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Respiration Flashcards

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508317467How many branches is the airway divided into?24 (trachea = 0 + 23 airway branches)0
616314922Which sections make up the conducting zone?Trachea + first 16 airway branches1
111579359What are the roles of the conducting zone?1) *Warm + humidify* air 2) *Distribute* air to depth of lungs 3) *Defence* - against bacteria/dust2
410606029What anatomical area do the areas in the conducting zone constitute? What is the size of this (ml)?anatomical dead space 150ml3
635721413What is the vascular system of the conducting zone called?Bronchial circulation4
287988947Which sections make up the respiratory zone?Last 7 airway branches (17-23)5
109124221What is the volume of the respiratory zone?2.5-3L6
1017204128What is Fick's law of diffusion?[C1]-[C2] = *pressure gradient*7
1013653939What is the thickness for diffusion from alveoli to blood?0.5µm8
11922957How do alveoli number and size change with age?Alveoli number and surface area ↑ from birth → adolescence After adolescence numbers say the same but size ↑9
55876675What are the three transmural pressures?*Transpulmonary pressure* = alveolar pressure - pleural pressure *Trans chest wall pressure* = pleural pressure - atmospheric pressure *Trans total system* = alveolar pressure - atmospheric pressure10
918577366What is Tidal Volume?The volume of inspiration and expiration at normal quiet breathing ~500ml11
109163710What is Inspiratory reserve volume (IRV)?Additional volume of inspiration on maximal inspiration ~3000ml12
109163711What is Expiratory reserve volume (ERV)?Additional volume of expiration on maximal expiration ~1200ml13
109163713What is Residual volume (RV)?Volume of gas remaining after maximal forced expiration ~1200ml14
803069951What is Inspiratory capacity (IC)?Tidal volume + inspiratory reserve volume ~3500ml15
803069952What is Functional residual capacity (FRC)?Expiratory reserve volume + residual volume ~2400ml16
309380982What is Vital capacity (VC)?Inspiratory capacity + expiratory reserve volume ~4700ml17
309380983What is Total lung capacity (TLC)?All the lung volumes18
198860723What is the STPD?*Standard Temperature and Pressure Dry* 0°C (273K) 1 atmosphere (760mmHg/101kilopascals) Dry19
550244542What is BTPS*Body Temperature and Pressure Saturated (BTPS)* Physiological conditions within the body 37°C (310K) 713mmHg Saturated20
2395980467What is the formula for working out the partial pressure exerted by an individual gas in a gas mixture?Fraction of mixture occupied by gas A x Total pressure exerted by mixture (mmHg)21
2396020529How can we measure Residual Volume and Functional Residual Capacity?RV and FRC cannot be measured by spirometry Need to be measured using dilution techniques22
2396039951What makes up the physiological dead space?*1) Anatomical Dead Space* 150ml (conducting zone) *2) Alveolar dead space* Alveoli that do not participate in gas exchange: a) Alveoli with no blood flow b) Alveoli with reduced blood flow such that ventilation > perfusion23
2396041653What is the dead space of a seated individual?It is equal to their weight (170lb person has a dead space of 170ml)24
2396047281What is the total inspired ventilation rate?Tidal volume x Breathing frequency 500 x 12 = *6L/min*25
2396048932What is the expired minute volume?Tidal volume x Breathing frequency 500 x 12 = *6L/min* This is based on the assumption that volume inspired = volume expired (not quite true because more O₂ is consumed than CO₂ is produced)26
2396077312What is alveolar ventilation?Volume of fresh air reaching alveoli *Simple equation* (Tidal volume - dead space volume) x frequency27
2396086061How can we directly measure alveolar ventilation?Volume of CO₂ expired per minute can be worked out using a spirometer (measure to total expired volume and the fraction conc. of expired CO₂) The fractional concentration of alveolar CO₂ can be worked out by sampling the last portion of tidal volume28
2396097164How can the alveolar ventilation formula be re-written to account for conversion of STPD to BTPS?29
2396115449What is the relationship between alveolar ventilation and alveolar PCO2?They are inversely proportional. Also because PACO₂ is in equilibrium with PCO₂ - alveolar ventilation has the same relationship with PCO₂ Doubling alveolar ventilation → 1/2 PCO₂ 1/2 alveolar ventilation → double PCO₂30
2396130654What is the relationship between alveolar ventilation and alveolar PAO2?↑ Avleolar ventilation → ↑ Alveolar PAO₂ *Doubling alveolar ventilation does not double alveolar PAO₂* This is because: 1) Inspired PO₂ is not zero 2) More O₂ is removed from gas than CO₂ is added31
2396141154What is the alveolar gas equation for working out PAO2?R = 0.82 (sea level) PACO₂ = 40mmHg PIO₂ = 149mmHg32
2396151979What is the normal alveolar values for P02 and Pco2?PAO₂ = 100mmHg PACO₂ = 40mmHg33
2396383297What two conclusions can be drawn from a pressure-volume loop?1) *Hysteresis* - Lung volume at any given pressure is higher during expiration 2) With no transpulmonary pressure, the lung volume is never zero34
2396400940What is lung compliance?The volume change per unit change in transpulmonary pressure35
2396419094What are the factors that affect lung compliance?*1) Lung volume* ↑ volume → ↓ compliance *2) Elastic properties of the lung* *3) Lung size* ↑ size → ↑ compliance *4) Surface forces inside alveoli* ↓ surface tension → ↑ compliance Pulmonary surfactant ↓ surface tension *5) Regional lung compliance* in normal conditions, base of lung is more compliant than apex36
2396492399What pathologies cause loss or increase in compliance? What are their functional consequences?37
2396515279How is compliance measured on pressure-volume curves?The gradient of the slope38
2396577460Draw total pressure-volume relationship: What are the points to take away from this?1. At zero transmural pressure, lungs are at volume < residual volume but chest wall is at a volume ~75% of vital capacity 2. At FRC the transmural pressure of the chest wall is negative (opposes the tendency of the chest wall to spring out as a result of its elastic recoil forces) In contrast at FRC the transmural pressure of the lungs is positive (opposes the tendency of the lungs to recoil inwards as a result of their elastic recoil forces) The opposing pressures are exactly equal at FRC39
2396593162What determines chest wall compliance?*1) Rigidity of thoracic cage* *2) Shape of thoracic cage* Therefore compliance can ↓ if chest wall is deformed with obesity *3) Diaphragm and abdominal structures* Therefore compliance can ↓ in abdominal conditions that push the diaphragm up or in muscular conditions that lead to rigidity of thoracic and abdominal muscles40
2396626910What is Laplace's Law? How is it different in the alveolusPressure = (4x Surface tension)/radius Because the alveolus only has a single air-liquid interface, the numerator 4 is replaced with 241
2396756868What cells produce pulmonary surfactant?Alveolar Type II cells42
2396759411What is the main agent in surfactant that reduces surface tension? What is this produced from?DPPC (Dipalmitoyl phosphatidyl choline) Produced from glucose, choline and palmitate (provided by pulmonary circulation)43
2396763556What is the role of surfactant?*1) Increases compliance* (by reducing surface tension) This reduces work effort needed for breathing *2) Allows the coexistence of different sized alveoli* Reduces surface tension in smaller alveoli more *3) Keeps alveoli dry* Atelectaisa → -ve interstitial fluid that draws in liquid from capillaries44
2396772029How does surfactant reduce surface tension?DPPC is hydrophobic on one end and hydrophilic the other. This therefore resists the normal attractive forces between surface water molecules45
2396990584What is Poiseuille's law?46
2397003983What is the major site of resistance in airways?Medium sized bronchi47
2397043390What affect airway resistance?*1) Lung volume* ↑ volume → ↓resistance As lung expands parenchyma opens up airways *2) Contraction of bronchial smooth muscle* Dilation: Beta-2 agonists + ↑PCO₂ in conducting airways Constriction: Chemicals, Dust, Smoke, ↓PCO₂ in conducting airways *3) Viscosity and density of gas*48
2397119799What is the Equal Pressure Point (EPP)?The point along the airway in maximal expiration where transairway pressure = 049
2397145109What conclusions can we draw from EPP?1) Peak flow rate cannot be increased (regardless of how forceful the expiratory effort is) 2) Maximal flow rates are determined mainly by *elastic recoil of the lung*50
2397164385What sets the EPP?Compliance of the lung51
2397217533What is the normal: FVC FEV1 FEV1/FVCFVC = 5L FEV1 = 4L FEV₁/FVC = 80%52
2397220130What do we see on the spirometry of obstructive disease? (Asthma/COPD)FEV₁ reduces more than FVC Therefore FEV₁/FVC reduces (usually below 75%)53
2397225957What do we see on the spirometry of restrictive disease? (Fibrosis)FVC reduces Therefore FEV₁/FVC stays the same or increases54
2397886646What is the formula when we add Henry's law to Fick's law?ΔP = partial pressure gradient d = diffusion constant (Made up of solubility coefficient [s] and diffusion coefficient [D])55
2397912960What is the formula for the diffusion constant?Therefore smaller and more soluble particles will diffuse at a faster rate56
2397925064What is the solubility coefficient for O2 in plasma?0.03ml O₂/litre plasma/mmHg57
2397928536What is the solubility coefficient for CO2 in plasma0.7ml CO₂/litre plasma/mmHg *23 times more soluble than O₂* But overal CO₂ is 20 times faster at diffusion (because due to its larger size cf. O₂ it brings it down from 23 to 20)58
2397961029What maintains the diffusion gradient for gas exchange at the alveoli?1) Alveolar ventilation 2) Pulmonary circulation59
2397965154What is the *transit time*?Time for blood to flow from beginning to end of pulmonary circulation <1sec60
2397966895What is the *Diffusion reserve*?Gas exchange between the alveoli and the pulmonary capillaries happen in a way such that the gas equilibrium is reached with room to spare (compared to the transit time)61
2398064228What is the bound O2 capacity of blood?1 gram Hb contains 1.39ml O₂ Blood has 15ml Hb/100ml Therefore blood can carry 20.8ml O₂/100ml62
2398124966Why is the O2 dissociation curve sigmoidal?This reflects the cooperative nature of O₂ binding to Hb63
2398128152What is the loading plateau?Above Po₂ 60mmHg the Hb saturation is high and starts to level off Below this, curve is steep and significant loss of O₂64
2398133489What pushes O2 dissociation curve to the right?1) CO₂ 2) ↓pH 3) 2,3 DPG 4) Temperature 5) Exercise CADET face right (CO₂, Acid, DPG, Exercise, Temperature)65
2398139466What is the Bohr effect?Right shift of dissociation curve due to CO₂ and ↓pH66
2398223303What is the formula for total concentration of O2 in blood?67
2398234561What are the different types of hypoxia? What is hyperoxia, hypercapnia and hypocapnia?68
2398250775Why is CO poisoning so dangerous?*1) High Hb affinity* ~240 times more than O₂ *2) Left shift to O₂ dissociation curve* Thus, little O₂ bound can't unload in tissues *3) No physical signs of hypoxia* COHb is bright red too *4) PO₂ remains normal* Total O₂ content plummets but PO₂ is normal *5) Colourless, odourless and non-irritant*69
2398545443How is CO2 transported in the blood?1) Dissolved CO₂ 5-10% 2) As bicarbonate (HCO₃⁻) Majority (90%) 3) Carbamino compounds 5%70
2398548940What is the Haldane effect?• Amount of CO₂ carried by blood depends on PO₂ (and ∴ saturation of Hb) • More CO₂ is carried in deoxygenated blood over oxygenated blood • Mechanism of this: *1. Dynamic proton dissociation constant for Hb* • Deoxygenated Hb is a weaker acid ∴ retains more protons • This retaining of more protons means that the chemical gradient favours the formation of HCO3- *2. Deoxygenated blood forms more carbamino compounds* ∴ overall, change in PO₂ → change in CO₂71
2398561485What buffers the protons produced by carbonic anhydrase in the RBCs?*imidazole groups* on the *histidine* amino acid residues of the alpha and beta polypeptide chains of Hb72
2398567862What is Hamburger's Phenomena?Most of the HCO₃⁻ produced in RBCs (for CO₂ transport) leaves the RBC down its concentration gradient This charge movement is compensated by influx of Cl⁻ ∴ the RBCs accumulate Cl⁻ in exchange for HCO₃⁻ This is referred to as the *Cl⁻ shift* or *Hamburger's phenomena* This exchange occurs very rapidly in the capillary beds as a result of the high anion permeability of the RBC membrane The extra intracellular HCO³⁻ and Cl⁻ increase the intracellular osmolarity and osmotic pressure resulting in *water influx and cell swelling*73
2410348395What are the functions of the pulmonary circulatory system?1) Gas exchange 2) Blood reservoir 3) Filtration 4) Metabolism of vasoactive hormones74
2410349164What hormones are metabolised by pulmonary circulation?*Angiotensin I* *Hormones inactivated* Noradrenaline Bradykinin Prostaglandins *Hormones unaffected* Histamine Adrenaline Vasopressin75
2410358246What catheter can be used to measure both pulmonary arterial and venues pressure?*Swan-Ganz catheter* Wedge-pressure = venous pressure76
2410360572What is the pressure gradient across the pulmonary circulation? What is the pressure gradient across the systemic circulation?Pulmonary circulation = ~10mmHg Systemic circulation = ~85-90mmHg Pulmonary circulation must have very low resistance for flow to occur77
2410383185How is pulmonary circulation resistance kept low?1) Large number of vessels 2) Vessels are dilated (NO CONTROL FROM AUTONOMICS)78
2410383890How does the following effect pulmonary vascular resistance? a) Cardiac output b) Lung volume c) Hypoxia*a) Cardiac output* ↑CO → ↓ resistance This is because of capillary recruitment and distension *b) Lung volume* Effect on alveolar and extra alveolar vessels. Extra-alveolar (affected by intracellular pressure. ↑volume → ↓resistance) Alveolar (affected by alveolar volume. ↑volume→↑resistance) *c) Hypoxia* ↑Hypoxia → ↑resistance Regional hypoxia → little effect on pulmonary arterial pressure General hypoxia → ↑ pulmonary arterial pressure (could lead to pulmonary hypertension and oedema)79
2410406689What can cause oedema in the lung?*1) ↑ pulmonary capillary pressure* Left heart failure / general hypoxia *2) ↑ capillary permeability* Oxidant damage (O₂ therapy/ozone) Endotoxins *3) ↓ capillary colloid osmotic pressure* Loss of capillary proteins (starvation) *4) ↑ Surface tension* Surfactant loss → ↑interstitial hydrostatic pressure *5) Lymphatic blockage*80
2410417391What are the different zones that explain the interaction of blood flow and alveolar pressure?*Zone 1 (Upper zone)* Alveolar pressure > arterial pressure ∴ pulmonary capillaries = collapsed and there is no flow *Zone 2 (Middle zone)* Arterial pressure > alveolar pressure This is ∵ of ↑hydrostatic influence due to moving closer to the level of the heart But alveolar pressure > venous pressure ∴ blood flow in this region is determined by the different between the arterial and alveolar pressure Venous pressure has no influence on flow until it exceeds alveolar pressure *Zone 3 (Lower zone)* Arterial pressure > venous pressure > alveolar pressure Flow is determine by the arterial-venous pressure difference In healthy individuals, zone 1 conditions do not exist ∵ arterial pressure in upper lung is usually sufficient to overcome small alveolar pressures. This condition can however exist if pulmonary arterial pressure ↓(e.g. severe haemorrhage) or if alveolar pressure ↑ (e.g. forced ventilation)81
2410440138What is alveolar ventilation at rest?~4L/min82
2410440265What is blood flow at rest?~5L/min83
2410440986What is the average ventilation:perfusion ratio?0.884
2410444292What happens to ventilation and perfusion as we move down the lung? How does this affect ventilation:perfusion ratios?Ventilation ↑ (2x more at base) Perfusion ↑ (5x more at base) V:Q ratio ↓85
2410450510What effect does increasing V:Q ratio have on the gas complex found in the alveoli?↑V:Q ratio → ↑PO₂ and ↓PCO₂ therefore TB tends to localise at apex of lung (↑PO₂ is favourable for Mycobacterium tuberculosis)86
2410454599What is venous admixture?Mixing of oxygenated blood with non-oxygenated blood87
2410461235What are the causes of venous admixture?*1) Shunting* a) Right to left shunting (septal defects/bronchial circulation [20% of admixture]) b) Alveolar shunting (blood reaching the alveoli but no access to oxygen - oedema, pneumonia, atelectasis) *2) Low V:Q ratio* (causes 80% of admixture) Normal differences at base88
2410528705What is the function of the pneumotaxic centre?Limits inspiration89
2410546253What is the function of the apneustic centre?Prolongs inspiration90
2410547691What is the function of the medullary centre?Central pattern generator91
2410547961What is the function of the vagi with regards to breathing?Terminates inspiration92
2410563609What are the different groups in the medullary centre?*1) Dorsal respiratory group (DRG)* - inspiratory neurons *2) Ventral respiratory group (VRG)* - inspiratory and expiratory neurons93
2410564836What is the group in the pneumotaxic centre called?*Pontine Respiratory Group (PRG)* Send inhibitory signals to the inspiratory ramp94
2410568841What variable is under closest control by the respiratory system?*Arterial PCO₂* Usually 40mmHg95
2410572139What is the average respiratory drive?Respiratory drive is the increase in ventilation rate per increase in PCO₂ It is usually: *2-3L/min/mmHg increase in PCO₂*96
2410852088Where are central chemoreceptors found?Ventral surface of medulla In chemosensitive areas (CSA) CNVIII → CNXI and CN XII97
2410823551Where is CSF formed?Choroid plexuses98
2410829931Compared to plasma, what is low/high in CSF?Low = Protein, HCO₃⁻, Ca²⁺, K⁺ High = Na⁺, Cl⁻99
2410844312What changes in CSF do central chemoreceptors respond to?H⁺ ions (pH) Not PCO₂100
2410861255Where are peripheral chemoreceptors found?Carotid and aortic bodies Type I Glomus cells101
2410862447What do peripheral chemoreceptors respond to?1) PCO₂ (↑) 2) PO₂ (↓) 3) pH (↓)102
2410881408When do peripheral chemoreceptors respond to reduced PO2?↓PO₂ is exclusively picked up by carotid bodies When PCO₂ is normal, PO₂ must be below 60mmHg to elicit a response When PCO₂ is ↑, PO₂ below 100mmHg elicits a response103
2411401024What are the respiratory systems responses to high altitude?1) Hyperventilation 2) Polycythemia 3) Alveolar hypoxia induced pulmonary hypertension 4) ↑ 2,3 DPG (therefore right shift in dissociation curve)104

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