LESSON 12 - gas exchange and transport within blood Flashcards
what are the two types of circulation within the oxygen cascade ?
pulmonary and peripheral cascade
differences in partial pressure are responsible for the exchange of O2 and CO2 that occurs between :
- alveoli and pulmonary capillaries
- tissues and tissue capillaries
alveoli and pulmonary capillaries are what type of interface ?
alveolar-arterial interface
tissues and tissue capillaries are what type of interface ?
arterial-myocyte interface
describe inspired air PO2 and PCO2 right outside of the trachea :
PO2 = 159 mmHg
PCO2 = 0.3 mmHg
describe trachea PO2 and PCO2 :
PO2 = 149 mmHg
PCO2 = 0.3 mmHg
describe arterial blood PO2 and PCO2 :
PO2 = 100 mmHg
PCO2 = 40 mmHg
describe tissue capillary around skeletal muscle PO2 and PCO2 :
PO2 = 40 mmHg
PCO2 = 46 mmHg
why does PO2 drop so much from 100 mmHg to 40 mmHg within the skeletal muscle ?
diffuses into bicarbonate or hydrogen
what dos he PO2 at 100 mmHg in the arterial blood drop to in the skeletal muscle ?
from 100 mmHg to 40 mmHg
describe PO2 and PCO2 of venous blood :
PO2 = 40 mmHg
PCO2 = 46 mmHg
when venous blood PO2 and PCO2 enters the alveolus what do PO2 and PCO2 levels change to ?
in venous blood : PO2 = 40 mmHg & PCO2 = 46 mmHg
in alveolus : PO2 = 100 mmHg & PCO2 = 40 mmHg
what does PCO2 from the arterial blood (at 40 mmHg) change into in the skeletal muscle ?
changes from 40 mmHg into 46 mmHg
does PCO2 in the arterial blood go up or down once it hits the skeletal muscle ?
goes up from PCO2 of 40 mmHg to PCO2 of 46 mmHg in the skeletal muscle
what is the average range the PO2 and PCO2 should be within the arterial blood ?
PO2 = 90 - 105 mmHg
PCO2 = 38 - 42 mmHg
what is the average range the PO2 and PCO2 should be within the venous blood ?
PO2 = 40 - 50 mmHg
PCO2 = 45 - 50 mmHg
how many steps are there of external gas exchange are there ?
3
what is the first step of external gas exchange ?
- O2 diffuses into arterial ends of pulmonary capillaries and CO2 diffuses into alveoli because of differences in partial pressure
what is the second step of external gas exchange ?
- as a result of diffusion at the venous ends of the pulmonary capillaries, the PO2 in blood is equal to the PO2 in the alveoli and the PCO2 in blood equals PCO2 in alveoli
what is the third step of external gas exchange ?
- PO2 in blood in pulmonary veins is less than in pulmonary capillaries due to a A- mismatch
how many steps to internal gas exchange ?
2
what is step one (step 4 total) of gas exchange ?
- O2 diffuses out of arterial ends of tissue capillaries and CO2 diffuses out of tissue because of differences in partial pressure
what is step two (step 5 total) of gas exchange ?
- as a result of diffusion at the venous ends of tissue capillaries, the PO2 in blood is equal to the PO2 in the tissue and the PCO2 in blood equals PCO2 in tissue
where does internal gas exchange occur ?
all occurring within the body in the muscles
within internal gas exchange descibe whats high versus low in regards to CO2 and O2 :
high CO2 and low O2
why is oxygen low in internal gas exchange ?
diffusion of where oxygen is to where it is needed
why is carbon dioxide high in internal gas exchange ?
CO2 is always higher within the muscle
what is oxygen transport cascade ?
describes the physiological ‘steps’ that bring atmospheric oxygen into the body where it is delivered and consumed by tissue
what are the two reasons that ?
- its gradient drives diffusion
- impacts how O2 and CO2 are transported and delivered
how many steps (levels) are there to the oxygen transport cascade ?
5
what are the 5 levels of the oxygen transport cascade ? (from highest number to lowest)
- air
- alveolar
- arterial
- mean capillary
- myoglobin
describe the number of partial pressure on each of the 5 levels of the oxygen transport cascade :
- air (159)
- alveolar (103)
- arterial (98)
- mean capillary (40)
- myoglobin (2-3)
what two ways are O2 transported in the blood ?
red blood cells and hemoglobin
what is erythrocytes ?
red blood cells
describe red blood cells :
- no nucleus (unable to reproduce)
- life span around 4 months
- produced and destroyed at equal rates
- contain hemoglobin
where are red blood cells carried ?
carried in the blood
what is hemoglobin associated with ?
iron
what is hemoglobin ?
protein within red blood cells
describe hemoglobin :
- O2 transporting protein in red blood cells
- heme + globin
- 250 million hemoglobin per red blood cell
what is hemoglobin made up of ?
heme and globin
what is heme ?
pigment , iron and O2
what is globin ?
protein
what is the co-operativty of hemoglobin ?
O2 binding increases affinity for subsequent O2 binding
describe blood components ?
55% plama and 45 % formed elements
describe what is found within the formed elements portion of blood (45%) :
- around 99% red blood cells
- around 1% white blood cells and platelets
describe what is found within the plasma portion of blood (55%) :
- 90% H20
- 7% plasma proteins
- 3% other
how do we calculate hematocrit ?
45 % formed elements / 100% total blood volume = 45 %
where do we find capillaries ?
anywhere that you have diffusion
until how long do we raise partial pressure ?
until we reach equilibrium
what are the two ways blood transports O2 ?
- dissolved in fluid portion of blood
- combined with hemoglobin (Hb) in red blood cells
what % of blood transports O2 through being combined with hemoglobin ?
98%
what % of blood transports O2 through being dissolved in fluid portion of blood ?
(2%)
what establishes PO2 ?
dissolved in fluid portion of blood
what does arterial O2 content mean ?
O2 carrying capacity of blood
what does CaCO2 stand for ?
content arterial oxygen
CaO2 expressed in mL O2 per 100mL of blood is equal to the sum of :
- O2 bound to hemoglobin (HbO2)
- the dissolved O2
what does SaO2 stand for ?
saturation oxygen
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___ is O2 carrying capacity of hemoglobin
1.34
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_____ is % saturation of Hb
SaO2
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__ is hemoglobin concentration
Hb
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_____ is partial pressure of O2
PaO2
what does PaO2 stand for ?
partial pressure oxygen
what is the reverse of O2 transport alveoli to blood ?
blood to muscle
“how much O is being extracted by the tissue”
arterial
what does a-VO2 difference tells us ?
tell you how well the body is working
how many directions are there for the oxyhemoglobin dissociation curve ?
2
what are the two directions of the oxyhemoglobin dissociation curve ?
oxygenating and deoxygenating
which way is curve going if there is an increase in unloading of oxygen (deoxygenating) ?
towards right
which way is curve going if there is decreased unloading of oxygen (oxygenating) ?
towards left
as PP (partial pressure) increases what happens to saturation of hemoglobin ?
saturation of hemoglobin increases
if there is a higher concentration of O2 what does this mean for saturation ?
higher saturation
describe loading portion of the curve of oxyhemoglobin dissociation curve ?
saturation stays high even with large changes in PO2
describe unloading portion of the curve of oxyhemoglobin dissociation curve ?
saturation changed quickly with even small changes in PO2, allowing oxygen unloading to tissues
what is the oxyhemoglobin dissociation curve showing us ?
oxygen content
oxyhemoglobin saturation %
PO2 mmHg
what does blood going through muscle cause venous oxygen level pressure to do ?
causes venous oxygen level pressure to drop (muscle can use that oxygen)
what are the two shifts in the oxyhemoglobin dissociation curve shifting ?
left and right curve
describe left curve :
- decrease unloading of O2
- more basic (increase pH)
- increase affinity
- decrease PCO2
- decrease temp
- decrease 2,3-diphosphoglycerate
describe right curve (Bohr shift) :
- increase unloading of O2
- decreased affinity
- more acidic
- increased temperature
- increased PCO2
- increased 2,3-diphosphoglycerate
which shift is more acidic ?
right shift
which shift is more basic ?
left shift
which shift is artery / vein ?
right shift = artery
left shift = vein
which shift is increased / decrease H+ ?
right shift = increased H +
left shift = decreased H +
which shift is basic ?
left shift
which shift is acidic ?
right shift
which shift is hypothermic (holding onto O2 as much as you can) ?
left shift
which shift is hyperthermic (fever and hot) ?
right shift
what is a Bohr shift ?
explains the increased release of oxygen by haemoglobin in respiring tissues
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“in areas where CO2 is high (e.g., active muscle), O2 is less tightly bound with hemoglobin and O2 is released more _________ “ (the Bohr effect)
more readily
does CO2 mean increased of decreased concentration of H+ ions?
increased
how does CO2 transport versus O2 ?
opposite
how many ways does blood transport CO2 ?
3 ways
what are the three ways blood transports CO2 ?
- dissolved in fluid portion of blood (establishes PCO2)
- combined with hemoglobin (Hb) in red blood cells
- combined with water as bicarbonate
list the % of each of the three ways blood transports CO2 :
- dissolved in fluid portion of blood = 10%
- combined with Hemoglobin in red blood cells = 20%
- combined with bicarbonate = 70%
what is the Haldane effect ?
when O2 binds with hemoglobin and CO2 is released
what terms/effect is used to describe :
- binding of O2 with hemoglobin tends to displace CO2 from the blood
CO2 dissociation curve and the Haldane effect
what is the effect that describes “when O2 binds with hemoglobin (lung), and CO2 is released”
Haldane effect
in the Haldane effect, what happens to CO2 when O2 offloads from hemoglobin (tissue)
CO2 binds to increase CO2 transport