Part 1 Respiratory PDF

Part 1 respiratory The tubes that make up our respiratory passages are sometimes described as resembling a tree, the bronchial tree, the trachea serves as the trunk of the tree. So it is an upside down tree and the bronchi and bronchioles are similar to the branches of a tree. There is a sign...

Part 1 respiratory The tubes that make up our respiratory passages are sometimes described as resembling a tree, the bronchial tree, the trachea serves as the trunk of the tree. So it is an upside down tree and the bronchi and bronchioles are similar to the branches of a tree. There is a significant amount of anatomy in the respiratory system. We do divided it up into upper and lower respiratory system. This graphic doesn't match our author's breakpoint for the upper and lower. Generally, the larynx is included in the lower respiratory tract, so be aware of that. But this is still a nice image of the conduit or the conduction of the air through the body that ultimately reaches the small structures, the alveoli, where the diffusion of gasses occurs, the oxygen that the alveoli are picking up and the carbon dioxide that is being dropped off. The main function of the respiratory system is, of course, to remove the waste product, the carbon dioxide, and pick up oxygen to fuel our tissues, some of the other smaller functions are the regulation of blood pH. We'll see that through breathing, we can eliminate volatile acid, carbon dioxide. We know from our special senses that we have receptors for smell in our olfactory epithelium. The elimination of water - it's a little subtle, but if you you can feel the moisture on your hand. So there is a little bit of water that's eliminated with breathing. Filtration of the air. We have both coarse hairs and fine cilia that can trap debris and pathogens potentially. And also for the production of sound, there are resonance chambers in the skull and we also have our vocal cords in our larynx for sound. The process of respiration is not just breathing, but that is a big part of it. But there are three additional steps that are involved in the respiration process. The part that we consider breathing is called pulmonary ventilation, and it does include inspiration and expiration. You might remember that the diaphragm was our prime mover of breathing and inspiration. We also had our external intercostal muscles, those muscles that are between the ribs. We'll see how the contraction of those muscles changes the size of the thoracic cavity and therefore the pressure that's experienced there. The second step is external or sometimes called pulmonary respiration, and this is the exchange of the gases, it does occur in those very small alveoli. So those are little air sacs. That's the terminal end of the movement of the gases into our body. And you can see that it's due to a pressure difference. We're going to see there's a pressure gradient that is the driving force for the movement of the oxygen into our red blood cells so it can attach to the iron on the hemoglobin and then the carbon dioxide is going to move with its pressure gradient into the alveoli so that we can exhale that waste product. The third step is the transportation of those gases, and you might remember that we had the two circuits that allow for the movement of blood. We had our pulmonary circuit. So that is really moving the blood so that we can have that oxygen picked up and the carbon dioxide dropped off. But we also have our systemic circuit, which is where that newly re oxygenated blood is going to travel and be dumped off at the tissues. And tissue respiration is the next step, sometimes called internal respiration, because it's occurring in those more internal areas of the body. Just like we saw before, we do have a pressure gradient that's going to be the driving force. It's a gas pressure difference that is going to drive the oxygen into the tissues. This is our tissue here. And then the carbon dioxide is going to be moved into the blood. Some of it is carried by hemoglobin, but we'll see the majority of the carbon dioxide is carried in the plasma. That was an overview of the functions of the respiratory system. Now we're going to dig into the different divisions of the respiratory system. And there are anatomical divisions as well as physiological divisions. The anatomical divisions are, of course, structures. And as I mentioned before, we divided it up into upper and lower divisions. In fact, physicians usually specialize in one or the other. So you might have an ear, nose and throat doctor who specializes in the upper respiratory system. Or you might have a pulmonologist who specializes in the lower structures. Our upper respiratory subdivision is structural. And you can see a list of the structures that are included in this subdivision. The nostrils sometimes called the naris or nares, the nasal cavity that we explored a little bit when we looked at bones. Remember, the nasal septum. Pharynx is our technical term for the throat. The paranasal sinuses - we also looked at with the bones. Remember, those are pockets within the bone and we have a few other associated structures. The oral cavity is helpful if you are more of a mouth breather. The lower respiratory tract is generally agreed to start with the larynx, our voice box, and then it has that trachea, which was the trunk of the tree in our bronchial tree. The tubing branches into two main or primary bronchi, bronchus is the singular form of the word. And then we have bronchioles, the smaller tubes that are all within the lungs, and there are a few other associated structures. One important one here labeled the carina. We'll see that's within the trachea and very important to our cough reflex. Now we'll look at the functional subdivisions and we have two zones, one zone is the conducting zone. So think of that as the tubing that is moving the air or carrying the air to the other zone. It's also helpful in filtering, moistening. There are a lot of capillaries close by warming the air, also a role of the capillaries, especially on cold days. The end of this functional subdivision is the terminal bronchiole that you see here that feeds into the respiratory bronchioles, which we'll see are a part of the respiratory zone. And that's next. That is where the exchange of gases is occurring, so we have still small tubes, the bronchioles and then even smaller tubes. The alveolar ducts are feeding into a cluster of those alveoli, those small sacs. And you also see the pulmonary capillaries there because those are instrumental in providing for the exchange of gases. This dashed line here basically shows you where the respiratory zone starts. So everything prior to that would be the conducting zone ending with the terminal bronchioles. And here's that picture again now, it is actually labeled conducting zone and respiratory zone there. Nice visual of that. Oh, right. So the movement of the air does start with the nose and we are familiar with the bones that surround the nose and the nasal cavity. Technically the only bones that form the nose are the nasal bones forming the bridge of the nose. We also have a structure called the root, which is between the eyebrows. You might remember from biology 430 that the bulk of the nose is formed from hyaline cartilage. It is the most common cartilage in the body and we do have a little bit of dense, fibrous, connective tissue forming the flared ala of the nostrils, the nares. The nasal cavity is the first place that the air is entering. And so it is responsible for warming the air, filtering it. We've got some coarse hairs in there. Also at the roof of our nasal cavity is our olfactory epithelium for our sense of smell. And we also have the nasal cavity acting as a resonant chamber, providing for sounds. If we dig into the nasal cavity, we see that we have some conchae, those might sound familiar from when we looked at our ethmoid bone and our inferior nasal conchae. The most anterior portion in the nasal cavity is the nasal vestibule, which is right here. So a vestibule is a small room and it is before we get to those shelves, we've got some very coarse hairs there, sometimes called vibrissae that are often coated with mucus so that we can trap things. The nasal conchae should sound familiar. We had two on our ethmoid bone and then our inferior nasal concha is an individual bone all by itself. So the conchae are the shelves. And then just beneath that, we have the meatus. So this shows you the conchae as well as the meatuses. So just a little small groove that's formed just beneath. So each concha has a meatus and it is paired, we have this on both the right and the left side of the body. The nasal septum is our divider, dividing our nasal cavity into left and right halves, roughly equal unless you have a deviated septum, which might mean that one half is a little larger than the other. And we, of course, have hyaline cartilage there. Now, don't get confused by the fact that the vomer is blue there. And we know the vomer is made of bone. It's not hyaline cartilage, but the septal cartilage is hyaline cartilage. And then we also had our perpendicular plate of our ethmoid bone forming the rest of the nasal septum. The floor, you might remember, the floor of the nasal cavity is formed by the hard palate, which is formed by the palatine process of the maxilla and the palatine bone. That's also the roof of our oral cavity. So we can put our tongue up there and feel that hard palate. We also have this soft palate to remember, the uvula. It's the little part of the soft palate that sticks down. We'll see. That's very important to closing off the nasal cavity when we ingest food because we don't want food to go into the nasal cavity. There's the roof again, ethmoid bone. And remember, we had those olfactory foramina that the olfactory nerves could pass through for our sense of smell. And the bones that have sinuses, pockets within the bone are paired and you can see them listed. There are frontal bone, ethmoid bone, our sphenoid sinuses and our very large maxillary sinuses. If you suffer from sinusitis, it's an inflammation of the mucous membrane in there. Most often the maxillary and the frontal sinuses get that inflammation. Here's the type of epithelium in the nasal cavity, pseudostratified ciliated columnar epithelium with those gorgeous goblet cells that you see here for the mucus production and of course, the very fine cilia. Remember, it falsely looks stratified. It is not really stratified. I do use the abbreviation PSCCE for short just to make things a little bit faster to write. The exit point of the nasal cavity is the posterior nasal aperture, sometimes called the internal naris. You will see that used instead, but that is basically exiting into the first portion of the throat, which we call the nasopharynx. Here's a little bit of labeling for you. I didn't label all of the conchae. I just labeled the middle. It would be the same for the others. So you're welcome to do that as well. There's our external naris or simply naris, nostril and the nasal vestibule, as well as our posterior nasal aperture. This piece of art is nicely colored to show the different sections of the pharynx, the throat. We were just looking at the nasopharynx. But next in line would be the oropharynx, where air could exit the oral cavity. And then finally we have the laryngopharynx which sits right posterior to the larynx. Here's our voicebox here and it hooks up with the esophagus. So the throat is really for the passage of food as well as air. We're focusing on the movement of air, but it can be used for food as well. Perhaps some added new information is the tissue type, but since it's right behind the nasal cavity, it makes sense that it too would have the pseudostratified ciliated columnar epithelium. There are a couple important openings in our nasopharynx. One is for the pharyngotympanic tube. Remember, that is what travels to the middle ear, unfortunately, it can cause middle ear infections. But that is how we equalize the pressure in our middle ear when we are changing altitude. We also have our pharyngeal tonsil here called the adenoids when it's inflamed. The oropharynx is just behind the soft palate. We have our palatine tonsil in here. The tissue type changes. Notice that now we have nonkeratinized stratified squamous epithelium and remember, form follows function. So the tissue type here is going to be more subject to abrasion because food is going to travel from the oral cavity as well as air. And we need those layers to protect us. Just think of eating potato chips and if you don't chew, they might still be a little sharp. So we need those layers to protect us. The fauces is the name for the exit of the oral cavity and really the entrance into that oropharynx. There's the palatine tonsil. Remember, it does not hang from the uvula. There's one on either side of the uvula. So if you look at that in an anterior position, you can see those tonsils a little better. The most inferior or distal portion of the throat is the laryngopharynx, which is just beneath the oropharynx. It starts about the level of the hyoid bone, which is right here, and it basically feeds into the esophagus. So the esophagus is the rest of the tube that will carry food to the stomach. The tissue type is the same as we saw with our oropharynx. It's nonkeratinized stratified squamous epithelium because we still will have food and air passing through this part of the throat. The larynx is sometimes commonly known as the voice box because this is where our vocal cords, also called vocal folds, are located for the production of sounds and especially speech. There are a number of cartilages in here. The thyroid cartilage might sound familiar because recall we had our thyroid gland just beneath it. Sometimes the protruding portion of the cartilage is referred to as the Adam's apple. These cartilages are joined by membranes sometimes referred to as ligaments. So our hyoid bone and our thyroid cartilage connect via the thyrohyoid membrane in this region. We also have the epiglottis, our guardian of the airway, remember, that's composed of an elastic cartilage. It's one of the rarer types of cartilage when we swallow our larynx elevates. And this causes the epiglottis to flap over and protect our airway because food is traveling through the esophagus, just posterior to our voicebox. Here's a picture of the epiglottis, the thyroid membrane decomposes, and so we don't have that left in here, that's why it appears as an empty space. There's a little bit of it remaining, but it would fill in the gap there. This is a cadaver photo. The next piece of cartilage we have is the cricoid cartilage, which is sometimes confused with the tracheal cartilage. What's different about this is the cricoid cartilage is a full ring. It's not open at the back like the cartilage of the trachea are. You can't see that from this view here. But in a posterior view, you would be able to see that. Similarly, we have a ligament connecting the cricoid cartilage to the thyroid cartilage and it's nicely named cricothyroid ligament. Our cricoid cartilage is able to attach to this tracheal cartilages via the cricotracheal ligament. Now we're going to do a little labeling of our own. We have our epiglottis first. You would be able to see the epiglottis a little better in a posterior view, the hyoid bone, we know where that's located. And next step, we have the thyroid cartilage connected by the thyro- hyoid membrane right there. There is that prominence. The laryngeal prominence sometimes is called the Adam's apple, cricoid cartilage and the cricothyroid ligament connecting those two cartilages. And we have our tracheal cartilages and the ligament that attaches are single ring to our C shaped cartilages, which are the tracheal cartilages. We also have some cartilages that we can see posteriorly, so we have the arytenoid cartilage which is paired, there's one here and one here, and this is what attaches to our vocal cords, our vocal folds for the production of sound. There's also some muscles in there that will be responsible for tightening the vocal cords similar to guitar strings so that we can produce different pitches when we speak or sing. The corniculate cartilages are on top of the arytenoid cartilages. You can see one here and one here. It does mean horn-like so they sort of look like horns on top of the arytenoid cartilages. All of these are hyaline cartilage only the epiglottis is elastic cartilage. The cuneiform cartilages are embedded into the tissue. So it is sort of hard to see them. This is a sagittal section. There would be one on the left and the right and cuneiform literally means wedge shaped. So that is where they get their name. without the prior info. Back to tissue type. So we're still in the larynx and all of the tissues above the vocal folds are going to be nonkeratinized stratified squamous epithelium because there's still the potential for abrasion. But below the vocal folds, it's going to be pseudo stratified ciliated columnar epithelium. Need those fine hairs to move and help protect us. The vestibular folds are sometimes called the false vocal cords, and you see them here located more superior than the true vocal chords. They look very similar, but they're not able to produce sound. The glottis is really an opening, you see that here in the cadaver photo, it's a hole and the vocal folds are right here. Sometimes the glottis is referring to just the hole, as you see the leader line pointing to here. But technically, it does also include the tissue that forms that hole. I won't get that confusing with you guys, but that is how we use that term. Some authors use rima glottidis to describe the tissue and separate it from the hole, but we'll just keep them all together. Speech is produced by altering the tension of those vocal folds, and we do have intrinsic muscles that help with that, the movement of those vocal folds is also adjusting the size of the glottis, the opening that you see here. In general, if we pull them tighter, the vocal cords are going to vibrate faster and that is going to correspond to a higher pitch. Men have deeper voices for a couple different reason. Their vocal folds are thicker, so they have a harder time pulling them so tight so they can't produce those higher pitches. Also, the thicker thyroid cartilage deepens their voice as well. So that would be a lower pitch, would be a deeper voice. We do have some resonance chambers, those pockets within the bone are helping with the production of sound in the body. We are still passing through the conducting zone of the respiratory system from the larynx. Air moves into the trachea, which is sometimes called our windpipe. You are not responsible for memorizing the length or diameter. It's just to help you visualize this tube. And at the end of this tube, it branches into the bronchi and there are different types of bronchi, primary, secondary and tertiary. Our primary bronchi we call our main. There are only two one on the left and one on the right. We will see with tubes in the body there are some patterns that emerge for this tube. We have an epithelium which is very similar to what we saw with our blood vessels and this one is ciliated. Look at those little fine hairs that we know. That epithelium is going to be pseudostratified, ciliated columnar epithelium, and that's forming our mucosa, which is closest to the lumen. Then we have a submucosa just beneath. Then in this tube we have cartilage, hyaline cartilage that is C shaped. Notice it looks like a C, it's open in the back because we have the esophagus located posteriorly. The outer layer is called the adventia. Mucosa and epithelium, we're very familiar with it does have goblet cells. That mucus production is instrumental in trapping and keeping things from going into lower regions of the respiratory system, capillaries to continue to warm the air. Here is a photomicrograph of pseudostratified ciliated columnar epithelium. There's those nice cilia not stratified, but it appears to be the sub mucosa has areolar connective tissue, which we're familiar with as well, and some glands in there that continue to produce a mucous like secretion. There's that hyaline cartilage. What completes the ring is the trachealis muscle, some smooth muscle that is attaching to our trachea and just completing the ring for that tube. There's the hyaline cartilage. Remember, it's the one that is very weak, doesn't have many fibers, but still has the condrocytes. More areolar connective tissue in the adventitia. It helps the trachea to attach to surrounding tissues. There it is in all its glory at the distal portion of the trachea. We have a patch of mucosa that is especially sensitive to debris and it triggers our coughing reflex. So if something were to go down our windpipe or our trachea, such as food, we would be able to cough it up ideally and not have it move into those lower regions. And the structures that branch from the trachea are the bronchi left and right, they are a little bit different. So the right bronchus over here is a little more vertical and wider. The fact that it's more vertical makes it more likely that something might get lodged in here, whereas this one's more horizontal, easier to cough up. The next type of bronchi are sometimes called secondary, but we have shifted that to lobar, the lungs have lobes, the right lung has three lobes and the left lung has two lobes. So the number of lobar bronchi correlate to the number of lobes. And here you can see those lobes, three on the right, two on the left, the next type of bronchi are segmental because the lobes of the lungs are divided up into segments. In fact, if someone has lung cancer, sometimes it's possible to just remove a segment without having to remove an entire lobe. That was the end of the bronchi. The next part of the tubing are the bronchioles. The smaller microscopic tubes and the bronchi are getting smaller as we go from our primary secondary to tertiary. They're getting smaller as well so that they can feed into those very small bronchioles. The final branch of the bronchioles is referred to as the terminal bronchioles. And this is the last tube in the conducting zone. Those bronchioles will feed into the respiratory bronchioles, which are the first part of the respiratory zone. And here you can see a terminal bronchiole here feeding into the respiratory bronchioles. All right, the lobes of the lungs, the tissue in the bronchi is pseudostratified, ciliated columnar epithelium initially, but then it changes as we move into those smaller tubes, into the bronchioles, there are a few other changes that occur. The cartilage starts out similar to the trachea. But when you look at these smaller branches, the cartilage is more irregular. We don't need to worry about the airway collapsing once it's into the lungs. So it doesn't need to be as regular. When we move from the bronchi into the bronchioles, there's no cartilage at all. The epithelium is changing as well, so we start out with the pseudostratified ciliated columnar epithelium, we lose the cilia and it becomes simple columnar. And then when we get into those terminal bronchioles, you see one here, it would be simple cuboid. Now we don't have a cross section of that to see those cells, but we know that those look like little cubes. Another thing that changes is the amount of smooth muscle, so as we get into those bronchioles, we have more and more smooth muscle that gives us more control over the internal diameter of the tube. With contraction of that smooth muscle, we can constrict the airway or with dilation, we can open it up.