L24. Gas Transport Flashcards
Which is more diffusible, CO2 or O2?
CO2
Name 2 gas diffusion properties in the respiratory and circulatory systems.
- Large surface area for gas exchange
2. Mechanisms to transport CO2 and O2 between lungs and tissues
Describe the relationship between the partial pressures of O2 and CO2.
They are generally opposites
Complete the sentence:
The sum of the partial pressures of a gas (in mmHg or torr) must _________________________________
be equal to the total pressure
Give the abbreviation and value for barometric pressure at sea level.
760mmHg
Give the pressure of water vapour at 37 degrees c
47mmHg
How do you calculate the internal pressure of O2?
P I O2 = (Barometric pressure - water pressure) x fraction of O2
Describe the 2 methods that oxygen can travel in the blood
Dissolved or bound to haemoglobin
Name the type of sample which measures dissolved blood.
Arterial blood sample (PaO2)
What is arterial blood pressure at rest?
3ml/L
How much oxygen is needed per minute of strenuous exercise?
3L/minute
Haemoglobin is composed of a protein with 2-alpha and 2-beta chains with how many haem groups?
4
How many haemoglobin units are in each blood cell?
280 million
Name the reader which can detect O2 saturation on your finger. Give a range of values for a healthy/unwell person.
Pulse oximeters
A healthy person should have 96-100%
An unwell person has 70-80% saturation
What is the normal respiratory exchange rate?
0.8 (80 CO2 to 100 O2)
This becomes greater than 1 during strenuous exercise
Name the 3 ways that CO2 can be transported
- Dissolved
- Bound to haemoglobin
- as bicarbonate
In a dissociation curve, which variable is ALWAYS on the x-axis?
Partial pressure of oxygen
As temperature decreases, what happens to the speed of haemoglobin’s oxygen saturation?
speeds up
As blood becomes more acidic, what happens to the speed of haemoglobin’s oxygen saturation?
speeds up
What is the total O2 capacity for each litre of blood?
211ml
In P O2 in mmHg, what state of oxygen-ation is the blood at before 100 and at 100?
Before 100 = deoxygenated
At 100 = oxygenated
