Respiratory Flashcards
What are the functions of the respirator system
Gas exchange: O2 passes form air to blood; CO2 passes from blood into air
Speech
Smell
How can the function of respiratory be divided
Conducting portion: transports air; conditions air (warms, moistens, filters)
Respiratory portion: thin, moist, delicate membrane; site of caseous exchange
What are the paranasal sinuses and their role
Cavities within the skull sitting parallel to the nasal cavity
Produces mucus to protect from pathogens which trickles out when infected, to cause a runny nose
Frontal sinuses
Ethmoidal air cells
Sphenoid sinus
Maxillary sinus
What are the chonchae in the nasal cavity
Three ridges which create turbulence
What is a meatus
Hole which allows the air to pass from the chonchae into the sinuses
What is the mediastinum
Midline region which encloses the heart, major vessels, major nerves, trachea and oesophagus
What are the structures of left and right lungs
Right:
3 lobes: superior, inferior, middle
Fissure: oblique, horizontal
Left:
2 lobes: superior, inferior
Fissure: oblique
There are segments with their own venous drainage, arterial supply and nerve supply
What is on the medial surface of the lungs
Bronchi: most posteriorly
Pulmonary arteries: anterior to bronchi, superior to veins
Pulmonary veins: anterior and inferior
What is the upper vs lower respiratory tract
Everything above the larynx is upper and everything below the larynx is lower respiratory tract
What are the functions of the thoracic cage
Protection: bony cage around vital organs
Respiratory: Changes in thoracic volume underlie movement of fresh air into lungs and stale air out
What is in each intercostal space
3 thin muscle layers:
External intercostal
Internal intercostal
Innermost intercostal
Neurovascular bundle:
Intercostal vein
Intercostal artery
Intercostal nerve
What are the characteristics of the pleura
A membranous sac that encloses the lung and forms the pleural cavity
Visceral and parietal
What is breathing
The bodily function that leads to ventilation of the lungs
What are the pleural cavities
Two pleural cavities either side of the heart in the thoracic
Pleural cavity contains a thin film of fluid which help the lung to slide and creates surface tension between parietal and visceral layer to aid inspiration
What are the two types of disease that can affect ventilation and some examples
Obstructive: Increased RV, FRC (emphysema) Reduced TLC (COPD) Examples: Asthma, COPD, lung cancer Restrictive: Reduced RV, FRC, VC, TLC Intrinsic: pulmonary fibrosis Extrinsic: pneumothorax, disorders if the thoracic skeleton
How does pressure change in inspiration vs expiration
Inspiration: atmospheric pressure > alveoli pressure
Expiration: atmospheric pressure < alveoli pressure
What is the equation to determine how airway obstruction has a major effect on air flow
Flow= (k. change in pressure. r4)/ L
What inspiratory muscles are used for each type of breathing
Quiet: diaphragm, external intercostals stabilise rib cage
Increasing effort: diaphragm, external intercostal lift and expand rib cage, accessory muscles, neck muscles, shoulder girdle muscles
What expiratory muscles are used for each type of breathing
Quiet: elastic recoil of tissues
Increasing effort: internal intercostals, abdominal wall muscles
How are the respiratory muscles innervated
Diaphragm: phrenic nerve (C3, C4, C5)
Intercostals: segmental thoracic nerves
What is tidal volume
The volume of air move in or out of the lungs during normal breathing
at rest 6-7 ml/kg
during exercise 15ml/kg
What is inspiratory reserve volume
As deep a breath in as possible
typical: 430 ml/kg
What is expiratory reserve volume
as deep a breath out as possible
typical: 22ml/kg
What is the residual volume
air remaining in lungs even after a maximal expiration
typical: 14.5 ml/kg
What is total lung capacity
Tidal volume + inspiratory reserve volume + expiratory reserve volume + residual volume
What is vital capacity
Tidal volume + inspiratory reserve volume + expiratory reserve volume
What is functional residual capacity
Expiratory reserve volume + residual volume
What is measured by vitalograph
Forced vital capacity (FVC)
Forced expiratory volume in 1 second (FEV1)
What is measured by a peak flow meter
Peak expiratory flow rate (PEFR)
What is compliance
The change in lung volume pre unit change in intrathoracic pressure
What is the surfactant layer
Reduces surface tension by acting as a detergent Produced by type II alveolar cells 90% phospholipid 10% protein Increases pulmonary compliance Prevents atelectasis Aids alveolar recruitment Minimises alveolar fluid Deficient in infant respiratory distress syndrome
What is the equation of proportion for rate of diffusion
Rate of diffusion @ surface area @ pressure gradient
@ = proportional to
What is the pressure gradient
The difference in partial pressure of the respective gases in the alveolus and the blood
What is the partial pressure of a gas in mixture of gases
The pressure that it would exert if it was the only gas in the container
What is the universal gas equation
PV =nRT
Pressure x volume = number of moles x the gas constant x temperature (kelvins)
How can the partial pressure of a gas be calculated?
Fractional conc x pressure of full mixture of gas
What are the characteristics of partial pressure of oxygen in alveoli
Lower than in room air because:
inspired air is humidified in the upper airway
o2 and co2 mixed
more O2 molecules consumed than CO2 molecules produced
How is oxygen diffusing capacity measured
Oxygen uptake/ (alveolar PO2 -mean pulmonary capillary PO2)
How is carbon monoxide diffusing capacity measured
carbon monoxide uptake/ alveolar PCO
What are problems which can occur within alveoli and how do these look
Alveolar fibrosis: thickening of alveolar wall
Pneumonia: alveolar consolidation
Pulmonary edema: frothy secretions
Interstitial edema
Emphysema: alveolar-capillary destruction (COPD)
Atelectasis: alveolar collapse
What is the process of pharyngeal dilator reflex
Pressure receptors -> brainstem -> pharyngeal muscle contraction
What are afferent and efferent signals
Afferent are going towards brain
Efferent are going away from brain
What are the characteristics of the upper airway
Continuous muscle activity is needed to keep the airway patent
Reflex control of the muscles is rapid and critical
Control of the muscles is often poor such as during sleep or with sedative drugs
What are the types of epithelial cells
Pseudostratified: nose and pharynx, long and thin
Columnar: trachea and bronchi, quite tall
Cuboidal: bronchioles, as tall as they are high
What are goblet cells
Secrete mucin in granules
Sit in epithelia cells
What are the two layers above the epithelial cells
Periciliary layer: Salty and watery
Mucous layer: sticky and mucousy
What inhibits cilia function
Tobacco smoke
Inhaled anaesthetics
Air pollution
Infection
What are the function of the airway lining fluid
Humidification
Airway defence
Where are inhaled particles deposited
Very large: nose and pharynx
Large: large airways
Small: bronchioles
Very small: exhaled again
What are the non-immunological pulmonary defences
Physical barrier and removal
Chemical inactivation: lysozyme, protease enzymes e.g. elastase, antimicrobial peptides e.g. human B defensins
Alveolar macrophages
What are the immunological pulmonary defences
Humoral:
IgA (nose and large airways)
IgG (small airways)
IgE (allergic disease
Cell-mediated:
Epithelial cells
Macrophages
How is oxygen carried
Dissolved in blood
Combined with haemoglobin
What is the volume of O2 in blood
0.0232 x PO2(12.5) = 0.29ml.dl-1
How is O2 saturation calculated
HbO2/ HHb+HbO2
Oxygenated Haemoglobin/ De-oxygenated haemoglobin + oxygenated haemoglobin
What is the Hufner constant
1.39ml.g-1
Number of ml of O2 that one g go Hb can bind
What is a buffer
A solution that can minimise changes in the free H+ conc and therefore in pH
What are some buffer systems in blood
Bicarbonate
Plasma proteins
Haemoglobin
Phosphate
What is the blood pH
7.35-7.45
How is CO2 carried
Dissolved in blood
Carbamino compounds
Bicarbonate/carbonic acid
What is the equalibrium equation of CO2 and HCO3- and what acts as a catalyst on this
CO2 + H2O H2CO3 H+ + HCO3-
Carbonica anydrase
What is the Henderson-Hasselbalch equation
pH = pK + log10 [HCO3-] / [CO2]
What is the difference of respiratory and metabolic acidosis and alkalosis
R acidosis: Low pH, High PCO2, High HCO3-
M acidosis: Low pH, Low PCO2, Low HCO3-
R alkalosis: High pH, low PCO2, normal HCO3-
M alkalosis: High pH, normal PCO2, high HCO3-
What part of the respiratory tract is formed by endoderm and mesoderm
Endoderm: Inner lining of respiratory tract
Mesoderm: Vasculature and connective structures
How and when does the lung bud form
Grows ventrocaudally
Tracheo-oesophageal ridges separate the respiratory diverticulum from the foregut
Dorsally oesophagus
Ventrally trachea and lung bud which has now divided to form lung buds
How can formation of the lung bud go wrong
Tracheo-oesophageal fistulas
Result from incomplete division of foregut into oesophageal and respiratory portions
Most commonly associated with oesophageal atresia (closed or absent) resulting in abdomen rabidly distending as stomach fills with air
What is a fistula
Abnormal communication
What are congenital abnormalities which are often found together
Vertebral defects Anal atresia Cardiac defects Tracheo-oesophageal fistulas Oesophageal atresia Renal abnormalities Limb defects
VACTERL
What is pulmonary agenesis
Occurs when lung bud fails to split
Complete absence of bronchi and vasculature
Can be unilateral or bilateral
Bilateral genesis is incompatible with life
What is pulmonary hypoplasia
All components are present but incompletely developed
Severity determines the degree of respiratory compromise
May be found in association with congenital diaphragmatic hernia
What four parts can maturation of the lungs be divided into and what happens in each stage and at what time
Pseudoglandular: branching of respiratory tree to form terminal bronchioles; 5-17 weeks
Canalicular: Terminal bronchioles give rise to respiratory bronchioles, mesodermal tissue becomes highly vascularised; 16-25 weeks
Saccula/terminal sac: further terminal sacs (primitive alveoli), epithelium thins and differentiates, blood-air barrier; 26 weeks- birth
Alveolar period: Increase number of respiratory bronchioles and alveoli; 36 weeks - 8years old
What are the two types of epithelium in the terminal sac period
Type I pnuemocytes: across which gaseous exchange takes place
Type II pneumocytes: which secrete surfactant
What is ventilation, where does it occur and how is it measured
Movement of gases in and out of the lungs
Occurs through airways
Measured as change in volume per unit time
What is perfusion, where does it occur and how is it measured
Blood flow through any organ
Occurs through blood vessels
Measured as flow of blood per unit time
What is emphysema
Widespread destruction and dilation of distal airway
Regional destruction of vascular beds
Poor gas exchange and hypoxia
What is hydrostatic oressure
Force exerted by weight of a fluid due to gravity
What is a shunt
Deoxygenated blood reaching left side of the heart either bypassing lungs or failing to get oxygenated when in the lungs
What are the steps in the oxygen cascade
1: humidification
2: alveolar gas
3: alveolar-capillary diffusion
4: ventilation-perfusion mismatch and shunt
5: tissue diffusion
6: diffusion within cell
What is oxygen delivery
Amount of oxygen leaving the heart in one minute
DO2
How is oxygen delivery calculated
Amount of oxygen in blood (O2 carried by haemoglobin + dissolved O2) x amount of blood leaving heart (cardiac output)
What is oxygen consumption
Amount of oxygen used by the body in one minute (VO2)
How is VO2 measured
Direct calorimetry
Indirect calorimetry
What are factors that affect VO2
Age: peak at age 0-2 years, then falls for rest of life
Temperature: metabolic rate doubles with every 10 degrees C
Exercise
What is the respiratory exchange ratio (respiratory quotient)
The ratio of carbon dioxide production (VCO2) to oxygen comsumption (VO2)
RER
How is the respiratory exchange ratio affected
Acid-base balance
Hyperventilation
Metabolic fuel
How is energy generated
Glycolysis
Tricarboxylic acid cycle
Oxidative phosphorylation
What are the characteristics of glycolysis
Occurs in cytoplasm
Glucose to pyruvate or lactate
No oxygen required
2 ATP molecules per glucose
What are the characteristics of tricarboxylic acid cycle
Occurs mostly in mitochondria
Acetyl CoA (from glycyolysis) to CO2
38 ATP molecules per glucose
What are the characteristics of oxidative phosphorylation
Occurs in mitochondria
NADH provides H+
H+ combines with O2 to produce water
ATP produced
What are the causes of cellular hypoxia
Anoxic: lack of O2 in blood
Anaemic: lack of haemoglobin
Stagnant: lack of blood supply
What is the ventral respiratory group (VRG)
Contains mixed neurones, some fire during inspiration, some during expiration
What is the dorsal respiratory group (DRG)
Contains neurones which fire during inspiration
What does the bpneustic centre do
Stimulates inspiratory neurones
What does the pneuomotaxic centre do
Inhibits inspiratory neurones
What are pulmonary stretch receptors
Afferent fibres from smooth muscle of bronchi and trachea
Run in the vagus nerve to the respiratory centre (medulla)
What generates a cough
Receptors throughout the airways which when stimulated initiate an explosive expiration
What are baroreceptors
Sense blood pressure, can also influence ventilation
Increase in BP leads to decrease in ventilation and vice versa
What are J-receptors
Juxtacapillary
Lie close to capillaries around the alveolar walls
Activated by trauma such as pulmonary oedema, inflammatory agents, pneumonia
Activation triggers increased ventilation
What do chemoreceptors do
The chemical regulation of breathing
What are central chemoreceptors
Specialised regions close to medulla respiratory centres but also close to a rich blood supply
Sensitive to O2, CO2 and H+
How does the body respond to altitude
Hyperventilation and respiratory alkalosis
Increased 2,3-DPG causes better unloading of oxygen
Polycythaemia-slow to develop
Bicarbonate excretion from CSF and kidneys
Diuresis
Hyponatraemia
Acetazolamide
What is surface pressure
1 atmosphere
100 kPa
How does pressure change in the sea
10m depth increases pressure by 1 atmosphere
What is the mechanism of a cough
Cough receptors or lung irritant receptors -> cough centre in medulla -> vagal stimulation leading to cough
What do expectorants do
Increase volume of secretion in a productive cough
What do mucolytics do
Decrease the viscosity of mucus in a productive cough
What is useful vs useless cough
Useless: persistent and unproductive, dry cough
Useful: expels secretions, productive cough
How is a dry cough suppressed
Afferent side: reduce stimuli
Efferent side: medullary cough centre
What are the most common causes of chronic cough
Upper airways cough syndrome
Bronchial asthma
Chronic obstructive pulmonary disease (COPD)
Gastroesophageal reflux disease
What does chronic lung disease do
Inflammation
Bronchoconstriction
Secretions
What are types of bronchial asthma
Asthma associated with allergic reactions
Asthma not associated with specific allergen
Exercise induced asthma
Asthma associated with chronic obstructive pulmonary disease
How is asthma treated
Non specific reduction of bronchial hyperactivity: life style, corticosteroids
Dilation of narrowed bronchi: Mimicking dilator neurotransmitter: sympathomimetics
Direct acting bronchodilators: methylxanthines
Blockade of constrictor transmitter: anticholinergics
Prevention of release of transmitter: mast cell stabilisers
Antagonism of released transmitter: leukotriene receptor antagonists
How do corticosteroids work and how can they be taken
Anti-inflammatory
Reduced bronchial reactivity
Inhaled and orally
What are the characteristics of leukotriene receptor antagonists
Uses: allergen induced asthma, exercise induced asthma, reduced frequency of exacerbations
Given orally
Not effective in acute asthma
Minor adverse effects: headaches, gastritis, flu-like symptoms, CS syndrome
What are some sympathomimetic agents
B2 agonist agents:
Short acting: salbutamol, terbutaline
Long acting: salmeterol, formetrol
Non-selective: adrenaline
What are the characteristics of COPD
Slowly progressive Airflow obstruction Little or no reversibility Does not change much over several months Predominantly caused by smoking Symptoms improve in 90% if stop smoking Reduced FEV1/FVC ratio
What is FEV1
Forced expiratory volume in 1 second
Volume of air that can be expelled from maximum inspiration in the first second
Time dependent and reflects airway caliber
What is FVC
The forced vital capacity of the lung
The volume of air that can be forcibly expelled from the lung from the maximum inspiration to the maximum expiration
Volume dependent and reflects lung volume
What are the symptoms of COPD
Breathlessness
Wheezing
Phlegm
Cough
How are pack years calculated
(Number of cigarettes per day/ 20) x number of years
What is asthma
A chronic inflammatory disorder of the airways
Airway hyper-responsiveness
Recurrent episodes of wheezing and breathlessness
Chest tightness, Coughing particularly at night or in the early morning
Variable airflow obstruction that is often reversible, either spontaneously or with treatment
Investigated using peak flow meter
What are the differences between intrinsic and extrinsic asthma
Extrinsic: Family history, starts in childhood, eczema/rhinitis, percipitating factors, positive skin tests, episodic
Intrinsic: Adulthood, negative skin tests, persistent symptoms, no clear percipitating factors, exacerbated by infections
What are the symptoms of lung cancer
Cough Breathlessness Wheeze Stridor Dysphagia Hoarse voice Chest pain Bone pain Neurology Anorexia Weight loss Clubbing
What investigations are done in lung cancer patients
Chest X-ray CT scan Bronchoscopy Percutaneous fine needle aspiration/biopsy Mediastinoscopy VATS Bone scan Endobronchial ultrasound
What are the symptoms of Cystic Fibrosis
Weight loss Increase cough Thich green sputum Haemoptysis Fatty stools Reduced vision Clubbing
What is bronchiectasis
Chronic dilation of one or more bronchi
Poor mucous clearance
Predisposition to bacterial infection
What are the symptoms of bronchiectasis
Persistent purulent sputum Haemoptysis Breathlessness Wheeze Sinustitis nasal symptoms Weight loss Pleurisy Nasal polyps
What investigations are done for bronchiectasis
History Genetics Sweat test Faecal elastase Ciliary beat frequency Sperm analysis Autoantibody screen Sputum analysis Aspergillus antibodies Lung function
What treatment is given for bronchiectasis
Physiotherapy Prompt antibiotics Intravenous antibiotics Nebulised antibiotics Annual influenza vaccination
What are the symptoms of pneumonia
Progressive breathlessness
Fever with shivering attacks
Left sided sharp chest pain
General lathargy
What are the treatments of pneumonia
Antibiotics Oxygen Analgesia Fluids Physiotherapy Nutrition Stop smoking
What is type 2 vs type 1 respiratory failure
Type 1: Low level of oxygen in the blood without an increased level of CO2 in the blood, so PaCO2 may be normal or low
Type 2: Buildup of CO2 levels (PaCO2) that has been generated by the body but cannot be eliminated
What is a tension pneumothorax
The tissue forms a one way valve allowing air to enter the pleural space and preventing its escape, pushing the mediastinum to the opposite side resulting in obstruction of venous return to the heart
What are the symptoms of a tension pneumothorax
Very bruised
Excrutiating pain in his left chest which is tender to touch
Very short of breath
