S9) The Respiratory System Flashcards
How can you locate the 2nd rib?
- Finding the sternal angle (between manubrium and the sternum)
- Move laterally
- Palpate the attachment of the 2nd rib
Why is the inferior aspect of each lung curved upwards?
The inferior aspect lies on top of the domed diaphragm
What sort of membranes are found in the respiratory system and what do they do?
- A mucous membrane; which lines the conducting portion of the respiratory tract, bearing mucus-secreting cells
- Serous membranes; which line the pleural sacs, enveloping each lung
The pleural cavity can fill with four different substances.
What are they and what is the resulting condition named?
- Air – pneumothorax
- Blood – haemothorax
- Pus – empyema
- Transudate/exudate – pleural effusion
How can fluid be drained from the pleural cavity?
Fluid is drained by the insertion of a wide-bore needle through an intercostal space (usually 7th posteriorly), performed under ultrasound guidance
Identify the different lobes and respiratory airways observed in the image below:
Identify the 7 components of the conducting portion of the respiratory tract
- Nasal cavity
- Pharynx
- Larynx
- Trachea
- Primary bronchi
- Secondary bronchi
- Bronchioles
- Terminal bronchioles
Identify the 3 components of the respiratory portion of the respiratory tract
- Respiratory bronchioles
- Alveolar ducts
- Alveoli
What does one observe as you progress down the respiratory tract?
The walls of the passageways become thinner as their lumens decrease in diameter
Which components of the respiratory tract are extrapulmonary?
What are the intrapulmonary components of the respiratory system?
There are epithelial changes in the respiratory system.
What sort of epithelium can be found in the nasal cavity, pharynx, larynx, trachea, primary bronchi and secondary bronchi?
Pseudostratified epithelium, with cilia and goblet cells
There are epithelial changes in the respiratory system.
What sort of epithelium can be found in the bronchioles and terminal bronchioles?
Simple columnar epithelium with cilia, Clara cells and no goblet cells
There are epithelial changes in the respiratory system.
What sort of epithelium can be found in the respiratory bronchioles and alveolar ducts?
Simple cuboidal epithelium with Clara cells and a few sparsely scattered cilia
There are epithelial changes in the respiratory system.
What sort of epithelium can be found in the alveoli?
- Simple squamous cells (type 1)
- Septal cells (type 2)
Identify 3 characteristics of olfactory regions
- Particularly thick pseudostratified columnar epithelium
- No goblet cells
- Located in posterior, superior region of each nasal fossa
Identify 4 characteristics of non-olfactory regions
- Pseudostratified ciliated epithelium
- Venous plexuses swell often to prevent overdrying
- Arterial blood flow warms inspired air
- Patency maintained by surrounding cartilage/ bone
Identify some key anatomical features on the larynx diagram below:
Describe the features of the ventricular folds of the larynx
- Lined by pseudostratified epithelium
- Contain mucous glands
- Contain numerous lymph nodules
Which 2 structures contribute to the resonance of the voice?
- Ventricles
- Ventricular folds
What are the components of each vocal cord of the larynx?
- A vocal ligament (large bundle of elastic fibres)
- A vocalis muscle (bundle of skeletal muscle)
Identify 2 functions of the vocal cords
- Stop foreign objects from reaching the lungs
- Close to build up pressure when coughing is required
The trachea divides into two primary bronchi in the mid-thorax.
How does the cartilage in these structures differ?
- Trachea has cartilage crescents which partially enclose the lumen
- Primary bronchi have cartilage rings which completely encircle the lumen
What are the features of Chronic Obstructive Pulmonary Disease?
- There is goblet cell hyperplasia
- A smaller proportion of ciliated cells
- Hypertrophy of the submucous glands
As bronchioles get smaller, goblet cells give way to Clara cells, interspersed between ciliated cuboidal cells.
What is the role of Clara cells?
Clara cells secrete a surfactant lipoprotein, which prevents the walls sticking together during expiration
Clara cells also secrete abundant Clara cell protein (CC16).
What is the importance of this protein?
- A measurable marker in bronchoalveolar lavage fluid (lowered in lung damage)
- A measurable marker in serum; if raised then leakage across air-blood barrier
Which different structures can alveoli open up to?
- A respiratory bronchiole
- An alveolar duct
- An alveolar sac
- Another alveolus (via an alveolar pore)
Describe the features of alveolar walls
- Abundant capillaries
- Basketwork of elastic and reticular fibres
- Covering of type I pneumocytes
- Scattering of intervening type II pneumocytes
What is emphysema?
- Emphysema is a condition resulting in the destruction of alveolar walls and permanent enlargement of air spaces due from smoking or alpha 1-antitrypsin deficiency
- Alveolar walls are damaged, bronchioles collapse during exhalation, so lungs cannot empty and air becomes trapped in the alveoli.
What is a hallmark sign of emphysema?
Pursed-lip breathing
What is pneumonia?
- Pneumonia is a condition involving the Inflammation of the lung by bacteria (commonly Streptococcus pneumoniae)
- The lung consolidates as the alveoli fill with inflammatory cells
Lung cancer often results in a pancoast tumour on the apex of the lung.
Describe the effects of this form of cancer
- Tumour impinges on either phrenic nerve = part of diaphragm paralysed
- Tumour impinges on the brachial plexus = muscle wasting in lower arm
- Tumour impinges on the sympathethic trunk = Horner’s syndrome
- Tumour impinges on left recurrent laryngeal nerve = hoarse voice
Identify the 3 hallmark signs of Horner’s syndrome
- Miosis
- Partial ptosis
- Anhidrosis
What is cohesion?
Cohesion refers to the attraction of identical molecules towards each other e.g. H2O molecules have strong cohesive forces due to H2 bonding
Cohesive forces are responsible for surface tension. What is it?
Surface tension is the tendency of a liquid’s surface to resist rupture when placed under tension or stress e.g. H2O molecules at the surface will form hydrogen bonds with their neighbours
Lungs are surrounded by thin tissue called the pleura, a continuous membrane that folds over itself.
Distinguish between the visceral and parietal pleura.
- Parietal pleura lines the chest wall
- Visceral pleura covers the lung
Normally, the two membranes of the lung are separated only by lubricating pleural fluid.
What is the purpose of this fluid?
- Reduces friction, allowing the pleura to slide easily during breathing
- Provides the surface tension needed to prevent the lung from recoiling and collapsing
Normally, a vacuum (negative pressure) in the pleural space keeps the two pleurae together and allows the lung to expand and contract.
Discuss this in terms of inspiration and expiration
- During inhalation, the intrapleural pressure is approximately -8cmH20 (below atmospheric)
- During exhalation, intrapleural pressure is approximately -4cmH20 (below atmospheric)
Demonstrates Boyle’s Law in terms of volume and pressure in a container
- When the volume of a container increases, the pressure decreases
- When the volume of a container decreases, the pressure increases
In 4 steps, describe inhalation
⇒ Diaphragm contracts
⇒ Intrathoracic volume increases
⇒ Intrathoracic pressure decreases
⇒ Air moves from atmosphere into the lungs
In 4 steps, describe exhalation
⇒ Diaphragm relaxes
⇒ Intrathoracic volume decreases
⇒ Intrathoracic pressure increases
⇒ Air flows out from lungs to atmosphere
What is pressure inside the lungs called?
Intrapulmonary pressure
Describe the intrapulmonary and intrapleural pressure changes
- Intrapulmonary pressure fluctuates during breathing and equalises to atmospheric pressure at end-exhalation (0 cmH2O)
- Intrapleural pressure also fluctuates during breathing and is ~ 4 cmH2O less than the intrapulmonary pressure
What is significant about the differences between intrapleural and intrapulmonary pressure?
The pressure difference of 4 cmH2O across the alveolar wall is the force that keeps the stretched lungs adherent to the chest wall
What happens during pneumothorax?
If air enters the pleural space between the parietal and visceral pleura (in pneumothorax), the -4cmH20 pressure gradient disappears and the lung recoils and collapses
What is open pneumothorax?
Open pneumothorax is a condition cause by an opening in the chest wall allowing atmospheric air to enter the pleural space due to a penetrating trauma (stab, gunshot, impalement, surgery)
What is closed pneumothorax?
Closed pneumothorax is a condition wherein atmospheric air enters the pleural space due to the rupture of the lung and visceral pleura with the chest wall still intact
What is the role of surfactant during inhalation and exhalation?
- During inhalation – when alveoli expand, surfactant molecules move apart
- During exhalation – when lungs shorten, surfactant molecules move together and become concentration i.e. surface tension is reduced
