Ch 22 Notes for BSC 216
Ch 22 Notes for BSC 216 10617
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This 14 page Class Notes was uploaded by Gretchen Pierce on Friday February 27, 2015. The Class Notes belongs to 10617 at University of Alabama - Tuscaloosa taught by Jason Pienaar in Spring2015. Since its upload, it has received 163 views.
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Date Created: 02/27/15
BSC 216 Chapter 22 Notes Respiratory System 1 Introduction a Breathing represents life i First breath of a newborn baby ii Last gasp of a dying person b All body processes directly or indirectly require ATP i ATP synthesis requires oxygen and produces carbon dioxide ii Drives the need to breath to take in oxygen and eliminate carbon dioxide 2 Functions of the respiratory system Provides 02 and C02 exchange between blood and air Serves for speech and other vocalizations Provides the sense of smell Affects pH of body fluids by eliminating C02 Affects blood pressure by synthesis of vasoconstrictor angiotensin 11 Breathing creates pressure gradients between thorax and abdomen that promote the flow of lymph and venous blood 9 Breathholding helps expel abdominal contents during urination defecation and childbirth Valsalva maneuver 3 Principal organs of the respiratory system nance a Nose b Pharynx c Larynx d Trachea e Bronchi f Lungs 4 Majo divisions of the respiratory system a Conducting division of the respiratory system i Those passages that serve only for airflow ii No gas exchange iii Nostrils through major bronchioles b Respiratory division of the respiratory system i Consists of alveoli and other gas exchange regions 5 General divisions of the respiratory system a These are more in line with medical practice ex upper respiratory infection but are not standard among fields i Upper respiratory tract in head and neck 1 Nose through larynx ii Lower respiratory tract organs of the thorax 1 Trachea through lungs 6 Pathway of airflow a Conducting division i Nasal cavity ii Pharynx iii Larynx iv Main bronchi Right and Left v Lobar secondary bronchi left vi Segmental tertiary bronchi right vii Bronchioles viii Terminal bronchioles b Respiratory division i Respiratory bronchioles ii Alveolar ducts iii Alveolar sacs 7 Nasal cavity 1 a Functions of the nose i Warms cleans and humidifies inhaled air ii Detects odors in the airstream iii Serves as a resonating chamber that amplifies the voice b Nose extends from nostrils nares to a pair of posterior openings called the posterior nasal apertures choanae c Nasal fossae right and left halves of the nasal cavity i Nasal septum divides the nasal cavity d Occupied by three folds of tissue nasal conchae i Superior middle and inferior nasal conchae turbinates 1 Meatus narrow air passage beneath each concha 2 Narrowness and turbulence ensure that most air contacts mucous membranes 3 Cleans warms and moistens the air e Olfactory epithelium detects odors i Covers a small area of the roof of the nasal fossa and adjacent parts of the septum and superior concha ii Ciliated pseudostratified columnar epithelium with goblet cells iii lmmobile cilia to bind odorant molecules f Respiratory epithelium lines the rest of the nasal cavity except vestibule i Ciliated pseudostratified columnar epithelium with goblet cells ii Cilia are motile iii Goblet cells secrete mucus and cilia propel the mucus posteriorly towards the pharynx iv Swallowed into digestive tract 8 Why does one of my nostrils always seem more open than the otherand then it changes to the other a Erectile tissue extensive venous plexus in inferior concha i Every 30 to 60 minutes erectile tissue on one side swells with blood ii Restricts airflow through that fossa iii Most air directed through other nostril and fossa iv Allowing engorged side time to recover from drying v Preponderant flow of air shifts between the right and left nostrils once or twice and hour 9 The pharynx 2 a Pharynx throat a muscular funnel extending about 13 cm 5 in from the choanae to the larynx b Three regions of the pharynx i Nasopharynx 1 Only passes air 2 Receives auditory tubes and contains pharyngeal tonsil 3 90 downward turn traps large particles gt10 um ii Oropharynx 1 Passes air food and fluid 2 Contains palatine tonsils iii Laryngopharynx 1 Passes air food and fluid 2 Esophagus begins where laryngopharynx ends 10The Larynx 3 a Larynx voice box cartilaginous chamber about 4 cm 15 in long b Primary function is to keep food and drink out of the ainNay i Has evolved to additional role phonation the production of sound c Epiglottis flap of tissue that guards the superior opening of the larynx i At rest stands almost vertically ii During swallowing extrinsic muscles of larynx pull larynx upward iii Tongue pushes epiglottis down to meet in iv Closes ainlvay and directs food to esophagus behind it v Vestibular folds of the larynx play greater role in keeping food and drink out of the ainNay 11The Trachea 4 a Trachea windpipe a rigid tube about 12 cm 45 in long and 25 cm 1 in in diameter i Supported by 16 to 20 Cshaped rings of hyaline cartilage ii Reinforces the trachea and keeps it from collapsing when you inhale iii Opening in rings faces posteriorly toward esophagus iv Trachealis muscle spans opening in rings 1 Gap in C allows room for the esophagus to expand as swallowed food passes by 2 Contracts or relaxes to adjust airflow b lnner lining of the trachea is a ciliated pseudostratified columnar epithelium i Composed of mainly mucussecreting cells ciliated cells and stem cells c Mucociliary escalator mechanism for debris removal i Mucus traps inhaled particles ii Upward beating cilia drives mucus toward pharynx where it is swallowed 12 Tracheostomy a Tracheostomy Trach to make a temporary opening in the trachea inferiorly to the larynx and insert a tube to allow airflow i Prevents asphyxiation due to upper ainlvay obstruction b Reasons for tracheostomy i Patients that need to be on a ventilator longterm 1weeks ii Blockage or narrowing of ainlvay iii Paralysis of vocals or muscles associated with swallowing iv Throat cancer leading to blockage v Severe trauma to neck mouth nose 13The lungs of the bronchial tree a Lungs are crowded by adjacent organs the neither fill the entire ribcage nor are they symmetrical i Right lung 1 Shorter than left because the liver raises higher on the right 2 Has 3 lobes superior middle and inferior separated by horizontal and oblique fissures ii Left lung 1 Taller and narrower because the heart tilts and occupies more space on this side of the mediastinum 2 Has indentation cardiac impression 3 Has 2 lobes superior and inferior separated by a single oblique fissure 14The pleura a Visceral pleura serous membrane that covers the lungs b Parietal pleura adheres to mediastinum inner surface of the ribcage and superior surface of the diaphragm c Pleural cavity potential space between pleurae i Normally no room between the membranes but contains a film of slippery pleural fluid d Functions of pleurae and parietal fluid i Reduce friction ii Create pressure gradient 1 Lower pressure than atmospheric pressure assists lung inflation iii Compartmentalization 1 Prevents spread of infection form one organ in mediastinum to others 15The bronchial tree a Bronchial tree a branching system of air tubes in each lung i From main bronchus to 65000 terminal bronchioles b Main primary bronchi 5 supported by Cshaped hyaline cartilage I39I gs c Lobar secondary bronchi 6 supported by crescent shaped cartilage plates i Three right lobar secondary bronchi superior middle and inferior 1 One to each lobe of the right lung ii Two left lobar bronchi superior and inferior 1 One to each lobe of the left lung d Segmental tertiary bronchi 7 supported by crescent shaped cartilage plates i 10 on right 8 on left ii Each tertiary bronchus ventilates one Bronchopulmonary segment functionally independent unit of the lung tissue e Bronchioles 8 i Lack cartilage ii 1 mm or less in diameter iii Pulmonary lobule portion of the lung ventilated by one bronchiole iv Have ciliated cuboidal epithelium v Welldeveloped layer of smooth muscle vi Divides into 50 to 80 terminal bronchioles 1 Terminal bronchioles 9 a Final branches of conducting system b Measure 05 mm or less in diameter c Have no mucus glands or goblet cells d Have cilia that move mucus draining into them by mucociliary escalator e Each terminal bronchiole gives off tow or more smaller respiratory bronchioles f Respiratory bronchioles 10 i Having alveoli budding from their walls ii Considered the beginning of the respiratory division since alveoli participate in gas exchange iii Divide into 2 to 10 alveolar ducts 11 iv End in alveolar sacs 12 1 Alveolar sacs grapelike clusters of alveoli arrayed around a central space called the atrium 16Alveoli a 150 million alveoli in each lung providing about 70 m2 750 ft2 of surface for gas exchange i Average living room size 400 ft2 b Each alveolus surrounded by a basket of blood capillaries supplied by the pulmonary artery c Respiratory membrane the barrier between the alveolar air and blood 17 Pulmonary ventilation a Breathing pulmonary ventilation consists of a repetitive cycle one cycle of inspiration inhaling and expiration exhaling b Respiratory cycle one complete inspiration and expiration i Quiet respiration while at rest effortless and automatic ii Forced respiration deep rapid breathing such as during exercise c Flow of air in and out of lung depends on a pressure difference between air pressure within lungs and outside body d Breathing muscles change lung volumes and create differences in pressure relative to the atmosphere 18The respiratory muscles a Diaphragm i Prime mover of respiration ii Contraction flattens diaphragm enlarging thoracic cavity and pulling air into lungs iii Relaxation allows diaphragm to bulge upward again compressing the lungs and expelling air iv Accounts for 23 of airflow v When you contract your diaphragm it moves down vi When you relax your diaphragm it moves up 19 The respiratory cycle a Accessory muscles of respiration act mainly in forced respiration b Internal and external intercostal muscles i Synergist to diaphragm plus some neckchest muscles ii Between ribs iii Stiffen the thoracic cage during respiration iv Prevent tit from caving inward when diaphragm descends v Contribute to enlargement and contraction of thoracic cage vi Adds about 13 of the air that ventilates the lungs 20 The respiratory muscles more than just breathing a Valsalva maneuver consisting of taking a deep breath holding it by closing the glottis and then contracting the abdominal muscles to raise abdominal pressure and push organ contents out i Childbirth urination defecation vomiting 1 Depression of the diaphragm 9 increased abdominal pressure 9 contents baby expelled 21 Neural control of breathing a No autorhythmic pacemaker cells for respiration as in the heart i Exact mechanism for setting the rhythm of respiration remains unknown Breathing depends on repetitive stimuli of skeletal muscles from the brain Neurons in medulla oblongata and pons control unconscious breathing Inspiratory neurons fire during inspiration Expiratory neurons fire during expiration Innervation i Fibers of phrenic nerve supply diaphragm ii Intercostal nerves supply intercostal muscles g Unconscious cycle of breathing is controlled by 3 pairs of respiratory centers in the medulla oblongata and the pons cameo i Medulla oblongata 1 Ventral respiratory group VRG a Primary generator of the respiration rhythm b Inspiratory neurons in quiet breathing eupnea fire for about 2 seconds signals send down phrenic and intercostal nerves inspiration c Expiratory neurons in eupnea fire for about 3 seconds allowing inspiratory muscles to relax elastic recoil of thoracic cage expels air from lungs d Produce a respiratory rhythm of 12 breaths per minute 2 Dorsal respiratory group DRG a Receives influences from external sources see below b Modifies the rate and depth of breathing ii Pons 1 Pontine respiration group PRG a Modifies rhythm of the VRG by outputs to both the VRG and DRG b Adapts breathing to special circumstances such as sleep exercise vocalization and emotional responses 9 crying 22 Central and peripheral input to the respiratory centers a The 3 respiratory centers that control breathing do not act alone b They respond to input from several other levels of the nervous system i Mostly deals with monitoring pH and C02 levels in the blood or cerebrospinal fluid CSF ii But also with stretching and irritation of the lungs 23 Four receptors provide input to the respiratory centers 3 Central chemoreceptors brainstem neurons that respond to changes in pH of cerebrospinal fluid i pH fcerebrospinal fluid reflects the C02 level in the blood ii By regulating respiration to maintain stable pH respiratory centers also ensures stable C02 level in the blood b Peripheral chemoreceptors located in the carotid and aortic bodies of the large arteries above the heart i Respond to the 02 and C02 content and the pH of blood c Stretch receptors found in the smooth muscles of bronchi and bronchioles and in the visceral pleuras i Respond to inflation of the lungs ii Inflation HeringBreuer reflex triggered by excessive inflation 1 Protective reflex that inhibits inspiratory neurons stop inspka on d lrritant receptors nerve endings amid the epithelial cells of the airway i Respond to smoke dust pollen chemical fumes cold air and excess mucus ii Trigger protective reflexes such as bronchoconstriction shallower breathing breathholding apnea or coughing 24A general model of C02 detection in the CSF a C02 diffuses easily into cerebrospinal fluid 9 hydration causes formation of carbonic acid 9 cerebrospinal fluid pH drops 9 chemoreceptors are excited in CNS 9 stimulates breathing 25 Facts about breathing a Hyperventilation anxietytriggered state in which breathing is so rapid that it expels COZ from the body faster than it is produced i As blood COZ levels drop the pH rises causing the cerebral arteries to constrict ii This reduces cerebral perfusion which may cause dizziness or fainting iii Can be brought under control by having the person rebreathe the expired COZ from a paper bag b Voluntary control over breathing originates in the motor cortex of frontal lobe of the cerebrum i Sends impulses down corticospinal tracts to respiratory neurons in spinal cord bypassing brainstem respiratory centers c Limits to voluntary control i Breaking point when C02 levels rise to a point when automatic controls override one s will 26 Pressure Resistance and airflow a Respiratory airflow is governed by the same principles of flow pressure and resistance as blood flow i The flow of a fluid is directly proportional to the pressure difference between two points ii The flow of a fluid is inversely proportional to the resistance b Atmospheric pressure drives respiration i The weight of the air above us ii 760 mm Hg at sea level or1 atmosphere 1 atm 1 Lower at higher elevations c Boyle s law at a constant temperature the pressure of a given quantity of gas is inversely proportional to its volume i If the lungs contain a quantity of a gas and the lung volume increases their internal pressure intrapulmonary pressure falls 1 If the pressure falls below atmospheric pressure the air moves into the lungs d lfthe lung volume decreases intrapulmonary pressure rises i If the pressure rises above atmospheric pressure the air moves out of the lungs 27 Inspiration a Another force that expands the lungs in Charles s law b Charles s law the given quantity of a gas is directly proportional to its absolute temperature i On a cool day 16 C 60 F air will increase its temperature by 21 C 39 F during inspiration ii Inhaled air is warmed to 37 C 99 F by the time it reaches the alveoli iii Inhaled volume of 500 mL will expand to 536 mL and this thermal expansion will contribute to the inflation of the lungs 28 Resistance to airflow a Pressure is one determinant of airflow resistance is the other i The greater the resistance the slower the flow b Three factors influencing ainlvay resistance i Diameter of the bronchioles 1 Bronchodilation increase in the diameter of a bronchus or bronchiole 2 Bronchoconstriction decrease in the diameter of a bronchus or bronchiole ii Pulmonary compliance 1 The ease with which the lungs can expand iii Surface tension of the alveoli and distal bronchioles 1 Thin film of water needed for gas exchange 29 Spirometry the measurement of pulmonary ventilation a Spirometry the measurement of pulmonary function i Aid in diagnosis and assessment of restrictive and obstructive lung disorders b Spirometer a device that recaptures expired breath and records such variables as rate and depth of breathing speed of expiration and rate of oxygen consumption c Restrictive disorders those that reduce pulmonary compliance i Limit the amount to which the lungs can be inflated ii Black lung disease tuberculosis d Obstructive disorders those that interfere with airflow by narrowing or blocking the ainNay i Make it harder to inhale or exhale a given amount of air ii Asthma chronic bronchitis iii Emphysema combines elements of restrictive and obstructive disorders 30 Respiratory volumes and capacities a Tidal volume TV the amount of air exchanged with each breath during normal quiet breathing i Measures about 500 ml in a healthy adult b Expiratory reserve volume ERV the volume of air that may be expired after a tidal expiration i Averages between 700 and 1200 ml of air c Inspiratory reserve volume IRV the amount of air that may be inspired after a tidal inspiration i Averages between 199 and 3100 ml of air d Residual volume RV the amount of air that remains in the lungs after maximal expiration this amount of air accounts for the difference between g the IRV and ERV i Generally equal to about 11001200 ml of air Inspiratory capacity IC the amount of air a person can maximally inspire after a tidal expiration it is equal to the TV IRV i Averages between 2400 and 3600 ml of air Functional residual capacity FRC the amount of air normally left in the lungs after a tidal expiration the sum of the ERV RV i Averages between 1800 and 2400 ml of air Vital capacity VC the total amount of exchangeable air that moves in and out of the lungs it is equal to the sum of the TV IRV ERV i Averages between 3100 and 4800 ml of air Total lung capacity TLC the total amount of exchangeable and non exchangeable air in the lungs the total of all four respiratory volumes and is not measurable with general spirometry i Averages between 4200 and 6000 ml of air Lung Volumes and Capacities 6 000 Maximum possible inspiration l 5000 I A Ins irat Inspiratory EI 4 000 mange VOWmo capacnty v Vital capacity OE Tidal g 3000 volume 9 Total lung capacity t O C 2000 3 I 1000 A 7Mmd39oedo 31 What is partial pressure a b C Dalton s law of partial pressure the total atmospheric pressure is the sum of the contributions of the individual gasses Partial pressure pressure exerted by one gas in a mixture of gasses i Atmospheric pressure at sea level 760 mmHg ii Composition of gases in air 21 02 78 N2 1 other iii Partial pressure 02 P02 21 x 760 mmHg 160 mmHg iv Gasses will always diffuse from higher partial pressure to lower partial pressure 3 reasons that inspired air differs from alveolar air i Humidification of air increased H20 ii Mixing of inspired and residual air less 02 more C02 iii Alveolar exchange of 02 and C02 less 02 more C02 32Alveolar gas exchange a Alveolar gas exchange the backandforth traffic of 02 and C02 across the respiratory membrane i Air in the alveolus is in contact with a film of water covering the alveolar epithelium ii For oxygen to get into the blood it must dissolve in this water iii Pass through the respiratory membrane separating the air from the bloodstream iv For carbon dioxide to leave the blood it must pass the other way v Diffuse out of the water film into the alveolar air b Gases diffuse down their own concentration gradient until the partial pressure of each gas in the air is equal to its partial pressure in water c Henry s law at the air water interface for a given temperature the amount of gas that dissolves in the water is determined by its solubility in water and its partial pressure in air i The greater the P02 in the alveolar air the more 02 the blood picks UP ii Since blood arriving at an alveolus has a higher PC02 than air it releases C02 into the air iii At the alveolus the blood is said to unload C02 and load 02 iv Each gas in a mixture behaves independently v One gas does not influence the diffusion of another 33Aveoar gas exchange simplified a Higher P02 in alveolar air i 02 diffuses into blood until equilibrium b Higher P02 in arriving blood i C02 diffuses into alveolus until equilibrium 34 Moving gas from lungs to blood Pulmonary arteries contain blood devoid of 02 P02 40 mm Hg Alveolar P02 104 mm Hg Steep concentration gradient 02 diffuses from alveoli to blood Diffusion occurs until equilibrium P02 104 mm Hg is met This happens fast About 13 of the time blood spends in pulmonary capillaries sobood can flow 3x as quickly wo losing efficiency f Carbon dioxide moves in opposite direction but along a very gentle gradient only 5 mm Hg difference between blood and alveoli blood gt alveoli so C02 diffuses out of blood 35Alveolar gas exchange a Soconsidering the high pressure difference between alveolar P02 and blood P02 approx 60 mm Hg AND FDPPP39P b The low pressure difference between alveolar PC02 and blood PC02 approx 5 mm Hg c Do you think that more 02 diffuses across the respiratory membrane than C02 i No because of solubility of the gases A C02 is 20 times as soluble as 02 2 Equal amounts of 02 and C02 are exchanged across the respiratory membrane because C02 is much more soluble and diffuses more rapidly 36 Gas transport a Gas transport the process of carrying gases from the alveoli to the systemic tissues and vice versa b 0xygen transport i 985 bound to hemoglobin ii 15 dissolved in plasma c Carbon dioxide transport i 70 as bicarbonate ion ii 23 bound to hemoglobin iii 7 dissolved in plasma Remember the red numbers we will visit them laterthe other numbers are not as important for out purposes 37 How is oxygen transported a Hemoglobin molecule specialized in oxygen transport i Four protein globin portions 1 Each with a heme group which binds one 02 to the ferrous ion Fe2 0ne hemoglobin molecule can carry up to 4 02 Oxyhemoglobin Hb02 02 bound to hemoglobin Deoxyhemoglobin HHb hemoglobin with no 02 100 saturation Hb with 4 02 50 saturation Hb with 2 02 molecules 38 How is carbon dioxide transported a Carbon dioxide transported in three forms i Carbonic acid carbamino compounds and dissolved in plasma b Most C02 is hydrated to form carbonic acid i co2 H20 9 H2C03 a HC0339 H ii Then dissociates into bicarbonate and hydrogen ions c Some binds to the amino groups of plasma proteins and hemoglobin to form carbamino compounds chiefly carbaminohemoglobin HbC02 i Carbon dioxide does not compete with oxygen ii They bind to different moieties on the hemoglobin molecule iii Hemoglobin can transport 02 and C02 simultaneously d Some is carried in the blood as dissolved gas 39 Systemic gas exchange a Systemic gas exchange the unloading of 02 and loading of C02 at the systemic capillaries b Our focus here is really just the 02 and C02 interacting with RBCs c C02 loading i C02 diffuses into the blood from tissues ii Carbonic anhydrase in RBC catalyzes 1 C02 H20 9 H2CO3 9 HCO3 H mmeww iii Chloride shift 1 Keeps reaction proceeding exchanges HC03 for CI 2 H binds to hemoglobin a This is the most important factor leading to 02 unloading d Oxygen unloading i H binding to HbOz reduces its affinity for 02 ii Tends to make hemoglobin release oxygen which then travels to the tissues These two exchanges are the most important and work in concert to load C02 and unload 02 40Aveoar gas exchange revisited a Reactions that occur in the lungs are reverse of systemic gas exchange b Again our focus is really just the 02 and C02 interacting with RBCs c C02 unloading i As Hb 02 its affinity for H dissociates from Hb and binds with HCO3 1 H HCO3 9 H2CO3 9 C02 H20 ii Reverse chloride shift 1 HC03 diffuses back into RBC in exchange for Cl free C02 generated diffuses into alveolus to be exhaled 41 Carbon monoxide poisoning a Carbon monoxide CO competes for the O2 binding sites on the hemoglobin molecule b Colorless odorless gas in cigarette smoke engine exhaust fumes from furnaces and space heaters c Carboxyhemoglobin C0 binds to ferrous ion of hemoglobin i Binds 210 times as tightly as oxygen ii Ties up hemoglobin for a long time iii Nonsmokers less than 15 of hemoglobin occupied by CO iv Smokers 10 in heavy smokers v Atmospheric concentrations of 02 CO is quickly lethal 42 Respiratory disorders a Smoking and lung cancer i Lung cancer amounts for more deaths than any other form of cancer 1 Most important cause is smoking 15 carcinogens ii Squamouscell carcinoma most common 1 Begins with transformation of bronchial epithelium into stratifies squamous from ciliated pseduostratified epithelium 2 Dividing cells invade bronchial wall cause bleeding lesions 3 Dense swirls of keratin replace functional respiratory tissue iii Adenocarcinoma originates in mucous glands of lamina propria iv Smallcell oat cell carcinoma 1 Least common most dangerous 2 Named for clusters of cells that resemble oat grain VI vii viii 3 Originates in primary bronchi invades mediastinum metastasizes quickly to other organs 90 originate in primary bronchi Tumor invades bronchial wall compresses ainNay may cause atelectasis lung collapse Often first sign is coughing up blood Metastasis spread to other parts of the body is rapid usually occurs by the time of diagnosis 1 Common sites pericardium heart bones iver lymph nodes and brain Prognosis poor after diagnosis 1 Only 7 of patients survive 5 years
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