If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Main content

What is an upper respiratory infection (URI)?

Created by Ryan Scott Patton.

Want to join the conversation?

  • blobby green style avatar for user Nazim Nazie
    How did you understand it is Strep A bacteria which is causing the problem and not any virus?
    (2 votes)
    Default Khan Academy avatar avatar for user
  • blobby green style avatar for user Upkar Malhi
    how to differentiate viral from bacterial infection?
    (2 votes)
    Default Khan Academy avatar avatar for user
  • aqualine ultimate style avatar for user AimeeYong
    How do we actually catch a virus? And can you 'create' (didn't catch it from anyone) one?
    (2 votes)
    Default Khan Academy avatar avatar for user
    • mr pink red style avatar for user delilah
      You can not "create" a virus however there are millions of them around you at all time and the most common way to get one is from another human. Viruses and bacteria spread in pretty much the same way. A colleague who's at work even though he has a cold, can spread an infection by coughing and sneezing on the environment, by greeting a hand full of contagious bacteria or viruses or by leaving behind microorganisms on the things he/she has touched. Some bacteria, however, can infect you through a so called "endogenous" source, meaning you can have it on your own skin and it only makes you sick if it gets access to mucuous areas where it is not supposed to be - then I guess you can say you "created" your own infection.
      (1 vote)
  • starky sapling style avatar for user P.Martinez
    Which one is more harmful, bacteria, virus or does it vary depending on the pathogen?
    (1 vote)
    Default Khan Academy avatar avatar for user
    • leaf green style avatar for user Joanne
      It depends on the pathogen. There are dangerous bacteria and dangerous viruses. Flesh eating bacteria, Strep. pyogenes for example, certain E. coli, antibiotic resistant microbes come to mind. Viruses such as Ebola, and Rabies are also deadly. Likewise, we have many benign or even helpful bacteria on our skin and GIT. Viruses may also be benign. As scientists examine our DNA, they realized there are many insertions of viral DNA that may not have an effect or the effect is not yet known.
      (2 votes)
  • orange juice squid orange style avatar for user .
    Why do all the names end with "itis"?
    (0 votes)
    Default Khan Academy avatar avatar for user

Video transcript

- [Voiceover] OK, so it's going to become more apparent, I'm sure, as you hear my voice in this video, but I do not feel well and I'll tell you, but particularly, I guess why I don't feel well. So this is me, I'm drawing, kind of, myself. I've got some red hair and I'm also going to draw in my throat and, kind of, my nasal passages. So, here's my throat, kind of carry mine down and it connects with my nasal passages and the back of my throat, so I've got those structures kind of drawn in here for you. And I'll tell you that part of the reason I don't feel well is because I have a really sore throat. It feels like, at times, fire to be honest right now. So, kind of right in back here, at the back of my throat, it's really sore. I'm also, probably you can tell by the sound of my voice and how nasal it is, I'm pretty congested, so kind of right up here in my nose, I'm pretty congested and believe it or not, right now as I'm making this video I have a fever. I have a 101.8 degree fever and that's in Fahrenheit, so that's actually about a 38.8 degrees Celsius fever. And the reason I have all of these terrible symptoms, excuse me, is because I have an upper respiratory infection. So let me write that in for us, "upper respiratory, respiratory infection, infection." Or sometimes this is shortened to URI, URI. And so, that's what I want to talk about. I want to talk about upper respiratory infection, so let's start by thinking about what an infection is. Well, an infection, let me get the right pen, is a disease causing agent, so an infection is a disease causing agent that's going to come in and it's going to invade our host tissue, so in me, my cells, it's going to invade those cells and it's going to cause a reaction. And in the case of upper respiratory infections, those disease causing agents are typically either going to be bacteria, so let me kind of draw some bacteria in here. I'll draw like the little chain cut out of bacteria, or viruses, so this would be a virus, this is kind of a classic little cartoon of a virus. So, these are the disease causing agents, so that's the infection part. What about the upper respiratory? Well, this is actually a pretty non-specific term here because there's a lot of parts of our upper respiratory tract, but let's just go through them, they kind of make intuitive sense, so our respiratory tract is the tract that we're going to breathe through, so let's think about where the air that's going to go, eventually down into our lungs here, where that air starts. So, it's going to start at our nose, we breathe in through our nose sometimes. And right here we have, excuse me, our nasal cavity and if that becomes infected by something, we have rhinitis. So, rhi, rhinitis, yeah right, kind of, up here and you might be able to remember this if you think of rhinoceroses, rhinos that have, excuse me, a big horn on their nose, so we've got rhinitis in our nasal cavity and then kind of where the back of our throat is, where your uvula, that little thing that hangs in the back of your throat. That area is called the pharynx, so if that becomes infected, in this area, we have pharyngitis, so phar, pharyngitis. And then, as we continue to go down, the respiratory tract, underneath the pharynx, we actually have a little flap that covers... That, sorry, protects the airway in the back coming in the bottom back of our throat, it protects our airway or our esophagus, respectively when we're either swallowing food or breathing in air and that little flap, kind of, in the bottom back of our throat is called our epiglottis. And if that becomes infected, we can get epiglottitis. So epiglottitis, and so, as we continue to go down beneath the epiglottis, we have an area called the larynx and that's where our vocal cords, our voice box sits, so if that becomes infected, we can get laryngitis, so laryngitis. And then, not typically talked about with the upper respiratory tract, usually that's kind of where we end the upper respiratory tract and start talking about the lower respiratory tract, but in a case of upper respiratory infection, sometimes included is the top part of the trachea, which is going to eventually kind of split off to the lungs. So, if that becomes infected, we can get tracheitis, so tracheitis. Right there, now you might have picked up, as I've gone down this list, that all of these end in -itis. So you see, rhinitis, pharyngitis, itis, itis, itis, itis, itis. Well, -itis is actually a suffix that's often used in a description of inflammation. When something becomes inflamed and that's what happening, that's what's causing some of these symptoms. As these little disease causing agents invade my cells, they cause damage and that causes a response like I told you in our body and that's the inflammation. So that's where all of these -itises are coming from. So most commonly, these disease causing agents are a virus. That's kind of the majority of upper respiratory infections. And of those viruses, which are already the majority, the majority of viruses are going to be rhinovirus. And that's so common that rhinovirus is also called the common cold. So when you think of the common cold and how crummy you feel, you have rhinovirus, probably. And you can imagine that with the same kind of root, that rhino root, that this virus loves to hang out in your nose and, kind of, your nasal cavity and cause a head cold. That would be the common cold. Another type of virus, though, that might cause an upper respiratory infection, a little bit less common, but still prevalent would be the influenza virus. We hear a lot about that, influenza. This is another virus that can cause an upper respiratory infection and then, aside from these, there are viruses like the coronavirus, corona, the adenovirus and really, there are more than 200 different viruses that can cause an upper respiratory infection and that's kind of the majority of the disease causing agents, but we also do have bacteria that can be the culprit. And probably the most common of those is streptococcus. I'm going to shorten that to strep. Streptococcus, it's a line of these little coccaceae, these spherical kind of ball-shaped bacteria and there are a few different forms of streptococcus. There's strep A, there's strep C, there's strep G that can all cause an infection in the upper respiratory tract, but probably the most common of these is strep A. And I'm particularly loathsome of strep A because that's what's currently causing my upper respiratory infection, so you can imagine probably a ton of these little strep A bugs hanging out in my body as I'm speaking to you. And I mentioned to you that my current upper respiratory infection is causing me some symptoms and, really you can think that these symptoms are a direct result of the infection and subsequent inflammation caused by these little bugs. So, some symptoms I mentioned some of the most common ones because I'm currently experiencing them, but you're going to have things like runny or stuffy nose. So runny or stuffy or congested, would be a little bit more appropriate word. So it's either, kind of, we've got some nasal leakage that would be, leakage, kind of that runny coming out of the nose, nasal leakage or some nasal congestion, that stuffy nose, but that's a pretty common symptom. What's happening with that is that your body, as part of that inflammatory response, is trying to clear these disease causing agents out of your body and so, that's going to produce more mucus to try to trap these things and then eventually expel them. And as this mucus accumulates, it can congest and cause that stuffy nose, but eventually it's going to kind of drain out and it's either going to cause, it's either going to leak down the back of your throat here, so let me kind of draw some mucus, mucus kind of traveling down he back of your throat, from your nasal cavity and irritating your throat even more or it's going to come, kind of, out of your nose. And that would be the runny side of the symptoms and you're also going to have like I said, that sore throat. So, sore throat and as these little agents invade these cells, they kill these cells. These bacteria will, you know, jump inside these cells and so will these viruses and they're destroy these cells. So it actually is hurting our body and that's part of that soreness that we're feeling. So we might have a sore throat. And another kind of big, hallmark sign of the inflammatory response to infection is a fever, a fever. And again, I really did just check my temperature and it was 101.8, so I'm not feeling super, super well. Now, if you had to guess how I came about this particular strep A infection, what might you guess as a reason? Why do you think I got strep A into my upper respiratory tract so that it could infect it? Well, I'll tell you that one thing I do and you do probably a whole lot is I touch, with my hand, my nose and my mouth. So all the time, I'm touching my nose. I don't ever pick my nose, I've never ever done that before, ever. But I do touch my nose and I touch my mouth frequently. All the time throughout the day. And I also a lot of other things. I touch doors, I touch objects around the room, I touch other people and I probably got a handy amount of these germs on my hand and put them right on the entrance to my upper respiratory tract. So I put them right on my nares, that's the nostrils, and right on my mouth, which opens into my oral cavity here. And so that's one of the most common ways that you can get these infections. Another way is, say I were to sneeze, maybe I were to sneeze or I were to cough. I'm expelling a lot now, of these kind of these infected little parts all throughout the air, so people that are around me, these particles might land on them. Land on their hands or land on their face and they might become infected. And so, these are kind of big ways that upper respiratory infections are transmitted. With hand-to-hand contact and kind of through the air. But, really both of these are really, really heavily preventable. So, with hand-to-hand contact, if I wash my hands a whole lot, so hand washing, hand washing. I can try to get some of these germs off my hands A: Before I touch my mouth and B: Before I touch other people, which is going to prevent a lot of this transmission. Also, when I do cough or when I do have to sneeze, I can be really polite and I can cover that, maybe with my shoulder. So, I'm going to cover, cough, excuse me, cough and sneeze. I'm going to try to prevent those particles from flying throughout the air and then lastly, some of these infections, like the influenza virus, there are actually vaccines against, so that's why we get flu shots and that can prevent me from getting it and also from, you know, potentially spreading it if I were to get it. But, to be honest, preventing these illnesses is not what I'm most worried about right now because I already have my upper respiratory infection. Now, I'm worried about treatment, how do I feel better? So, let me write "treatment" down for us. And I'll tell you that really, with a lot of these, since, again, the majority are caused by viruses, there isn't a specific treatment to kill these viruses. We kind of have to let our body's immune system identify and start to kind of attack back against these and we kind of have to wait it out. So, a lot of the treatment is going to be really supportive. One of the things we can do is we can hydrate, we can drink lots of clear fluids like water. Hydrate and hydration is going to do two things for us. One, it's going to replete, it's going to replace a lot of the fluids that we've probably lost. One of the things that our body is trying to do is it's trying to get rid of these infections, so we might be trying to urinate more just so we can eliminate as much of these infections as possible. So, I'm going to replace some of the fluids that I've already lost. Hydrating also is going to help me thin some of this mucus that's produced in order to kind of trap and expel the bacteria, which is going to change the stuffy nose into more of a runny nose. I can also kind of try to relieve the symptoms, so with treatment I'm going to put in symptom relief. So I can do things like suck on a lozenge that might have a little bit of menthol in it or something that's going to make my throat feel better. I might use an over-the-counter nasal decongestant. So, I've got a congested nose and I might decongest it to allow some of that mucus to flow out. If I had a fever like I do right now and I actually did this symptom relief, I took some Tylenol. You can get over-the-counter Tylenol or ibuprofen. Something that has some antipyretic that's really, I'll write that up here, antipyretic. That's kind of a fancy word for fever buster, antipyretic. So a medicine that has an antipyretic quality to it like Tylenol or Oran or ibuprofen and I'm going to try to get a lot of rest. I'm going to get a lot of rest because I don't want my body to have to expend any more energy than it has to on peripheral things like running around the block or lifting a bunch of weights so that it can divert that energy into fighting off this infection with me. Now, that's for these viral infections that there's not a real cure for. For bacterial infections, we can use antibiotics and again, these aren't very common upper respiratory infections. The majority of these upper respiratory infections are caused by viruses, so antibiotics aren't going to do anything for those. But if it caused by bacteria like strep A, we can use some antibiotics, which our doctor will give us when we go see him.