Conducting zone allows movement of air in and out of lungsRespiratory zone allows diffusion of oxygen and carbon dioxide across capillary membranes
Larynx is a short 1.5 inch tube located in the throat below the base of the hyoid bone and tongue and oesophagusIn its walls it has supportive cartliges, interconnecting ligaments, intrinsic and extrinsic muscles and a mucosal lining.Its primary function is to provide a carefully guarded pathway between the pharynx and the trachea
9 laryngeal cartlidges2 sets of musclesIntrinsic muscles control the voiceExtrinsic muscles adjust the position of the larynx during swallowing
Thyroid cartlidge consists of two plates of hyaline cartlidge arranged in a wedge shape. These plates are fused along the anterior edge.At the top of the fused border the cartlidge extends anteriorly forming the laryngeal prominence or Adams appleHyoid bone serves as an attachment for the tongue muscles
Laryngeal muscles can adjust the size of the glottic openingThe glottis expands into a triangular shaped opening when breathingTo make sounds the laryngeal muscles reduce the size of the opening
Trachea is 4-5 inch vertical tube anterior to the oesophagusHas a wide lumen 1 inch to conduct air between the larynx and the primary bronchiEmbedded in the wall are tracheal rings made of hyaline cartlidge
4 Distinct layersMucosa with goblet cellsSubmucosa with blood vessels, neurons and glands which secrete combination of water and mucus to the surface of the tracheaCartilagionous layer containging C shaped ringsTrachealis muscles contracts on coughing which narrows lumen and increases velocity of airflow.Adventitia is loose connective tissue which binds the to the oesophagus and other nearby organs
The secondary bronchi are also known as lobar bronchi as each one directly conducts air to and from one of the lungs five lobes.
Point out apex and baseLeft lung has less volume because of space taken up by the heartPoint out pleura- will talk about this on next slide
Point out Hilum and what it is
Lung lobes are divided by connective tissue walls into compartments called bronchopulmonary segmentsEach segment functions independantly and is supplied by its own tertiary bronchus, artery, lymph vessels and autonomic nerves
When two or more alveoli share the same opening to an alveolar duct they are referred to as an alveolar sac.Approx 300 million alveoli in the lungs providing massive surface area for diffusion of gases.
MusclesInspirationDiaphragmInserted into lower ribsSupplied by phrenic nerves from C3,4,5In normal breathing moves about 1cmIn forced inspiration/expiration can move about 10cmExternal intercostal musclesConnect adjacent ribsSupplied by intercostal nerves coming off at C3,4,5Paralysis does not seriously affect breathing because diaphragm is so effectiveAccessory musclesScalene- elevate first two ribsSternomastoids- elevate sternum
Inhaler Technique Scoring Prepares Device (e.g. Shakes inhaler) 1 Exhales fully 1 activates and inhales 1 holds breath for several seconds 1
Common Problems – Chronic Obstructive Pulmonary Disease (COPD)Detailed historyIn an acute exacerbation patients usually present following a cold with deterioration of dyspnoea in association with a productive cough and discoloured sputum.Time courseTreatment given and effectsAny hospital admissions in the last yearBaseline functionHow far can you walk?Can you climb one flight of stairs easily?Chronic bronchitisHistory of cough, productive of sputum on most days, for 3 consecutive months, for at least 2 years.Emphysema is a pathological diagnosis of dilatation and destruction of the lungs distal to the terminal bronchioles
Past Medical HistoryPrevious admissions to hospital with acute exacerbations of COPDOther smoking related illnesses (ischeamic heart disease, peripheral vascular disease, strokes, hypertension)Other causes of lung disease (occupational exposure to dust, previous TB)AsthmaDrug HistoryBronchodilatorsHome oxygenWho initiated and on what evidenceHow many hours per day is it being usedLTOT should be used for greater than 15 hours per day and its aim is to prevent cor pulmonaleCaused by increase in blood pressure in the pulmonary artery which leads to enlargement and subsequent failure of the right side of the heart.Theophyliine.. Have levels been measuredSteroidsInhaler techniqueSocial HistoryConsider all aspects of daily livingNeed to stop smoking!!
CoughDuration, productive or drySputum ProductionQuantity, colour, recent changesDyspnoeaQuantitative account of exercise tolerance at baseline and during the illnessWheezePleuritic chest painCommon feature of pneumonia- be aware of pulmonary embolusFever.If symptoms are prolonged , recurrent or associated with weight loss consider the possibility of an underlying malignancy especially if they are a smoker.
Respiratory Anatomy and Physiology
Terminal bronchioles have aBroncioles branch many diameter of 0.5-1mm intimes and each division diameter.produces tubules which are They are too thick for airsmaller exchange and considered to be the last of the conducting zone structures
Type I cells account for gasexchange.Type II cells secrete surfactant
Functions of the lung• Main function is gas exchange – Allow passage of O2 – Allow removal of CO2
Functions of the lung• Metabolic functions – Surfactant synthesis – Protein synthesis – Metabolism of vasoactive substances • ACE/Bradykinins• Blood reservoir – Volume = 450mls• Allows phonation
Functions of the lung• Heat exchange• Immunological – Alveolar macrophages – IgA production – Mucociliary escalator
Ventilation MechanicsHow air gets to the alveoli. Gas Exchange How gas crosses the blood gas interface. Gas Transport How they are carried around the body.
Ventilation Mechanics How air gets to the alveoli.Muscles Diaphragm Inspiration External Intercostal Muscles Accessory muscles Abdominal Muscles Expiration Internal Intercostal muscles assist
Ventilation MechanicsHow air gets to the alveoli. Forces acting on the lung Elastic Tissue Elastic tissue of lungs is stretched under normal conditions. Resulting tension acts as a force pulling inwards on visceral pleura As chest wall and diaphragm pull on outwards on parietal pleura causing a negative pressure in interpleural space. This keeps the lungs inflated
Ventilation Mechanics How air gets to the alveoli. Airway Resistance Lung ComplianceIf radius halved then resistance increases the slope of the pressure-volume curve at a 16 fold particular lung volume => i.e. volume change per unit of pressureChief site of airway resistance is the medium change (mL/cmH2O)sized bronchi. normal value = 200mLs/cmH2OPeripheral airways contribute little resistance Lower compliance = more effort of breathing Considerable small airway disease can be present before being detected in pressure changes. Posture affects lung volume, therefore complianceFactors determining Disease states Lung volume Asthma leads to hyper-inflation Bronchi supported by surrounding Fibrosis, collapse and consolidation all tissue decrease distensibility Their calibre is increased as the lung Emphysema increases compliance expands So as lung volume is reduced resistance is increased Contraction of bronchial smooth muscle
Ventilation Mechanics How air gets to the alveoli. Functional Residual CapacityFRC- volume of gas remaining in lungs at end of FRC increases withnormal expiration Height Changing from supine to erectVolume of lung at which elastic forces causing Emphysema- gas trappingrecoil = thoracic chest wall forces causingexpansion FRC decreases with ObesityFRC = 30mls/kg = 2200 mls in supine 70kg adult Muscle paralysis and GA Changing from supine to erect Restrictive lung disease Pregnancy Raise intra-abdominal pressure
Gas ExchangeHow gas crosses theblood gas interface. Rate of diffusion is: Directly proportional to cross sectional area across which diffusion occurs Inversely proportional to the thickness of the membrane Directly proportional to the partial pressure of the gas across both sides
Gas Exchange How gas crosses the blood gas interface.The amount of time that blood is in contact withthe alveolus also influences gas exchange.The speed of blood flow past the alveolus is: 0.75 seconds under normal conditions 0.25 seconds with heavy exercise
Gas ExchangeHow gas crosses theblood gas interface. Ventilation- Pleural pressure are higher at the bases of the lungs. So they receive 4 times more ventilation than apices. Circulation- Low pressures in pulmonary circulation are affected by gravity Bases of upright lungs receive 20 times more blood flow than apices.
Gas TransportHow they are carried around the body.
Respiratory Examination• Common Problems- Asthma. – Baseline control • Usual exercise tolerance • Frequency of attacks • Best Peak expiratory flow rate • Usual precipitating factors • Medication • Usual response to therapy • Previous hospital/ITU admissions • Symptoms suggestive of poor baseline control Jonathan Downham 2010
Respiratory Examination• Common Problems – Asthma – Drug History • Do they have a nebuliser at home? • Do they use a bronchodilator? • Do they take theophylline or aminophylline? (bronchodilators). • Do they take steroids? • Are they on medication which aggravates the symptoms... Beta blockers, aspirin. • Demonstrate inhaler technique. Jonathan Downham 2010
Respiratory Examination• Common Problems – Chronic Obstructive Pulmonary Disease (COPD) – Detailed history • Time course • Treatment given and effects • Any hospital admissions in the last year • Baseline function • Chronically deteriorating exercise tolerance. • Quantify normal amounts of sputum Jonathan Downham 2010
Respiratory Examination• Common Problems – Chronic Obstructive Pulmonary Disease (COPD) – Past Medical History – Drug History – Social History – Review of systems. Jonathan Downham 2010
Respiratory Examination• Common Problems – Chest Infection – History • Cough • Sputum Production • Dyspnoea • Wheeze • Pleuritic chest pain • Fever. – Drug History. Jonathan Downham 2010