welcome to unit seven sorry about that respiratory system so we have now covered the digestive system the circulatory systems and now we will be moving on to the respiratory system so part one respiratory system structures the respiratory system is designed to allow oxygen to move from the air into the blood and for the carbon dioxide to move out of the blood into the air the respiratory system works with the circulatory system to accomplish the following external respiration this is the gas exchange between air and blood transportation of gases so tuned from the lungs and tissues as well as internal respiration gas exchange between blood and tissue fluid first let's see the anatomy it's always really important to know these structures that we're talking about so please head over to the handouts and biozome practice under our respiratory system and you'll see a handout like this please take the time to go through check out what the structures are if the answer key is also located there please pause the video at this point okay so pathway of air now that we're a bit more familiar with the anatomy of the respiratory system now we're going to be talking about these structures and their functions their physiology so the air is going to enter through the nose via the nostrils and this is going to lead to two nasal cavities the nasal cavities function to first filter air for the hair and mucus so 99 of this is done here it's going to moisten the air via the mucus and will also warm the air by the blood so it's highly vascularized so the warm moist air results in better gas exchange and we also have tear ducts cranial sinuses and ears that empty into our nasal cavities so these first three are all used to protect protect our delicate lungs we don't want anything foreign going into our lungs and we also want to be able to have the most efficient gas exchange as possible so we've seen the pharynx in our digestive system this is going to connect our nasal cavities to our larynx so remember our pharynx is the back of the throat which helps in our swallowing reflex however in the respiratory system it's going to connect our nasal cavity which is up here so here's our pharynx to our larynx here because this is going to be a respiratory system and instead of going down the esophagus which we saw in the digestive system it's going to be going into our trachea pasteur larynx so our tonsils form a protective ring and our larynx and trachea are normally open and the esophagus is normally closed our glottis is the opening to the larynx our larynx is our voice box how we're able to speak the larynx has two bands of elastic ligaments so these are called our vocal cords and these will vibrate as air goes over them which produces sound so if you're not able to take air in you're not going to be able to make any sounds and remember our epiglottis is the covering of our goddess to prevent food from going down the track yet we don't want any food going down the wrong tube as we say then from our larynx it goes into the trachea so the air is moving from the larynx or through the larynx into the trachea the trachea is commonly known as our windpipe and it's held open by cartilaginous rings which prevent it from collapsing so if you put your head back and you feel in your neck just be very very careful you don't want to be pushing in it will be very uncomfortable but if you just lightly touch your neck you're going to feel some rings so those rings are actually the cartilaginous rings of your trachea but please do not touch your throat too much because it is sensitive so your trachea is lined with cilia so those little tiny hairs on ourselves and mucous glands so this helps cleanse the respiratory system often if we have something down there we'll cough and coughing is actually help aiding our mucous and cilia to bring up those particles up through our larynx and glottis and then it will actually swallow it down through our esophagus so our trachea here is going to branch into two bronchi if we was talking about one by itself we'd call it a bronchus so bronchus is singular bronchi is plural so we have two of them and it goes into the right and left lungs both of these will also have cilia and both have cartilage rings to help keep them open so the air can flow through each bronchi branches into smaller branches called bronchioles and the walls get thinner and the diameter gets smaller so they're much smaller you can see them here the bronchioles so we have our trachea and our into our bronchis or a bronchi and there are bronchioles out here they're ciliated but they no longer have cartilaginous rings next we have our alveoli singular is alveolus and this is located at the end of each bronchiole and are clusters of tiny air sacs so our alveoli are surrounded by capillaries for oxygen and carbon dioxide exchange and there are a lot there's about 3 million alveoli per lung so we have a lot we want a lot and they are one cell thick for easy diffusion because you don't want to have our gases having to travel far away we want to be very efficient we have macrophages which is part of our immune system inside to help keep our alveoli clean they also have a film of lipoprotein so lipo stands for lipids protein so it's a lipid on a protein and this helps the elbow alveoli from sticking together like you can almost think of like the fats on them make it a little bit greasy so they don't stick together they also have stretch sensors which are in the walls of the alveoli they fire when the alveoli are full of air and send a signal to the brain to trigger exhalation so once there's nice full of air so you breathe in then we're able to feel oh we're full our stretch receptors are saying okay we're full now and it sends a signal to the brain to say now we can exhale and again this is all happening not in our conscious control so a large number gives a large surface area for gas exchange so here we can see the bronchiole coming in and branching into the alveoli so one of these is an alveolus and you can see that they're highly vascularized because we want our blood to go here to release our carbon dioxide and to gain all the oxygen for our body so our lung structure in the thoracic cavity is an airtight space surrounded by the ribcage which has intercostal muscles between them and a muscular floor which is the diaphragm separating it from the abdominal cavity so here we can see this is the thoracic cavity we have this really big muscle this is our diaphragm that goes all the way through us and that helps separate the thoracic cavity from the abdominal cavity and we're also going to see that in between our ribs we have intercostal muscles and this is going to help with inspiring and expiring the lungs are suspended in the thoracic cavity inside the rib cage and on top of the diaphragm and the rib cage is there to help protect our lungs because we don't want any damage happening to them the right lung has three lobes the left lung has two lobes so why do you think maybe the left lobe or the left lung only has two lobes what else do we find here there's a structure that's missing here and that's the reason why so you can see one lobe two lobe three lobes and then one lobe two lobes we have a structure here so each lung is enclosed in a double membrane sac which is called a pleural membrane outer membrane lines out the wall of the thoracic cavity and the inner membrane lines the lungs and these are going to function to protect the lungs and control the air pressure through the air tight seal and we're also going to have pleural fluid inside of that in order to not have any friction because when we breathing in and out we don't want to create any friction because friction causes heat so the space between the two layers is filled with the intrapleural fluid to reduce friction as i was just mentioning on the lungs and so it allows our lungs to slide the surface tension caused by the interpleural fluid keeps the lungs from collapsing so it's a bit like two pieces of glass stuck together with a film of water if you've ever tried to pull that apart you're not able to you'd have to slide them across same with plastic if you have two pieces of plastic with water between so lungs are made out of tubes so our bronchi and our bronchioles are alveoli and capillaries so next our ventilation how we actually bring air in and exhale as well so a quick note on surface tension and pressure surface tension is a tendency for water molecules to cling to each other due to hydrogen bonding remember from unit 1 in your first assignment and then pressure is the measurement of force exerted over a given area so all matter exerts pressure atmospheric pressure is the pressure exerted by the atmosphere and a partial pressure is the pressure exerted by gas in a solution so matter is pushed from areas of high pressure to low pressure remember that air is matter it is made up it has molecules in it so our ventilation which is also known as breathing this is including inspiration which is also known as inhalation so you can inspire or inhale and we also have expiration or exhalation both are accepted so you can expire or exhale remember there is a continuous column of air from the pharynx to the alveoli the thoracic cavity is sealed so the rib cage and intercostal muscles form the front and the sides the ribs connect to the sternum which is a bone in the front and the vertebrae which is your backbone in the back your diaphragm and connective tissue forms the floor your lungs adhere to the thoracic wall via the pleura so your pleural membranes very little space between the pleura due to the surface tension of the intrapleural fluid so this is what you're going to see as i always like to tell my students your body is your best way of kind of being your cheat sheet so when you inhale or inspire like in this first one we can see that our ribcage moves up and out so take a deep breath if you put your hand on your sternum just below your neck you can feel that your rib cage is going to move up and out okay so your chest moves up and you should be able to tell that from even inspiring yourself so our intercostal muscles are going to be contracting and our diaphragm contracts and actually moves down so it's creating a lot more volume inside of our thoracic cavity so that's going to be pulling the air in we're going to also see when expiring that our ribcage moves down and in so if you take a deep exhale you should feel your chest move down and in and that you're actually creating a smaller volume within your thoracic cavity so everything i just said i'm going to explain here again so our inspiration our inhalation is considered as our active phase and it should feel like that when you're taking a deep breath in it should feel like a bit more energy whereas when you are exhaling which is passive so inhaling requires atp your diaphragm and external intercostal muscles are going to contract it's the active stage so your muscles are contracting our thoracic cavity volume increases so the pressure in our cavity and our alveoli decrease pressure and volume are related so we're creating a bigger space so volume increases so the pressure is going to decrease pressure pressure is now higher outside the thoracic cavity so air is pushed into our lungs so by creating this bigger volume we're actually sucking air into our lungs which is pretty neat steps of inhalation first the respiratory center in the medulla oblongata remember medulla oblongata is a part of our brain and we'll be focusing on that in the nervous system more this is going to send a stimulatory message to our diaphragm and intercostal muscles so we do this without conscious control however we can control our breath as well so the diaphragm is going to contract so our diaphragm is this huge muscle below and it's going to flatten which means it's going to drop down relaxed it's actually in a dome shape so it's going to flatten which is moving down our intercostal muscles the muscles between our ribs are going to contract moving the rib cage out and up our lungs are going to expand so this is going to increase our lung volume which is increasing the space in our lungs the pressure in the lungs decrease which then air is sucked in and this is called negative pressure breathing because it's going from an area of high pressure to low pressure next we will look at exhalation this is the passive phase of respiration no atp energy isn't required the elastic nature of the lungs and the thoracic cavity is going to create a recoil so when we relax they're going to recoil back into their resting position the surface tension in the alveoli encourage closure and the diaphragm and external intercostal muscles relax the thoracic cavity volume decreases we're getting a smaller space so pressure inner cavity and alveoli increase pressure is now higher inside the thoracic cavity so air is pushed out of the lungs the steps of exhalation first the diaphragm relaxes and resumes dome position so this is the dome position here which is the relaxed state the intercostal muscles relax and the ribcage moves down and in our lungs will recoil which is going to have a lung volume decrease and the pressure in our lungs because of this will increase and the air is forced out some respiratory volume definitions so here you can see the respiratory volumes a tidal volume is the amount of air inhaled and exhaled in a normal breath so it's about 500 milliliters so half a liter so if you are just normally breathing that's going to be your tidal volume your vital capacity is the maximum volume of air inhaled and exhaled in forced breathing so if you were to try and force as much air as possible into your lungs and exhale the most it's going to be probably around 6 liters so you might be doing this if you have any kind of lung function worries that you have been having some problems breathing you might go to your doctor and you might go to a specialist and actually measure this your residual volume is the air remaining in lungs after exhaling as much air as possible so if you can try and get as much of the air out of your lungs as possible you will never be able to get it fully out we don't want that because we don't want our lungs sticking together we always have a little bit that's our residual volume that's remained and it's generally about a liter so control of our ventilation so our autonomic nervous system is responsible for controlling our breathing this includes the respiratory center in our medulla oblongata this also regulates our heart rate if you remember from the circulatory system so it's going to regulate our breathing rate as well via the nerve impulses that trigger the contraction of the intercostal muscles and diaphragm so our medulla oblongata is sending down messages saying okay contract contract contract and that is our active inhalation stage and then they'll rest for the exhalation phase some influences so for forced inhalation stretch receptors in our alveolar walls send inhibitory nerve impulses to the respiratory center so this is going to halt the generation of a nerve impulse so we're able to bypass that and you can think about that when you're not thinking about your breathing you will just be breathing as normal however you can have a forced inhalation and exhalation there are some chemical inputs about how fast we breathe so our blood concentration of carbon dioxide and the concentration of our hydrogen ion this is monitored by our respiratory centers or a medulla oblongata and if our carbon dioxide or our hydrogen ion concentrations increase our breathing increases and this is the main trigger actually about how we are ventilating is our carbon dioxide and our hydrogen ion that's the main one we also monitor our blood oxygen concentration this is monitored by chemoreceptor cells called the carotid and aortic bodies they're located in the carotid artery and the aorta so if oxygen concentration decreases too much the respiratory center is signaled so our medulla oblongata and again our breathing increases just keep remember or keep in mind that these square brackets represent the word concentration so this means concentration of carbon dioxide concentration of hydrogen ion internal and external respiration gas exchange in the body the respiratory tract is simply a conduit that allows the exchange of gases between the body's cells and the environment gas exchange happens in both the lungs and the tissues of the body so the forms of gas exchange and respiration that we will see are external respiration this occurs at the lungs internal respiration happens up the body tissues and cellular respiration which happens inside the cells internal and external respiration both processes are dependent on two factors partial pressure and hemoglobin hemoglobin is a globular protein found in red blood cells it contains four heme groups heme groups are ringed molecules with iron two ions at the center heme groups have an affinity for oxygen this means that they really like oxygen and they're going to want to bond with it there are four forms of hemoglobin which you will need to know the formula so the formulas are these on the left here as well as the full name be careful of your spelling hb capital h small b is deoxyhemoglobin hbo2 be careful that your b is small and that the two is subscript there might be times that you might not be able to input this but that's okay oxyhemoglobin hbco2 is carbaminohemoglobin and hhb is reduced hemoglobin the affinity of hemoglobin for oxygen varies with ph and temperature this can cause a slight denaturation of hemoglobin to occur to help hemoglobin accept or release oxygen so it's just enough to denature it to help accept or release it does not denature it to a point of where it loses function if the ph is high we're talking 7.4 and a low temperature of 37 degrees celsius then hemoglobin takes up oxygen this occurs at the lungs for our external respiration if the ph is low 7.3 and the temperature is high around 38 degrees celsius then the hemoglobin releases oxygen and this occurs at the tissues gas is exchanged between first the lung alveoli and the pulmonary capillaries this is our external respiration the blood plasma and the tissue fluid so this is our capillary tissue fluid exchange and this is our internal respiration we saw a little bit of this in our circulatory systems alveoli and capillaries are both one cell thick making the diffusion of oxygen and carbon dioxide possible sternum respiration this occurs at the lungs oxygen diffuses into the pulmonary capillaries and carbon dioxide diffuses into the alveoli to be exhaled out of the body carbomino hemoglobin hbco2 just to show it states into carbon dioxide and deoxyhemoglobin here's the formula below here we can see carbo amino hemoglobin is disassociating or turning into deoxyhemoglobin as well as carbon dioxide so this is occurring at the lungs make sure to keep track of what's happening at the lungs what's happening at tissues and what's happening within the cell most of carbon dioxide in the blood is carried as bicarbonate ions in the lungs carbon dioxide is formed from carbonic acid and diffuses out of the blood extra bicarbonate ion keeps the blood at ph at 7.4 by absorbing extra hydrogen ions so we're going to see that carbon dioxide is transported to the lungs in three different ways one way is going as the carbon amino hemoglobin as we saw in the previous slide most of it goes with the bicarbonate ion so it's important to see this formula here we can see that our bicarbonate ion is going to form with a hydrogen ion to form our carbonic acid which is then going to with the help of carbonic anhydrase an enzyme create water and carbon dioxide so this is occurring at the lungs we're going to see the opposite reaction happening at the tissues reduced hemoglobin hhb disassociates at the alveoli into hydrogen ion and deoxyhemoglobin so hhb is going to turn into the hydrogen ion plus a deoxyhemoglobin the hydrogen ions increase in concentration which lowers the ph of blood and helps trigger inhalation so as it gets more acidic it's going to trigger inhalation and the hydrogen ions from this reaction is going to go and form with our bicarbonate ion in order to release the carbon dioxide at the lungs in the alveoli the conditions are right for deoxyhemoglobin in the red blood cells to grab hold of four oxygen molecules so this is at 37 degrees and a ph of 7.4 which is going to form oxyhemoglobin hbo2 oxygen can now be taken to the tissues where internal respiration will occur so be here we have our deoxyhemoglobin plus oxygen gives oxyhemoglobin which occurs at the lungs now we will move to internal respiration the tissues the reason for breathing so cells get oxygen for cellular respiration this is the production of atp our body's energy source so remember that our cellular respiration which is down below is glucose which is c6h12o6 plus oxygen which is o6 or o2 gives carbon dioxide co2 plus water h2o plus atp at the tissues the blood is warmer about 38 degrees celsius and has a slightly lower ph of 7.3 due to cell metabolism the difference in temperature and ph causes the hemoglobin to denature just a little bit this causes hemoglobin to release the oxygen from oxyhemoglobin to the tissue fluid the capillary tissue fluid exchange is where it's happening so we have oxyhemoglobin turning into deoxyhemoglobin plus oxygen so we're releasing our oxygen to our tissues from our capillaries into our extracellular fluid the carbon dioxide produced by cellular respiration now diffuses into the blood so it's leaving the cells into the extracellular fluid and then it will diffuse into the blood some enters the red blood cells and some combines with deoxyhemoglobin forming carb amino hemoglobin so hb plus carbon dioxide equals carbon amino hemoglobin so remember that the hemoglobin is going to be transferring carbon dioxide and some hydrogen ions from the tissues up to the lungs whereas from the lungs down to the tissue hemoglobin carries oxygen most of carbon dioxide combines with water forming carbonic acid which disassociates into hydrogen ion and bicarbonate ion so co2 plus h2o with the help of carbonic anhydrase and enzyme will form carbonic acid which will then disassociate into the hydrogen ion and a bicarbonate ion the bicarbonate ion is how most of the carbon dioxide will move up to the lungs carbonic anhydrides found in the red blood cells drives the reaction but this time is the opposite direction so we saw this exact formula but the arrows were pointing the opposite way at the lungs ions diffuse out of red blood cells and are carried in blood plasma where it buffers the blood against a drastic ph change you see you can see the carbonic acid can go back and forth between carbonic acid and the hydrogen ion and bicarbonate ion or it can go the opposite way that's why there's the double-headed arrow so it helps regulate from a drastic change in ph we also see that excess hydrogen ions can bond to hemoglobin to be transported as reduced hemoglobin hhb this buffers blood against ph change as well as the bicarbonate ion therefore carbon dioxide is transported in three ways first most of it as carbonic acid which is just dissociated into hydrogen ion and bicarbonate so most of it is actually transported as bicarbonate ion because the carbonic acid automatically dissociates into the bicarbonate ion so most of it is transported as bicarbonate ion some of it is done as carbon hemoglobin and a very little amount is transported as just dissolved carbon dioxide gas in the blood plasma so back to external respiration remember this is going to move all the way back up to the lungs so we're in the systemic circuit and then we'll do the pulmonary circuit blood arrives at the lungs capillaries where the temperature is again 37 degrees and the ph is 7.4 this is going to cause the hemoglobin to change shape just a little bit releasing the carbon dioxide from the carbo-amino hemoglobin so it can diffuse into the alveoli to be exhaled carbon dioxide is formed from carbonic acid and diffuses out of the blood in the alveoli to be exhaled and its dissolved carbon dioxide in blood plasma diffuses into the alveoli to be exiled reduced hemoglobin releases hydrogen ion to trigger inhalation hemoglobin is now free again to pick up oxygen forming oxyhemoglobin to be taken to the tissues for internal respiration and the cycle continues to reple repeat monoxide versus carbon dioxide carbon monoxide co is a dangerous gas that is colors and odorless and it can be found from gas appliances fireplaces wood stoves coal or oil furnaces space heaters charcoal grills camp stoves gas-powered lawn mowers and power tools car exhaust fumes smoking cigarettes and pollution here we can see the structure of carbon monoxide there's one carbon and one oxygen they are triple bonded together whereas carbon dioxide has two oxygen atoms bonded to one carbon atom and there's only two double bonds the effects of breathing carbon monoxide once inhaled carbon monoxide attaches to the hemoglobin which normally carries oxygen when it attaches it blocks the oxygen we need for creating problems now breathing low levels of carbon monoxide can cause headache nausea dizziness weakness and confusion disorientation so it blocks all the concentration we need this creates problems because if we're not able to bring the oxygen down to our tissues we're not able to continue to have cellular respiration so we're not creating any energy for our body breathing high levels of carbon monoxide can also cause sleepiness nausea anxiety or depression vomiting confusion impaired vision impaired coordination and it can also be fatal so please be careful and this brings us to the end of respiration thanks for listening and we'll see you next time in unit 8 our nervous system