Amy's Asthma Flashcards
Why are inhaled foreign objects more likely to enter right lung?
It is more vertically orientated and wider than the left
Where are higher centres of breathing located?
Pons
What is the aim of asthma therapy?
Symptomatic relief
Which types of hypersensitivity are most important in asthma?
Type I and IV
Which vertebrae does the trachea extend over in the adult?
C6-T4
Where does cricothyroid membrane lie?
Below level of vocal chords
What factors does peak flow depend on?
Age, sex, height, pathologies
What is the mucociliary escalator?
Inhaled particles are trapped in the mucus of the respiratory tract and cels secrete an antibiotic fluid and then cilia beat to waft this fluid either upwards (in the case of trachea and bronchi) or downwards (in the case of nasal cavities) so the fluid containing pathogens is swallowed (and destroyed by stomach acid) or coughed out.
What is the arterial oxygen pressure below which cyanosis will generally appear?
7 kPa
What do the paranasal sinuses do?
Decrease relative weight of bones of the face, increase resonance of voice, provides a buffer against blows to the face, insulates eyes and dental roots from temperature fluctuations of nasal cavity, humidifies and heats inhaled air due to slow air turnover
How do glucocorticoids work?
Suppression of pro-inflammatory cytokine gene activation by sequestering nuclear transcription factors from gene production preventing infiltration and activation of inflammatory cells in the airways reducing mucosal oedema and improving airflow
Where does the oesophagus pass through the diaphragm and why?
Through the muscular portion of the diaphragm as it acts as a sphincter to prevent reflux of food
Name 5 extrinsic irritations which cause coughing.
- Large heart due to congestive heart failure compressing bronchi and recurrent laryngeal nerve
- Pericarditis
- Large lymph node due to Hodgkin’s disease
- Trauma where force is applied to lung, mediastinum or pericardium
- Diverticula of oesophagus pressing on trachea
What are the attachments of the sternocleidomastoid muscle?
Superiorly to mastoid process of skull, then to the clavicle then inferiorly to the sternum
Name two xanthines.
Theophylline, aminophylline
What percentage of the population have chronic illness or disability?
15%
What is the main mechanism of anti-cholinergics?
Block effects of acetylcholine released from parasympathetic efferents, blocking mucus oversecretion and SM contraction
What do afferent nerve fibres of the lung do and what are they?
Sense stretch, chemical environment (J-receptors) and noxious stimuli (irritant receptors) via the vagus nerve
Which type of hypersensitivity is antibody independent?
Type IV
Where are the chemoreceptors affecting breathing located?
Around the exit of cranial nerves IX and X
Where in the lung does pneumonia usually affect?
One lobe
What increases broncho-motor tone?
Parasympathetic vagal stimulation, inflammatory mediators and irritants
What do central chemoreceptors respond to?
PCO2 of blood
What is instantaneous breathlessness a sign of?
Pulmonary embolism or pneumothorax
What is atopy?
Hypersensitivity to allergens, allergy
What is infection of paranasal sinuses caused?
Sinusitis
What are the 4 paranasal sinuses and where are they found?
Frontal- frontal bone of forehead
Maxillary- cheekbones on either side of nose
Ethmoidal- above nasal cavity
Sphenoidal- behind the ethmoidal sinus
Name two inhaled glucocorticoids.
Fluticasone and beclomethasone
Name an anti-cholinergic drug used to treat asthma.
Ipratropium
Where does the left phrenic nerve run on its course to the diaphragm?
It enters the thoracic inlet anterior to scalenus anterior and anterior to lung root, running over the left border of the heart until finally piercing the muscular portion of the diaphragm
Where do chemical and stretch receptors feed in to to control breathing?
Medulla
How is visceral pain of the lung transmitted?
Sympathetic nerves T1-4
What is the primary role of the larynx?
As the sphincter of the airways
What are the opposing forces applied to the visceral and parietal pleura?
The elastic recoil of the lungs pulls the visceral pleura inward and the muscle tone of thoracic wall and diaphragm pulls the parietal pleura outward
What causes breathlessness in asthma?
Increased work of breathing
What recruits eosinophils in type IV hypersensitivity?
IL-4, IL-5, IL-13
Which cells are involved in the pathology of asthma?
Th2 cells and eosinophils
What generation are bronchioles (non-respiratory)?
13-16
Which immunoglobulin plays a major role in type I hypersensitivity?
IgE
Which chemoreceptors does low PO2 stimulate?
Peripheral chemoreceptors
What could indicate a tension pneumothorax or collapsed lung in one side?
The chest expanding differentially
What are the anaphylatoxins of complement?
C3a and C5a
Where does the right phrenic nerve run on its course to the diaphragm?
It enters the thoracic inlet anterior to scalenus anterior and anterior to lung root, running over the right border of the heart until finally piercing the central tendon of the diaphragm
What decreases broncho-motor tone?
Sympathetic stimulation of B2 receptors by adrenaline
How does sabutamol work?
It is a B2 agonist that increases cAMP levels in target cells to induce smooth muscle relaxation, mast cell stabilisation (anti-histamine) and improved mucus clearance due to cilia activity
What does arterial baroreceptor stimulation cause?
Inhibits ventilation
What are the attachments of scalene muscles?
Proximally, the scalene muscles attach to cervical vertebrae and distally to first and second ribs
Where are irritant receptors located?
Between airway epithelial cells
Which muscles are used during quiet expiration and what is their action?
Expiration is quite a passive process, only the intercostals contract to prevent intercostal spaces bellowing outwards. Expiration really occurs due to relaxation of inspiratory muscles and elastic recoil of lungs.
What is adherence?
The extent to which the patient’s behaviour reflects agreed recommendations from practitioner
What factors affect the effectiveness of a placebo?
Size, shape, colour of pill, administration of medication. Setting: at home, in hospital. Patient’s characteristics (beliefs, anxiety, adherence) Practitioner characteristics: status, empathy. Patient-Dr. relationship
What is the laryngeal inlet?
The superior margin of the larynx
What is bronchial thermoplasty?
Radio-frequency ablation of parts of the airway to reduce smooth muscle contractility.
Where does the aorta pass through the diaphragm?
Posteriorly
Where does the breathing pattern get generated?
Brainstem
What are the physiological effects of asthma on the epithelium and respiratory tract?
Thickening of basement membrane, smooth muscle hypertrophy, vasodilation, mucus gland hyperplasmia, desquamation of epithelium, mucus plug in lumen, oedema of mucus, white blood cells presence
What is compliance?
The extent to which the patient’s behaviour reflects the recommendations from practitioner
Which membrane connects cricoid and thyroid cartilage in the larynx?
Cricothyroid membrane
What happens during inspiration of the cough reflex?
Glottis opens, bronchioles enlarge, lungs expand with help of diaphragm and thoracic and abdominal muscles so lungs are stretched ready for recoil
Where are pneumotaxic and apneustic centres located?
Pons
What is the name of a consultation process where doctor and patient agree on therapeutic decisions?
Concordance
Why do ingested liquids not flow into the trachea?
The laryngeal inlet is raised allowing liquids to escape down the piriform fossae on either side of it
What is said to increase compliance in Leg’s model?
Understanding, satisfaction and memory
Which immunoglobulin is produced in plasma by B cells and controls infection in intracellular fluid?
IgG
What does the epiglottis do?
Ascends during swallowing to prevent food from entering trachea by blocking it off
Name 5 intrinsic irritations which cause coughing.
- Hypertrophied tonsils
- Viral infections (some pharyngitis, influenza)
- Asthma
- Toxic gases (chlorine, cigarette smoke)
- Bacterial infections (whooping cough, streptococus, diphtheria, pneumonia)
When may cromones be useful?
In children as fewer side effects than glucocorticoids
Which receptors are responsible for deep augmented breaths taken every 5-20 min, coughing and some reflex larnygenal/bronchoconstriction?
Irritant receptors
What are the main determinators of non-adherence?
Cost, time, side effects, benefits e.g. progression, symtoms
Which asthma drugs are preventers?
Glucocorticoids, cromones, anti-leukotrienes, xanthines
Why do visceral and parietal pleura not separate?
The surface tension of pleural fluid, which must be below atmospheric pressure
Why is it sometimes worse to give hypoxic pateints 100% O2?
Especially overnight, when they do not control breathing voluntarily, breathing 100% O2 leads to absence of CO2 and loses the hypoxic drive so they may stop breathing all together
Which muscles are used during forced inspiration and what is their action?
Diaphragm descends fully
Scalene and sternocleidomastoid muscles elevate the first rib
External and internal intercostals, erector spinae, pectoralis muscles and serratus anterior raise the rib cage
Quadratus lumborum stablises lower ribs
Where does the IVC pass through the diaphragm and why?
Through the central tendon, there is no sphincter so the pressure of the chest aids venous return
How is parietal pleura innervated?
Via phrenic (C3,4,5) and intercostal nerves
What epithelial type is only found in the respiratory system?
Pseudostratified ciliated columner epithlium
What happens if the pleural sac is perforated (pneumothorax)?
Air rushes into the pleural space and surface tension of pleural fluid is lost so the visceral and parietal pleura separate. The elastic recoil of the lungs causes them to collapse.
What is type II hypersensitivity?
IgM antibodies react to cell membrane proteins of body as if they were foreign, recruiting inflammatory cells in classical pathway such C3a and C5a (chemoattractants) to attract killer cells to attack.
What are the half lives of sabutamol and salmeterol respectively?
5-6 hours and 17 hours
Where are chemosensitive areas located in the medulla?
Ventrolateral
What do cromones do? Give an example of a cromone.
Cromoyln sodium
Mast cell stablisers, mechanism uncertain.
How are vocal chords fully abducted during breathing?
Contraction of posterior cricoarytenoid muscles
What does stimulation of juxtapulmonary receptors cause?
Hyperventilation
What is the diaphragm?
A sheet of skeletal muscle separating thorax from abdomen. It has a central tendinous portion and a peripheral muscular part
What are the two classes of anti-leukotrienes? Give examples.
5’lipoxygenase inhibitors e.g. zileuton
Leukotriene receptor antagonists e.g. Monkelukast
Why are lungs elastic?
Due to elastic connective tissue and surface tension from the fluid lining the alevoli
Which muscles are used during forced expiration and what is their action?
Intercostals prevent bellowing.
Diaphragm is elevated forcefully by contraction of anterior abdominal wall muscles which depress ribs and compress diaphragm.
Posterior abdominal wall muscles depress 12th rib
Latissimus dorsi of the backmay also depress ribs especially in coughing and sneezing
What stimulates IgE release?
CD4 and Th2 cells
What does hyper resonance on percussion of the chest indicate?
Collapased lung or surgical removal of the lung
Where are ventral and dorsal respiratory groups?
Medulla
Which cells mediate type IV hypersensitivity?
CD4 and Th2 cells
Which asthma drugs are relievers?
B2 receptor agonists, anti-cholinergics, xanthines
What are the adverse effects of B2 agonists?
Muscle tremor- common
Tachycardia and palpitations- rare
Why are you more likely to hyperventilate in acidosis?
In acidosis, it takes a lower CO2 level to cause ventilation to increase and vice versa
Where is the cough centre?
The medulla
What bounds the laryngeal inlet?
Aryepiglottic muscles
How is sabutamol taken in and how much of the dose reaches the target cells?
MDI- metered dose inhalation, 15-20% reaches lungs
What is DerP?
The allergen produced by duct mite gut bacteria, main allergen involved in asthma
What is the mechanism of xanthines?
Inhibit phosphodiesterases, potentiating cAMP production inducing SM relaxation, blocking mucus hypersecretion, reducing survival of eosinophils
Which chemoreceptors does low O2 content stimulate?
None. There are no receptors for this.
What are the signs of hypercapnia?
Flushed skin, vasodilation, hyperventilation
How long may a granulomatous reaction occur after exposure in type IV hypersensitivity?
3-4 weeks
What is pneumotaxic centre?
A network of neurones in the pons which regulate the amount of air a person can take into the body with each breath.
What causes the wheal after a skin prick test?
Histamine released by degranulated mast cells increases permeability of vessels to fluid and causes the localised oedema, or wheal.
Where in the brain is higher, direct central control of breathing, which can bypass ANS, located?
The medulla, below the pons
What innervates bronchial smooth muscle to cause contraction?
1) Parasympathetic vagal efferents with M3 receptors.
2) Excitatory non-adrenergic, non-cholinergic ‘c-fibre’ efferents using substance P and neurokinin
Why is sleep apnoea more common in the overweight?
Larynx and soft tissue in the neck become looser and reduce breathing space
What happens during the expiration of the cough reflex?
Glottis closes at height of inspiration, chest contracts so intrathoracic pressure soars. When the glottis gives way and opens the air is expelled with great force and speed.
Which muscles are used during quiet inspiration and what is their action?
Diaphragm- moves downwards and decreases pressure in chest so air rushes into lungs
Scalene muscles- hold 1st rib stable
Intercostals- prevent the intercostal spaces bellowing inwards
Name an oral glucocorticoid.
Prednisolone
What mediates airway smooth muscle contraction in the nervous system?
Parasympathetic system, Ach, M3 receptors
What are the main factors which control autonomic breathing?
Neural controls from brainstem and lung receptors , chemical control via central chemoreceptors
What generation are respiratory bronchioles?
17-19
What is type IV hypersensitivity?
Delayed response in inflammation, antibody independant. T cell mediated, APC find allergen and present it to T killer cells.
Which dome of the diaphragm is higher and why?
The right dome sits higher than the left due to the presence of the liver below
What is the typical rate of non-adherence?
30-50%
At what oxygen saturation does haemoglobin lose the ability to retain oxygen?
40%
Which immunoglobulin is produced in the spleen by B cells and binds specific antigens?
IgM
What is the Henring-Breuer inflation reflex?
The rule that inhalation innately inhibits exhalation and vice versa
Which membrane connects thyroid cartilage and hyoid bone in the larynx?
Thyrohoid membrane
Where are breathing stretch receptors located?
Bronchial smooth muscle
What generation are bronchi?
2-12
How are arytenoid cartilages fully abducted during breathing?
Pull of lateral cricoarytenoid muscles
What are the adverse effects of xanthines?
Many, very narrow therapeutic window. Cause headaches, nausea, arrhythmias, diuresis, convulsions, behavioural changes
Where are vocal chords and arytenoid cartilages during speaking?
Partially separated, forcing air over the vocal chords so they vibrate
How could non-adherence be measured?
Survey, self-complete questionnaire, self monitoring, pill counts, biomedical indictors
Which structures pass through the diaphragm?
Aorta, IVC and oesophagus
Which is the main immunoglobulin on mucosal linings?
IgA
What are the adverse effects of glucocorticoids
Inhaled: oral candidiasis, hoarseness, cough
Oral or long term inhaled use: growth retardation, bruising, osteoporosis, water retention, diabetes, hypertension, weight gain
What innervates bronchial smooth muscle to cause relaxation?
1) Sympathetic stimulation to adrenal medulla causing more circulating adrenaline which activates B2 receptors
2) Sympathetic efferents to parasympathetic ganglia
3) Nitric oxide
What generation are alveolar ducts and sacs?
20-23
How many deaths per year are there from asthma in the UK?
1000
What are the attachments of the diaphragm?
Anteriorly the diaphragm can, but doesn’t always, attach to the xiphoid process of the sternum.
Laterally it attaches to the 6 inferior costal cartilages and their adjoining ribs on each side.
Posteriorly, it attaches to the left and right crura which arise from the bodies of the superior three lumbar vertebrae.
The diaphragm is also attached on each side to medial and lateral arcuate ligaments which are thickenings of the fascia covering psoas major and quadratus lumborum respectively.
What is said to improve adherence?
Removing barriers e.g. cost, repeat prescription, talking about symptoms, concerns, improving communication and doctor-patient relationship, memory cues, simple and well organised information
What is the nerve supply of the diaphragm?
Left and right phrenic nerves from anterior rami of C3-5give motor and sensory supply. Some sensory supply of peripheral diaphragm comes from intercostal (T5-11) and subcostal (T12) nerves
