4. Respiratory Physiology II Flashcards

1
Q
To understand gas exchange
We need to know a few basic laws
• how gas behaves alone(\_\_\_\_)
• in a mixture(\_\_\_\_) 
• in a fluid(\_\_\_\_)
A

diffusion
dalton’s law
henry’s law

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2
Q

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

A

high partial pressure
low partial pressure
diffusion
kinetic

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3
Q

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
A

force
alone
partial pressures

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4
Q

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
A
independently
carbon dioxide
partial pressure gradient
equilibrium
two-way
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5
Q

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 ____
A

water
higher partial pressure
lower partial pressure

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6
Q

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 \_\_\_\_
A

fluid
soluble
concentration
concentration divided by solubility coefficient

H2O
dissolve
in
temp

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7
Q

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
A

0.024
0.57
0.012
20
O2
partial pressure
lattice

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8
Q

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
A

solubility
longer
area

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9
Q

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
A

lipophilic
diffusion
thicken
increases

uncharged
pathological
rate-limiting

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10
Q

• The partial pressure of oxygen and carbon dioxide in each breath is dependent on
whether you are taking a ____ breath.

A

deep or shallow

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11
Q

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
A

change
humidity
dead space air
O2/CO2

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12
Q

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
A

2.3
normal
exponential
1

pH
CO2

16
deadspace

buffer

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13
Q

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
A

300
0.2
respiratory bronchioles
atria

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14
Q

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 \_\_\_\_
A
contact
alveolar membrane
thin
negative pressure
diffusion
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15
Q

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
A
0.6
fluid
alveolar
epithelial basement
interstitial space + matrix
capillary basement membrane
capillary endothelial membrane

diffusion
single-file
area
squeezing

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16
Q

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)
A

ede,a
fibrosis
molecules

increased
adaptation
this way or that way

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17
Q

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

A
ventilation
perfusion
air
blood
Q

ventilation
blood
lung

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18
Q

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 \_\_\_\_
A

1
1
humidified air

19
Q

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
A
0
40
45
blood
fresh air
reduction
20
Q

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 \_\_\_\_
A
infinity
149
0
wasted
infinity
blood
21
Q

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 \_\_\_\_
A

lower
increase
fresh air
PO2

high
CO2
PCO2

22
Q

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
A

blood flow
air flow
blood flow
air flow

2
exercise
top

air flow
shunt
oxygen

23
Q

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
A

shunt
dead space
capillaries

24
Q

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 – ____
A
additive
lowers
proportional
slowly
buffers
small

air to blood
physiologic dead space
physiologic shunt

25
Q

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
A
change in PO2
safety factor
half
faster
complete
95
deep lung tissue
rapidly
third
pulmonary shunt
lung
0.3
0.6
300
26
Q

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
A
23
distance
low
1-3
safety factor
27
Q

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
A
hemoglobin (Hb)
heme
loosely
allosteric
likely
shape
releases
28
Q

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
A

four

pO2

29
Q

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
A
97
75
backup
sigmoidal
binding

95-97
75

non-negotioable

30
Q

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
A

O2
steep

steeper
rapidly

31
Q

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
A

right
released

lower pH
higher temperature
BPG
release
CO2
release
BPG
32
Q

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.
A
t state
oxygenation
release
exercise
allosteric
33
Q

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
A
carbonic anhydrase
H+
pH
binds
H+
right
release
34
Q

Carbonic Anhydrase
catalyzes reversible conversion of water and C02 into carbonic acid

* Critical for manipulating \_\_\_\_
* Carbonic acid (H2CO3) > unstable > dissociates into \_\_\_\_
A

CO2

protons

35
Q

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
____.

A
protons
right
released
minor
bind
36
Q

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
A

5
diffusion
1/3
capillary

40
1/3

37
Q

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
A

gas
easily

7
23
70
acetazolamide
tissue
80

93
protons
70
hemoglobin

38
Q

Transport of CO2: multiple identities

CO2 and H+ binds hemoglobin at ____

Both sites distinct from the ____ used for O2

____&raquo_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
A

different sites
heme binding sites
H-Hgb

39
Q

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
A
cellular pH
Cl-
venous blood
arterial blood
reverse

AE1
venous blood
lung

40
Q

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
A
H+
H2CO3
CO2
HCO3
CO2

7
protons
CO2

Cl-
lungs

41
Q

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
A
CO2
curves
CO2
importantt
O2
CO2
lungs
42
Q

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
A
H+
H2CO3
CO2
HCO3
CO2

allosteric
independent
CO2

bicarb
bicarb
chloride

43
Q

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

A

7
23
70
AE1

44
Q

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
A
fast
PO2
PCO2
increased
O2
40
75
exercise
CO2
H+
plasma
Cl- shift
CO2