Oxygen and carbon dioxide week 4 Flashcards
In what ways are alveolar atmospheric air different from normal atmospheric air?
the alveolar are has more CO2 and water, thus it is more dilute.
Which is more soluble in water (blood), CO2 or O2?
CO2 is highly soluble and oxygen is much less
The rate of diffusion in the net direction is affected by what 5 things?
- solubility of the gas in liquid
- Surface area of the barrier across which diffusion occur
- Distance of diffusion(membrane thickness)
- Molecular weight of gas
- Temperature ( not really an issue due to constant body temp
Why is aqueous diffusion the limiting factor?
because respiratory gases are highly soluble in lipids (cells/tissues)
rate of diffusion =
change in pressure x surface area x solubility constant / distance of diffusion x MW
what is tidal volume?
the actual amount of air displace between inhalation and exhalation. roughly 350 mL while 2300mL stays in lungs
What does the functional residual capacity do?
acts as a buffer that prevents sudden changes in the alveolar gas mix, which is useful for keeping blood gas levels fairly constant
What 2 things control the amount of oxygen in the alveoli at a given time?
- ventilation from breathing
2. rate of absorption from the blood
Describe the ventilation/perfusion ratio?
the relationship between alveolar ventilation and alveolar perfusion.
VA= ventilation of a given alveolus
Q= the blood flow to that alveolus
expressed as a function of pp of O2 and CO2
what happens when VA/Q=0
no air is reaching the alveolus, thus Q=0. The partial pressures will equilibrate with that of the pulmonary blood
what happens when VA/Q=normal
you have normal blood flow and ventilation to the alveolus.
What happens when VA/Q = infinity
you have poor blood flow to the alveolus thus no profusion and no gas exchange occurs. thus the partial pressure of O2 is equal to humidified air, while no CO2 is exchanged.
What is the physiological shunt?
when you can’t get enough O2 to blood, the blood will pass by without be oxygenated and is called shunted blood. This occurs as VA/Q approaches 0.
When does physiological dead space air increase?
as supplied ventilation is greater than perfusion, thus you have left over oxygen to do nothing with
In a normal standing person where is there physiological dead space and where is there shunted blood in relation to the lungs?
- at top of the lung there will be more physiological dead space due to the natural decreased blood flow
- at the bottom of the lung there will be increased shunted blood due to a higher amount of blood flow, resulting in more deoxygenated blood passing out of the lung.
Transport of blood gases depends on what 2 things?
rate diffusion and movement of blood(how much passes a given point per time)
what are the partial pressures of O2 in the alveoli, arteries, tissue capillaries, and venous return?
alveoli=105 mm Hg
artery= 95 mm Hg
tissue capillary= 95 dropping to 40
venous return= 40 mmHg
high partial pressures of O2 _____ binding to hemoglobin, and low pressures ______disassociation of O2 from hemoglobin?
increase
favor
T/F oxygen binds to hemoglobin as a diatomic molecule?
True, at each binding site you get two oxygens
What does cooperative binding mean?
for each site on hemoglobin (hb) occupied by O2, the affinity of the following site for O2 is increased. Thus more O2= more affinity for hb binding.
Hemoglobin release of O2 increases or decreases as partial pressure of O2 decreases
increases, and leads to more oxygen release from hemoglobin. Thus the reverse of cooperative binding
what is the utilization coefficient?
the percentage of blood that gives up its O2.
around 25% at rest and exercise increases this to about 85%
A shift to the right on the O2 disassociation curve means what?
there is a decreased affinity for O2 on hb, thus hb wants to get rid of O2
what 4 things can causes a shift to the right?
increased temp, partial pressure of CO2, 2,3-DPG and a decrease of pH. basically think about exercise and what happens to the body when you exercise.
What is a a hemoglobin called that binds to CO2? and how many molecules can bind to a heme group?
carbaminohemoglobin
4 CO2/ heme just like O2
Which has to most affinity to hemoglobin: CO, O2, or CO2?
CO thus carbon monoxide poisoning is dangerous and persons need to be subject to a saturation of oxygen
What is the Haldane effect?
states that deoxygenated blood has an increased ability to carry carbon dioxide, and oxygenated blood carries less CO2
What is the Bohr effect?
relates to how pH and CO2 affect the blood capacity for carrying O2.
