SF3 Exam 2 O2 And CO2 Transport Flashcards
How do gasses move?
They move down partial pressure gradients
When do gasses exert partial pressure?
They exert pressure as long as they do not go under a chemical reaction with something else.
Ex)O2 and CO2 with hemoglobin
What relationship exists between partial pressure and dissolved gas?
Direct.
If you go from
0.3 vol O2 and 100mmHg
To
0.6 vol O2, the mmHg will be 200.
How do partial pressure and hemoglobin interact? When does oxygen have partial pressure?
A low partial pressure causes fewer hemoglobin to be bound with oxygen.
A higher partial pressure causes more oxygen to bind to hemoglobin.
Partial pressure of oxygen is only when the oxygen is not bound to the hemoglobin. Oxygen on the hemoglobin has no partial pressure.
How does high altitude effect hemoglobin and oxygen interaction?
Breathing 100% oxygen?
Hypoxic conditions?
Shifts left to unbound Hb and gas O2 due to less O2 present
Shifts right to more Hb(O2)4 due to more O2 present
Shifts left to unbound Hb and gas O2 due to less O2 present
Calculate the Oxygen in the artery and vein given
16g/100ml Hb Art PO2= 100mmHg Art blood= 97.4% saturated Venous 40mmHg venous sat 75%
Art= 21.18
Vein= 16.2
What does hemoglobin act as? Why is this important?
A buffer.
It allows you to go to higher altitudes and maintain a high saturation of oxygen in hemoglobin despite the lower PaO2.
It also allows you to be in pure oxygen environments and still have a normal range of oxygen content internally.
How does anemia effect PO2 in the blood?
The PO2 of the blood is the same in arterial blood at 100mmHg, but the O2 content is lower because there is less hemoglobin in anemia.
After losing the normal 5%, the PO2 of the blood is considerably lower in the anemic blood.
How does CO interact with hemoglobin? What does this cause? What is the classic presentation?
It is very drawn to attach to hemoglobin (200x greater than O2)
O2 does not have binding sites anymore. Patients usually have cherry red skin color.
How do you treat CO poisoning?
Use hyperbaric conditions in junction with a 95% oxygen 5% carbon dioxide mixture. The CO2 stimulates respiratory centers in the brain
What is higher in concentration when 650nm wavelength is used to check saturation?
HbO2
When a pulse oximeter is used, what is it measuring?
What does the value tell you?
It takes the ratio of reflection of both the 650nm and 900nm and presents that ratio as 650(red)/900(IR)
When the value is higher, more blood is oxygenated.
How does someone with anemia present on results from a pulse oximeter?
What about CO poisoning?
Anemia-They present as normal. This test CANNOT tell you how much hemoglobin a person has.
CO- They present as normal. The test only tells you saturation of hemoglobin. Not the substance bound to it.
Explain oxygen transport in tissues when exercising
H+ goes up and PCO2 increases (Bohr effect)
Temp is high
This causes an increase in P50 and results in a shift to the right on the graph. This gives more O2 to the tissue.
What does 2,3 DPG do?
Decreases Hb affinity for oxygen
What is different about Fetal Hemoglobin?
It has a higher affinity for oxygen, which makes a higher P50. This is a shift to the left.
2,3 DPG does not interact with fetal hemoglobin.
What compensatory mechanism occurs in people that live in high altitudes? What effect does this have?
Erythropoiesis occurs and makes more RBCs.
Increased hematocrit (Thicker Blood) ——— Causes heart to work harder
Additional O2 capacity
What effect would moving to a higher altitude have on:
DPG O2 content Hematocrit Hb saturation Art. PO2 Alv. PO2
DPG- increase O2 content- decrease then increase Hematocrit- increase Hb saturation- decrease Art. PO2- decrease Alv. PO2- decrease
Which is more easily diffused into blood? O2 or CO2
What does this result in in terms of pressure differences required for transport of each gas?
CO2
O2 has a larger difference (100 v 40)
CO2 has a much smaller difference (40 v 46)
What are the 3 ways to transport CO2?
Dissolved in plasma
as bicarbonate most common
Bound to Hb
What is the phenomenon that occurs during bicarb transport? Explain this.
Hamburger/ chloride shift
CO2 goes into the blood cell.
Meeting carbonic anhydrase and H20 results in:
H+
HCO3-
Deoxygenated Hb buffers the H+
HCO3- moves OUT
Cl- moves IN
In lungs, O2 displaces the H+ on Hb.
HCO3- comes IN and binds H+
Cl moves back OUT
CO2 goes into alveoli
What unique property does PCO2 and CO2 content of blood have?
It is a linear relationship, so you can average numbers together to find mixed PCO2s
How do you find PO2 when mixing 2 samples?
What would the PO2 be here? (Assume equal volumes)
1) PO2=120
2) PO2=70
Find the O2 content of each then average that.
Take this average O2 and find the corresponding PO2
The example comes to around 80-81 PO2
What functions so the lungs perform other than respiration?
1) Defense- Alveolar macrophages take care of bacteria and foreign particles and release lysozyme which activates the immune cells.
2) Heating and humidifying air
3) Olfactory receptors used for sniffing
4) cilia removing particles, mucous
5) Filter to trap clots and other things
6) Blood reservoir
7) metabolism of circulating substances
Why are immobile cilia syndrome patients more susceptible to respiratory disease in the lung?
Cilia do not function normally, so mucus does not get coughed up. particles and bacteria can more easily enter the lungs.
This repeat infection is called bronchiectasis where the lungs are scarred.
