Respiratory System Flashcards
How many people die from respiratory disease in the UK?
1 in 5
What is the biggest cancer killer in the UK?
Lung cancer
What might cause breathlessness?
- Lung disease
- Heart disease
- Pulmonary vascular disease
- Neuromuscular disease (e.g. diaphragm weakness)
- Systemic disorders (e.g. anaemia, hyperthyroidism, obesity)
What nerves provide a sense of smell?
Olfactory nerve
Where do the olfactory nerves connect to?
Olfactory bulb and then the olfactory tract
What sinus lies above the eyebrows?
Frontal sinus
What sinus lies in between the eyes?
Ethmoid sinuses
What sinus lies under the eyes?
Maxillary sinuses
What is the most posterior sinus?
Sphenoidal sinuses
What are the parts of the pharynx, starting superiorly?
Nasopharynx
Oropharynx
Laryngopharynx
What is the muscle in the trachea called?
Trachealis muscle
What ligaments are found in the trachea?
Anular ligaments
What reduces surface tension in bronchioles and alveoli?
Surface tension
What are the main areas of the chest?
Lungs and mediastinum
How many lobes in the lungs?
Left lung: 2 lobes
Right lung: 3 lobes
What are the names of the fissures in the lungs?
Left: Oblique fissure
Right: Oblique fissure and horizontal fissure
How many segments are there in each lung?
Left lung: 8
Right lung: 10
What is the pressure of oxygen in the air and in the blood?
PO2 Air= 100mmHg
PO2 Blood= 40mmHg
Where is the diaphragm? When is it highest?
Margin attached to costal margin
Highest in expiration
What nerve provides motor innervation to the diaphragm? Where does it originate in the spine?
Phrenic nerve
C3, 4, 5
What is minute ventilation?
The volume of air expired in one minute (VE) or per minute
What is respiratory rate?
(RF) The frequency of breathing per minute
What is alveolar ventilation?
(Valv) The volume of air reaching the respiratory zone
What is respiration?
The process of generating ATP either with an excess of oxygen (aerobic) and a shortfall (anaerobic)
What is anatomical dead space?
The capacity of the airways nincapable of undertaking gas exchange
What is alveolar dead space?
Capacity of the airways that should be able to undertake gas exchange but cannot (e.g. hypoperfused alveoli)
Alveoli without a blood supply
What is physiological dead space?
Equivalent to the sum of alveolar and anatomical dead space
What is hypoventilation?
Deficient ventilation of the lungs; unable to meet metabolic demand (increased PO2- acidosis)
What is hyperventilation?
Excessive ventilation of the lungs atop of metabolic demand (results in reduced PCO2- alkalosis)
What is hyperpnoea?
Increased depth of breathing (to meet metabolic demand)
What is hypopnoea?
Decreased depth of breathing (inadequate to meet metabolic demand)
What is apnoea?
Cessation of breathing (no air movement)
What is dyspnoea?
Difficulty in breathing
What is bradypnoea?
Abnormally slow breathing rate
What is tachypnoea?
Abnormally fast breathing rate
What is orthopnoea?
Positional difficulty in breathing (when lying down)
What pleural membrane surrounds the lungs?
Visceral pleural membrane
What pleural membrane covers the chest wall?
Parietal pleural membrane
What fills the pleural cavity?
A protein-rich pleural fluid
fixed volume
What is a haemothorax?
Intrapleural bleeding
When are the forces in the lungs equal?
At the end of a normal breath out
What is tidal volume?
The amount of breathing you are doing to meet metabolic demand (∼500mL - increases with exercise)
What is your inspiratory reserve volume?
The amount you can breath in (up to total lung capacity) after a normal tidal breath inhalation
∼3100mL
What is expiratory reserve volume?
The amount you can exhale after a normal tidal breath exhalation
∼1200mL
What is risidual volume?
The amount of air left in the lungs which you cannot exhale
∼1200
What is total lung capacity?
Total lung volume
= IRV+TV+ERV+RV
∼6L
What is vital capacity?
Total of the volumes in the lungs we have access to
=IRV+TV+ERV
∼4800mL
What is functional residual capacity?
Amount of air in your lungs at the equilibrium point (when forces are equal at the end of normal expiration)
=ERV+RV
∼2400mL
What is inspiratory capacity?
From your functional residual capacity how much air can you draw into the lungs, if you put the effort in (air in from equilibrium point)
=IRV+TV
∼3600mL
What factors affect lung volumes and capacities? (5)
1) Body size (height, shape)
2) Sex
3) Disease (pulmonary, neurological)
4) Age (chronological, physical)
5) Fitness (innate inheritance, training)
What is negative pressure breathing? When do we do this? What is the relationship between Palv and Patm?
Normal healthy breathing- creating a negative pressure in the lungs for the air to be sucked into
Palv is reduced below Patm
What is positive pressure breathing? When so we do this? What is the relationship between Palv and Patm?
Occurs when on ventilation or undergoing CPR
Patm is increased above Palv
What is the pressure in the pleural cavity?
Ppl=-5cmH2O
What is transmural pressure? What affect does it have on ventilation?
The pressure difference (Pinside - Poutside)
A negative transrespiratory pressure will lead to inspiration
A positive transmural pressure leads to expiration
Describe the changes that occur during quiet breathing and the mechanism which allows this to happen
1) At equilibrium: No volume change, pressure at equilibrium
2) Chest wall expands and diaphragm pulls down: create negative pressure, volume goes up
3) More air flows in and pressure goes back to equilibrium
4) Recoil forces pull the lungs closed: pressure goes up and volume starts to go down
5) Return to equilibrium
What is the conducting zone in the lungs? What is the volume of this area?
Anatomical dead space
Doesn’t participate in gas exchange
16 generations. Typically 150mL in adults at FRC
What is the respiratory zone in the lungs? What is the volume of this area?
Alveolar ventilation
Where gas exchange takes place.
7 generations. Typically 350mL in adults
If someone has an obstructive disease, how would this affect their FVC?
It would be lower
What percentage of lung capacity can a healthy person expect to exhale for FEV1?
75-100%
What percentage of lung capacity can a person with an obstructive disease expect to exhale for FEV1?
50%
If someone has a restrictive disease, how would this affect their FVC?
It would be lower
What percentage of lung capacity can a person with a restrictive disease expect to exhale for FEV1?
75-100%
What are the approximate FEV1/FVC ratios for normal, restrictive and obstructive disease?
Normal= 73% Restrictive= 87% Obstructive= 53%
Restrictive = >75%
Obstructive=
What happens to a flow-volume loop with obstructive disease? (mild and severe)
Displaced to the left with coving on exhalation
Mild: Flow rate not much lower than normal
Severe: Shorter curve (flow rate) than normal
What happens to a flow-volume loop with restrictive disease?
Displaced to the right
Narrower curve
How does obstruction effect a flow-volume loop? What are the different types?
e.g. tumour
Extrathoracic: Inspiratory blunting, otherwise normal
Intrathoracic: Expiratory blunting, otherwise normal
Fixed airway obstruction: Inspiratory and expiratory blunting, otherwise normal
What is Dalton’s Law?
Pressure of a gas mixture is equal to the sum of the partial pressures of the gases in that mixture
What is Boyle’s Law?
At a constant temperature, the volume of a gas is inversely proportional to the pressure of that gas
What percentage of gases make up the air?
Nitrogen: 78.09 Oxygen: 20.95 Argon: 0.93 Carbon dioxide: 0.04 Ne, He, H, Kr etc:
If inspiring dry air at sea level: PO2 = 21.3kPa PCO2 = 0kPa PH2O = 0kPa what changes occur to the gas as it passes through the conducting airways to the respiratory airways?
Air is WARMED, HUMIDIFIED, SLOWED and MIXED Conducting airways: PO2 = 20kPa PCO2 = 0kPa PH2O = 6.3kPa
Respiratory airways:
PO2 = 13.5kPa
PCO2 = 5.3kPa
PH2O = 6.3kPa
How much greater is the affinity for the fourth oxygen molecule binding to haemoglobin, than the first one?
300 times greater
What does haemoglobin binding allow the binding of in the centre of a haemoglobin molecule?
2, 3-DPG
What is methaemoglobin? What disease is associated with it?
Haemoglobin with iron in Fe3+ state which does not bind haemoglobin
Methaemoglobinaemia
At what point is haemoglobin 50% saturated?
P50
What is a rightward shift of the oxygen dissociation curve associated with?
↑ temperature
Acidosis (Bohr effect)
Hypercapnia
↑ 2, 3-DPG
What is a leftward shift of the oxygen dissociation curve associated with?
↓ temperature
Alkalosis
Hypocapnia
↓ 2, 3-DPG
What causes a downward shift of the oxygen dissociation curve?
Anaemia
Impaired oxygen-carrying capacity
What causes an upward shift of the oxygen dissociation curve?
Polycythaemia
Increased oxygen-carrying capacity
What does carbon monoxide do to the oxygen dissociation curve?
Causes a downward and leftward shift
What is myoglobin?
A monomer that is found in muscles that stores oxygen needed in exercise
What are the gas values in post-alveolar venular blood? PO2 SaO2 HbO2 CDO2 CaO2
PO2 = 13.5kPa SaO2 = 100% HbO2 = 20.1mL/dL CDO2 = 0.34mL/dL CaO2 = 20.4mL/dL
What are the gas values once the blood has returned to the heart? Why are they different? PO2 SaO2 HbO2 CDO2 CaO2
Blood supplying the lungs is added to the oxygenated blood so the values drop PO2 = 12.7kPa SaO2 = 97% HbO2 = 20mL/dL CDO2 = 0.32mL/dL CaO2 = 20.3mL/dL
What are the gas values that return to the right side of the heart? PO2 SaO2 HbO2 CDO2 CaO2
PO2 = 3.5kPa SaO2 = 75% HbO2 = 15mL/dL CDO2 = 0.14mL/dL CaO2 = 15.1mL/dL
What is the oxygen flux?
△ = -5mL/dL △ = -250mL O2/min
How is CO2 transported in the body?
Dissolves in the plasma
CO2 + H2O ⇌ H2CO3 ⇌ H+ + HCO3-
What are the gas values of carbon dioxide in arterial blood? PaCO2 CO2 as HCO3 HbCO2 CDCO2 CaCO2 pH
PaCO2 = 5.3kPa CO2 as HCO3 = 43mL/dL HbCO2 = 2.5mL/dL CDCO2 = 3.0mL/dL CaCO2 = 48.5mL/dL pH = 7.40
What are the gas values of carbon dioxide in venous blood? PaCO2 CO2 as HCO3 HbCO2 CDCO2 CaCO2 pH
PaCO2 = 6.1kPa CO2 as HCO3 = 45.2mL/dL HbCO2 = 3.8mL/dL CDCO2 = 3.4mL/dL CaCO2 = 52.4mL/dL pH = 7.36
What is the CO2 flux?
△ = +4mL/dL △ = +200mL CO2/min
What happens to CO2 when it enters a red blood cell?
CO2 + H2O ⇌ H2CO3 (carbonic anhydrase) ⇌H+ + HCO3-
HCO3- (bicarb) ⇌ Cl- + H2O (swapped in plasma- Chloride shift)
CO2 + amine end → carbaminohaemoglobin
What are the three roles of haemoglobin?
1) Oxygen transport
2) Carbon dioxide transport
3) Buffering (accepts H+ from CO2 reaction)
How is carbon dioxide transported in arterial and venous blood? Include proportions
Arterial = 48mL/dL HCO3- = 43.0mL/dL HbCO2 = 2.5mL/dL Dissolved = 2.5mL/dL
Venous = 52mL/dL HCO3- = 45.2mL/dL HbCO2 = 3.0mL/dL Dissolved = 3.8mL/dL
What are cardiac output and ventilation roughly?
CO = 5L Ventilation = 6L
What part of the lungs is most perfused?
Basal area
How do you calculate alveolar ventilation?
= (Tidal volume - dead space) x respiratory frequency
How do you calculate the ventilation perfusion ratio?
= Alveolar ventilation / cardiac output
How do the branches of the lungs divide?
Dichotomous branching
What is the structure of the cartilage in the trachea?
C shaped
What cells make up the surface of the airway?
Cilia cells
Goblet cells
What are the contractile cells of the airway?
Smooth muscle
What are the secretory cells of the airway?
Goblet (epitheliul)
Mucous, serous (glands)
What connective tissue is found in the airway?
Fibroblast, interstitial cell (elastin, collagen, cartilage)
How do goblet cells secrete mucus?
Upon stimulus granules move to the surface of the cell and fuse. Lots of water is taken into the cell, it expands and explodes out
What are the different types of cells which make up the airway submucosal glands? What do they do?
Mucous acini: secrete mucous
Serous acini: secrete antibacterials (e.g. lysozyme) (produce a watery secretion which flushes over the mucous acini)
Glands also secrete water and salts (e.g. Na+ and Cl-)
How many cilia are there per cell?
Around 200 per cell
What are the functions of the airway epithelium?
1) Secretion of mucins, water and electrolytes (components of mucus)
2) Movement of mucus by cilia (mucociliary mediators
3) Physical barrier
4) Production of regulatory and inflammatory mediators
- NO (by NOS)
- CO (by hemeoxygenase, HO)
- Arachidonic acid metabolites (e.g. prostaglandins COX)
- Chemokines (e.g. IL-8)
- Cytokines (e.g. GM-CSF)
- Proteases
What three things does inflammation of airway smooth muscle cause?
1) Structure Hypertrophy, proliferation 2) Tone (airway calibre) Contraction, relaxation 3) Secretion Mediators, cytokines, chemokines
What happens when there is inflammation in airway smooth muscle?
Smooth muscle cells upregulate NOS, COX and cause inflammatory cell recruitment (cytokine, chemokines and adhesion molecules)
(e.g. asthma causes enlargement of the muscle)
How much of the cardiac output supplies the airway?
1-5%
100-150ml/min/100g tissue
What are the functions of the tracheo-broncial circulation?
1) Good gas exchange
2) Contributes to warming of inspired air
3) Contributes to humidification of inspired air
4) Clears inflammatory mediators
5) Clears inhaled drugs (good/bad depending on drug)
6) Supplies airway tissue and lumen with inflammatory cells
7) Supplies airway tissue and lumen with proteinacious plasma (plasma exudation)
What is plasma exudation in the airways?
Where venules in the airway contract which causes the cells to pull away from each other and form a gap which allows plasma to flow through
What condition is plasma exudation associated with?
Asthma
What nerve innervates the airway? What part of the nervous system does this belong to?
Vagus nerve
Parasympathetic pathway
What causes relaxation of the airway?
Nitric oxide by nitric oxide synthase (NOS)
If there are airborne irritants in the airway what is the cholinergic mechanism in the airway?
Sensory nerves feedback to CNS Vagus nerve to parasympathetic ganglion Postganglionic releases ACh on muscarinic receptor to 1) Submucosal gland 2) Smooth muscle 3) Blood vessel
What are the regulatory-inflammatory cells in the airway?
Eosinophils Neutrophils Macrophage Mast cell T lymphocyte
What three respiratory diseases cause a loss of airway control?
Asthma
Chronic obstructive pulmonary disease (COPD)
Cystic Fibrosis
What is asthma?
A clinical syndrome characterised by increased airway responsiveness to a variety of stimuli
Airway obstruction: varies over short periods of time and is reversible (spontaneously or with drugs)
Dyspnea, wheezing and cough (varying degrees- mild to severe)
Airway inflammation causes remodelling
What is the pathology of asthma?
Mucus plug Epithelial fragility Basement membrane thickening Vasodilation (congested vessels) Cellular infiltration of tissue Airway wall thrown into folds
What is the order of the airways from trachea to alveoli?
Primary bronchus Secondary bronchus Tertiary bronchus Bronchiole Terminal bronchiole Alveoli
Where are the vocal cords located?
In the larynx
What are the functions of epithelium in the lungs?
1) Forms a continuous barrier, isolating external environment from host
2) Produces secretions to facilitate clearance, via mucociliary escalator, and protect underlying cells as well as maintain reduced surface tension (alveolae)
3) Metabolises foreign and host-derived compounds
4) Releases mediators
5) Triggers lung repair processes
What happens to the airway epithelium in COPD?
Increased goblet cell numbers (goblet cell hyperplasia) and increased mucus secretion
(causes chronic bronchitis)
How much of the epithelium is made up of goblet cells?
Normally 20% of the epithelium
What happens to goblet cells in smokers?
Goblet cell number at least doubles
Secretions increase
Secretions are more viscoelastic
Cigarette smoke particles are trapped but also harbours microorganisms, enhancing chances of infection
What airways are goblet cells found in?
Large, central and small airways
What airways are ciliated cells found in?
Large, central and small airways
How much of the epithelium is made up of ciliated cells?
Normally 80% of the epithelium
How do cilia beat?
Metasynchronously
What happens to the cilia in smokers and smokers with bronchitis?
Ciliated cells are severely depleted
Cilia beat asynchronously
Ciliated cells found in bronchioles (further down respiratory tract)
Cilia unable to transport thickened mucus
Reduced mucus clearance leading to respiratory infection and bronchitis. Airways obstructed by mucus secretions
What happens in COPD?
Small airways disease and emphysema
- Decreased elasticity of supporting structure
- Plugging, inflammatory narrowing and obliteration of small airways
- Destruction of peribronchiolar support
What cells are found in the respiratory bronchiole?
Bronchiolar ciliated cells
Clara (club) cells
What are clara cells? How much of the bronchiole is made up of them?
∼20% of epithelial cells (lower in smokers)
Secretory cells
Detoxification
Repair/ progenitor cells
What cells make up the alveoli?
1) Type I epithelial cells
2) Type II epithelial cells
3) Stromal cells (myo) fibroblasts
What are type I epithelial cells?
95% of the alveolar surface
Large cells (∼80μm)
Very thin to allow gas exchange
0.2-0.5μm thin
What are type II epithelial cells?
Cuboidal (∼10μm)
Secrete surfactant
Repair/progenitor cells
Precursor of type I cells
Outnumber type I cells but are much smaller
Contain lamellar bodies which store surfactant prior to release onto the air-liquid interface
What are stromal cells?
(Myofibroblasts)
Make ECM- the lung’s cement
Collagen, elastin, to give elasticity and compliance
Divide to repair
What is the ratio between type I and II cells and what percentage of the surface of the alveoli are made up of each?
Type I : Type II
1 : 2
95% : 5%
What is the function of surfactant?
Lowers surface tension and prevents alveolar collapse on expiration
What happens during alveolar repair?
Increased type II cells (ie repair)
Increased fibroblasts
Increased collagen deposition
What is xenobiotic metabolism?
Process and detoxify foreign compounds such as carcinogens in cigarette smoke
How do the number of leukocytes differ in smokers?
Increases 10 fold
What is the function of leukocytes in the airway?
Phagocytosis
Antimicrobial defence
Synthesise antioxidants e.g. glutathione
Xenobiotic metabolism
What is the difference in leukocytes in the primary bronchus between a healthy individual and a smoker?
Healthy
30% Neutrophils
70% Macrophages
Smokers
70% Neutrophils
30% Macrophages
In the periphery of the lung what percentage of the leukocytes are macrophages?
80-90%
What proteases are produced by neutrophils and macrophages?
Neutrophil: serine proteinases (e.g. neutrophil elastase NE)
Macrophage: Metalloproteinases (e.g. MMP-9)
What effect do macrophage metalloproteinases and neutrophil elastase have on emphysema?
If you can’t produce MMP or NE you can’t produce emphysema
What do proteases do?
Substrates: proteins; connective tissues, elastin, collagen
Actiate other proteinases (e.g. NE degrades and activates MMP), inactivates antiproteases (e.g. MMP degrades and inactivates α-1 antitrypsin)
Activate cytokines/chemokines and other pro-inflammatory mediators
What is the function of oxidants produced by leukocytes?
Antimicrobial Generate highly reactive peroxides Interact with proteins and lipids Inactivate α-1 anti-trypsin Fragment connective tissue
What mediators do leukocytes secrete?
1) Chemokines
- IL-8 (neutrophil)
- MCP-1 (monocytes)
2) Cytokines
- IL-1β, IL-6, TNFα (inflammation)
3) Growth factors
- VEGF, FGF, TGFβ (cell survival, repair and remodelling)
What percentage os patients diagnosed with lung cancer die within 1 year? How many is this?
80%
40,000
What are the main causes of lung cancer?
SMOKING
Radon
Asbestos
What is p53?
Housekeeping gene- causes apoptosis (cell death) when cells threaten to become cancerous
What housekeeping genes prevent cancer?
pRB
p53
bax
How does smoking cause cancer?
Disrupts the housekeeping genes
What are the clinical features of lung cancer?
Haemoptysis (coughing up blood)
>3 weeks of: cough, chest/shoulder pains, chest signs, dyspnoea, hoarseness, finger clubbing
What are the two types of lung cancer?
Non-small cell cancer
Small cell lung cancer
What is the staging of lung cancer?
TNM classification Tumour (T1-4): T1: 30mm and in periphery T3: Close to other organs T4: Close to mediastinum Nodes (N0-3): N1: Hila nodes same side N2: Mediastinal nodes same side N3: Nodes on contralateral (other) side Metastases (M0 or 1): M1a: Metastases in same tissue M1b: Metastases in bone or brain etc
What treatment is used on small cell cancer?
Localised with fit patient: aggressive treatment of chemo and radio
Widespread: chemo
Widespread or weak: Palliate them
What treatment is used for non-small cell lung cancer?
Early detection: Surgical resection (if no metastases)
If metastases: Chemo or palliation
On average how long has lung cancer been present before detection?
13 to 15 years
What type of samples are used for cytology?
- Sputum
- Bronchial washings and brushings
- Pleural fluid
- Endoscopic fine needle aspiration of tumour/enlarged lymph nodes
What type of samples are used of histology?
- Biopsy at bronchoscopy
- Percutaneous CT guided biopsy
- Mediastinoscopy and lymph node biopsy (staging)
- Open biopsy at time of surgery (frozen section)
- Resection specimen
What is the difference between benign and malignant lung tumours?
Benign (e.g. chondroma):
Do not metastasise, can cause local complications (e.g. airway obstruction)
Malignant:
Potential to metastasise, but variable clinical behaviour from relatively indolent to aggressive. Commonest are epithelial tumours
What are the different types of non-small cell carcinoma?
- Squamous cell carcinoma (20-40%)
- Adenocarcinoma (20-40%)
- Large cell carcinoma (uncommon)
What percentage of lung cancers are small-cell carcinoma?
20-25%
What type of lung cancer is squamous cell carcinoma? Where does it normally arise?
Non-small cell carcinoma
Arise in the airways
What causes squamous cell carcinoma in smokers?
Smoking causes irritation to ciliated cells
Cells adapt to squamous cells which are “tougher”
Prevents mucus from being clear
Carcinogens become trapped in mucus which cannot be cleared from the airway. Repeated exposure to carcinogen causes mutations to cells, leading to carcinoma
As tumours develop they acquire more and more mutations
What type of lung cancer is adenocarcinoma? Where does this normally arise? How does it progress?
Non-small cell carcinoma
Arises in the periphery of the lung
Moves along the surface of the alveolar walls until it acquires the mutation to become invasive
Who is adenocarcinoma most common in?
Far east, females and non-smokers
What is the progression of a lung cancer?
Mutation caused by carcinogen
Carcinoma-in-situ
Invasive carcinoma
What type of cancer is large cell carcinoma? What is the most likely cell type?
Non-small cell carcinoma
Probably very poorly differentiated adeno/squamous cell carcinoma
Where are small cell carcinomas typically located? Who are these type of cancer normally present in?
Often central near bronchi
Almost always seen in smokers
What treatment is typically used in small cell lung carcinoma? What is the prognosis?
Chemoradiotherapy (surgery very rare as has usually spread by diagnosis)
Survive 2-4 months untreated
10-20 months with current therapy