Session 10_Respiratory System and Gas Exchange Flashcards
What is emphysema?
lung condition characterized by an abnormal, permanent enlargement of the air spaces distal to the terminal bronchioles accompanied by destruction of their walls.
Why are people with emphysema short of breath?
(irreversible alveolar damage resulting in loss of elastic recoil and the normal tethering of the alveolar, which renders the lung parenchyma excessively compliant and floppy. Excessive distension and dilatation of the terminal bronchioles and destruction of alveoli reduce the surface area for gas exchange. –> diffusing capacity is reduced.
Dead space in lungs and TLC increase.
Breathing at normal tidal volume, the pts airways close beyond the degree normally occurring with aging, contributing to ventilation and per-fusion mismatch and hypoxemia.
What causes emphysema?
prolonged history of smoking and chronic bronchitis. indicates significant irreversible lung damage.
Diffusion =
process of randomly moving molecules making their way back and forth across the respiratory membrane
What determines movement of gases?
concentration; high –> low
Dalton’s law of PP =
Ptotal = P1+ P2+ P3.. etc
What type of motion does diffusion require?
molecular motion
What gases are in the atmospheric pressure?
oxygen, nitrogen, carbon dioxide and water
How much oxygen is in the atmospheric pressure?
20.84% of 760mmHg = (158.384mmHg)
How much nitrogen is in the atmospheric pressure?
78.62% of 760mmHg = (597.512mmHg)
How much carbon dioxide is in the atmospheric pressure?
0.04% of 760mmHg = (.304mmHg)
How much water is in the atmospheric pressure?
0.5% of 760mmHg = (3.8mmHg)
Pressure creates a ___________ impact on the surface
molecular
Partital pressure =
multiple gases in air
Each gas exerts a pressure (partial pressure of whole); rate of diffusion is directly related to:
partial pressure of a gas
Total pressure at sea level =
760mmHg
Gases dissolved in fluids continue to:
exert forces
Partial pressure of a gas in fluid is determined by:
- concentration
* solubility coefficient of the gas
solubility coefficient of the gas is related to the partial pressure which is equal to =
concentration of dissolved gas / (divided by) solubility coefficient
What is the solubility coefficient of atmospheric O2?
0.024
What is the solubility coefficient of CO2?
0.57
Alveolar gas and molecules of same gas dissolved in:
blood
What will be the direction of the net diffusion of the gas?
depends on multiple factors.
What factors does net rate of diffusion depend on?
- pressure difference
- solubility of the gas in the fluid
- cross-sectional area of the fluid
- distance the gas must diffuse
- molecular weight of the gas
- temperature of the fluid
Gas diffusion (D) is proportional to:
∆ P x A (cross sectional area) x S (solubility) / d (distance of diffusion) x square root of MW (molecular weight)
∆ P x A x S / d x √MW
PP difference –>
PP @ arterial end and PP @ venous end
Diffusion coefficient =
relative rate that gases @ same PP will diffuse
Diffusion coefficient of oxygen =
1
Diffusion coefficient of carbon dioxide =
20.3
Diffusion coefficient of carbon monoxide =
0.81
Diffusion coefficient of nitrogen =
0.53
Diffusion coefficient of helium =
0.95
Diffusion coefficients give us a method by which to:
interpret how gases diffuse in water and/or blood
Respiratory gases are very soluble in lipids; therefore ___________________________________________.
Diffusion across membranes occurs relatively easily
What is a limiting factor for the rate of diffusion?
through tissue water
Rate of diffusion through tissues ≈
diffusion through water
O2 is constantly being:
constantly being absorbed from alveoli
CO2 is constantly being:
constantly diffusing from blood into alveoli
In H2O,
air is humidified in respiratory tract (water vaporizes) AND PH2O at body temperature = 47mmHg
What makes the concentrations different between atmospheric air and alveolar air differ?
O2, CO2, H2O, and N2
N2 makes up the balance of total atmospheric air at :
760mmHg
Can alveolar air be higher than atmospheric air?
NO
Know slide 16
Know slide 16
At what location is N2 highest?
in atmospheric air, @ 597mmHg
At what location is O2 highest?
in atmospheric air, @ 159mmHg
At what location is CO2 highest?
in alveolar air, @ 40mmHg
At what location is H20 highest?
same in humidified, alveolar and expired air, @ 47mmHg
At what location is N2 lowest?
in humidified air @ 563.4 mmHg
At what location is O2 lowest?
in alveolar air @ 104 mmHg
At what location is CO2 lowest?
in atmospheric and humidified air, @ 0.3 mmHg
At what location is H20 lowest?
in atmospheric air, @ 3.7mmHg
We get partial replacement of alveolar air when?
with each breath
New air into alveoli with each breath ≈
305ml (same amount of old air expired)
_____ alveolar air replaced by new air each breath.
1/7
What is the significance of alveolar air replacement?
to maintain balance of O2 and CO2
Alveolar oxygen concentration is controlled by:
rate of absorption AND rate of oxygen entry
Rate of absorption by pulmonary capillaries =
amount leaving the alveoli
Rate of oxygen entry into alveoli via ventilation =
amount entering the alveoli
PO2 in alveoli can never exceed?
149mmHg at sea level (if individual is breathing normal atmospheric air)
Why can’t alveoli exceed 149 mmHg???
??
Explain figure on slide 19
Explain figure on slide 19
Know figure on slide 20
Know figure on slide 20
In the respiratory membrane, diffusion of gases occurs very rapidly: large surface area of respiratory membrane with _________ amount of ________ spread throughout
small
blood
At the respiratory membrane, what size diameter are the pulmonary capillaries?
small
In the respiratory membranes gases travel from _______________________________.
one capillary to the next
Diffusion of gases through the respiratory membrane is similar to:
diffusion of gases through water
Diffusion of gases through the respiratory membrane is affected by:
• _______________ of membrane
• _______________of respiratory membrane
• _______________ coefficient
• _______________ difference across the membrane
- THICKNESS of membrane
- SURFACE AREA of respiratory membrane
- DIFFUSION coefficient
- PRESSURE difference across the membrane
What is the respiratory membrane’s diffusion capacity?
volume of a gas that will diffuse through the membrane each minute for a partial pressure difference of 1 mmHg
see slide 24
see slide 24
Va / Q normal =
Va for an alveolus is normal and Q is normal for the same alveolus
(4/5) = 0.8
Va/Q (0/5) =
(0/5) =0
Va is zero and there is blood flow
ex: holding breath // not breathing
Va/Q (4/0) =
(4/0) = ∞
Va (breathing) is adequate and there is no blood flow (ex: short lives situation –> ischemia)
Va =
Q =
ventilation
perfusion
Does gas exchange occur if ratio is zero or infinity?
no
every 4 part air / _____ parts blood
5
What 2 factors determine the PO2 and PCO2 in the alveoli?
- how fast brining in air; respiratory rate
2. rate of transfer across respiratory membrane
What is the ventilation ratio?
4 O2 / 5 blood = 0.8
What is the main drive behind gas exchange?
???
PO2 in alveoli ~
104mmHg
PCO2 in alveoli ~
40mmHg
What is the PO2 in venous blood of pulmonary capillary at its arterial end?
40mmHg
What is the PCO2 in venous blood of pulmonary capillary at its arterial end?
~45mmHg
What is the drive behind O2 diffusion from alveoli to capillaries?
pressure difference
Pulmonary diffusion (alevoli –> capillary) at rest occurs in the first ____________________.
1/3 of the capillary length
Diffusion of O2 at interstitial fluid :
internal respiration
PO2 in interstitial fluid surrounding the tissue cells at about what?
~40mmHg
Which direction will O2 brought by the capillaries move?
Why?
??? (leaving alveolar capillaries, O2 will be exhaled at PO2 120mmHg)
???
What will the PO2 be in the venous return?
Why?
??? (104mmHg; blood leaving alveolar capillaries)
??? (in lungs the blood is re-oxygenated)
Tissue PO2 is determined by what to rate?
- rate of O2 transport to tissues
2. rate at which O2 is used by the tissues
What do the bronchial arteries supply?
Supply deep tissues of lungs and do not come into contact with lung air (- returned via pulmonary veins)
What is the result when this blood returns to the left atrium?
??? (it is oxygenated blood that then is pushed to the tissues of the rest of the body)
shunt flow blood:
???
shoots past the alveolus, never comes into contact. Shunted blood PO2 40 mixes with oxygenate and drops PP to 95
… diluted 95PP actually goes out to body
Blood that doesn’t come into contact with the lung air:
serves the lungs
(tiny bit of blood)
98% of blood entering left atrium from lungs has gone through alveolus, and has been oxygenated, but 2% goes to aorta via bronchial circulation
O2 continually used to support __________ processes in the cell
chemical
Interstitial fluid surrounding tissue cells: PO2 ~
~40mmHg
PO2 in tissue cells =
5-40 mmHg (average 23mmHg)
What is the result of PO2 in tissue cells having 5-40mmHg?
???
Cells require about ___________ to support chemical processes
1-3 mmHg
CO2: tissues –> _____________ –> lungs –> _____________
tissues –> BLOOD –> lungs –> AIR
CO2 produced in cell when O2 used; what happens?
cellular CO2 rises
The pattern of diffusion and transport from tissue cell to alveoli follow same reasoning as O2 in:
opposite direction
CO2 diffuses much more __________ than O2, whY?
rapidly
solubility
Therefore, less ____________________ needed to cause CO2 diffusion than O2 diffusion
pressure difference
intracellular PCO2 =
46 mmHg
Interstitial PCO2 =
45mmHg
Venous end of tissue capillary PCO2 =
45mmHg
Arterial end of pulmonary capillary PCO2 =
45mmHg
PCO2 of alveolar air =
40mmHg
Venous end of pulmonary capillary PCO2 =
40mmHg
Decrease in blood flow at tissue interstitial fluid increases:
PCO2 in the fluid
Increase in blood flow at tissue interstitial fluid =
decreases PCO2 in fluid
Increase in metabolism increases interstitial:
fluid PCO2 at all blood flow levels [decreases has opposite effect]
True or false: Blood flow affects PP.
True
Hemoglobin transports ~97% of O2 from lungs to tissues, how is the rest carried?
Rest is carried in H20 of plasma and RBCs
Hemoglobin and O2 transport allows transport of ___________ the amount of O2 than if O2 was transported as dissolved gas in ________________________.
30-100x
gas in water of the blood
With exercise are you increasing or decreasing the hemoglobin affinity for O2?
decreasing
-so O2 can pop off onto the tissues
The oxygen-hemoglobin dissociation curve illustrates % of hemoglobin saturated by:
oxygen at any given point along transport route
PO2 has direct effect on O2 ___________ capacity
binding
PO2 high, O2 binds with:
hemoglobin
PO2 high, O2 binds with hemoglobin [when should this happen?]
???
PO2 low, O2 is releases from hemoglobin [example?]
???
Where in the body would you consider to be 100% saturated by oxygen?
lungs
At tissue level, what is the hemoglobin saturation level?
75% (low)
What is demonstrated on oxy-hemoglobin curve?
percent saturation of Hgb
In lungs with 100mmHg PO2, what is the percent O2 saturation?
100%
In tissues with 40mmHg PO2, what is the percent O2 saturation?
75%
If lungs have 20 mlO2 and tissue have 15mlO2 –> unloaded:
5mlO2 / 100ml bood
O2 leaving the lungs has PP of ~_____.
95mmHg (because of 2% shunted blood)
With PO2 @ 95mmHg, have hemoglobin saturation of:
~97%
O2 leaving the tissue has a PP of ~
~40mmHg
With a PO2 of 40mmHg, hemoglobin saturation is ~___.
75%
15 grams of Hgb can carry _________ O2 in 100ml blood (if Hgb is 100% saturated)
20ml
Normal conditions : With 97% Hgb saturation in arterial blood, ________ ml O2 carried to the tissue.
19.4ml
Leaving the tissues with ~14.4ml O2, what is the PO2 % Hgb saturation at this point?
???? about 70% -75%
Thereforre, ~5ml O2 left in the tissues per 100ml blood
Increased O2 ____ with exercise.
use
Interstitial fluid PO2 can drop from ___________ to ____________.
40mmHg to 15mmHg
With 4.4ml O2 left in 100ml blood, net delivery of _____ml to tissues.
15ml
** 3x normal amount of O2 is delivered
Combined with increased cardiac output by 6-7x norma, can get _____________________________.
20 fold increase in O2 delivery to tissues
Normal O2 delivery: ____ O2 per 100 ml blood
5ml
requires PO2 to drop to 40mmHg (19.4ml to 14.4ml) ; Hgb releases enough O2 at a PO2 of 40mmHg for the normal 5ml of O2 to be delivered and therefore sets the upper limit on O2 partial pressure.
With exercise, PO2 in tissues may drop to 15 mmHg; relatively small change in PO2 (___________) can cause very large additional release of ______________.
(40 to 15mmHg)
O2 from Hgb (20%)
With exercise, which way does the Oxygen-Hemoglobin Dissociate Curve shift?
to the right (to the right)
With exercise, also see ____________ of dissociation curve and get an increase in blood flow with ___________ O2.
steepness
decreased
(due to vasodilating of blood vessels)
Ex –> ____PP
15mmHg
True or false: There is a relative change in Tissue PO2 with variation in atmospheric [O2].
true
Drop in PO2 in alveoli from 104mmHg to 60mmHg –> changes Hgb saturation from 97% to ______ (small effect) ; PO2 of tissue changes to ______mmHg
89%
35mmHg
Increase PO2 to 500mmHg in alveoli - ________________________; O2 delivered to tissues and reduced PO2 to only a few mm greater than 40mmHg
can’t increase Hgb saturation >100%
** Demonstrates O2 buffer function of Hgb
List 4 factors that shift the curve to the right:
- increase in blood acidity (lower pH)
- increase CO2
- Increased blood temperature
- Increased 2, 3-biphosphoglycerate (BPG)
What causes a shift in the curve to the left?
Higher pH
In the BOHR effect: an increase in H+ and CO2 shifts the curve to the right which enhances:
- the release of O2 from Hgb in tissues, and oxygenation of blood in lungs
- oxygenation of blood in lungs
Bohr effect =
weakening of the hemoglobin-oxygen bond
i.e. O2 unloaded where it is most needed
At the tissue capillaries, the curve shifts to the right (effect of exercise on dissociation), what is the overall affect?
??? more oxygen available to tissues, less in Hgb??
The shift in the curve seen during EX are due to:
- increased CO2 produced
- increased [H+] in muscle capillary blood
- increased temperature of blood
At the lungs, curve shifts to the left - what is the overall effect?
red blood (Hgb) cells do not have enough O2.
Normall, PO2, of >__mmHg is sufficient for cellular reactions
1mmHg
ATP –> ADP, ADP increases metabolic use of O2, releases energy, then re-converts ADP–>ATP. Limited oxygen in cells is due to:
limited ADP
Diffusion limited:
increased distance for oxygen to travel, will take body longer to get oxygen
(increased D from capillary to cell)
** usually due to pathology
Blood flow limited:
if little blood flow, not able to bring enough oxygen.
–> leads to tissue ischemia, and tissue dies.
In carbon monoxide (CO) poisoning:
CO combined with Hgb in same location as O2
body is kind of tricked
PCO of 0.4mmHg allows CO to compete with O2 in combining with ______; allows ____ of _____ to bind with CO
Hgb
1/2 of Hgb
What is the lethal level of PCO?
0.6mmHg PCO
Hyperbaric Rx can displace _____ with _____ on Hgb.
CO with O2
* administered 5% of CO2 into the system, stimulates respiratory center, breathing faster, blow off more CO2. exhale off the excess.
also gives you supplemental O2
True or False: In carbon monoxide poisoning, show same signs and symptoms of lacking O2
FALSE, NOT the same signs and symptoms (color blue).
Normal conditions of carbon dioxide transport:
4ml CO2 per 100ml blood is transported from the tissues to the lungs
CO2 can be transported from tissues to lungs in various forms:
- As CO2 in plasma (7%)
- Combines with H20 to form carbonic acid in RBC
- Carbonic acid dissociates into H+ and HCO3-
- CO2 hooks up to Hgb
When carbonic acid dissociates into H+ and HCO3- what happens:
- H+ combines with Hgb - “buffered”
* HCO3- diffuses out of RBC into plasma (70% of CO2 transport) CI- diffuses into RBC
learn slide 53
slide 53
Carbon dioxide dissociation curve: Normal [CO2] in blood, ie., volumes percent, is 50 volumes percent:
(50ml CO2 per 100ml blood)
CO2 from tissue to blood is fast (70%)
CO2 from tissue to blood is fast
Carbon dioxide dissociation curve: _____ exchanged during normal blood transport
4ml
Dissociation curve - normal range of blood PCO2 is 45mmHg in tissues and ________ in arterial blood.
40mmHg
CO2 picked up in tissue capillaries, under normal conditions, can slightly decrease the ph from _________ (arterial blood pH) to __________.
7.41 to 7.37
CO2 change acidity in blood?
decrease pH and increases acidity
With release of CO2 in blood, pH returns to:
arterial value of 7.41
Potentially EX will ______ PP CO2
decrease
Respiratory Quotient: ratio of metabolic _____ exchange
gase
RQ =
CO2 produced / O2 consumed
RQ differs depending on the type of ______________________.
substrate metabolized (carb, fat, protein)
RQ approximates the nutrient mixture catabolized for energy during:
rest and exercsie
Precise determination of energy expenditure requires measuring both:
RQ and oxygen consumption
Respiratory Exchange ration (RER) compares:
compares the CO2 output to O2 intake
RQ = rate of __________ output and rate of _______ uptake
rate of CO2 output and rate of O2 uptake
R changes based on fuel for body metbolism.
Carbs : R ~
Fats: R~
Mix carbs, fats, protein R~
Carbs : R ~ 1.00
Fats: R~ 0.7
Mix carbs, fats, protein R~ 0.85
Can RER exceed “1”?
yes
High RER quotient (>1.00) can be due to:
- hyperventilation
- exhaustive EX
- lipogenesis
Low RER quotient =
recovery from exhaustive exercise
