Resp Session 1 Flashcards
What is inspiratory reserve volume?
Additional volume that can be breathe in over that at rest
What is expiratory reserve volume?
Additional volume that can be breathed out at rest
What is partial pressure?
The fraction of total air pressure exerted by each gas
What is the partial pressure of gas proportional to?
Volume of the gas in the mixture
What is the partial pressure of oxygen in air at atmospheric pressure?
21.1 kPa
What does Boyle’s law state?
Pressure of a gas is inversely proportional to its volume of the temperature and amount of gas remain constant
Why does air become less dense as altitude increases?
Fewer molecules pressing down therefore molecules are more widely dispersed
What does Charles’s law state?
Is volume and amount of gas present is constant pressure is proportional to absolute temperature
What is saturated vapour pressure?
Pressure exerted by water molecules as they enter and leave the gas phase as in gas exchange at mucosal surfaces
What does saturated vapour pressure exclusively depend on?
Pressure
What is saturated vapour pressure at 37 degrees Celsius?
6.28 kPa
Why is air saturated with water vapour as it passes the URT?
To reduce the risk of damage to the LRT?
What causes The Bends?
Swimming up to the water surface too quickly so partial pressure changes are not gradual resulting in gas exchange which is not quick enough –> nitrogen bubbles
Describe the movement of gas molecules with relation to a liquid for example in gas exchange at a mucosal surface.
Gas molecules move in and out until an eqm of tension exerted by the gas in the liquid = partial pressure of gas in air
What can we assume about the gas tension of oxygen in arterial plasma?
It is equal to the partial pressure of oxygen in air assuming exchange time is sufficient
How is the amount of a gas dissolved in a liquid calculated?
Solubility x tension
What does using the tension of a gas dissolved in a liquid take into account when calculating how much gas is presentation?
any reaction that takes place so calculates the total content of reacted and dissolved gas
What components of oxygen transport need to be considered when considering the amount of oxygen dissolved in blood?
Fraction dissolved in plasma + fraction reacted with Hb
Why does the pulmonary circulation form basically no tissue fluid?
Low resistance
Low pressure
Receives whole cardiac output
Ventilation/perfusion ratio
Lost the airways in the lungs from largest to smallest.
Trachea –> bronchi –> bronchioles –> terminal bronchioles –> respiratory bronchioles –> alveolar ducts –> alveolar sacs
In which airways does gas exchange take place?
Respiratory bronchioles
Alveolar ducts
Alveolar sacs
Describe the blood supply to the airway tree.
Similar structure with bronchial arteries supplying bronchi themselves
What is tidal volume?
Volume breathed in and out with each breath during quiet respiration at rest
What are conducting airways?
Larger airways where gas exchange does not take place
Which airways are the last of the conducting airways?
Terminal bronchioles
Where do mucous membranes line in the respiratory tract?
Conducting portion
Are the number of mucus secreting cells in the mucus membranes constant throughout the respiratory system?
No
Where do serous membranes line the respiratory tract?
Pleural sacs which envelope each lung
Why does the lung appear ‘shiny’ on examination?
Covered by moist visceral pleura
What are Clara cells?
Domed cells without cilia that secrete lipoprotein surfactant and CC16 (Clara cell protein 16)
What does raised CC16 in serum indicate?
Leakage across air-blood barrier
What is the function of the lipoprotein surfactant secreted by Clara cells?
Prevents bronchiole collapse
What epithelium lines from the nasal cavity to the largest bronchioles?
Pseudostratified columnar with cilia and goblet cells
What epithelium lines the bronchioles to respiratory bronchioles?
Simple columnar with cilia and Clara cells
What epithelium lines respiratory bronchioles to alveolar ducts?
Simple cuboidal with Clara cells and a few sparse cilia
What type of cells are found in the alveoli?
Type I and II pneumocytes
What pushes odorons away from the olfactory regions of the respiratory tract?
Bauman’s glands
Describe the epithelium in the olfactory regions of the respiratory tract.
Thick pseudostratified columnar (particularly tall)with microvilli and no goblet cells
LP blends with submucosa
Where are the olfactory regions of the respiratory tract found?
Posterior and superior region of each nasal fossa
What maintains patency of non-olfactory regions in the nasal cavities?
Surrounding cartilage and bone
What is the function of venous sinuses in the non-olfactory regions of the nasal cavities?
Swell every 20-30 mins to alternate airflow and prevent over drying
What is the effect of arterial blood flow on inspired air in the nasal cavity?
Warms inspired air
What are olfactory cells?
Bipolar neurones where one dendrite extends to the surface to form swelling from which non-motile cilia extend parallel with surface to detect scents
What forms an olfactory nerve?
Axons of bipolar neurones joining
What is located in the ventricle of the larynx which contributes to resonance of voice?
Ventricular folds
What epithelium lines the true vocal cord?
Stratified squamous
What forms the true vocal cord?
Vocal ligament and vocalis muscle combined by a large bundle of elastic fibres front and back
What is the action of the vocal cords in coughing to prevent entry of a foreign object into the lungs?
Cords close to build up pressure
What lines the ventricular folds of the larynx?
Pseudostratified epithelium with mucus glands and lymph nodules
Why are foreign objects more likely to lodge in the right lung?
Right bronchus is more vertical so provides easier passage
What is found in the submucosa of the trachea?
Seromucous glands
What type of cartilage if sound in the trachea?
Hyaline
What allows variable trachea lumen diameter?
Trachealis muscle
What is the trachealis muscle contained in?
Fibroelastic membrane
Describe the cilia found in the trachea.
~250 per cell beating at 12Hz
What is the structure of the tracheal wall?
Pseudostratified ciliated columnar epithelium
Lamina propria
Submucosa with seromucous glands
C-shaped cartilage rings
What is the lamina propria of the trachea rich in?
Elastin fibres
Immune cells
What does the epithelium and submucosa of the trachea secrete?
Mucins Water Serum proteins Lysozymes Anti proteases Lymphocytes contribute IgA
How does the histology of the bronchioles compare to the primary bronchi?
Largely the same except cartilage decreases in size and turns from ring-shape to more irregular islands
What do bronchioles rely to keep them open as they decrease in diameter?
Elastic properties of surrounding alveoli
How does the lining epithelium of bronchioles change as their diameter decreases in size?
Pseudostratified –> simple columnar ciliated –> cuboidal
Goblet cells give way to Clara cells
What causes collapse of bronchioles in expiration of asthma pts which exacerbates the bronchoconstriction already present?
Lack of cartilage and surrounding alveoli not being able to maintain a patent airway
How does the number of alveolar openings vary from terminal bronchioles down to alveolar sacs?
Progressively increases
What can alveoli open into?
Repository bronchiole
Alveolar duct
Alveolar sac
Another alveolus via an alveolar pore
When do new alveoli stop developing?
When you reach 8 y.o.
What are found in type II pneumocytes?
Lamellar bodies
What is the function of type II pneumocytes?
Cuboidal cells to secrete surfactant to decrease surface tension and prevent alveoli collapse
What line the alveolar surface to decrease the likelihood of infection?
Macrophages which reach through into alveolar lumen
What is the advantage of having a capillary basket around each alveolus?
Short diffusion distance
Slow blood flow but RBCs spend
What is the pathogenesis of emphysema?
Smoking or alpha-1-antitrypsin deficiency –> destruction of alveolar walls –> permanent enlargement of air spaces –> bronchioles collapse on exhalation whilst air is still in the lungs
What is the hallmark function of emphysema and what is its action?
Pursed lip breathing to create back-pressure to prevent bronchiole collapse
What is the pathogenesis of pneumonia?
Bacterial infection –> inflammation of lung –> lung consolidation due to filling of alveolar spaces with fluid and inflammatory cells –> prevention of gas exchange
What are the borders of the three parts of the pharynx?
Nasopharynx: above lower border of soft palette
Oropharynx: lover border of soft palette –> tip of epiglottis
Laryngopharynx: below tip of epiglottis
Why does URT lead to middle ear infections, especially in children?
Nasopharynx connects to eustaschian tube
What can viral URTIs lead to?
Sinusitis
Middle ear infection
What can cause laryngeal obstruction leading to respiratory difficulty?
Oedema in anaphylaxis or severe infection –> vocal cord swelling
Tumour
Aspiration of foreign body
What can cause pharyngeal obstruction causing respiratory difficulty?
Tongue in unconscious pts or sleep apnoea where pharyngeal muscle tone decreases during sleep and floppy muscles obstruct the airway
What is the glottis?
2x vocal cords and aperture between them (rima glottidis)
What controls movement of vocal cords?
Intrinsic muscle of the larynx
What supplies all intrinsic laryngeal muscles except one?
Recurrent laryngeal nerve
What is the course of the RLN?
Arises form vagus nerve, curves around subclavian artery on R or arch of aorta on L and moves back up to larynx
Why does hoarseness of voice >3 weeks indicate investigation of RLN?
Suggests possible damage in the thorax due to lung tumour or aortic aneurysm
What is the function of the vocal cords with reference to the trachea?
Act as a valve to guard the entrance to the trachea
How does the position of the vocal cords change in different situations?
Open during respiration
Closed during swallowing
Partially closed during speech
Initially closed them rapidly open in coughing
What defines speech in admiration to partial opening of vocal cords?
Pharynx, tongue and lips
How are the false vocal cords found?
Red tissue located adjacent to the pearly true white vocal cords
Why are mechanisms to prevent aspiration of food particle important?
Air and food have common passage through the oropharynx and laryngopharynx
What are the features of the external nose?
Root (radix) Bridge (dorsum) Wing (alar) Nostril Septum Tip
What are the functions of the nose in respiration?
Filters air using hairs in nostrils and mucus
Humidifies air using watery nasal secretions
Warms air using BV just below epithelium
Turbinates air and slows its flow
What does the mucus in the nose contain?
Ig and other antibacterial components
How does the nose act as the organ of smell?
Olfactory mucosa at roof of nasal cavity is specially adapted
Where do local secretions received by the nose arise?
Sinuses and the nasolacrimal duct
What are the bony processes in the nasal cavity called?
3x Concha/turbinate - superior, middle and inferior
What are the spaces between the bony processes in the nasal cavity called?
3x meatus - superior, middle and inferior
Where does the nasal cavity extend from and to?
From nostrils –> posterior nares
What forms the medial wall of each nasal cavity?
Nasal septum = cartilage and 2 bones
What are the four paranasal sinuses?
Frontal
Ethmoid
Maxillary
Sphenoid
How are the paranasal sinuses names?
By the bones they are located in
What lines the paranasal sinuses?
Pseudostratified columnar epithelium with cilia and goblet cells
What are the respiratory functions of the paranasal sinuses?
Humidify and warm inspired air
Which sinus is only visible on lateral view?
Sphenoid
Why does the frontal bone which forms the roof of the nasal cavity have perforations?
For olfactory nerves
