Resp 1 - Overview and anatomy Flashcards
What is the overall name for the airways where gas exchange DOESN’T take place?
Conducting airways
What is the overall name for the airways where gas exchange takes place?
Respiratory airways
Name the smallest airway which is a ‘conducting’ airway:
Terminal bronchiole
conducting = no gas exchange
Name the largest airway which is a ‘respiratory’ airway:
Respiratory bronchiole
respiratory = gas exchange takes place
What is the cumulative surface area of all the alveoli in the lungs?
~ 70 m^2
What brain center controls inspiration and expiration, and where is it located?
Respiratory center
Medulla
Where is the respiratory system of the brain?
Medulla
Describe inspiration:
- Resp. center sends impulses to inspiratory muscles (ext. intercostals + diaphragm)
- Inspiratory muscles contract = chest expands
- Volume of lungs increases = pressure decreases
- When alveolar pressure is lower than atmospheric, air rushes into lungs
Describe expiration:
- Resp. center stops sending impulses to inspiratory muscles (external intercostals + diaphragm)
- Inspiratory muscles relax = chest volume decreases = pressure increases
- When alveolar pressure is higher than atmospheric, air flows out of lungs
FORCED = Contraction of Internal Intercostals + Abdominal muscles decrease chest volume further
What is Boyles law?
Pressure is inversely proportional to volume
- for a fixed quantity of gas, at a constant temperature
Define the ‘partial pressure’ of a gas:
Individual pressure exerted by a gas in a gas mixture
Define the ‘partial pressure’ of a gas in liquid:
The pressure exerted by a gas within a liquid (due to collision between the dissolved gas molecules)
How do you calculate the ‘content’ of gas in a liquid?
Solubility coefficient of the gas x partial pressure it is exposed to
What are the units of a solubility coefficient?
mmol/L/kPa
Define saturated water vapour:
The pressure exerted by a gas mixture saturated with water vapour
How do you calculate the partial pressure of a gas?
Atmospheric pressure x % gas in the atmosphere
Calculate the pO2 of dry air:
where 20.9% of dry air is O2
101 kPa x 0.209 = 21.1 kPa
As altitude increases, what happens to atmospheric pressure?
Atmospheric pressure decreases
What is the SVP of H2O @ 37’?
6.28 kPa
Calculate the pO2 of humidified air:
where 20.9% of dry air is O2
(Atmospheric pressure - SVP) x % gas in atmosphere
(101 - 6.28) x 0.209 = 19.8 kPa
How do you calculate the content of a gas in plasma?
Solubility coefficient x Pgas
How do the solubility coefficients of O2 and CO2 differ?
CO2 is 23x O2, as CO2 dissolves 23x faster than O2.
What structures make up the URT?
- Nose
- Paranasal sinuses
- Pharynx
- Larynx
What is the boundary between the URT and LRT?
Lower border of Cricoid cartilage (where larynx becomes trachea)
What prevents the nasal cavity from overdrying?
Venous plexuses swell every 20-30 mins, alternating airflow from side-to-side
Name the borders of the nasal cavity
Roof = Cribriform plate
Floor = Hard + Soft palates
Lateral walls = Contain conchae and meatuses
Medial wall = Nasal septum
List the functions of the conchae in the nasal cavity:
- Slow air flow
- Increase surface area (for filtration, warming and humidifying air)
What part of the nasal cavity transmits olfactory nerve fibres?
Cribriform plate
Upper posterior nasal cavity roof
Where do the paranasal sinuses and lacrimal ducts drain?
Superior/Middle/Inferior meatuses in nasal cavity
Name the paranasal sinuses:
- Frontal
- Ethmoid
- Maxillary
- Sphenoid
How many paranasal sinuses do we have?
8
4 paired sinuses (frontal, ethmoid, maxillary, sphenoid)
List the functions of the nasal cavity:
- Filter, humidify, and warm air
- Smell
- Drain paranasal sinuses and lacrimal ducts
What type of epithelial cells is found within the nasal cavity?
Pseudostratified columnar ciliated epithelium
Name the 3 parts of the pharynx:
1) Naso-pharynx
2) Oro-pharynx
3) Laryngo-pharynx
Name the tube which connects the nasopharynx to the middle ear:
Eustachian tube
Name the region of the URT which connects the pharynx to the trachea:
Larynx
Name the 5 cartilages which support the larynx:
1) Thyroid cartilage
2) Cricoid cartilage
3) Epiglottis
4) Paired Arytenoid cartilages
What are the main functions of the epiglottis?
- Phonation
- Guards air passage
- Allows cough reflex
Why must the glottis be able to close to allow the cough reflex?
The glottis must close to allow increase in intrathoracic pressure, for early part of cough reflex
What are the symptoms of injury to a recurrent laryngeal nerve?
- Hoarse voice
- Aspiration
- Dysphagia
How does recurrent laryngeal nerve injury cause a hoarse voice?
Cause paralysis of ipsilateral vocal cord
What are the causes of Recurrent Laryngeal Nerve injury?
- Tumour
- Compression
- Trauma
- Burn
If one of the recurrent laryngeal nerves is injured, will the ipsilateral or contralateral vocal cord be affected?
Ipsilateral (same side)
Which recurrent laryngeal nerve can be injured in the thorax (ie by lung tumour)? Why?
Left RLN
During heart ‘descent’, LRLN becomes hooked around the ductus arteriosus, while the RRLN becomes hooked around the Right Subclavian artery.
= RRLN not present in thorax
