Respiratory Session 1- Introduction And Upper Respiratory Tract Flashcards
Roughly how many alveoli do you have and what is their combined surface area?
3 million with a combined surface area of 70m^2
How many generations of dividing airways are there between the trachea and alveoli?
23
What is the difference between divisions 1-16 and divisions 17-23?
1-16 are conducting airways and do not take part in gas exchange
17-23 make up the respiratory zone and participate in gas exchange
Define ventilation
Process of inspiration and expiration
How is the normal rhythmic involuntary breathing pattern controlled?
Neurones in the respiratory centre in the medulla of the brain generate automatic rhythmic impulses
In terms of pressure changes, how is air forced into the lungs?
As the volume of air in the lungs increases the pressure decreases- when pressure drops below atmospheric pressure air flows into the lungs
How is expiration achieved?
Neurones cease generating impulses, inspiratory muscles relax, chest returns to original size- compressing inflated lungs. Air pressure in lungs increases, air flows out
How does oxygen move from the alveoli into the blood?
Diffuses across the air-blood interface down its partial pressure gradient
What is the universal gas law? (Equation)
PV=nRT
P=pressure, V=volume, n=amount of gas, R=gas constant, T=temperature
What is Boyle’s law?
Pressure is inversely proportional to volume for a fixed quantity of gas at a constant temperature
What is Dalton’s law?
In a mixture of gases, the molecules of each type behave independently so each gas exerts a partial pressure. Each component of a gas mixture exerts a partial pressure in proportion to its volume percentage in the mixture
What 2 things happen if a gas mixture is in contact with water?
- Gas molecules enter the liquid to dissolve
2. Water molecules evaporate to enter the gas phase
What is the partial pressure of a gas in liquid and how is it caused?
When gas and liquid are in contact, gas molecules will enter the liquid until an equilibrium is established between rate of solution and dissolution of gas- collision of dissolved gas molecules generates a pressure within the liquid
Define the solubility coefficient of a gas
Amount of the gas that will dissolve in a litre of plasma at 37 degrees when exposed to a given partial pressure
What is the equation to work out the amount of a gas that is dissolved?
Amount of gas dissolved= solubility coefficient of that gas x the partial pressure it is exposed to
Why is the oxygen content of whole blood greater than just plasma?
Haemoglobin in RBC binds large amounts of oxygen in addition to the dissolved
Define saturated vapour pressure
The pressure exerted by the water vapour when the gas mixture is saturated at equilibrium
What is the total pressure of humidified air in the airways and why?
101kPa because this gas is continuous with outside air, and pressure will equilibrate to atmospheric pressure
At 37 degrees what is the SVP of water and what is its relevance?
6.28kPa- this must be taken away from 101kPa when looking at air within the respiratory system as this air is saturated. Then can use the same gas proportions as are in dry air
What structures does the upper respiratory tract comprise of?
Nose and paranasal sinuses
Pharynx
Larynx
What are the respiratory functions of the URT?
- Conducting air from the atmosphere to lower respiratory tract
- Conditioning (warming, humidification and trapping of particles) inspired air
- Protection of the airway during swallowing (larynx)
What are some of the other functions of the URT?
- Swallowing (oropharynx and laryngopharynx)
- Smell (olfactory epithelium in nose)
- Speech (larynx)
What 2 structures does the nose consist of?
External nose and nasal cavity
What makes up the borders of the nasal cavity?
Median- median nasal septum
Anterior- nostril (anterior nares)
Posterior- posterior nares (posterior choanae)
Lateral- wall containing superior, middle and inferior conchae and meatus
Floor- hard and soft palates (also form roof of mouth)
