventilation is gas in the alveoli is normally removed, showing that with: 1-Normal alveolar ventilation, about half the gas is removed in half the normal and RR=6/min 17 seconds. 3- The lower curve is when normal ventilation is 2-When a person’s rate of alveolar ventilation is only half- doubled and RR=24/min normal, half of the gas is removed in 34 seconds, 3-and when the rate of ventilation is twice normal, half is removed in RR: Respiratory Rate about. ‫معدل يستهلكه االنسان‬ ‫خالل النشاط الطبيعي كل‬ ‫هذا معدل االنسان بنشاط مرتفع مثال‬ ‫في حالة التمارين الرياضية‬ ‫دقيقه‬ due to the increased alveolar ventilation Figure 39-4 Effect of alveolar ventilation on the alveolar Po2 at two rates of oxygen absorption from.the alveoli-250 ml/min and 1000 ml/min. Point A is the normal operating point *Upper limit of alveolar PO2 is 150 mm Hg. *Point A in graph is the alveolar PO2 at normal ventilatory rate. *Normally, a person utilizes 250 ml O2/min In this graph, the red curve shows the normal alveolar ventilation at rest. Normal values: 02 consumption of 250 ml 02/min Ventilatory rate)of 4.2 L/min The blue dashed curve shows alveolar ventilation of a person during moderate exercise. Values -OZ consumption of 1000 ml 02/min Ventilatory rate of nearly 17 L/min Explanation: Alveolar partial pressure of 02 (PO2) should remain 100 mm Hg. So, when we do exercise, the 02 is gets absorbedAtimes rapidly than normal "250->1000." As a result, in order to maintain the normal P02 value (100 mm Hg), the ventilatory rate gets increased "4.2->17. " Terminal bronchiole Smooth muscle Branch of Branch of pulmonary pulmonary artery vein Respiratory bronchiole Alveolus Pulmonary capillaries Alveolar Pores of Kohn sac Pulmonary artery transports deoxygenated blood from heart to lungs for oxygenation. Pulmonary vein transports oxygenated blood from lungs back to the heart to pump it all over the body. Why does pulmonary artery contain deoxygenated blood and why does pulmonary vein contain oxygenated blood?! You should know the ORIGINAL DEFINITION of artery and vein: Artery: transports blood AWAY from the heart. Vein: transports blood TO the heart. So, why do lungs have opposite situation?! This is because the function of the lungs is to: 1. Oxygenate the deoxygenated blood coming from the heart, and since blood is coming from the heart, the vessel transporting the blood is called artery (Pulmonary artery). 2. Bringing back oxygenated blood to the heart, and since blood is heading to the heart, the vessel transporting the blood is called vein (Pulmonary vein).  Alveolar fluid lining with pulmonary surfactant Alveolar Type II alveolar cell macrophage Type I alveolar cell Interstitial fluid Alveolus Pulmonary capillary Thickness of respiratory The oxygen will pass membrane is: from here to the blood Erythrocyte Here are the cells that will carry oxygen; as O2 Diameter of RBC is 7.2 micron passes through, it will Thickness in the middle of RBC is 1 micron or bind to them. 4. What are the normal values of PO2, SO2, PCO2, HCO3- & pH in the alveoli, arterial blood & mixed venous blood? n< um be 01/29/24 >r  A : stand for alveoli a : stand for artery Mixed Arterial Oxygen saturation Alveoli Venous Blood is a measure of the Blood amount of hemoglobin that is bound to molecular oxygen at a PA O2 (mmHg) PaO2 PvO2 given time point. SAO2 SaO2 SvO2 PA CO2 PaCO2 PvCO2 (mmHg) HCO3 mE/L HCO3 HCO3 pH pH pH 01/29/24 PAO2= partial pressure of O2 in the alveolar gas. PaO2= partial pressure of O2 in the arterial blood. PvO2= partial pressure of O2 in the mixed venous blood. PACO2= partial pressure of CO2 in the alveolar gas. PaCO2= partial pressure of CO2 in the arterial blood. PvCO2= partial pressure of CO2 in the mixed venous blood. SAO2= Saturation of O2 in the alveolar gas. SaO2= Saturation of O2 in the arterial blood. SvO2= Saturation of O2 in the mixed venous blood. *the v (mixed venous blood) has a bar above it.  Mixed Arteri Venou Alveoli al s Blood Blood PA O2 104 PaO2 100 PvO2 40 (mmHg) SAO2 SaO2 97% SvO2 75% PA CO2 40 PaCO2 40 PvCO2 46 (mmHg) 22-28 22-28 mEq/L The normal pH of the human HCO3 mE/L HCO3 mEq/L HCO3 body typically ranges from the venous is a little more acidic 7.35 to 7.45. pH pH 7.45 pH 7.35 MED220 The dash above the V means mixed venous blood which is carried by IVC and Mixed venous blood v: is the blood in the right atrium carried by Inferior SVC into the right atrium. vena cava & Superior vena cava. Bicarbonate HCO3 is very important for the blood (it is a buffer). Buffer means that it makes the plasma pH stable. HCO3 is called ALKALI RESERVE of From where this bicarbonate comes ? body, whenever acid is produced, When CO2 is produced in the tissue, it HCO3 will immediately neutralize it. comes to the blood and adds up with H2O Sometimes, HCO3 is injected intravenously when acid-base H2CO3 then dissociate to give H and imbalances occur HCO3 ( this is one of transport 1/25/22 mechanisms for CO2). 219 pH: venous blood is more acidic than arterial blood. Why? Because it can gain more CO2 and CO2 is a potential acid ( in water it becomes carbonic acid H2CO3) Average resting Normal PO2 PO2 at systemic at capillaries pulmonary This is called capillaries Oxygen–hemoglobin dissociation curve The hemoglobin's oxygen content increases as Po2 increases until the maximum capacity is reached. As this limit is approached, very little additional binding occurs, and the curve levels out as the hemoglobin becomes saturated with oxygen. This makes the curve sigmoid or S-shaped. References. Guyton & Hall, Textbook of Medical Physiology, 14th Edition, Elsevier, Philadelphia PA, 2021 Chapter 40. Page:511-520 n< um be 01/29/24 >r  Quiz Q1/ How does CO2 move from venous blood to the lungs? a) Active transport b) Simple diffusion c) Facilitated diffusion d) Osmosis Q2 /How does an increase in the thickness of the respiratory membrane affect the rate of gas transfer? a) Increases the rate of gas transfer b) Decreases the rate of gas transfer c) Has no effect on the rate of gas transfer d) Stabilizes the rate of gas transfer 1/B - 2/B Good Luck !