hey guys welcome back to another tease review lesson today we are going to look at the respiratory system and you are expected to know the different parts of the system the function for each part some of the common problems associated with the respiratory system and also how the respiratory system and the circulatory system interact with one another the respiratory system is a system that supplies oxygen to the entire body right because it contains a bunch of tubes and the lungs so when you inhale you take in air which is rich in oxygen when and when you exhale you dispose of the carbon dioxide the the air that you exhale is rich in carbon dioxide now there are four processes in respiration you do not need to memorize these four processes i just want to list them there and kind of go over the steps with you so that you're familiar with how the respiratory system works the first step is a pulmonary ventilation this is basically breathing the second step is external respiration so this happens at the lungs and you can really think of as gas exchange at the lungs and we'll explain what exactly happens at the lungs during external respiration what's called external that's because your lungs are connected to the external environment right through the respiratory tract so that's external respiration next step the blood is going to transport the oxygen that the blood picks up at the lungs to the body right to deliver the oxygen to the cells and then pick up the carbon dioxide from the cells so that's the transport the last step is internal respiration and the internal respiration is again it's gas exchange but this time it happens at the tissues the blood brines in oxygen and the cells will pick up oxygen but the cell will also drop off carbon dioxide which is picked up by blood so after the internal respiration the good blood which is the oxygenated blood now becomes the bad blood deoxygenated very low in oxygen level there are quite a few structures in the respiratory system we're going to look at the upper respiratory system first and we'll just kind of really follow the pathway for air when you inhale so the air is going to go through nasal cavity first right so the nasal cavity is going to warm up moisture and filter air when you have nose hair in the nasal cavity you also have mucus so that can filter the air after the nasal cavity air will go through pharynx which is commonly known as the throat when you look at pharynx there are two subdivisions nasal pharynx oral pharynx and laryngologics i do not think you need to memorize all the three subsections just know that after the nasal cavity air is going to go through the pharynx which is the throat and the pharynx is shared by the respiratory system and the digestive system digestive system so food also goes through the pharynx now in the pharynx there are a few structures you can see uvula when you open your mouth really white you can see a little kind of structure hanging from the roof of your mouth right that's uvula now when you swallow uvula is going to kind of move up and it's going to block the pathway to your nasal cavity so you don't get food going into your nose the next structure is called epiglottis so epiglottis is over here when you swallow epiglottis it is going to come down and close the pathway to the trachea so you don't get food down your raspberry tract right down your wood pipe after firing's air is going to go through larynx which is the section over here so the larynx is known for speech it's got the voice box it generates speech now we're moving on to the lower respiratory system which which starts at the trichia so this is the trickier you can see there a lot of kind of ring-like structures which are made of cartilage so those are ring-like structures will prevent the trachea from collapsing so that here that keeps your airway open so the air can enter the lungs after trachea you're gonna have two bronchi bronchi so the singular is bronchus each bronchus will go into each lung right so this is going to be the right bronchus and will bring air to the right lung right now in the lungs you can see the bronchi are going to branch off to smaller tubes and they're called bronchioles bronchioles and eventually at the end you are going to have alveoli alveoli so alveoli are the primary sites for gas exchange and they look like clusters of grapes so basically they're just kind of air sacs and we'll talk about mvoi in a second the right lung has three lobes and is slightly bigger than the left lung and that's because the heart is slightly more to the left side right so that gives more space to the right lung and for both lungs they are surrounded by a double membrane structure called a pleura pleura so what happens is it looks like this let's say this is the long right and then you have let me use a different color let's say uh this is the plural but remember plural has two layers right so you can have oops you can have a one layer and then there's going to be another layer there is a very small space which is called the pleural space the pleural space has a fluid called pleural fluid so the pleural fluid really can provide a duplication so that when the lungs deflate and inflate it moves they move around right so the pleura fluid can reduce the friction it provides lubrication okay last structure alveoli alveoli like i said that's the main site for gas exchange and that's what they look like like clusters of grapes so these alveolar stacks are surrounded by capillary beds basically you know a bunch of very small blood vessels so what happens is the um over here so when you inhale you know the air is going to go through all those structures in raspberry tract and then trachea bronchioles and then alveoli right so you have a fresh air going into these air sacs and they are high in oxygen level and low in carbon dioxide levels right so i probably should use a different color but i'm going to use purple for blood vessels um and these alveoli are surrounded by kepler beds right so i'm just going to draw one uh capillary as an example okay so let's say this is a capillary okay all right and then the capillary you have a blood okay now remember the blood that goes into the lungs comes from the right ventricle the right ventricle and the blood is low in oxygen and high in carbon dioxide because because the blood has just completed the systemic circuit right so that's the bad blood so as the blood kind of flows kind of past the alveoli there's going to be diffusion so that's the movement of molecules from higher concentration area to low concentration area okay so the blood has low oxygen but high carbon dioxide so as a result let me use a different color oxygen molecules are going to move from high concentration to low concentration right so oxygen is going to move from alveoli to blood and then carbon dioxide is going to move the opposite direction right it's high in blood below in alveolar stacks so carbon dioxide is going to move out of blood into the alveol uh into the alveolar sacs and eventually the carbon dioxide will be exhaled out your body and so that's kind of the basic process for gas exchange happening at alveoli now alveoli these little this air sacs are bathed in surfactant so surfactant is really kind of a mixture of lipid and fat and the function is to prevent collapsing when you exhale um so the air stacks don't just collapse and you know which could present serious problems uh how does gas exchange work we mentioned that it's really kind of based on the principle of diffusion oxygen and carbon dioxide those molecules will move from high concentration to low concentration and again we talk about where is a high where is low right so let me just do that one more time if you already know this stuff you can skip it alveoli high in oxygen low in carbon dioxide and when you look at blood low in oxygen but high in carbon dioxide right so the oxygen is going to move into the blood so that's oxygen and the carbon dioxide is going to move out of blood into alveoli and then carbon dioxide is going to leave your body through exhalation all right now after the lungs after the gas exchange at the lungs now the blood is going to be changed from the bad blood to the good blood and the good blood is going to go back to the left atrium right and then it's going to get it's going to move into left ventricle and it's going to start the systemic circuit all right now the t study manual does mention some of the factors involved in diffusion so besides concentration gradient there are also some other factors that may influence the process such as surface area and the more surface area you have the more diffusion can take place the next factor is the distance where the molecules have to travel so if it's a shorter distance then that will facilitate the diffusion so it's easier for the molecules to travel