4. Respiratory Physiology II Flashcards
To understand gas exchange We need to know a few basic laws • how gas behaves alone(\_\_\_\_) • in a mixture(\_\_\_\_) • in a fluid(\_\_\_\_)
diffusion
dalton’s law
henry’s law
Diffusion of gases
• Diffusion of gasses moves along concentra3on gradient, from areas
of ____ to areas of ____
• Movement of gases between cells and the blood in the capillaries and across the respiratory membrane of the alveoli is via ____
• ____ mo%on of molecules provides energy for movement
high partial pressure
low partial pressure
diffusion
kinetic
Partial pressure of gas: Dalton’s Law
Pressure is an effect which occurs when a ____ is applied on a surface. P=F/A
The partial pressure of an ideal gas in a mixture is equal to the pressure it would exert if it occupied the same volume ____ at the same temperature.
Dalton’s Law of Partial Pressures: The total pressure of a mixture of ideal gases is equal to the sum of the partial pressures of the ____ in the mixture.
Ptotal = Pgas1 + Pgas2 +…. + PgasN
• The partial pressure of various gases is additive
force
alone
partial pressures
Consequences of Dalton’s Law
Each gas in a mixture (air) tends to diffuse ____ of all other gases
Diffusion of oxygen does not interfere with diffusion of ____ or vice versa
Each gas diffuses at a rate proportional to its ____ until it reaches ____
This allows for ____ traffic of gases in the lungs and in the
body tissues
• Forces on O2 and CO2 are independent ○ Movement of O2 in one direction doesn't interfere with CO2 going in the other direction • Dalton's law lets us understand that gases in a mixture behave independently ○ How we have O2 going out, and CO2 going in
independently carbon dioxide partial pressure gradient equilibrium two-way
What about gas in fluid?
- Important because O2 and CO2 are exchanged between air and blood, which is mostly ____
- Even when dissolved in water, gases exert a partial pressure and diffuse from regions of ____ toward regions of ____
water
higher partial pressure
lower partial pressure
Henry’s Law: solubility of gases in a liquid
- Concentration of gas in fluid proportional to amount of gas in air above ____
- If more ____, get higher ____ of gas before building pressure
- So, partial pressure of gas in liquid determined by ____
• Henry’s Law:
partial pressure = concentration divided by solubility coefficient
• CO2 is more soluble in \_\_\_\_ than O2 • The more soluble, the more that gas can \_\_\_\_ before exerting a given partial pressure • (Partial pressure of a gas in fluid) • Solubility coefficient ○ Constant for a given gas ○ Affected by what it's dissolved \_\_\_\_ and the \_\_\_\_
fluid
soluble
concentration
concentration divided by solubility coefficient
H2O
dissolve
in
temp
Solubility coefficients of gasses in water
Oxygen: ____
Carbon dioxide: ____
Nitrogen: ____
CO2 stable in H20, ____x more soluble than ____
Thus, the same concentration of CO2 will exert proportionally less ____ than O2 as the solubility coefficient is much greater
• The solubility of CO2 is 20x more soluble than O2 ○ Can have same cxn of CO2, and the partial pressure will be 1/20th that of oxygen • Based on the: ○ Binding of atoms in \_\_\_\_ ○ How well they fit before exerting a pressure
0.024
0.57
0.012
20
O2
partial pressure
lattice
How rapidly do gasses move in fluid? Diffusion Rate
Although DP for CO2 low in gas exchange, moves quickly because of increased ____
* Diffusion is going to be approx equal to the difference in partial pressure, times the SA and solubility coefficient * Length of diffusion distance > the further apart your capillaries are in the tissue, the \_\_\_\_ it will take * Want to make sure you optimize the \_\_\_\_ for gas exchange in the lung
solubility
longer
area
Diffusion through tissues
Key gasses of respiratory importance are very ____
Thus diffusion through tissue basically ____ through water
If tissues ____ and length ____, takes longer
• In alveoli most of the gas exchange occurs ○ Type I cells ○ Covered in surfactant • The O2 and CO2 have to go from liquid compounds in blood through the cells ○ Both are very lipophilic, \_\_\_\_, small ○ Want to make this distance as short as possible § \_\_\_\_ situations arise when length increases ◦ When the length increases diffusion goes down, which may make it \_\_\_\_ for getting enough oxygen across the membrane
lipophilic
diffusion
thicken
increases
uncharged
pathological
rate-limiting
• The partial pressure of oxygen and carbon dioxide in each breath is dependent on
whether you are taking a ____ breath.
deep or shallow
Partial pressures of respiratory gasses
How does pO2 of expired air vary with shallow vs. deep breaths?
• Humidified air is normal air, but inside the body it's not as dry > concentrations \_\_\_\_ with a little bit of \_\_\_\_ • Humidified air ○ 150mmHg of O2 ○ Close to 0 of CO2 ○ Dead space air > air in mouth that gets as far as conducting passageways § No exchange of gases • Alveolar air ○ O2 > 100mHg ○ CO2 > 40mmHg • Expired air ○ Will vary ○ Shallow > a lot of \_\_\_\_ and alveolar air > closer to humidified ○ Deep breath > as you force air out from bottom > partial pressure of closer to \_\_\_\_ in alveoli
change
humidity
dead space air
O2/CO2
Replacement of alveolar air
Functional residual capacity (FRC) = ____ L, 0.35 L new air into alveoli per ____ breath, Takes ____ effort to fully dilute out old air with new, normally >____ min
Slow change useful, stops sudden change in blood gas concentration
Buffers ____, O2, ____ in blood
• Consequence of normal breathing > takes \_\_\_\_ breaths to turnover the air in your alveoli • FRC - when you breathe out the whole way • A lot of breath goes to the \_\_\_\_ (0.35 of 2.3L goes to alveoli) • Normally, exponential decay > after a minute you have some air left ○ You want to \_\_\_\_ concentrations; our bodies do not response well to sudden changes in concentration of oxygen in the alveoli
2.3
normal
exponential
1
pH
CO2
16
deadspace
buffer
Respiratory unit
Or, where the real business takes place
____ million alveoli in both lungs
____ mm diameter hole surrounded by epithelial cells that are in turn surrounded by blood
Exchange takes place in ____, alveolar ducts, ____ (necks), alveoli
* Epithelial cells are surrounded by capillaries * The lungs are designed to optimize interaction between air and blood * Gas exchange in bronchioles, but most occurs in the alveoli
300
0.2
respiratory bronchioles
atria
Exchange of gas
across respiratory membrane – designed to increase ____
Maximize exchange, blood always close to ____
Surrounded on all sides “Sheet of flowing blood”
70 m2 SA, perfused by 100 ml blood – very ____
Imagine spilling 100 ml of water over 25 x30 foot room
- very thin coating if spread across whole surface
* Interstitial space in between the capillaries * Lymphatic vessel - drainage, that stops the buildup of fluid in the lungs; \_\_\_\_ * There to optimize the exchange of gases from blood in your alveoli - depends on \_\_\_\_
contact alveolar membrane thin negative pressure diffusion
Exchange of gas
across respiratory membrane
Layers for gas to cross for exchange
Mean thickness ____ μm (Typical cell 10 μm)
- ____ (+ surfactant)
- ____ epithelium
- ____membrane
- ____
- ____
- ____
Pulmonary capillary 5 μm diameter so red blood cell must squeeze, touch wall, less ____ through plasma
• Fluid and surfactant covers edges of alveolar epithelial cells • Then it goes through epitheilail cells, basement membrane, interstitial space, capillary BM, and the tissue > and then in the portio • This distance is typically 0.6um ○ Each cell is 10 um ○ 1/20th the diameter • RBC have to line up \_\_\_\_ in this orientation, so they optimize the \_\_\_\_ for exchange, and squeezed in capillaries > \_\_\_\_ releases compounds that facilitates gas exchange • Getting oxygen into your tissues becomes a key aspect for life on earth
0.6 fluid alveolar epithelial basement interstitial space + matrix capillary basement membrane capillary endothelial membrane
diffusion
single-file
area
squeezing
Diffusion of gas across respiratory membrane
- Diffusion equation applies
- l - diffusion distance – increased by ____ in interstitial fluid, ____
- A = surface area - ____, walls collapse, less area,
- DP - # ____ of a given gas striking alveolar or capillary membrane• If you have an edema, and you swell the space; you have fibrosis and the interstitial distance is ____, you will take longer to get oxygen into the capillary and to get CO2 out
• The system has evolved with the capacity for ____
• Area decreases in emphysema > walls collapse and you have less area
○ Hundreds of little alveoli > decreased the area for gas exchange across that surface
○ As this decreases, the diffusion rate goes down
• Difference in partial pressure is the number of molecules striking the surface to go ____ (inside or outside)
ede,a
fibrosis
molecules
increased
adaptation
this way or that way
Ventilation-perfusion: matching blood flow and air flow
. V-____
. Q-____
Even if total blood flow and total air flow are ok, they must meet
The ventilation:perfusion (V:Q) ratio summarizes how the amount of ____ coming into the lungs matches with the amount of ____ that comes into the lungs
◦This matching is essential for efficient transfer of gases from alveoli to the blood and vice
Versa
• In normal situations V is usually = to ____ (V:Q is about 1)
◦Right amount of air to blood
• If you have a shunt — blocks air into alveolus
◦Blood is still going there but the air has slowed down
◦Shunt is perfusion without ____
• Dead space
◦Plenty of air but the ____ is not getting there
• You can measure the amount of air going into lung and the total perfusion
◦You can have a mismatch even if the total levels are good
◦They need to go to the same part of the ____ — if its unbalance you wont get normal function
• Used to describe pathology by clinicians
ventilation perfusion air blood Q
ventilation
blood
lung
Partial pressure of alveolar air; healthy case
Healthy case
VA / Q = ____v
Alveolar air:
PO2= 104 mmHg, PCO2 = 40 mm Hg
• In healthy perfusion cases the ratio is about \_\_\_\_. There is the right amount of air and blood coming into the alveoli • In alveolar air there is a partial pressure of oxygen of about 104 mm Hg and 40 mm Hg of carbon dioxide. • ( She doesn’t make sense here, but this is what she says) We get those partial pressures because there is a compromised between air diffusing through the conducting pathways and then you have gas exchange from the blue arterial air coming into the lungs exchanging before it goes out. • And so this 104 vs 40 reflects the diffusion of Co2 and oxygen back and forth when it meets up with the \_\_\_\_
1
1
humidified air
Partial pressure of alveolar air in physiologic SHUNT; like venous levels
• Physiological SHUNT - When ventilation blocked Va/ Q => \_\_\_\_ Alveolar air Þ venous gas levels PO2=\_\_\_\_ mmHg, PCO2 = \_\_\_\_ mm Hg \_\_\_\_ has less O2
• Low ventilation, and very high normal perfusion • Exchange of arterial blood going through, and no opportunity for \_\_\_\_ to come in ○ The partial pressures of CO2 and O2 are very low • If you can ventilate adjacent alveoli, you will have a \_\_\_\_ in amount of oxygen in the blood
0 40 45 blood fresh air reduction
Partial pressure of alveolar air in DEAD SPACE; like humidified air
• Physiologic DEAD SPACE - When blood supply blocked VA /Q => \_\_\_\_ Alveolar air Þ Humidified air PO2=\_\_\_\_ mmHg, PCO2 \_\_\_\_ mm Hg Work of ventilation \_\_\_\_
• Don't have any extra CO2, or low O2 blood coming around ○ Good ventilation, and no perfusion > infinity ○ Alveolar air approaches \_\_\_\_ ○ The work of ventilation is wasted § Cannot deliver any gases inhaled to the \_\_\_\_
infinity 149 0 wasted infinity blood
Alveolar gas levels with V/Q variation
• Ventilation-perfusion relationship ○ Within the alveolar space (within the alveoli) • In a shunt - cannot get fresh air ○ O2 levels in alveoli become much \_\_\_\_ (40mmHg), and the CO2 levels \_\_\_\_ because you cannot dilute out the CO2 with \_\_\_\_ ○ More sensitive for \_\_\_\_ • In a dead space - blood is an issue ○ \_\_\_\_ levels of oxygen (150 mmHg) and no \_\_\_\_ because there's no ability for diffusion of blood from the alveoli ○ More sensitive for \_\_\_\_
lower
increase
fresh air
PO2
high
CO2
PCO2
Abnormal VA/Q in normal lung
At apex (under pathological condi8ons), ____ < ____
Physiologic ____
At Base, ____ > ____
Physiologic shunt
Blood to bronchial vessels also shunted normally - ____% does not get O2
____ increases blood flow to ____ of lungs, less dead space, more efficient
• Because of vertical posture, we have mild degrees of dead space in the apex of the lung ○ No zone 1 under normal conditions ○ Under pathological conditions > blood flow substantially less than \_\_\_\_, and dead space in apex ○ In the base > \_\_\_\_ > blood flow greater than air flow • Shunted blood from lungs normally (2% is used to supply tissue) - this is not used for gas exchange > leads to drop in levels of \_\_\_\_ leaving the lungs
blood flow
air flow
blood flow
air flow
2
exercise
top
air flow
shunt
oxygen
Abnormal V/Q in
Chronic Obstructive Lung Disease
• After smoking
– small bronchioles
obstructed – ____
– Alveolar walls destroyed but ventilation – ____ because no ____
Most common pulmonary disabilities due to V/Q mismatch
• Mismatch between ventilation and perfusion ○ All the diseases we look at will satisfy this
shunt
dead space
capillaries
Summary: Gas Exchange – Lung
- Dalton’s Law – partial pressures ____
- Henry’s Law – solubility of gas in fluid ____ partial pressure
- Diffusion rate ____ Dpressure, area, solubility
- Alveolar air replaced ____, ____ blood gasses
- Respiratory exchange across ____ distance, many layers
- V/Q matches ____
- V/Q >1 – ____
- V/Q <1 – ____
additive lowers proportional slowly buffers small
air to blood
physiologic dead space
physiologic shunt
O2 delivery to pulmonary capillary
- O2 diffuses quickly into capillary – large ____
- Fast normal saturation is ____ – usually complete before blood flows through ____ of pathway
- During exercise, flow ____ but still enough time for ____ in capillaries
- When mixes with pulmonary shunt blood, PO2 drops to ____ mm Hg
- Shunt blood supplies ____ not exposed to air exchange
How long does it take for blood to pass through the lungs normally? During exercise? Recall from previous lecture.
Blood enters pulmonary capillary has a PP of O2 of 40 mm Hg (1) ◦The PP O2 increase \_\_\_\_(2) ◦1/3 of the way through the capillary the PP of O2 in the blood rise to the point where it is equal to the PP in the alveoli (3) • Level of diffusion complete within a \_\_\_\_ of the distance ○ Make sure you don't run out of oxygen ○ Need more oxygen > the blood is flowing faster • Alveolar blood levels is 104 mmHg, the blood that goes to the tissues is 95 mmHg ○ Reason it decreases, blood is coming from the \_\_\_\_ ○ Small % of lung goes from oxygenating the tissues of the \_\_\_\_ • How long does it take blood to go through the lung normally? ○ \_\_\_\_ second during exercise, and \_\_\_\_ second normally ○ Takes \_\_\_\_ ms for the full diffusion of oxygen into that blood
change in PO2 safety factor half faster complete 95 deep lung tissue
rapidly third pulmonary shunt lung 0.3 0.6 300
Diffusion of O2 to tissues and blood flow
- O2 diffuses quickly into interstitial fluid – large DPO2
- Mean tissue O2 ____ mmHg
- Tissue PO2 lower depending on ____ from capillaries
- Tissues with high rates of activity also have ____ O2 levels
- Only ____ mmHg O2 needed for cellular respiration - big ____• Tissue O2 depends on the tissue type, how far away it is, how much exercise you’re doing
○ Further away from the capillary, the O2 will be lower
• Diffusion of oxygen from capillary to tissue is as quick as possible
• 23 mmHg is a long way from hypoxic death, want to avoid situation where your tissues are close to death
○ Safety factor built in
23 distance low 1-3 safety factor
Hemoglobin – transporting O2
- 97% of transported O2 uses ____
- 4 subunits - each with ____. O2 binds ____ and reversible
- Cooperative binding – Binding of O2 produces ____ changes that make binding of subsequent O2 more ____• Hemoglobin undergoes cooperative allosteric binding
○ Once one molecule binds > shift in ____ of molecule that make it easier for oxygen to bind in other places
§ Important when picking up oxygen, and it also ____ oxygen into tissues where it’s needed
hemoglobin (Hb) heme loosely allosteric likely shape releases
Hemoglobin saturation with oxygen
Full saturation
– All ____ heme groups of the Hb molecule are bound to O2
• Partial saturation
– Not all of the heme groups are bound to O2
• Hb saturation is largely determined by the ____ in the blood
• High cxn of oxygen ○ Every hb has 4 oxygen bound to it • Partial saturation ○ Even distribution of amount of oxygen to the amount of hemoglobin
four
pO2
Hemoglobin saturation curve
- In lungs PO2 95mmHg–Hb ____% saturated
- In tissues PO2 40 mmHg, Hb ____% saturated
Questions:
Is this an efficient system?
Why is there so much excess O2 around?
____ to ensure you always have O2
• Showing saturation of hb compared to the partial pressure of O2 ○ \_\_\_\_ curve ○ Between 20 and 40 > rapid increase in \_\_\_\_ of oxygen to hb • PO2 of lungs > 100; \_\_\_\_% of binding sites of hb is full with oxygen • At 40, hb is still \_\_\_\_% full with oxygen ○ Why is there so much oxygen on Hb molecule when leaving the tissues? § Back to the fact that having enough oxygen is \_\_\_\_ for living beings § A lot of backup to make sure you have enough oxygen
97 75 backup sigmoidal binding
95-97
75
non-negotioable
Hemoglobin satura0on curve
During strenuous exercise, PO2 drops, Hb releases much more ____ because of ____ Po2/saturation curve
Thigh in exercise
* Partial pressure of oxygen in middle of thigh * \_\_\_\_ slope > portion where hb releases oxygen most \_\_\_\_ in response to changes * Difference between fully oxygenated hb and the rapid > amount of oxygen being delivered to the tissues
O2
steep
steeper
rapidly
Several factors shifts hemoglobin dissociation curve to right
Shifts curve to ____, ____ O2 when need greater in tissues
____
____
____ - if sustained hypoxia, 2,3- biphosphoglycerate (BPG) increases to enhance O2 ____
____ - Bohr effect
• If up top > not releasing a lot of oxygen, the further you move down, the more oxygen you're releasing to the tissue • At 40 mmHg, where at about 70% release > releasing 25-30% oxygen on hb • Don't want only hypoxia to be the only signal: ○ Listed on slide • As shifted to right, for a PO2, there is a slower saturation/increased \_\_\_\_ of oxygen • \_\_\_\_ important in releasing oxygen in exercising muscles
right
released
lower pH higher temperature BPG release CO2 release BPG
Binding of BPG to hemoglobin
BPG binding stabilizes the ____ of deoxyhemoglobin
The binding pocket for BPG disappears on ____
- BPG changes the shape of hemoglobin to encourage the ____ of more oxygen
- Important signal during ____ — part of ____ signaling.
t state oxygenation release exercise allosteric
Bohr Effect - CO2 (via H+) shi7s Hb satura:on curve as needed
CO2 + H2O H2CO3 H+ + HCO3-
CO2 rapidly converted to carbonic acid by ____, carbonic acid dissociates to ____ and HCO-3, so CO2 > H+
In lung, CO2 (and H+) leave blood, ____ rises, more O2 ____
In tissue increased CO2 leads to more ____, shifts O2-Hb curve to ____, ____ O2
• Ability of CO2 to kick off a little bit more oxygen ○ Hb in areas of higher CO2, lose greater proportion of oxygen
carbonic anhydrase H+ pH binds H+ right release
Carbonic Anhydrase
catalyzes reversible conversion of water and C02 into carbonic acid
* Critical for manipulating \_\_\_\_ * Carbonic acid (H2CO3) > unstable > dissociates into \_\_\_\_
CO2
protons
Bohr Effect - CO2 (via H+) shifts Hb saturation curve as needed
• Carbonic anhydrase converts the CO2 in exercising tissues into ____
• When protons are present in the tissue it shifts the oxygen/ hemoglobin curve to the ____
◦which allows for more oxygen to be ____
• In the lung the opposite occurs, in the lung it has a ____ effect but it allows more oxygen to
____.
protons right released minor bind
Diffusion of CO2 from tissues to alveoli
- In tissue, DPCO2 only ____ mmHg, but CO2 20x greater solubility coefficient than O2, so rapid ____
- In alveoli, DPCO2 only 5 mmHg, but CO2 20x greater solubility coefficient than O2, so diffusion before passed through ____ of capillary.
- Gives safety factor for ____ flow• In tissue, PCO2 is 45/46 mmHg > rapid diffusion of CO2 across capillary wall into the blood
• Opposite is seen in the lung
○ Blood enters thru the pulm cap at 45 mmHg, and rapidly reaches equilibrium of alveolus cxn of ____ mmHg
○ Rapid so you have enough leeway where under conditions where you’re exercising, where blood is moving more quickly
• 40 to 45 is a low change > only 5 mm
○ Stressed about solubility of CO2 being 20-fold that of O2
• Can have normal equilibrium through only ____ of the capillary
5
diffusion
1/3
capillary
40
1/3
Transport of CO2: multiple identities
CO2 transported from 5ssue to blood as ____
- CO2 crosses membrane ____
In Plasma \_\_\_\_% stays as gas \_\_\_\_% transported as carbaminohemoglobin \_\_\_\_% as HCO-3 – Carbonic anhydrase inhibitor \_\_\_\_ raises \_\_\_\_ pCO2 by \_\_\_\_%
• Three primary ways that CO2 is transported from tissue to blood: ○ Can cross rapidly via the cells on basic diffusion § But 7% of this CO2 stays as gas in plasma § \_\_\_\_% of it goes into the RBC, and of that > 23% of the total is bound to Hb and transported as carbaminohemoglobin ○ Vast majority of CO2 that is leaving the tissue is transported after conversion into carbonic acid > separates into bicarc and \_\_\_\_ § Via carbonic anhydrase - responsible for \_\_\_\_% of the CO2 that is leaving your tissues § The H+ binds to \_\_\_\_, and the bicarc leaves • [equation at the bottom] ○ Acetoazolamide § Blocking carbonic anhydrase rasies tissue PCO2 by 80% § No carbonic anhydrase, can only remove slight amount of CO2 away from your tissues
gas
easily
7 23 70 acetazolamide tissue 80
93
protons
70
hemoglobin
Transport of CO2: multiple identities
CO2 and H+ binds hemoglobin at ____
Both sites distinct from the ____ used for O2
____»_space; HbgCO2
• Binding site that hb has for CO2 is different from the site for protons, and they are both distinct from the heme binding site • 70% of it is transported out via bicarb, and the 70% of H+ binds into the hb ○ Will have more than 2x as much of H+ bound here in hb than the other pathway
different sites
heme binding sites
H-Hgb
Transport of CO2/HCO3 Chloride shift keeps intracellular pH low
Large production of HCO3- in RBC raises ____.
Maintain cell pH by exchanging HCO3- for ____
Mean RBC [Cl-] higher in ____ than ____
____ when get to lung
• Cannot have huge amounts of bicarb accumulating in RBC ○ The chloride shift § 70% of CO2 that's converted by carbonic anhydrase into bicarb, most of this is exported from the cell in exchange for Cl via the \_\_\_\_ (one of the most important antiporters in your body) ○ The cxn of Cl- is much higher in RBC in \_\_\_\_ returning, than those in the arterial system because of the swap • When get to the \_\_\_\_ > chloride shift is reversed
cellular pH Cl- venous blood arterial blood reverse
AE1
venous blood
lung
CO2 transport from blood to alveoli
In lung, oxygenation of Hb causes dissociation of ____ from Hb
H+ binds to HCO3, →____
Converted to ____ by CA
Pulls more ____ into cell – reverses Cl- shift
____ is released from RBCs Crosses membrane readily
• \_\_\_\_% in plasma diffuses across the space • Oxygenation of hb causes dissociation of \_\_\_\_ bound to Hb > increases concentrations of protons (increase in bicarb), and then carb anhydrase catalyzes reverse reaction to increase the \_\_\_\_ > diffuses into the alveoli ○ Reverse of the reactions in the tissue to stock up CO2 and bicarb ○ Release of \_\_\_\_ from the RBC into the plasma here > decreased cxn of Cl- in the RBC in the \_\_\_\_ as compared to the tissues
H+ H2CO3 CO2 HCO3 CO2
7
protons
CO2
Cl-
lungs
CO2 transport from blood to alveoli The Haldane effect: O2 kicks CO2 off Hb
Haldane effect means less ____ in blood for given pCO2 extra kick
Haldane effect – difference between ____
Doubles amount of ____ released in lungs
Quantitatively more ____ than Bohr effect
• Haldane kick - \_\_\_\_ kicks CO2 off of hb • When higher PO2 of oxygen, hb is going to release the \_\_\_\_ more readily • More important than the Bohr effect, contributes to a massive release of CO2 in the \_\_\_\_ ○ Doubles the amount released
CO2 curves CO2 importantt O2 CO2 lungs
CO2 transport from blood to alveoli
In lung, oxygenation of Hb causes dissociation of ____ from Hb
H+ binds to HCO3, →____
Converted to ____ by CA
Pulls more ____ into cell – reverses Cl- shift
____ is released from RBCs
Crosses membrane readily
• Oxygen leads to \_\_\_\_ changes in hb molecule ○ Oxygen is coming here \_\_\_\_ of Co2 leaving (dalton's), but the binding encourages the release of \_\_\_\_ from hb ○ The CO2 combines with the \_\_\_\_ that's been released ○ As bicarb is being used up, you see anion exchanger bringing \_\_\_\_ in and \_\_\_\_ out
H+ H2CO3 CO2 HCO3 CO2
allosteric
independent
CO2
bicarb
bicarb
chloride
CO2 – from tissue to blood to lung
What % in each form?
• In the tissues
○ Store ____% in plasma, ____% bound to hb, ____% following conversion to bicarb pumped out via the ____
• In the lung
○ Opposite happens
○ Haldane effect of O2 binding kicks off the CO2 and encourages the reaction
7
23
70
AE1
Summary: Gas Exchange – Tissues
- Diffusion of gas from alveolar to blood ____
- Increased blood flow increases tissue ____, decreases tissue ____
- DPCO2 small but ____ eases diffusion
- Hemoglobin (Hb) binds 4 ____ cooperatively
- Hb releases O2 when PO2 ____ mm, still ____% saturated so lots left when ____
- Bohr effect – ____ and ____ release O2 from Hb in tissue
- CO2 transported in ____, as H+Hb and as HCO-3 via ____
- Haldane effect - O2 kicks ____ off Hb in lung
fast PO2 PCO2 increased O2 40 75 exercise CO2 H+ plasma Cl- shift CO2
