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22 The Respiratory System Respiration • function - supply body with O2 and dispose of CO2 • respiration - process of gas exchange between the atmosphere and cells throat voicebox windpipe *gas exchange a. pulmonary ventilation (breathing) - movement of air into and out of the lungs b. external respiration - gas exchange between the blood and air in lungs (O2 in, CO2 out) c. gas transport - blood carries O2 to tissue cells and picks up CO2 d. internal respiration - gas exchange between blood and body cells (O2 out, CO2 in) • also involved in the sense of smell and with speech *breathing external respiration - O2 into blood, CO2 into lungs gas transport - O2 and CO2 ride the blood bus pulmonary ventiliation internal respiration - O2 into cells, CO2 out of cells WHY DO OUR CELLS NEED OXYGEN?????? *O2 is the golden ticket into the mitochondria where we make ATP! 22 The Respiratory System Respiratory Tract upper • functional divisions respiratory tract a. respiratory zone - site of gas exchange includes bronchioles, alveolar ducts, alveoli b. conducting zone - allow air to reach respiratory zone includes nose, nasal cavity, paranasal sinuses, pharynx, larynx, trachea, bronchi, lungs lower respiratory tract • structural divisions a. upper tract includes nose, nasal cavity, paranasal sinuses, pharynx strep throat, colds, allergies, sinus infection b. lower tract includes larynx, trachea, bronchial tree, lungs pneumonia, laryngitis, bronchitis High Card Wins...Best 2 out of 3 *movement of air *gas exchange RIGHT Winner...What are the 4 processes of respiration? Nonwinner...What's happening at each step? external respiration internal respiration LEFT Right...Differentiate between upper and lower respiratory tracts. Left...Differentiate between conducting and respiratory zones. 22 The Respiratory System 1 ____ refers to the process of normal breathing. 2 ____ means gas exchange. A Ventilation A pulmonary ventilation B Respiration B internal respiration C Pulmonary C external respiration D Inspiration D cellular respiration 3 All of the following are part of the upper respiratory system EXCEPT 4 MATA: The respiratory zone A starts with the nose and mouth A nasal cavity B is where gas exchange occurs B pharynx C includes the bronchioles and alveoli C trachea D warms, moistens, and filters incoming air D nares Nose & Nasal Cavity • functions - produce mucus, filter, warm, and moisten incoming air, resonating chamber for speech, houses olfactory (smell) receptors • nose bone and cartilage support nose internally nostrils (nares) provide openings for air to pass hairs prevent entry of large particles • nasal cavity nasal septum divides cavity into right and left nasal conchae creates passageways, supports mucous membranes, increases surface area receptors for smell ***** 22 The Respiratory System Mucous Membranes • mucous - structure that secretes mucus • mucus - sticky substance • pseudostratified ciliated epithelium lining nose and nasal cavity • extensive network of blood vessels • air passing over membrane is heated to within 1 of body temperature (98.6 F) by blood vessels • air is moistened as water evaporates from membrane • sticky mucus traps dust and other small particles • cilia push a thin layer of mucus with entrapped particles toward pharynx (throat) Paranasal Sinuses • functions - same as nose and nasal cavity, lighten skull • air-filled spaces located within the maxilla, frontal, ethmoid, and sphenoid bones • open to nasal cavity • mucous membrane lines sinuses and are continuous with nasal cavity swallowed - stomach acid destroys microorganisms expectorated - spit or blown out • sensory nerve endings trigger a sneeze when they come in contact with an irritant *warm, moisten, filter!!! Pharynx ...Upper respiratory tract structure and function. • functions: passageway for food/liquid to esophagus and air to larynx • commonly referred to as the throat • passageway connecting nasal cavity to larynx and oral cavity to esophagus • three divisions: nasopharynx (behind nose), oropharynx (behind mouth), laryngopharynx/ hypopharynx (behind larynx) lower respiratory tract 5 The ____ is a passageway for both air and food/liquid. 6 MATA: The mucous membranes function to A warm incoming air A Nares B moisten incoming air B Nasal conchae C filter incoming air C Sinuses D deionize incoming air D Pharynx 22 The Respiratory System Larynx • functions - air passageway, prevents food from entering lower respiratory tract, voice production • commonly referred to as the voice box • composed of muscle and cartilage bound by elastic tissue Vocal Cords, Glottis, & Epiglottis • vocal cords housed in larynx false vocal cords - upper pair of folds within larynx produces NO sound, but help close airway during swallowing true vocal cords - lower pair of folds in larynx produces sound through vibration • glottis - triangular slit/opening in vocal cords muscles in false vocal cords close glottis when swallowing • epiglottis - flaplike structure that closes over larynx during swallowing to prevent food/liquid from entering airways Trachea • functions - air passageway, cleans, warms, and moistens incoming air • commonly referred to as the windpipe • flexible, cylindrical tube about 2 cm in diameter and 10-12 cm in length • extends downward in front of esophagus into thoracic cavity • splits into right and left bronchi • about 20 C-shaped pieces of hyaline cartilage keep trachea from collapsing • backside composed of smooth muscle and connective tissue to allow esophagus to expand when swallowing food Bronchial Tree • functions - air passageways connecting trachea with alveoli; cleans, warms and moistens incoming air • branched airways leading from the trachea to the microscopic air sacs (alveoli) of the lungs • cartilage line bronchial tree (like trachea), but as branching gets smaller smooth muscle becomes more prominent • primary bronchi secondary bronchi bronchioles alveolar ducts alveolar sacs alveoli • alveoli - simple squamous epithelial cells through which gases can easily be exchanged (diffusion) increase surface area of lungs (1/2 size of a tennis court) about 300 million 22 The Respiratory System *site of external respiration *segmental bronchi keep dividing into smaller and smaller tubes eventually called terminal bronchioles Lungs & Pleurae ...Lower respiratory soft, spongy, cone-shaped organs in thoracic cavity mediastinum - separates right and left lung diaphragm - muscle underneath lungs suspended by a bronchus and some large blood vessels • pleurae - membrane that surrounds each lung • • • • tract structure and function. serous fluid in between the membranes reduces friction while breathing • right lung is larger and divided into 3 lobes • left lung is smaller and divided into 2 lobes 7 MATA: Protective structures of the respiratory system include the 8 Gas exchange occurs in the A trachea glottis B bronchi B nasal conchae C bronchioles C epiglottis D alveoli D tracheal cartilage A 22 The Respiratory System Respiration Review Mechanics of Breathing Pulmonary Ventilation • respiration - process of gas exchange between the atmosphere and cells a. pulmonary ventilation (breathing) - movement of air into and out of the lungs • 2 phases inspiration - air flows into lungs (inhale) expiration - gases exit lungs (exhale) • nonrespiratory movements - voluntary or reflexive movement of air into and out of the lungs coughing, sneezing, laughing, crying, hiccups, and yawning WHAT INCREASES Pressure Relationships in the Thoracic Cavity • atmospheric pressure (Patm) - pressure exerted by the air surrounding the body Patm = 760 mm Hg at sea level negative respiratory pressure is lower than 760 mm Hg positive respiratory pressure is higher than 760 mm Hg • intrapulmonary pressure (Ppul) - pressure in alveoli rises and falls with phases of breathing • intrapleural pressure (Pip) - pressure in pleural cavity rises and falls with phases of breathing ALWAYS negative (about -4 mm Hg) relative to Ppul • transpulmonary pressure - difference between intrapulmonary and intrapleural pressures (Ppul - Pip) partial vaccum keeps lungs from collapsing INTRAPULMONARY PRESSURE? fluid, air, or tumor X-ray of collapsed lung What's this? CYST CT scan Boyle's Law at constant temperature... PV = P V 1 1 where, P = pressure of a gas V = volume 1 = initial conditions 2 = resulting conditions • pressure of a gas varies inversely with its volume 2 2 Inspiration • normal inhale = quiet inspiration moves about 500 mL of air into lungs • inspiratory muscles increase intrapulmonary volume diaphragm - contracts and flattens external intercostal muscles - elevate ribs and sternum • as volume increases, Ppul decreases about 1 mm Hg relative to Patm • anytime Ppul is less than Patm air rushes into the lungs until the two are equal • Pip decreases to -6 mm Hg relative to Patm • deep or forced inspiration = accessory muscles increase volume further 22 The Respiratory System Sequence of Events - Inspiration 1. inspiratory muscles (diaphragm and external intercostals) contract 2. thoracic cavity volume increases 3. intrapulmonary pressure drops (-1 mm Hg) 4. air flows into lungs Sequence of Events - Expiration 1. inspiratory muscles relax 2. thoracic cavity volume decreases 3. intrapulmonary pressure rises (1 mm Hg) 4. air rushes out of lungs Expiration • normal exhale = quiet expiration • passive process dependent on elastic recoil of lung and thoracic wall tissue • when inspiratory muscles relax, lungs return to original/resting state • volume decreases, Ppul increases about 1 mm Hg above Patm • anytime Ppul is greater than Patm air is forced out of the lungs until the two are equal • forced expiration (deep exhale) is an active process that relies on contraction of the abdominal wall (pushes diaphragm higher into lungs) and internal intercostals (pull rib and sternum down and in) to further decrease lung volume Best 2 out of 3 ICH Pull OES THE WORK? NONWINNER...Review the process of inspiration. WINNER...Review the process of expiration. 22 The Respiratory System 1 MATA: Inspiration occurs when A the diaphragm relaxes B the thoracic cage expands C when intrapulmonary pressure is less than atmospheric pressure D air enters lungs 3 MATA: Pressure in the lungs increases A during expiration B when lung volume decreases C when the diaphragm relaxes D forcing air out 2 Intrapleural pressure should always be negative (less than atmospheric) to prevent the lungs from collapsing. True False Introduction to Lung Volumes normal breathing always there (reserve) WHAT HAPPENS WHEN YOU GET THE deep inhale WIND KNOCKED OUT OF YOU? Hmm... normal breathing deep exhale Pull always there (reserve) 22 The Respiratory System Respiratory Capacities • specific combinations of respiratory volumes • inspiratory capacity (IC) = 2400-3600 mL maximum amount of air that can be inspired after a normal expiration IC = TV + IRV • functional residual capacity (FRC) = 1800-2400 mL volume of air remaining in the lungs after a normal tidal volume expiration FRC = ERV + RV • vital capacity (VC) = 3100-4800 mL maximum amount of air that can be expired after a maximum inspiratory effort VC = TV + IRV + ERV • total lung capacity (TLC) = 4200-6000 mL maximum amount of air contained in the lungs TLC = TV + IRV + ERV + RV Respiratory Volumes • different intensities of breathing move different volumes of air into and our of the lungs (respiratory volumes) • normal inspiration = about 500 mL • normal expiration = about 500 mL • tidal volume (TV) = 500 mL amount of air that moves into and out of the lungs during quiet breathing • inspiratory reserve volume (IRV) = 1900-3100 mL amount of air that can be forcibly inhaled after normal tidal volume • expiratory reserve volume (ERV) = 700- 1200 mL amount of air that can be forcefully exhaled after a normal tidal volume exhalation • residual volume (RV) = 1100-1200 mL amount of air remaining in the lungs after a forced exhalation TALLER...Review the important lung volumes. SHORTER...What is VC and TLC? 4 ____ refers to the amount of air moving in and out during quiet breathing. 5 The amount of air that remains in our lungs after our biggest exhale is called A Tidal volume A expiratory reserve volume B Total lung capcity B total lung volume C Inspiratory reserve volume C minimal lung volume D Vital capacity D residual lung volume 22 The Respiratory System Factors Influencing Ventilation • airway resistance F = gas flow P = pressure R = resistance WHY DOES KNOWING THESE VOLUMES MATTER? Gas Exchange & Transport F= • alveolar surface tension P R surfactant - mixture of lipids and proteins that reduces the surface tension of water and prevents alveoli from collapsing • lung compliance - lung stretchy-ness determined by distensibility of lung tissue and alveolar surface tension diminished by decreases in lung elasticity (inflammation or infection) and decreases in surfactant Respiration Review • respiration - process of gas exchange between the atmosphere and cells a. pulmonary ventilation (breathing) - movement of air into and out of the lungs b. external respiration - gas exchange between the blood and air in lungs (O2 in, CO2 out) - DIFFUSION c. gas transport - blood carries O2 to tissue cells and picks up CO2 d. internal respiration - gas exchange between blood and body cells (O2 out, CO2 in) - DIFFUSION Two More Gas Laws Dalton's Law of Partial Pressures Dalton's Law of Partial Pressures LEFT... • the total pressure exerted by a mixture of gases is the sum of the pressures exerted independently by each gas in the mixture • partial pressure (pressure of each gas) is directly proportional to the percentage of that gas in the gas mixture • ex. atmosphere is 21% oxygen 0.21 x 760 mm Hg = 159 mm Hg PO2 = 159 mm Hg Henry's Law • the direction and amount of movement of a gas is determined by its partial pressure in the two phases (gas and dissolved in liquid) • gases move from higher partial pressure to lower partial pressure until they reach equilibrium • also affected by solubility of the gas and temperature of the liquid CO2 is more soluble than O2, so it dissolves more readily in water (ex. blood plasma) What is Dalton's Law? Henry's Law RIGHT.. What is Henry's Law? 22 The Respiratory System 1 ____ law states that gases diffuse from areas of higher partial pressure to areas of lower partial pressure. A Dalton's B Bohr's C Henry's D Boyle's Composition of Alveolar Gas ATMOSPHERE N2 - 78.6% and 597 mm Hg O2 - 20.9% and 159 mm Hg CO2 - 0.04% and 0.3 mm Hg H2O - 0.46% and 3.7 mm Hg ALVEOLI N2 - 74.9% and 569 mm Hg O2 - 13.7% and 104 mm Hg CO2 - 5.2% and 40 mm Hg H2O - 6.2% and 47 mm Hg Why the difference? 1. gas exchange occurring in lungs 2. humidification of air by conducting zone 3. mixing of alveolar gas during each breath External Respiration Partial Pressures • O2 loaded into blood, CO2 unload into alveoli • partial pressure gradients and gas solubilities driving force of diffusion across respiratory membrane gases diffuse from regions of higher partial pressure to regions of lower partial pressure (Henry's Law) *refer to picture on following slide • ventilation-perfusion coupling ventilation = gas reaching alveoli perfusion = blood flow in pulmonary capillaries high ventilation = high perfusion (and vice versa) ensures efficient gas exchange • thickness and surface area of respiratory membrane 2 epithelial cells (1 lining alveolus & 1 lining capillary) & a fused basement membrane a thin respiratory membrane increases gas exchange efficiency Ventilation-Perfusion Coupling mismatch (inefficient) stimulus restored response efficiency NOSE GOES 22 The Respiratory System Winner...Explain Henry's Law in relation to external respiration. 2 MATA: PO2 is ___ in the lungs and ___ in the blood. Nonwinner...How does the structure of the respiratory membrane support its function? 3 Which structure increases the efficiency of external respiration? A ciliated pseudostratified epithelium B capillary minivalves C respiratory membrane D alveolar surfactant A higher, lower B lower, higher O2 Transport • b/c O2 is poorly soluble in water, blood plasma only carries about 1.5% of O2 to cells • 98.5% of O2 is chemically combined with lungs hemoglobin (Hb) HHb + O2 HbO2 + H oxyhemoglobin - HbO2 tissues deoxyhemoglobin (reduced) - HHb loading/unloading equation • rate at which Hb reversibly binds or releases O2 depends on... PO2 temperature = Hb affinity for O2 blood pH = Hb affinity for O2 PCO2 BGP (2,3-bisphosphoglycerate) concentration *created during anaerobic respiration in RBCs Oxyhemoglobin Dissociation Curve 25% to tissues; Hb unloads more O2 75% stays HbO2 after 1 at rest trip 50% more to tissues; through 25% stays HbO2 body (decreased affinity) additional O2 unloading to exercising tissue Hb unloads less O2 (increased affinity) exercising tissue PO2 at rest + 22 The Respiratory System TALLER...How is O2 transported in the blood? SHORTER...What factors affect O2 unloading? 4 MATA: O2 is transported 5 Which of the following does NOT affect Hb's affinity for O2? A HHb B BPG C temperature D PCO2 CO2 + H2O loading @ tissues H2CO3 unloading @ lungs H + HCO3 + - A attached to hemoglobin B in blood plasma C connected to platelets D from higher partial pressure to lower partial pressure Internal Respiration • O2 unloaded into cells, CO2 loaded into blood • accomplished by simple diffusion driven by the partial pressure gradients of O2 and CO2 CO Transport 2 • blood flowing through capillaries picks up CO2 from tissues with an elevated PCO2 • blood transports CO2 3 ways 7% dissolves in plasma 23% binds to "globin" = carbaminohemoglobin 70% forms bicarbonate ions (HCO3-) • in RBC, CO2 combines with H2O to form carbonic acid (H2CO3) • RBCs contain carbonic anhydrase (enzyme) which reversibly catalyzes these reactions • carbonic acid then dissociates releasing H+ and HCO3• HCO3- then diffuse back into plasma chloride shift - HCO3- exchanged for Cl- (balanced exchange of neg. ions) • when blood reaches lungs, CO2 diffuses into alveoli due to low PCO2 in alveolar air • at the same time HCO3- re-renter RBCs and the reaction reverses 22 The Respiratory System CO2 + H2O loading @ tissues H2CO3 H + HCO3 + unloading @ lungs - 6 How does MOST CO2 travel in the blood? THIS ONE IS TRICKIER...work together to explain how CO2 is transported in the blood. Neural Mechanisms • medullary respiratory centers (medulla oblongata) > dorsal respiratory group (DRG) - helps VRG; still figuring this one out > used to be called pneumotaxic area • generation of respiratory rhythm seems to be autorhythmic, but still figuring this one out too combined with hemoglobin B dissolved in plasma C attached to albumin D as bicarbonate ions Factors Influencing Breathing Rate & Depth 1. rising CO2 - MOST POWERFUL 2. PO2 drops substantially > ventral respiratory group (VRG) - generates basic rhythmic rate of 12-15 breaths per minute • pontine respiratory centers (pons) influence and modify activity of VRG A > causes chemoreceptors to become more sensitive to PCO2 > falls below 60 mm Hg reflexively increases ventilation 3. arterial pH drops (becomes more acidic, more H+) > could be rising CO2 levels or metabolic activities like increased lactic acid during exercise Other Controls of Respiration emotions, pain, cold/hot *voluntary control until CO2 reaches critical levels protective response to keep lungs from over stretching trigger coughing and sneezing 22 The Respiratory System ...How is our breathing regulated? 7 The most important regulator of breathing rate and depth is the concentration of oxygen. True False 8 MATA: Which of the following play a role in regulating our breathing? A irritants B CO2 levels C blood pH D stretch relfex E VRG and DRG F pons G emotions