biology and Medicine videos please make sure to subscribe join the foring group for the latest videos please visit Facebook Armando huran in this video we're going to talk about blood gases so gases in the blood specifically focusing on oxygen and carbon dioxide so we are actually looking at the concentrations of these gases in our lungs the blood and the tissues and what I mean by concentration is actually the partial pressure the higher the partial pressure of a gas in an area technically means the higher the amount of that gas in that area so to begin we first must look at the partial pressure of oxygen in the atmosphere so we have a significantly actually higher partial pressure of oxygen than carbon dioxide in the atmosphere to be correct the partial pressure of oxygen uh is about 160 mm Mercury and the partial pressure of carbon dioxide is 0.3 mm Mercury and so this is what we actually breathe in during inspiration what we breathe out is a partial pressure of oxygen of about 120 mm Mercury and a partial pressure of carbon dioxide oide of about 27 mm Mercury so these figures they tell us two important things first is that we don't use that much oxygen so we don't use up all the oxygen we breathe in the second thing is that we only produce a little bit of carbon dioxide but why then is there such a low uh partial pressure of carbon dioxide in the atmosphere well this is because the plants the plants around us they use the carbon dioxide and together with water and sunlight they can produce energy and as a byproduct they produce oxygen and so this cycle continues we we will breathe in this oxygen and we will produce the carbon dioxide which will then be used by the plants etc etc so let's have a closer look at gas exchange in the lungs when we breathe in these gases the gases will travel down our respiratory tract to the terminals called uh called the alvioli um and here I am drawing three alviola sacs the pulmonary arteries come towards the alveoli carrying with it deoxygenated blood and then then they will leave the alveoli with reoxygenated blood uh through the pulmonary veins and this all is thanks to the gas exchange process that occurs within the alvioli so let's have a look at this gas exchange process in a bit more detail so here we are looking at um an Alvis here is the pulmonary artery carrying with it Deo oxygenated blood and then we have the pulmonary vein which has been reoxygenated by the Alvis and the pulmonary vein returns back to the hot so the principal thing here is that we breathe in oxygen which comes down to the alveoli and we breathe out carbon dioxide of course in reality we also breathe in carbon dioxide and we actually breathe out a lot more oxygen if you remember the partial pressure of oxygen in the alvioli is higher than carbon dioxide the partial pressure of oxygen in the alvioli is about 100 mm Mercury and the partial pressure of carbon dioxide is about 40 mm Mercury there's actually a slightly higher uh partial pressure of oxygen in the alveola it's like five or something but 100 just remember 100 anyway so this is the partial pressure that exchanges with the atmosphere during inspiration and expiration now as I mentioned the hot or if I didn't mention I'm mentioning it now but the hot it will pump deoxygenated blood to the lungs through the pulmonary artery now the pulmonary artery has a slightly higher partial pressure of carbon dioxide than um oxygen so the partial pressure of oxygen is actually about 40 mm Mercury and the partial pressure of carbon dioxide is about 46 mm Mercury so the carbon dioxide will move from an area of higher concentration higher partial pressure to an area of lower concentration lower partial pressure so carbon dioxide will move from the blood into the lungs into the alvioli and oxygen will move from an area of higher concentration to an area of lower concentration so the oxygen will move from the lungs from the alveoli into the blood and this is how the deoxygenated blood supply becomes reoxygenated so the new partial pressure in this reoxygenated blood is is oxygen of about 100 mm Mercury and the partial pressure of carbon dioxide which is now 40 mm Mercury so there is a higher partial pressure of oxygen than there is carbon dioxide this blood vessel is known as the pulmonary vein and will carry this oxygenated blood back to the heart the heart will then pump this oxygenated blood to the tissues through the systemic arteries remember this blood is rich in oxygen the partial pressure of oxygen is much higher than that of carbon dioxide and the and just recapping the partial pressure of oxygen is about 100 mm Mercury and the carbon dioxide is about 40 mm Mercury the tissues on the other hand has a slightly lower partial pressure of oxygen compared to the partial pressure of carbon dioxide the partial pressure of oxygen is less than 40 mm mercury in the tissues and the partial pressure of carbon dioxide is greater than 45 mm Mercury um here and remember that that gas they move from an area of higher concentration higher partial pressure to an area of lower concentration lower partial pressure so as a result oxygen will move from the blood into the tissues the tissues will use the oxygen oxygen and create carbon dioxide as a byproduct and then the carbon dioxide will move from the tissues into the blood so now the blood is deoxygenated because the oxygen has been used by the tissues this new deoxygenated blood supply has a partial pressure of oxygen of about 40 mm Mercury and a partial pressure of carbon dioxide of about 46 mm Mercury this deoxygenated blood um are the systemic veins and will return to the hot the hot will then pump this deoxygenated blood supply to the lungs through the pulmonary arteries and then the cycle continues the this deoxygenated blood supply will be reoxygenated and then the cycle continues Etc ET Etc we can actually take blood out from the archery and measure the arterial blood gas arterial blood GL gas analysis is used to measure the ph and the partial pressure of oxygen and carbon dioxide in arterial blood it can tell us if our body is suffering from acidosis or alkalosis and whether it is a problem of respiration or kidneys for example so let's take a quick look look arterial blood gas can measure um can tell us if if if our blood is acidic or basic so normally the pH is between 7.35 and 7.45 in arterial blood um changes in these figures can can result in acidosis or alkalosis arterial blood gas can also tell us the partial pressure of oxygen which is normally 80 to 100 mm Mercury if it's below 80 this will tell us that um it's sinosis that we have sinosis a partial pressure the arterial blood gas can also tell us the partial pressure of carbon dioxide which is normally between 35 and 45 mm Mercury changes in these figures can indicate possible respiratory acidosis or alkalosis then you have this other ion called bicarbonate H CO3 minus which is normally um 22 to 26 M I think it's mil equivalent per liter it's just remember 22 to 26 and changes in these figures can indicate metabolic acidosis or alkalosis but obviously you have to use all these readings together to uh formulate a a a proper uh a proper a proper cause of of acidosis or alkalosis and just an important note to make the saturation of hemoglobin um of hemoglobin with oxygen in the arterial blood gas is about 98% so the hemoglobin is saturated in oxygen but we can also measure the Venus blood so the me mixed Venus blood so obviously the Venus the the Venus blood is going to be different to the arterial blood in the in the acidbase readings so in the Venus blood the normal PH range is between 7.38 to 7.43 so it's slightly more acidic I think and this is because we have more carbon dioxide the partial pressure of oxygen is between 35 to 40 mm Mercury and this is quite normal because we've used up Oxygen by the tissues the partial pressure of carbon dioxide in the Venus blood analysis is between 41 to 52 52 mm Mercury and this is normal as well because we have an increase in carbon dioxide and the bicarbonate levels is between 24 to 28 and this is because bicarbonate will try to neutralize the acidity thanks to due to the carbon dioxide and an important thing to note is the saturation of hog hemoglobin in Venus blood is uh is about 75% and this is because oxygen has been used up by the tissues again so just to quickly end it this Venus blood will then travel back to the heart where it will be pumped the lungs and then this blood will be reoxygenated the carbon dioxide will be exhaled out um and enter the atmosphere and the carbon dioxide will then be used by the plants and then the cycle continues so I hope you enjoyed this video on blood gases and an introduction to arterial blood gas analysis thank you for watching bye