Session 1: Intro to the Respiratory System Flashcards
Main functions of the nasal cavity.
Induce turbulent flow Warm and moisten inspired air Recover water from expired air Speech production (phonation) Olfaction
How is turbulent flow induced?
By the nasal conchae which are sorts of invaginations that cause turbulent flow.
Why is it important to warm and moisten the inspired air?
Cold air can irritate the airways. Adding water to the air and moisten it increased its efficiency for gas exchange.
What is special about the floor of the nasal cavity? Why is this important?
It is in a horizontal plane. This is important for procedures like inserting a nasogastric tube.
What is the nasal cavity divided into? What is it divided by?
Right and left cavities. By the median nasal septum.
Each nasal cavity contains 3 bony projections. What are they called?
They are called conchae or turbinates.
There are also paranasal sinuses which contain 4 air cavities. Which?
Frontal Ethmoidal Maxillary Spheroidal All are called sinuses
How is the moistening of the air occurring?
Transudation of fluid through the epithelium To lesser extent by mucus secretion
How are large particles which are inhaled by air trapped?
By coarse hair in each nostril. Also mucus secreted by goblet cells traps almost all particles that are larger than 5 micrometers.
What are the three parts of the pharynx?
Nasopharynx Oropharynx Laryngopharynx
What is special about the pharynx which can cause food to get trapped in the trachea?
Inhalation of air via the nose and therefore nasopharynx runs posteriorly to then cross anteriorly in order to go down the trachea. Ingestion of food via mouth will pass anteriorly to cross posteriorly into the oesophagus. Air and food have a common passage through parts of the pharynx which allows them to get interchanged if something goes wrong.
What is the larynx?
A part which links the pharynx to the trachea. It contains the vocal cords also called vocal folds or vocal ligaments.
What is the glottis?
The vocal cords + the aperture between the cords.
Why does food not normally end up in the trachea upon swallowing?
When you swallow the laryngeal inlet becomes narrowed since the epiglottis folds downwards over the laryngeal inlet and the vocal cords come together. The vocal cords act like a sphincter that closes off the entrance to the trachea.
What causes the movements of the vocal cords?
Intrinsic laryngeal muscles.
Innervation of the intrinsic laryngeal muscles
Recurrent laryngeal nerve which supply all the intrinsic muscles except the cricothyroid muscle.
How can an aortic aneurysm or lung cancer relate to the recurrent laryngeal nerve?
The recurrent laryngeal nerve on the left side has a long course and some of it inside of the thoracic cavity. This means that intra thoracic disease can cause compression of the nerve or irritate it.
Clinical presentation of an impaired recurrent laryngeal nerve.
Risk of inhalation (aspiration) of food/liquid
Cough reflex might be impaired as the ability to close the vocal cords is necessary to build up the intra thoracic pressure in order to cough.
Can cause airway obstruction
Voice changes like a hoarse voice can be the first sign of serious intra-thoracic disease.
The trachea has cartilage like a horse shoe. Why is it not all around the trachea?
Because the oesophagus is juxtapositioned posteriorly to the trachea. If the trachea didn’t have a soft muscular portion where the oesophagus lies the oesophagus wouldn’t be able to expand properly.
What is the bony thorax made of?
Sternum
Ribs
Thoracic vertebrae
Costovertebral joins
Rib movements
The sternum has three parts. Which?
Manubrium
Body
Xiphisternum
What is the sternal angle?
What is its clinical relevance?
The junction between the manubrium and the body.
It is felt as a horizontal ridge upon palpation.
The 2nd costal cartilage articulates with the sternum at the level of the sternal angle. This means that it is possible to easily locate the 2nd rib and then find the other ribs with this as template.
Muscles of the intercostal space.
External intercostal muscle
Internal intercostal muscle
Innermost intercostal muscle
Innervation of the intercostal muscles.
Intercostal nerves
Action of the external intercostal muscles.
How do the fibres run?
What ‘type’ of movement are these muscles responsible for?
Responsible for about 30% of chest expansion during quiet respiration.
The fibres run in an antero-inferiorly (hands in pocket)
It elevates the ribs in a bucket handle to increase the lateral diameter of the thoracic cavity and increase volume (reduce pressure)
Action of the internal intercostal muscles.
How do the fibres run?
Downwards and posteriorly fibres running perpendicular to the external intercostal muscles.
Active supporting forced expiration.
Action of the innermost intercostal muscles.
How do the fibres run?
Run parallel to internal intercostal muscles.
Less developed than internal intercostal muscles but aid forced respiration.
Where does the intercostal vein, intercostal artery and intercostal nerve run?
In the groove of the rib called the costal groove.
This bundle runs in the costal groove inferiorly to the rib. Why is this important?
This means as you do a procedure which requires insertion you should do it superior to the given rib, in order to not risk damaging the intercostal bundle.
How is the diaphragm shaped?
Like a dome
Where does the diaphragm go?
Bulges into the thorax
Peripheral muscular fibres arise from the lower margin of the thoracic cavity and insert into the central tendon.
What does the central tendon fuse with?
It fuses with the inferior part of the fibrous pericardium superiorly.
Innervation of the diaphragm.
C3-5 by the right and left phrenic nerves.
On contraction the diaphragm moves downwards to increase vertical diameter and increase volume (decrease pressure)
What would a damaged phrenic nerve appear like on a chest x-ray?
The paralysis it causes to the affected side of the diaphragm. The hemi-diaphragm (affected side) will appear elevated as it can’t contract.
The diaphragm has three openings. For what?
The IVC
Oesophagus
Aorta
At what vertebral levels do the openings for the IVC, oesophagus and aorta appear?
IVC = T8
Oesophagus = T10
Aorta = T12
At what level (rib level) does the right dome of the diaphragm lie?
What about the left dome?
4th intercostal space or 5th rib for the right dome
Left dome is situated by the 5th intercostal space a bit lower.
Why is the right dome of the diaphragm slightly elevated?
Because it is pushed up by the liver.
The convexity of the diaphragm means that the thoracic cavity is much smaller than the bony thorax. Why is this clinically relevant?
This means that the liver, spleen and parts of the stomach and upper kidneys from the abdominal cavity lie in the bony thorax.
A stabbing wound to the chest might cause damage to these abdominal organs.
What are the movements of the thoracic wall and diaphragm upon respiration?
Elevation of lateral aspect of the ribs (bucket-handle)
Sternum moves forward because of rib elevation (pump-handle)
Diaphragm descends to increase thoracic capacity vertically.
What is the parietal pleura?
The outer layer of the pleura which lines the inside of each hemi-thorax and is continuous at the hilum of the lung with the visceral pleura lining the outside of the lung.
What is the visceral pleura?
The pleura that is the innermost lining the actual lungs.
It extends between the lobes of the lung into the depths of the oblique and horizontal fissures.
The spot where visceral pleura and the parietal pleura meet is called the reflection.
What is the costo-diaphragmatic recess?
What is its purpose?
The lungs don’t fully fill the thoracic cavity. There is a space around the outer edge of the diaphragm into which only the parietal pleura extends and not the visceral pleura. This means that the lungs do not fill the entire space.
This allows the lungs to expand even more during aspiration.
What is the clinical relevance of the costo-diaphragmatic recess and the pleural cavity?
This is where accumulation of fluid can occur called a pleural effusion.
Also a pneumothorax can occur if the pleural cavity is breached.
What are the parts of the conduction airways?
The trachea
Primary main bronchi (after the bifurcation)
The secondary lobar bronchi (found in each lobe of the lungs)
Tertiary segmental bronchi
Bronchioles
Terminal bronchioles
The trachea divides into to bronchi, a right one and a left one via a bifurcation.
Where does it occur?
What is this bifurcation called?
By the level of the sternal angle.
It is called the carina.
How do the right and left primary bronchi differ?
What is the clinical relevance of this?
The right bronchi is wider, it is more vertical (less angled) and also shorter.
This means that foreign bodies are more likely to lodge in the right main bronchus (or further down in the right lung)
Primary bronchi then divide into the secondary lobar bronchii.
How many are there? (In total)
5
Three in the right lung for each lobe and two in the left lung for each lobe.
What is a segmental bronchus? (bronchopulmonary segment)
Why are they surgically important?
A bronchus which supplies a segment of the lung (an area) and also the accompanying segmental branch of the pulmonary artery.
It is also drained by a segmental pulmonary vein.
They can be isolated and removed without much bleeding, air leakage or interfering with other bronchopulmonary segments.
It is the smallest resectable division of the lung.
What can be seen (which parts of the conducting airway) via a bronchoscopy?
Inner trachea
The carina
The main bronchi
Lobar bronchi
Origin of segmental bronchi.
What are the parts of the respiratory zone of the airway?
This is where gas exchange occurs.
Respiratory bronchioles
Alveolar ducts
Alveolar sacs
Alveoli
How many lobes is the left lung divided into?
Which?
What are the separated by?
2
Upper and lower lobes
Oblique fissure
How many lobes is the right lung divided into?
Which?
What are the divided by?
3 lobes
Upper middle and lower lobe
Horizontal/transverse fissure separate the right upper and middle lobes.
The oblique fissure separate the right upper and middle lobes from the lower lobe.
Why does the left lung only have two lobes?
Because the heart can be found slightly indenting the left lung.
Where is the apex of both lungs?
Extends above the level of the 1st rib into the root of the neck.
Why is the location of the apex of the lung clinically important?
Tumours of the apex of the lung can cause neurological and vascular problems in the upper limb by compromising the subclavian vessels and the brachial plexus.
Stab wounds of the lower neck and cannulation of the subclavian vein may puncture the lung and cause pneumothorax.
Where is the base of the lung?
Rest on each hemi-diaphragm.
What is the hilum of the lung?
An area through which the main bronchi, pulmonary vein, pulonary artery, lympathics and pulmonary plexuses enter/leave the lung.
What is the mediastinum?
The middle part of the thorax which seperate the lungs.
Which parts of the mediastinum are there?
Superior mediastinum
Inferior MS
(Anterior MS)
(Middle MS)
(Posterior MS)
Anatomical border of the superior and inferior MS.
The angle of louis by the sternal angle.
Anatomical borders of the anterior, middle and posterior MS.
Anterior = anything anterior to the heart (fat + thymus in children)
Middle = heart and pericardium
Posterior = Anything posterior to the heart (aorta, azygous veins, thoracic duct and oesphagus)
In the mediastinum, what can be found on the left side?
The lung is adjacent to the heart, aortic arch, descending aorta, oesophagus and several nerves like phrenic nerve, vagus nerve and the its recurrent laryngeal branch.
In the mediastinum what can be found on the right side? (Left to the right lung)
Superior vena cava, azygous vein, right atrium, oesophagus, phrenic and vagus nerves and the sympathetic trunk.
Blood supply of the lungs.
Dual blood supply.
One from the pulmonary artery
One from bronchial arteries
Bronchial arteries supply the bronchial tree and the visceral pleura but not the alveoli.
The pulmonary artery supplies oxygen to the alveoli and picks up oxygen via gas exchange.
There are some anastomoses between the bronchial and pulmonary arteries at the pre-capillary level and the capillary level. Why is this important?
Because these can maintain some blood supply in patients with pulmonary embolism.
Lymphatic drainage of the lungs.
Drain into hilar nodes (bronchopulmonary nodes).
Efferents of these nodes run to the tracheobronchial nodes which can be found inferior the carina and cause widening of it. (They can be found in other places as well)
Nerve supply of the lungs.
Right and left vagus nerves and the sympathetic trunk.
Parasympathetic efferent fribres from the vagus are motor for bronchial smooth muscle for bronchoconstriction and also secretomotor to mucous glands.
Vagal afferent fibres are those for the cough reflex and som subserving pain (like in the case of the parietal pleura).
Sympathetic efferent fibres are bronchodilators and vasoconstrictors.
Vertical lines of the the thoracic wall.
Anterior median line + midclavicular lines
Anterior axillary line, midaxillary line, posterior axillary line.
Posterior medial line + scapular lines.
Where does the oblique fissure extend from?
Either side of the spinous process of T2 vertebrae and run to the 6th costal cartilage anteriorly.
Surface marking is approxiamte to the medial border of the scapula when the arm is abducted.
Where does the horizontal fissure extend?
Runs from mid axillary line anteriorly along the 4th rib to the anterior edge of the lung.
Anatomical border of the lower edge of the lung.
6th rib at the midclavicular line
8th rib by the mid axillary line
10th rib by the scapular line.
Lower anatomical border of the pleural cavity.
2 ribs lower.
8th rib at midclavicular line
10th rib at mid axillary line
12th rib at scapular line
Why is it important to learn surface markings of the lungs?
For clinical examination and in order auscultate different lobes.
How is a pleural effusion detected on an x-ray?
The fluid collect in the costo-diaphragmatic recess in an upright position. This shows a blunting chost-phrenic angle.
Other than the diaphragm and the external intercostal muscles what further aids respiration?
Accessory muscles like pectoral muscles when pressing your arms onto your legs in or to fix humerus and reverse the action of the pectoral muscles.
Sternocleidomastoid by elevating the thoracic cage.
What is the azygous vein system of the thorax?
Azygous means unpaired which indicates that there is no paired artery to the vein system.
Azygous veins ascends the thorax and collects blood from the posterior intercostal veins. This is because these veins cannot reach the inferior vena cava or superior vena cava and won’t enter the RA directly.
So blood collects in the azygous vein and the hemiazygous vein (which anastomose) and drain into the superior vena cava.
Clinical relevance of the azygous vein system.
It forms an alternative for blood to reach the superior vena cava and the heart. If the inferior vena cava is obstructed some blood can flow via the azygous system.
