Respiratory movements 1 Flashcards
Describe the structure of the lungs
Trachea in middle and splits into 2 lungs:
1. Primary Bronchi- splits into smaller bronchi
2. This further splits into bronchioles
2. End of bronchioles = alveoli
- each division increases surface area to maximise gas exchange
Can posture affect your breathing?
Yes
Slouching doesn’t allow for air to fill the alveoli in the lower part of your lungs
How does SA change as the trachea divides?
As the windpipe divides further the SA increases - this is why alveoli are effective for gaseous exchange
more divisions = bigger SA
What are the 4 things that can affect the amount of oxygen that can enter the lungs?
- Volume
- Pressure (must be maintained)
- Temperature (this affects the pressure)
- Motion (affects final pressure of the lungs)
What is the kinetic theory of gases?
Change volume, temp or pressure- speed of particles will change
- Pressure is generated by collisions of molecules
- The more freq & harder the collisions = higher pressure
What is Boyle’s law?
Pressure is inversely proportional to volume at a constant temp
picture A- increased collisions due to reduced volume = increased pressure
picture B- pressure and volume equal
Picture C- more volume = less collisions = reduced pressure
What is inspired air saturated with and what does this cause?
with water vapour in upper airways
- saturation = dilution of gases
At 37 degrees, what is the partial pressure of saturated water vapour?
= 6.3kPa
What is the relevance of inspired air being saturated with water vapour?
enables effective gas exchange
What is the partial pressure of air?
101.3kPa = 100% = sum of partial pressure of individual gases that make up air
What is the partial pressure of oxygen?
21kPa = 21% = fraction of inspired gas
What is the partial pressure of oxygen after being inspired and why is this?
19.9kPa- diluted due to presence of water vapour in upper airway
What is Daltons law of partial pressure?
Pressure exerted by each gas in a mixture of gases is independent of the other gases present
Total pressure of mixture of gases is equal to the sum of individual gas pressures
What gases make up air and what are their partial pressures?
O2 = 21kPa
CO2 = 0.04kPa
Nitrogen = 79kPa
Argon
Water vapour
What do you have to take into account when measuring partial pressure?
Altitude
Temperature
How does the partial pressure of oxygen vary between dry air and moist air?
dry = 21.2kPa
moist = 19.9kPa- at sea level
How does the partial pressure of oxygen vary at sea level and at higher altitudes?
sea level = 19.9kPa
higher altitudes = 5.8kPa
assuming temp remains at 37 degrees
Describe alveolar gas exchange of oxygen
has single cell layer that gases need to travel into bloodstream down a partial pressure gradient
1. deoxygenated blood in veins comes in- O2 partial pressure = 5.3kPa
2. Oxygen is picked up = blood becomes oxygenated and goes to heart- O2 PP = 13.3kPa
3. O2 entering has partial pressure of 19.9kPa in upper airways, as it travels into alveoli- partial pressure of O2 reduces further = 13.3kPa
= creates pressure gradient
Describe gas exchange of CO2
- Venous deoxygenated blood CO2 PP = 6kPa
- CO2 in alveoli = 5.3kPa
- Oxygenated blood going to heart = 5.3kPa
= pressure gradient created
Why is it important that the partial pressure gradient is maintained in the lungs?
PP of O2 entering via veins is lower than PP of O2 in arteries= so O2 moves down gradient into blood to oxygenate it
PP of CO2 is greater in veins than PP in arteries = so CO2 moves down gradient out of blood and into alveoli for excretion
Name +define 2 basic mechanics of breathing?
Inspiration = breathing in
Expiration = breathing out
Describe the process of inspiration
- Rib cage expands
- Lungs stretched
- Diaphragm moves downward
- Alveolar pressure reduced
= air drawn into lungs
How do we measure the pulmonary ventilation rate?
Frequency x tidal volume
What is the alveolar ventilation rate?
= the actual amount of air that reaches the alveolar- not all air reaches alveoli
When calculating the alveolar ventilation rate what do you have to account?
allow for wasted ventilation of dead spaces
Describe the perfusion in the lungs
Deoxygenated blood passes through the lungs and becomes reoxygenated
What is the ventilation perfusion ratio?
ratio of alveolar ventilation to blood flow
In a normal person, what should the ventilation perfusion ratio be?
1
What happens if you have normal ventilation but no perfusion?
= no capacity to carry O2 away or bring CO2 to alveoli = no gas exchange alveoli and blood
What happens if you have no ventilation but normal perfusion?
Shunt can be inserted so gas can escape
= No new O2 into system = pressure gradient disrupted with venous blood
What happens if there is low O2 entering blood?
constricts pulmonary arterioles = hypoxia
What happens if there is high O2 entering blood and where is this observed?
dilates pulmonary aterioles- observed in foetus
What happens is there is high CO2 entering blood?
dilates bronchioles- lung disease e.g. COPD
