RESPIRATORY SYSTEM

RESPIRATION * Pulmonary ventilation * Moving air into + out of the lungs * External respiration- DOES NOT MEAN EXPIRATION OR EXHALATION * Gas exchange between the lungs + the blood (the aveoli and the blood) * Gas Transport * O2 + CO2 between the lungs + tissues * Internal respiration- internally! DOES NOT MEAN INHALATION OR INSPIRATION * Gas exchange between systemic blood vessels + tissues * (Additional functions: Smell, Speech)
CONDUCTING VS. RESPIRATORY ZONES * Conducting: Passages for air to flow through (everything except those structures that involve gas exchange, no exchange across the wall, just moves air in and out) * Cleanse, humidify and warm the air as it moves through these passages * Respiratory: Gas exchange function
NASAL CAVITY * High blood supply * Warms air * Mucous membran * Moistens air * Immunity (mucus, lysozyme, antibodies) * Pseudostratified ciliated epithelium (it moves things, like dirty mucous and mucous traps things so that you can either swallow it or blow it out of your nose) * Moves contaminated mucus toward throat * Hair * Filter air * Olfactory receptors * Smell * Contributes to speech sounds
PHARYNX
* Funnel-shaped tube that connects to the: * Nasal cavity and mouth superiorly * Larynx and esophagus inferiorly * Food and/or air passageway * Divided into 3 regions * Nasopharynx (next to the nasal cavity, ONLY EXPOSED TO AIR) * Air only: Pseudostratified ciliated columnar epithelium * Auditory tube (connected to middle ear, also called the pharyngotympanic tube which allows equalization of pressure on the outside and inside of the ear) * Tonsils (pharyngeal) – lymphatic tissue, the location allows for exposure to pathogens * Oropharynx (next to the oral cavity, usually signed to the digestive tract, mouth) * EXPOSED TO BOTH FOOD AND AIR (food offers friction to the wall): Stratified squamous epithelium (this is important to help deal with the friction) * Tonsils (palantine, lingual) * Laryngopharynx (most inferior part, next to the larynx) * EXPOSED TO BOTH FOOD AND AIR (food offers friction to the wall): Stratified squamous epithelium (this is important to help friction) * To larynx (anterior), esophagus (posterior)
LARYNX
* Pseudostratified ciliated columnar epithelium (at the top of the larynx is the epiglottis) * Functions: * Conducting airway * Direct food to esophagus and air to lungs * Epiglottis – ELASTIC cartilage, when the food comes down we want to round it to the back tube so that the food does not go down the airway and if it does we will choke * Speech – vocal cords * Thyroid cartilage (Adam’s apple, more prominent in males) * Larger in males in response to testosterone hormone * Cricoid cartilage is the ONLY cartilage that goes the whole way around, the other cartilages just provide support, this cartilage is rigid so it can help regulate airflow in and out of it * Vocal Fold figure 22.5, they have a certain degree of tension in them so when air moves in and out of it, it can produce sound, LOCATED IN THE LARYNX
TRACHEA- has rings of cartilage (that are made up of HYALINE cartilage and they are more rigid), C shaped cartilages in the trachea because the cartilage does not go all the way around the trachea, WE HAVE 1 TRACHEA SO WE SPLIT THE TRACHEA TO GET AIR TO BOTH LUNGS * Larynx to top of lungs; branch into R/L bronchi * Pseudostratified ciliated columnar epithelium (because it becomes air only) * Walls - cartilagenous rings connected by fibroelastic CT + smooth muscle * Can stretch but doesn’t collapse * Provides support + flexibility * ESOPHAGUS: has stratified squamous epithelium because food goes down it which creates friction
BRONCHI
* R + L primary bronchi * 23 orders of branching (tubes get smaller and smaller, no gas exchange takes place) * Primary (the first branching) → Secondary (the branches that split off the primary brach) → Tertiary (the branches that split off the secondary), etc. * “Bronchial or Respiratory Tree” * Cartilage (hyaline) in walls - open airway * Pseudostratified ciliated columnar epithelium
BRONCHIOLES
* < 1 mm * Branch to terminal (conducting zone) and respiratory bronchioles (respiratory zone) * They get smaller as the branches move away from the trachea (figure 22.11) * THE LINING IS STILL PSEUDOSTRATIFIED CILIATED COLUMNAR EPITHELIUM, as they get smaller, the walls get smaller during branching, we start losing the cartilage and as a substitute for the cartilage we have more smooth muscle (contract and relax) * Helps us regulate air flow * THE LAST BRONCHIAL IS CALLED THE TERMINAL BRONCHIAL (this is the last conducting bronchial)
STRUCTURAL CHANGES THAT OCCUR WITH BRANCHING: * Decrease cartilage (none at level of bronchioles, by the time we get to the bronchioles there is no cartilage left) * Increase smooth muscle * Significance – can change diameter of tube * Epithelium * 1. Gets thinner * Pseudostratified ciliated columnar → Simple cuboidal * 2. No cilia (bronchiole level) * Debris removed by alveolar macrophages, since the cilia helped move the dirty mucous then we will decrease the production of mucous, BUT MACROPAHGES ENGULPH DEBRI * 3. No mucus (bronchiole level)
RESPIRATORY ZONE * Respiratory bronchioles → alveolar ducts → clusters of alveolar sacs composed of alveoli (300 million) * Alveoli (looks like grapes, they are little air sacs)(they need to be able to stretch and recoil when we breathe) * Simple squamous epithelium (thin basement membrane) * Surrounded by fine elastic fibers and capillaries * Exchange of gases – LARGE surface area!
RESPIRATORY MEMBRANE – the structures that are involved in gas exchange * Alveolar and capillary walls (SIMPLE SQUAMOUS EPITHELIUM because it is the smallest you can make and still be a lining) * THIN walls for easy exchange * Gases move from alveoli into blood (O2) and from blood into alveoli (CO2) * They do NOT need active transport to move them, they move from an area of high concentration to low concentration * Alveolar wall * Simple squamous epithelium w/thin basement membrane * Capillary wall * Simple squamous epithelium (Endothelium) w/thin basement membrane
ALVEOLI-the aveolar wall is thin and wet because it has water around it * Alveolar pores * Equalize pressure faster * Type I alveolar cells * Epithelial cells (they make up the walls) * Type II alveolar cells * Produce surfactant (SURFACTANT DECREASES SURFACE TENSION) * Coats alveolar surface to decrease surface tension + keep alveoli from collapsing * Alveolar macrophages
LUNGS
* Right - 3 lobes * Left – 2 lobes; Cardiac notch (the little indentation in the lung because the heart sits there, the left lung has to be smaller because the hearts in the way) * HILUM – area where blood vessels, lymphatic vessels, bronchi and nerves enter/leave lungs, entrance and exit for pulmonary arteries and veins * Air spaces with elastic connective tissue * Elasticity decreases the “work” of breathing * Surrounded by pleural cavity * Visceral pleura on the heart- lays right on top of the lungs * Parietal Pleura- lays on top of the visceral pleura and there is some fluid in between them so that they stick together and do the same actions (if one goes inward then the other goes in and vise versa), lines the thoracic cavity
PLEURAE- THE OUTWARD RECOIL IS STRONGER THAN THE INWARD RECOIL, this makes it so that our lungs will never fully collapse and our lungs will always be somewhat inflated * Visceral pleura (membrane on outside of lung) * Parietal pleura (lines wall of thoracic cavity) * Both produce serous fluid * Pleural cavity = space in between * Lubricated to decrease friction during expansion + recoil * Has water in between them * High surface tension in pleural fluid keeps the membranes from separating – opposes lung collapse * Pulls lungs outward toward thoracic wall * Produces a “negative” intrapleural pressure * Atmospheric pressure * 760 mm Hg (0 mm Hg reference) * If the pressure on the inside, middle and outside is all the same then the lung will collapse * Intrapulmonary pressure (IN BETWEEN) - pressure in alveoli * Increases and decreases during breathing * Always equalizes with atmospheric pressure * Intrapleural pressure – pressure in the pleural cavity * Increases and decreases during breathing * Always is 4 mm Hg LESS than intrapulmonary pressure * Outward pull on the lungs > Forces causing collapse****(therefore there is a negative intrapleural pressure
BLOOD SUPPLY TO LUNGS * Pulmonary Circulation: (it ONLY goes to the aveoli and capillaries) * Pulmonary arteries → pulmonary capillary networks surrounding alveoli * Pulmonary veins – carry oxygenated blood to LA * Systemic (Bronchial) Circulation: * Aorta (carries oxygen rich blood that just came from the lungs to the rest of the body) → Bronchial arteries (takes blood to all the different airways) – provide systemic blood to lung tissue (except alveoli) * Bronchial veins (oxygen poor blood) → pulmonary veins (oxygen rich blood)→ Left atrium (it is a little bit contaminated because now there is some oxygen poor blood in it)

AUTONOMIC INNERVATION OF AIRWAYS (IT INNERVATES GLANDS, HEART AND SMOOTH MUSCLE) * Parasympathetic (Vagus Nerve) (rest and digest) * Contracts smooth muscle in walls - constriction * Sympathetic (fight or flight) * Smooth muscle relaxation – dilation * You are in total survival mode and you want more air going into the lungs then you want DILATION***** * If they are both involved in innervating then one will increase and the other will decrease
BREATHING MECHANICS * 2 Phases of Breathing: * INSPIRATION – air flows into lungs (in order for air to go into our lungs, the pressure in our lungs must be lower than the pressure in the atmosphere) * EXPIRATION – gases exit lungs (in order for air to go out of the lungs, the pressure in the atmosphere must be lower than the pressure in the lungs * Air moves from an area of higher pressure to an area of lower pressure – requires creation of a pressure gradient * VOLUME AND PRESSURE CHANGE TOGETHER * Air will only flow from an area of high to low concentration * We use SKELETAL MUSCLE for breathing to change the volume of your container
PRESSURE/VOLUME RELATIONSHIP * BOYLE’S LAW – the relationship between the pressure and volume of gases (there is an inverse relationship between volume and pressure) * P1V1 = P2V2 * P = pressure of a gas (mm Hg) * V = volume of a gas (cubic millimeters, mm3) * 1 and 2 represent the initial + final conditions * Gases will fill their container * If VOLUME INCREASES, then PRESSURE DECREASES * Gas molecules exert less force against walls of the container because they are further apart * If VOLUME DECREASES, then PRESSURE INCREASES * Gas is compressed, more gas molecules in less space means greater force against walls of container * During inspiration * Lungs expand - ↑ volume, ↓ pressure * Pressure in lungs < atmospheric * Air flow IN * During expiration * Lungs recoil – ↓ volume, ↑ pressure * Pressure in lungs > atmospheric * Air flows OUT
MUSCULAR CONTROL OF BREATHING * INSPIRATION * ACTIVE PROCESS – muscle contraction required, WE ARE GOING TO BE CONTRACTING MUSCLES TO MAKE IT HAPPEN * *DIAPHRAGM CONTRACTION (makes the volume change, when this muscle contracts the diaphragm moves downward which allows the lungs to get bigger) * Lowered to enlarge thoracic cavity * EXTERNAL INTERCOSTAL muscles contraction (THIS WILL PULL THE RIBS UP AND OUT) * Pulls ribs up and out * Increase volume in thoracic cavity * Increase intrapulmonary volume and decrease intrapulmonary pressure * Air rushes in - lungs expand * EXPPIRATION * PASSIVE process - muscle relaxation * Diaphragm and external intercostals relax * Decrease volume in thoracic cavity * Decrease intrapulmonary volume and increase intrapulmonary pressure * Air flows out – lungs recoil * FORCED OR DEEP INSPIRATIONS more muscles contract to create a larger pressure gradient in either direction by contracting other skeletal muscles to help create a larger inspiration * ACTIVE process (we are contracting muscles to make this happen) to further increase lung volume * Additional skeletal muscles are required to contract * Scalenes * Sternocleidomastoid * Pectoralis minor * Erector spinae * FORCED EXPIRATIONS- relax everything and then in addition to that we will contract our abdominal muscles and our internal intercostals * ACTIVEprocess to further decrease lung volume * Additional skeletal muscles are required to contract * Internal intercostals (they pull the ribs down to the next one, making the ribs come in) * Abdominal muscles (mostly transverse abdominus + obliques) * Factors that influence blood flow are the same as those that influence air flow (RADIUS (this is the biggest factor), BLOOD VISCOSITY AND LENGTH) * Remember: BF = ∆P * R * Also: Air Flow = ∆P * R * ∆P = pressure gradient between atmosphere and alveoli * R = resistance to air flow through air tubes
AIRWAY RESISTANCE * Changing airway diameter alters resistance to air flow * During inspiration – bronchi + bronchioles expand w/thoracic expansion * ANS (AUTONOMIC NERVOUS SYSTEM)(the main way we can control the amount of air in our tubes) * Sympathetic – bronchodilation (↓ R to ↑ air flow) * Parasympathetic – bronchoconstriction (↑ R to ↓ air flow) * Hormones * Epinephrine (RELEASED FROM ADREANAL MEDULLA) – bronchodilation (MORE AIR CAN GO THROUGH) * Histamine (RELEASED DURING ASMATIC ATTACKS, HARD TO BREATHE)– bronchoconstriction (LESS AIR CAN GO THROUGH) * Mucus accumulation + other obstructive factors * Increase resistance
ALVEOLAR SURFACE TENSION * Surface tension – water molecules are more attracted to each other at water/air surface * Why? Hydrogen bonds between water molecules * Alveolar wall is very thin – easily collapsed * Solution = Surfactant (Type II alveolar cells) * (RDS in premature newborns – surfactant deficiency)
LUNG COMLIANCE * How easily lungs can be expanded * High = easy expansion; Low = resist expansion * Depends on: * Elasticity of lung tissue + thoracic cage (if we have trouble expanding our thoracic cavity then we will have trouble breathing)(there is some elasticity to muscle and if that is compromised then it can affect our lung movement) * Surface tension of alveoli (your lungs will not be able to expand and contract properly if surfactant is messed with)
ANATOMICAL DEAD SPACE- referring to all of those airways that we call the conducting zones (those airways that only move AIR), ANATOMICAL DEAD SPACE IS WHERE THERE IS ONLY AIR NO GAS (trachea, bronchi, bronchioles, etc.) * Volume of conducting respiratory passages (150 ml) * Air moves in and out * NO gas exchange * Total dead space may increase in conditions of alveolar collapse or obstruction * FIGURE 22.16 any upward line is inspiration and down is expiration, we get 500mL of air moving during a normal inspiration, the purple area is called inspiratory conserve (the additional you can breathe in after a normal breathe) and expiratory conserve problem (the additional amount of air you can expire after a normal exhalation) * VITAL CAPACITY the amount of air that YOU can breathe in and out (guys will have a larger vital capacity (VITAL CAPACITY IS ABOUT 5 LITERS)**** * TIDAL VOLUME IS 500 ML*** QUANTITATIVE MEASUREMENTS * Volumes, capacities * Forced expiratory volumes * MINUTE VENTILATION (faster than alveolar ventilation) * Total amount of gas moved into or out of respiratory tract per minute * ~ 6 L/min * 500 mL/breath x 12 breaths/min = 6000 mL/min * ALVEOLAR VENTILATION (the amount of air that gets to the alveoli per minute, it is a lot SLOWER the minute ventilation because the dead space can slow it down) * Table 22.2 * Deep, slow breathing is most effective***** BASIC PROPERTIES OF GASES * DALTON’S LAW * Each gas in a mixture acts independently of the others; move in direction dictated by their concentration gradient * Partial pressure (indicates how much gas is present) of each gas is proportional to concentration (says that we breathe in 3 main gases): * N2 – 79% * O2 – 21% * CO2 – 0.04% * HENRY’S LAW * Quantity of a gas that will dissolve in a liquid depends on: * Partial pressure * Solubility * CO2 > O2 > N2 * CO2 is 20x more soluble than O2 * N2 - nearly insoluble * Carbon dioxide is better than oxygen and oxygen is better than nitrogen! * FICK’S LAW * O2 + CO2 move across membrane via DIFFUSION (there is no active transport, go from high to low concentration) * 4 factors that affect gas exchange: * Solubility * Membrane thickness (our respiratory membrane is as thin as it can possible be) * Alveolar/capillary membrane = respiratory membrane - very thin! * Surface area – huge! * Partial pressure difference across membrane (concentration gradient) EXTERNAL RESPIRATION * Exchange of gases between blood (pulmonary capillaries) + alveoli * Gases move down concentration gradients: * Pulmonary capillaries (blood from tissues) * PO2 40 mm Hg * PCO2 45 mm Hg * Alveoli (air from atmosphere) * PO2 104 mm Hg * PCO2 40 mm Hg *