Lecture 3/25 - Blood gases Flashcards
Test 3
1
Q
T/F: CO2 & O2 act the same in the blood
A
F
Act differently
2
Q
How does oxygen get dissolved into a solution?
A
PO2 in the environment, in a gas state, is used to push the O2 into a solution in a dissolved state
3
Q
What is the PO2 in a solution after equilibration?
A
100 mmHg
4
Q
O2 is _____ soluble. What does this mean?
A
Lipid
Not very soluble in plasma
5
Q
What happens at the air-water interface of a solution regarding oxygen?
A
Atmospheric O2 pushes the O2 in
Dissolved O2 pushes equally in the opposite direction (pushes out)
** after equilibration the forces are balanced though**
6
Q
1 dL =
A
100 ml
7
Q
How much O2 we have in a biological solution depends on the ________
A
solubility
8
Q
Solubility of O2 coefficient =
A
0.003ml O2/mmHg/dL
0.003ml O2/mmHg per dL (100ml)
9
Q
Equation: Dissolved O2 in solution =
A
PO2 x O2 Solubility coefficient
O2 Pressure of that solution x 0.003 ml O2/mmHg/dL
(Units: ml O2 per dL)
10
Q
PvO2 =
A
40 mmHg
(Venous O2 pressure)
11
Q
How much dissolved O2 do we have in the veins?
A
PvO2 = 40 mmHg
Solubility of O2 coefficient = 0.003ml O2/mmHg/dL
(40 mmHg) x (0.003ml O2/mmHg/dL) = 0.12 ml per dL
12
Q
How much dissolved O2 do we have in blood?
A
PO2 = 100 mmHg
Solubility of O2 coefficient = 0.003ml O2/mmHg/dL
(100 mmHg) x (0.003ml O2/mmHg/dL) = ** 0.3 ml per dL**
13
Q
We need ________ of O2 per _____ to stay alive
A
250ml of O2 per minute
14
Q
______ help increase O2 in the blood by assisting with O2 ________
A
Hemoglobin
transport/storing
15
Q
T/F: Dissolved O2 is enough to sustain life
A
F
Dissolved O2 is only 0.3ml per dL
We need 250 ml per minute - not enough
16
Q
For each gram of Hb, can can store/transport _______ of O2
A
1.34 ml
17
Q
What is the carrying capacity of 1 Hb?
A
1.34 ml/O2
18
Q
Hb =
A
Hemoglobin
19
Q
Normal Hb =
A
15 g/dL
20
Q
What is the O2 carrying capacity in the blood w/ Hb at normal value?
A
Normal Hb = 15g/dL
Carrying capacity = 1.34 ml/O2
15 x 1.34 = 20.1 ml O2 per dL
21
Q
Equation: O2 carrying capacity in the blood =
A
Hb x Carrying capacity (1.34 ml/O2)
22
Q
What is O2 carrying capacity?
A
Max amount of O2 we can carrying w/ that amount of Hb
23
Q
What does O2 saturation tell you? How do we use this?
A
What percentage of O2 carrying capacity of Hb in blood are bound by O2
Multiply O2 sat by carrying capacity.
24
Q
How much O2 is on Hb at 15 g/dL at a O2 sat of 92%?
A
15 g/dL x 1.34 ml/O2 = 20.1 ml O2 per dL
20.1 x 0.92 = 18.492 ml O2 per dL
25
Men have _______ Hb than women
higher
26
AHb/HbA =
Adult hemoglobin
27
Describe AHb
Adult hemoglobin:
Tetromer: 4 component
-2 alpha subunits
-2 beta subunits
28
How many O2 molecules can Hb carry?
4
29
FHb =
Fetal hemoglobin
30
Whats the difference between AHb & FHb?
FHb: has 2 alpha & 2 gamma subunits
-higher affinity for O2 than AHb
31
What is the benefit of FHb?
Higher affinity for O2 --> fetus can pull O2 from maternal blood (O2 can unload into fetal circulation)
32
When does FHb turn into AHb?
fairly quick after birth
33
_________ is a significant contributor to deciding how much Hb we have
Erythropoietin
34
Where/how is Erythropoietin produced?
Produced in deep/medullary parts in kidneys in response to hypoxia --> EPO released --> increases RBCs (Hb)
35
Why would we need synthetic Erythropoietin? When would this be important?
kidneys are not functioning properly
Important in sickle cell disease
36
______ is structurally similar to Hb. Whats the difference between them?
myoglobin
-higher affinity to O2
-found in muscles that are constantly in use (supporting posture muscles)
37
What does myoglobin do?
Helps to unload O2 into muscles (esp. red muscles) during activity
38
Why are red musles red?
Contain myoglobin --> rich in iron
39
Equation: Total O2 content =
Dissolved O2 + Bound O2
40
What is the total oxygen content if PO2 = 100 mmHg & O2 sat is 100%?
Dissolved:
(100 mmHg) x (0.003ml O2/mmHg/dL) = ** 0.3 ml per dL**
Bound:
15 g/dL x 1.34 ml/O2 = 20.1 ml O2 per dL
20.1 x 1.00 = **20.1 ml O2 per dL**
20.1 + 0.3 = **20.4 ml O2 per dL**
41
O2 prefers to be bound to _____ than in dissolved state.
Hb
(This is why dissolved Hb is so low)
42
CO ______ the ability of Hb to carry O2. Why?
reduces
CO displaces O2 and binds tightly
43
If 50% of O2 binding sites on Hb were bound by CO, how would that affect O2? saturation? oxyhemoglobin dissociation curve?
O2 sat: 1/2
O2 bound: 1/2
curve: plateau decreaed by 1/2
shifted to L
44
What is the basic pathology of anemia? How does that affect the oxyhemoglobin dissociation curve?
Less Hb available --> Decreased O2 carrying capacity --> less O2 carried even when 100% saturated
oxyhemoglobin dissociation curve: lowers plateau
45
What is the Tx for CO poisoning?
**100% O2** displaces CO from Hb
46
O2 has a ______ affinity for Hb than CO
higher
47
What is special about CO & O2 affinity w/ Hb?
When 1 CO is bound to Hb, it increases that Hb affinity for O2 --> harder to unload O2
48
oxyhemoglobin dissociation curve: Left shift (decreased PO2) = ________ affinity = ________ unloading
increased affinity
decreased unloading
49
oxyhemoglobin dissociation curve: Right shift (increased PO2) = ________ affinity = ________ unloading
Decreased affinity
Increased unloading
50
What is a normal arterial oxygen saturation?
97.4%
51
What is the total carrying capacity with a normal physiological saturation?
19.58 ml O2 per dL
52
What is a normal venous oxygen saturation?
75% or 3/4
(Actually more like 70% on the graphs 😒)
53
What is the venous oxygen content?
15.08 ml O2 per dL
54
What is the coronary sinus? Describe it
Big, blue venous blood vessel on base of heart
55
In the systemic circulation, from the arteries to the veins about ____% of O2 is utilized
25%
(20ml O2/dl --> 15ml O2/dl)
56
In the heart/coronaries, about ____% of O2 is utilized. How does it change?
75%
97.4% --> 25% saturation
57
Blood exiting the heart via the ______ has an O2 saturation of ____%
coronary sinus
25%
58
What are the pros vs cons of the heart/coronaries being efficient?
They are able to bring O2 saturation to 25% leaving the coronary sinus
pro: decreases amount of coronary perfusion needed
cons: if coronary blockage happens not a lot of O2 left over for damage control (75% already extracted)
59
Fetal hemoglobin has a ______ shift. What does this mean?
Left
Increased affinity for O2
60
Increase PO2 = _________ oxyhemoglobin saturation
Increase
61
What does increased affinity mean?
Requires less PO2 to reach the same saturation.
or
Same PO2 will have higher saturation
62
Fetal hemoglobin is about 100% saturated at a PO2 of _______
30 mmHg
63
Adult hemoglobin is 100% saturated at a PO2 of _______
100 mmHg
64
Equation: Fick's Equation =
CO = (O2 consumption) / (Art blood content - venous blood content)
Ex) 250 ml O2/min / (20ml O2/dl - 15 ml O2/dl)
65
Why is systemic venous saturation slightly lower than 75%?
Venous blood has more CO2 & protons = more acidic
**Also shifts venous curve to the R**
66
In a dissociation curve that has "volumes %", what does that mean? What information does that tell us?
Volumes % = O2 blood content
Ex) PAO2 = 100 (x-axis) the curve will show that hb saturation is at 100% and **blood content is 20 ml O2 per dL (arterial)**
67
How does increasing CO2 affect the O2 dissociation curve?
Increase CO2 --> more acidic --> O2 more prone to falling off --> **curve shift to right**
68
How does decreasing CO2 affect the O2 dissociation curve?
Decrease CO2 --> more alkalotic--> O2 less prone to falling off --> **curve shift to left**
69
How does O2 shift into the interstitial fluid and into the cell?
Hemoglobin can't do this. **O2 can only do this in dissolved form.**
70
What is the Bohr effect?
**Shifting the dissociation curve from left to right**
Refers to O2 unloading in the tissue depending on conditions in the body
71
What causes a right curve shift?
-hypercapnia
-acidosis (decreased pH)
-metabolically active environment
-hyperthermia
-increase 2, 3 BPG/DPG
72
What causes a left curve shift?
-hypocapnia
-alkalosis (increased pH)
-hypothermia
-decreasing metabolic activity
-decrease or no 2, 3 BPG/DPG
73
What are 2, 3 BPG/DPG? What are their alt names?
2, 3 BPG: Biphosphoglycerate
2, 3 DPG: Diphosphoglycerate
**These are byproducts of metabolism**
Alt names: Biphosphoglyceric acid
Diphosphoglycerate acid
74
In the lungs, decreasing temperature & 2, 3 BPG/DPG increase __________ in the lungs. What does this mean?
O2 loading
In this lungs, if you decrease the temperature (or 2, 3 BPG/DPG) from 37C, O2 binding will increase to Hb
75
Systemic venous PCO2 =
45 mmHg
(This is also pulmonary artery pressure)
76
In the lungs, a left curve shift means _______ O2 loading in the lungs
Increased
77
In the lungs, a right curve shift means _______ O2 loading in the lungs
decreased
78
Systemic arterial PCO2 =
40 mmHg
(This is also Pulmonary venous pressure)
79
More acidotic = ______ saturated Hb. What does this mean?
less
The curve will shift more to the right --> requires more O2 to saturate hemoglobin to a certain percentage
80
In the hemoglobin oxygen dissociation curve, the Venous curve is to the ______ and the arterial curve is to the _____
Right
Left
81
What is P50?
PP of O2 required to bring Hb O2 saturation up to a level of 50% or bind 50% of sites
82
What is a normal P50?
PO2 = 26.5 mmHg
83
Right shift = ______ P50
increased
Hb less prone to grabbing O2 therefore need more O2 in solution
84
Left shift = _______ P50
Decreased
Hb less prone to letting go of O2 therefore need less in solution
85
What are the 3 forms of CO2?
1. Dissolved
2. Carbamino
3. Bicarbonate.
86
How much does each form of CO2 make up in the system?
1. Dissolved: 5%
2. Carbamino: 5%
3. Bicarbonate: 90%
87
What is the CO2 solubility coefficient?
0.06 ml CO2/ mmHg/dl
0.06 ml CO2/ mmHg per dl (100ml)
88
Equation: Dissolved CO2 in solution =
(CO2 solubility coefficient) x (PP of CO2 in solution)
Ex)
(0.06 ml CO2/ mmHg/dl) x (40 mmHg) = 2.4 ml CO2 per dL of arterial blood
89
What is the Dissolved CO2 in the blood? What percent is our CO2 make up is this?
(0.06 ml CO2/ mmHg/dl) x (40 mmHg) =** 2.4 ml CO2 per dL of arterial blood**
about 5%
90
How are Carbamino compounds formed?
Small amount of CO2 combined w/ proteins that have terminal groups.
Proton falls off protein --> carbamino attaches --> **now call a carbamino compound**
91
Increased CO2 = ________ carbamino compounds. Why?
increased
Increasing CO2 --> more protons falling off
92
Dissolved CO2 =
Carbamino compound
2.4 ml CO2/dL & 5% of makeup
93
CO2 combines with _____ to for carbonic acid (H2CO3)
water
94
H2CO3 =
carbonic acid
95
Carbonic acid is NOT stable. What does it fall apart into & why?
1. bicarb & a proton: high CO & low pH (acidosis)
2. CO2 & water: low CO2 & high pH (alkalosis)
96
HCO3- =
bicarb
97
_______ speeds up conversion to bicarbonate and break down of carbonic acid. How does it work?
carbonic anhydrase
Pulls water out of carbonic acid --> CO2 & water
98
What is the CO2 make up in the venous blood? Why is it different?
1. Dissolved: 10%
2. Carbamino: 30%: more CO2 available for binding in venous blood
3. Bicarbonate: 60%: more protons in Venous blood so protons to consume some bicarb
99
What is total content of CO2 in the blood? How did we find this number?
**48 ml CO2 per dL**
Dissolved blood = 2.4 ml & that is 5%
Cross multiply = 48
100
On the CO2 dissociation curve, which curve is the arterial curve?
Bottom curve (Most right)
101
On the CO2 dissociation curve, which curve is the venous curve?
MIDDLE CURVE!!!!!!!!!!!!!!!
THE ONE RIGHT ABOVE THE ARTERIAL!!!!!!!
Arterial is closest to the bottom.
102
At an venous PCO2 45, what should CO2 content be?
52.5 ml CO2 per dl (100ml)
102
At an arterial PCO2 40, what should CO2 content be?
48 ml CO2 per dl (100ml)
