Respiratory Histology - Pharynx, Larynx, Trachea, Bronchi, Bronchioles, Alveoli

hey guys it's medicos is perfection Ellis continuing our discussion about pulmonology this is the fourth video in this amazing playlist we have talked about anatomy in the previous two videos and then in the third video it was the fair cows note today we'll talk about respiratory histology is gonna be easy but we'll take it to the next level and make it clinically oriented and high yield and all of this fun stuff with that being said now let's get started [Music] now let me answer case three in case four from the second video CEO went to

visit the CFO in his house discuss the latest shady accounting practices that were published in the national newspaper this morning after a heated discussion and lots of cursing the CFO grabbed a four and a half inch kitchen knife it's a little kind of a long knife stabs you in the chest a knife passed just to the left of the sternum and pierced the chief chief executives chest add the left fourth intercostal space along the left sternal border the economy Lee regrets it la blah blah and then only few drops of blood came out called 9-1-1

the ambulance took the executive on the way to the hospital he did not he did not complain of shorts of breath and that's a very important clue and the trachea was central he arrived the ER and suddenly he was short of breath semi-conscious and in shock two minutes later he gasped for air became unconscious and died was the most likely cause of death now please pause and the answer here is cardiac tamponade oh why not pulmonary contusion all right so this is a surface anatomy question so here is your sternum all right crazy sternum forgive

me all right and this is a void process and then the ribs alright until we go to this fourth left intercostal space so here's here's this is the second rib so this is one two three and four along the sternal border now according to surface anatomy the pleura that pleura goes like this right but the lung goes like this there is a cardiac notch ooh so it didn't touch the lung yes it touched the pleura but it didn't touch along so why not tension pneumothorax since it has touched the pleura two reasons first the trachea

was central and the second he did not complain of shorts of breath and this is not tension pneumothorax its cardiac tamponade all right let me tell you the story he was stabbed by the knife and the knife was at the left fourth intercostal space okay fine this is how the knife went the knife went inside the chest in the fourth intercostal space through the right ventricle because it makes the the most of the anterior surface of the wall then the left ventricle and the aorta vestibule just below the aortic orifice so here is the otter

just below the orifice so this will lead to what massive bleeding it will accumulate in what in the pericardial sac and then will increase an increase and increase and then it will start causing symptoms how it's tamponade right it blocks the venous drainage yes loss of CORDIC output yes because there's no input therefore there is no output and when you lose the cardiac output there is less blood going to the lung that's why he gasped for breath before death then he lost consciousness why because there is no cardiac output going to the brain next case

is for one and a half year old boy started choking he couldn't cough it out his mother tried the Heimlich maneuver to get this a foreign body outside and then the toddler seemed to improve and stop coughing which is excellent forty-five seconds later he started coughing again was gasping for breath so this is Disney she took him to the ER the doctor Esther did he swallow any foreign body she remembered that there were some penis which of the following is a possible complication of the peanut inhalation now pause and the answer is G both B

and F let's start with B obstructive 8 Alexis's of a segment in the right lower lobe because it doesn't tell us the position of the baby so it's probably upright when its upright as you know this right main bronchus is more vertical so the peanut is going to land in the right lung which part right lower lobe and this is called gravity baby the right upper will happen if the kid was laying down on his right side of the chest but the question didn't mention this so we have to assume he was upright because it's

most likely now f is the chemical bronchitis and the line because the peanut will land here in the segment and will will block a bronchial or a bronchus and then it will start like fragmenting and all of this chemicals will go causing irritation called chemical pneumonitis so the answer is both B and F obstructive 8 Alexis's and chemical bronchitis now why did the kid initially seem to improve and stop coughing because the peanut past the Kareena and the Kareena is the last part that has cuff reflux now let's talk about your normal lung what is

that main job of the lung if you say to get oxygen and you're stupid I'm sorry forgive the language the main job of the lung is to get carbon dioxide out well I thought that well like the lung was there to give me oxygen that's true but this is not the number one priority the number one priority is to get carbon dioxide out second priority to get carbon dioxide out third priority to get carbon dioxide out and then to get oxygen in I don't believe you okay let's say that you have a patient and initially

the oxygen saturation was 97 and it dropped all the way to 93 percent Oh big deal it's not fun it's not good but he's not gonna die okay on the other hand let's say that your pH was 7.4 which is normal and then it dropped to 6.5 you're what's known as dead it's just loosely wood yes but life is only possible within a very narrow range of pH change change the pH too much either up or down and you will die you are only compatible with life between 7 and 7.7 pH less than that you

die from acidosis more than that you die from alkalosis so carbon dioxide is very crucial but I don't understand why it's carbon dioxide related to acid because your lung is wet it has water co2 plus water equals carbonic acid h2co3 which will give us you know this remember this the acid the protons and then hco3 you remember the name of the I'm carbonic anhydrase okay cool so now I get it the main job of the lung is to get carbon dioxide out because this is how we regulate the acid-base balance yes if the lung retains

the co2 n it will lead to respiratory acidosis because co2 is considered an acid if the lung keeps pushing the co2 out more than normal wash out the co2 this is called hyperventilation you're losing the acid which is a state of respiratory alkalosis functions of the respiratory system this is so easy regulation of acid-base balance regulation of water balance defense against pathogens help venous return also known as respiratory pump because the negative intrathoracic pressure in the pleura is negative so it sucks blood up it pulls it up so let's say that you have the pressure

in the pleura is less negative it's not that good of a negative so let's say COPD cor pulmonale pulmonary hypertension or pepaw positive and expiratory pressure it will make the ends with rezar pressure less negative decrease venous return it will can lead to ankle a demon that's why patients with COPD can get ankle edema so your ankle is very low there and your lung is up there but they are related to each other welcome to internal medicine next you have activation of antigens one two engines into vocalization and olfaction without my respiratory system medicos is

perfection Ellis would have never existed let's talk about regulation of acid-base balance respiratory alkalosis or acidosis in case of respiratory acidosis what's the definition of acidosis low pH what's the definition of respiratory acidosis high pco2 because pco2 is considered an acid why high hco3 the lung is I'm sorry the kidney is trying to make you alkalotic in order to compensate for this respiratory acidosis respiratory alkalosis you'll see the opposite high pH why because high pH is the definition of alkalosis low pco2 why because pco2 is an acid when you have less acid it's a state

of alkalosis caused by the lung respiratory alkalosis the kidney will try to compensate by getting rid of the alkali because your alcoholic when you get rid of the alkalete you can improve and mitigate and ameliorate the alkalosis types of respiration external and internal external ventilation which means getting air into the lung perfusion which means getting blood towards the lung and then diffusion the oxygen going from here to here and the co2 going from the blood to the outside this is called gas exchange and then there is internal or cellular respiration and this is at the

level of the cell mitochondria and the electron transport chain we use oxygen to form ATP and you remember all of this electrons and protons popping and all of this crazy stuff most of you think that for me to have hypoxia the cause has to be related to the ventilation and perfusion which is not true you can cause toxicity to the cell and it can lead to hypoxia do you remember carbon monoxide poisoning cyanide poisoning I've talked about all of this in my hematology playlist and also have a playlist called emergency medicine we have discussed these

topics before so sallied are poisons can lead to hypoxia it doesn't have to be related to the lung upper versus lower respiratory tract so this is I don't care so conducting zone which is a dead space because there is no gas exchange and then respiratory zone conducting zone from the tip of the nose all the way to the terminal bronchioles so we have tip of the nose then you have the nasal pharynx then you have the larynx and then after the lines you have the trachea you have the two main stem bronchi after bronchi you

have bronchioles all the way to the terminal bronchioles but not the respiratory bronchioles respiratory zone from the respiratory bronchioles it's called respiratory zone so it's sort with the respiratory bronchioles all the way to the alcohol so respiratory bronchioles and then they have the alveolar duct of their second alveoli and all of this fun stuff so conducting zone terminates with the terminal bronchioles respiratory zone starts with that respiratory bronchioles Carthage and goblin cell if your name is bronchus you have Carthage and goblet cell you have pseudostratified columnar epithelium with goblet cell the only sentence that I

still remember from my histology classes bronchioles no Carthage and no goblet cell if it has an O it's gotta be no respitory zone is busy with gas exchange it doesn't need Carthage or goblets of epithelium here we have the bronchi pseudo stratified ciliated columnar with goblet cells because they gonna secrete lots of mucus they need the cell to be columnar because squamous cell don't secrete anything there is no space and them to store the secretory granules but columnar can secrete lots of fun stuff and you need to secrete lots of mucus bronchioles up until the

terminal bronchioles which is the end of the conducting zone have pseudo stratified ciliated columnar and the respiratory zone respiratory bronchials you have cuboidal so cells start to get smaller why because we need gas exchange we need a bigger surface area in the alveoli and we need those cells that line the ly to be as small as possible and then as you see here the type one pneumo sites are actually squamous they are flat to allow for maximum space for gas exchange because these cells if they are big they will obstruct the gas exchange which is

bad however type two Nomo sites are cuboidal why because they will secrete they have secretory granules they will secrete the surfactant which is a great name because it means it's anti surface tension surface tension wants your lung to collapse surfactants keep your lung patent blood supply this is supplied by the bronchial circulation this is supplied by the pulmonary circulation that's why infarction tier lung is very unlikely if your lung is normal because you have two blood supply even if you tampered with this one this one is still working but if your lung is already screwed

and you occluded another vessel you can get an in fortune all right here is number one number two in fortune of the lung is it pale or is it red the answer is red it's a hemorrhagic infarction because if you block this one this gun can still bleed causing the tissue to be red called hemorrhagic or read in fortune next let's say that we have this Autry going to the lung and then we'll branch right and then the Autry will branch as you see here everything is a triangle so if you include this the unfortunate

like the shape of the triangle this is really important and if you have looked at like pathology samples like grow samples you will see the unfortunate alike a triangle beautifully I'm sorry it's not that beautiful because the patient already died no alveoli no gas exchange if you have alveoli of course you're gonna have gas exchange function wharves and humidifies mucus all right no mo sites we have type one no mo sites and type two new more sites type one has one function which is gas exchange therefore the shape is squamous because we would like to

give all of the space to gas exchange we don't like to obstruct the space or the interface type two animal sites has two functions regeneration it's a stem cell and surfactant production which is an anti surface tension that's why it's cubic oh it's not columnar because we need the space it's not squeamish because we're ins don't see quick anything it's kind of the in-between and has some granules those are the secretory granules because it's gonna secrete the surfactant defensive function the alveolar macrophages are also known as dust cells the milk owes the mucus escalator so

here is the shake s it works like an escalator pushes up pushes up beats it up mixed up until the foreign body goes out so it's an escalator this one will give it to the next one will give it to the next one will give it to the next one it's beautiful if you smoke cigarettes why would you do this with your life it's gonna damage this mucus escalator you'll have lots of stuff because the what's inhaled is gonna stay you're having trouble getting it out and it's horrible and it can lead to COPD you

know what we call it when you can't get the air out obstructive lung disease club cells or clara cells found in the bronchioles bronchial are exocrine cells they are dome-shaped with short micro villi so Clara cells the same as calypso if you're watching this video and your name is Clara and you happen to be a member of any club please let me know in the comment function we love Clara why because she secretes lots of fun stuff like cos Amina glycans as well as utero globin detoxifies harmful substance thanks to the cytochrome p450 and the

smooth endoplasmic reticulum it also acts as a stem cell multiplying and differentiating into ciliated cells to regenerate the bronchial or epithelium so the stem cell of the bronchi is Clara cell the stem cell of the alveoli is the type 2 Noma site this is really important to understand if you're struggling to memorize staph aureus streptococcus pneumoniae and Legionella and mycoplasma and all of this crazy stuff check out my friends website it's called pick monic the link in the description it's like an animated medical mnemonics it's amazing thank you for watching please subscribe and join the

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