A&P2 Unit 3/4 Flashcards

blood oxygen
Terms Definitions
3 different ways gases can exist in solution
-dissolved state in solution
-combined w/ proteins in solution (Hgb)
-chemically modified (CO2 combines w/ water to form carbonic acid)
normal oxygen consumption at rest
VO2=250ml/min
(this is how much is delivered to the tissues per minute)
normal cardiac output at rest
5L/min
how many mls of O2 is delivered to the tissues for every Liter of blood?
250ml/min / 5L/min=50ml
How many mls of oxygen per 100ml of blood is passing through the tissues?
5ml O2/100ml
(50ml O2/1000ml)
what percentage of oxygen delivered to the tissues is in the dissolved state?
3% of the 5mls=0.15mls of O2
what accts for the partial pressure of the gas?
the gas that is physically dissolved
volume of oxygen dissolved in the plasma is r/t to its ______?
solubility coefficient
solubility coefficient for oxygen in plasma at normal body temp?
0.003 mlO2/100ml blood/torr
volume of oxygen dissolved in the plasma is directly proportional to ?
And whose law is this?
the partial pressure of oxygen
henry's law
calculate the amt of oxygen dissolved in the plasma of arterial blood?
Sol coeff of O2 x PaO2=
.003ml/100ml blood/torr x 100
=
0.3ml O2/100ml blood
calculate the amt of oxygen dissolved in plasma of mixed venous blood?
sol coeff of CO2 x PvO2=
.003ml/100ml blood/torr x 40=
0.12ml O2/100ml blood
how do you determine the amt of oxygen delivered to tissue in dissolved state?
amt of oxygen dissolved in plasma of arterial blood -
amt of oxygen dissolved in plasma of mixed venous
actual calculation of the amt of oxygen delivered to tissues in dissolved state?
0.3ml/100ml blood -
0.12 ml/100ml blood=
0.18ml O2/100ml blood
(amt delivered to the tissues from plasma of every 100mls of blood flowing thru systemic capillaries)
how do you come up with 3% for the amt of oxygen delivered to tissues in dissolved state?
at rest, deliver 5ml of O2 for every 100ml/blood delivered to tissues & 0.18ml of this O2 is from plasma
(0.18ml O2/100ml blood
--------------------------------
5 ml O2/100 ml blood )
=.036---3.6%= approx 3 %
if breathing 100% at sea level, how much oxygen is dissolved in plasma?
1. determine PAO2
Patm-Ph2o-PACO2=673 torr
2. PAO2 x sol coeff:
673 x .003 ml/O2/100ml blood/torr=2.01 ml O2/100ml
(if all of this dissolved oxygen could be delivered to tissue, then approx 40% of tissues oxygen need can be met by the oxygen dissolved in plasma when breathing 100% oxygen)
how much oxygen is dissolved in plasma if breathing 100% at 2 atms?
2(760)-47-40= PaO2 of 1433 torr
1433 x .003ml/100ml/torr=4.3 ml O2/100ml blood
(80% of tissue needs could be met by doing this)
when does the amount of oxygen being delivered to the tissues from the dissolved state become significant?
-when breathing oxygen at high pressure
how does administering high FIO2 benefit pt's?
-increasing amt of O2 that can be delivered from the dissolved oxygen to the tissue
-increasing the initial O2 pressure gradient (imp for gas equilibration across pulm and systemic memb)
how much of the oxygen delivered to the tissue per min is combined w/ Hgb?
97%
3 steps needed in order for oxygen to combine w/ Hgb
1. oxygen diffuses across the pulm membrane and becomes dissolved in the plasma
2. oxygen diffuses from plasma and into the fluid of the RBC
3. oxygen combines with the Hgb molecules in the RBC
as oxygen becomes dissolved in plasma and the partial pressure rises, this creates a gradient b/t which two things?
the plasma and fluid of RBC
what increases oxygen binding to Hgb?
higher partial pressures of oxygen
what type of bond does oxygen form w/ hgb?
reversible
oxygen combined w/ Hgb =
oxyhemoglobin
if 100% saturated, each Hgb molecule is able to combine w/ how many molecules of oxygen?
4 (8 total)
composition of Hgb molecule
-globulin portion
-4 heme groups, each having a ferrous iron (Fe+2)
oxygen is specifically binding to iron in what state?
ferrous only (2+)
unoxygenated hgb is called ?
deoxygenated hgb or deoxyhemoglobin
the maximum amt of oxygen that can combine w/ hgb in 100ml of blood is termed?
oxygen carrying capacity of hgb
what does the oxygen-carrying capacity depend on?
the amt of hgb present in the blood
normal hgb concentration
15gm% ( 15gm of Hgb/100ml blood)
how many mls of oxygen can combine w/ 1gm hgb?
1.34 ml O2/ gm Hgb
what is oxygen carrying capacity in lab setting w/ pure Hgb (no impurities present)
1.39 ml O2/gm Hgb
normal oxygen carrying capacity for physiological man w/ Hgb of 15gm%?
20.1 ml O2/100ml blood
(20.1ml of O2 will combine w/ Hgb in every 100ml of blood)
if you change the Hgb concentration, what else will change?
the oxygen carrying capacity
2 things you have to know to determine Hgb saturation
-amt of oxygen combined w/ hgb
-the oxygen carrying capacity of Hgb
formula to determine the oxygen carrying capacity of Hgb (% saturation)
(O2 combined w/ Hgb/O2 carrying capacity of Hgb) x 100
what shows the relationship b/t the oxygen tension of the blood and the % saturation of Hgb w/ oxygen?
oxyhemoglobin dissociation curve
is the % saturation of Hgb w/ oxygen linearly related to the partial pressure of oxygen in the blood?
no, it is a S-shaped or sigmoid shaped curve
term used for mls of oxygen per 100ml of blood
volumes percent
does volumes percent or % saturation vary w/ the amt of Hgb present?
volumes percent
when using a volume percent of 20 for 100% saturation, this is only true when the Hgb is ?
15gm%
how do youcalculate volumes percent?
oxygen carrying capacity x Hgb
a normal PaO2 of 100, has a % saturation of ?
(arterial blood)
97.5%
how do you find out the amount of oxygen bound to Hgb in arterial blood?
a. 1.34ml O2 x 15gm/100=20.1(amt of O2 combined w/ Hgb in 100mls)
b. Oxy carrying capacity x % sat of arterial blood
(20.1 x .975=19.6)
**20 ml O2/ 100ml of blood**
how do you find out the oxygen content of the arterial blood?
add the amt dissolved and the amt bound to Hgb
(19.6 + 0.3=19.9 ml O2/100ml)
what would the arterial oxygen tension need to be to get 100% saturation of arterial blood?
250 torr
does hyperventilating add significant amts of oxygen to the arterial blood?
no
what is the oxygen saturation of mixed venous blood as it returns to the pulm capillaries?
75%
calculate the oxygen carrying capacity of Hgb in mixed venous blood?
20.1 x 0.75=15
(15 mls O2 bound to Hgb/100ml blood)
oxygen content of mixed venous blood?
15.1 + 0.1= 15.2
what is the utilization coefficient?
that fraction of oxygen that has been released from Hgb to the tissues
utilization coefficient of the arterial blood at rest?
25%
(5ml O2/100ml blood
--------------------------------
20 ml O2/100ml blood)
the utilization coefficient depends on what?
the metabolic activity of tissues and organs
(greater the metabolic activity, greater the utilization coefficient)
utilization coefficient of the blood in the coronary sinus at rest?
75%
(myocardium extracts 15ml of O2 per 100ml blood)
how do we increase the amount of oxygen available to the cardiac muscle?
we must increase perfusion b/c we are already releasing 75% at rest
which is more important:
% saturation or arterial oxygen tension in the blood
oxygen tension
the pulse ox provides us with a way to do what?
noninvasively estimate the arterial oxygen tension
3 parts to the oxyhemoglobin dissociation curve
steep middle portion
area b/t flat upper and steep
flat upper portion
steep middle portion of the curve corresponds to what?
oxygen tensions at the tissue level
oxygen tensions of the steep middle portion of the curve range from ?
40 torr to about 15/20 torr
what is the significance of the steep middle portion of the deoxyhgb curve?
a relatively small change in pressure causes a relatively large change in oxygen attached to hgb
a small decrease in pO2 in steep middle portion of curve, also causes a decrease in?
volume percent of O2 or percent saturation d/t a relatively large amt of oxygen being unloaded from hgb to the tissue
how does the steep middle portion of the curve facilitate oxygen delivery to the tissues?
it allows us to drop our pressure slowly so that we maintain our gradient which continues to allow oxygen to move into the tissues but still unload a large amt of oxygen
what is the significance of the flat upper portion of the curve?
that the pO2 can drop significantly (from 100-60) but the % saturation remains relatively high
what serves as a safety factor as it r/t the amt of oxygen bound to hgb?
the flat upper portion of the curve that asllows significant drops in pO2 without reducing the % saturation significantly
shifting the deoxy curve to the left and right, has little impact on which parts?
flat upper or very beginning
the greatest repositioning of the deoxy curve will be seen where?
at the steep portion, this occurs to pO2 seen at the tissue level...greatest impact is on oxygen delivery to tissues
a shift to the right of the deoxy curve results from?
Hgb's decreased affinity for oxygen, which means more will be given up to tissues
what is the significance of the part of the curve b/t the steep and flat upper part?
as blood is returning from tissues to pulm cap, mixed venous blood oxygen tension goes from 40-60, saturation goes from 75%-90%.
Fair amt of unloading of oxygen has already occurred, but there is still a PG left to allow the rest to unload (60-100)
how could you double oxygen delivery to the tissues?
shift the curve to right
factors shifting the curve to the right by decreasing Hgb's affinity for oxygen
-increase CO2 tension
-increase in H+ conc.
-increased temp
-increase in 2,3 DPG/ 2,3 BPG
-sickle cell anemia
the effect that H+ has on Hgb's affinity for oxygen is known as the?
Bohr effect
3 things that can increase H+ concentration causes shift to the right
ketoacidosis
lactic acid
exogenous acids from meds
what is produced in the RBC as a result of glycolytic metabolism?
2,3 DPG/BPG
(diphosphoglycerate/bis)
what happens to 2,3 DPG production during the first hour of strenous exercise?
it increases, which is beneficial b/c it decreases Hgb's affinity for oxygen, so it can be released to tissues which need it
a shift to the left results from?
increase in Hgb's affinity for oxygen
shift to the left causes:
less oxygen to be given up to the tissues
factors shifting curve to the left by increasing Hgb's affinity for oxygen are:
decrease in CO2
decrease in H+
decrease temp
decrease 2,3 DPG
increase in fetal Hgb
increase in methemoglobin
increase in carboxyhemoglobin
how was the Bohr effect first presented to us?
as Hgb effect due to CO2, now we understand it has Hgb effect due to H+ ions
what is directly causing the change in affinity of Hgb for oxygen?
the release of H+ in response to the increased CO2
an increase in CO2/H+ decreases Hgb's affinity for oxygen, curve is shifted to ____, and the shift occurs where?
left, tissue level
a decrease in CO2/H+ increases Hgb's affinity for oxygen, curve is shifted to _____, and this occurs where?
right, level of the lungs
events occurring in systemic & pulm capillaries in response to CO2 changes is referred to as?
the Bohr effect
what determines the relative position of the oxyhemoglobin dissociation curve? (whether it has shifted to right/left)
P50 test
what is P50?
the PaO2 at which the Hgb is 50% saturated with oxygen (or 50% is in deoxygenated state)
Normal P50 of arterial blood
26-27 torr
when P50 is increased, the curve is?
shifted to right, decreased affinity of Hgb for oxygen, more to tissues
when P50 is decreased, the curve is?
shifted to left, increased affinity of Hgb for Oxygen, less to tissues
why is the venous curve shifted to the right?
b/c of lower pH and PCO2 is higher
what is the pH and CO2 like in the arterial blood...generally speaking?
increased pH and decreased CO2
what is the binding site of CO?
same binding site as oxygen on Hgb, ferrous site
how could you treat CO poisoning?
100% oxygen b/c you are increasing odds that oxygen will bind d/t increasing gradient
-could add a little CO2 to increase ventilation
-hyperbaric chamber at 2atms
how much more of an affinity does Hgb have for CO than Oxygen?
210 times greater
carbon monoxide + Hgb=
carboxyhemoglobin
color of carboxyhemoglobin
cherry pink
2 ways that CO decreases oxygen delivery to the tissues
-it occupies some of the binding sites normally occupied by oxygen
-it increases affinity of Hgb for those oxygen molecules that are bound to Hgb, so makes it difficult to release
in pt exposed to CO, what will their PaO2 look like?
normal b/c CO doesn't interfer with ability of oxygen to dissolve in plasma
what law explains why PaO2 levels are normal in someone exposed to CO?
dalton's law of partial pressure:
each gas in a mixture exerts a pressure independent of other gases in mixture
in CO exposure, what happens to total oxygen content of the blood?
decrease in total content
what are readings like of someone's pulse ox that was exposed to CO?
normal or false high
/ 102
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