Test 2 Study Guide Flashcards
The net movement of molecules from
an area of high concentration to an area of low concentration.
Diffusion
This process continues until the molecules are evenly distributed, reaching equilibrium.
Diffusion
An example of ___ ____ ____ is ventilation, in which mouth and alveolar pressure differences cause all air molecules to move together, in and out of the lungs.
Bulk Gas Flow
Creates a pressure gradient between the air outside the body at relatively
high pressure and the alveoli at relatively low pressure.
Bulk Gas Flow
The gas moves down the pressure gradient through the airways of the lungs
and into the alveoli until the pressure of the air and that in the alveoli are
equal in this process
Bulk Gas Flow
Gas moves from an area of high pressure to an area of low pressure in this process.
Bulk Gas Flow
States that the rate of gas transfer across tissue is directly proportional to the surface area of the tissue, to the diffusion constants, and to the difference in partial pressures of the gas between the two sides of the tissue.
Fick’s Law
Fick’s Law states that the rate of gas transfer across tissue is directly proportional to the ____ _____ of the tissue, to the diffusion constants, and to the difference in partial pressures of the gas between the two sides of the tissue.
Surface Area
This law summarizes the factors that determine the rate of gas diffusion
through the alveolar capillary membrane
Fick’s Law
Fick’s Law is inversely proportional to the ____ of the tissue
Thickness
Formula for Fick’s Law
Vgas = [A x D x (P1 – P2)] / T
A = surface area
D = diffusion coefficient (solubility)
(P1– P2) = diffusion gradient
T = membrane thickness
These conditions cause decreased alveolar surface area:
Atelectasis, alveolar fluid, emphysema,
secretions, pleural effusion
This causes decreased partial pressure gradient across the membrane:
High altitudes
These conditions cause increased alveolar thickness (diffusion path length):
Fibrosis, alveolar edema
What is the alveolar air equation?
PAO2 = PIO2 – PACO2 [FIO2 + (1 – FIO2/R)]
The number ____ in the alveolar air equation is a factor that adjusts for alteration in oxygen tension due to
variations in the respiratory exchange ratio.
1.2
States that the rate of diffusion of a gas through a liquid is directly
proportional to the solubility coefficient of the gas, and indirectly proportional to
the square root of the gram-molecular weight (GMW) of the gas.
Graham’s Law
Because O2 is a lighter molecule, it diffuses through a medium ____ times faster than CO2
.
1.17
GMW of CO2 = 44
GMW of O2 = 32
States that the amount of a gas that dissolves in a liquid at a given
temperature is proportional to the partial pressure of the gas.
Henry’s Law
The amount of gas that can be dissolved by 1 mL of a given liquid at 760 mm Hg
and specific temperature is known as the ____ _____ of the liquid.
Solubility Coefficient
CO2 solubility
0.592 = 24
O2 solubility
0.0244 = 1
_____ _____ means that the movement of gas across the alveolar wall is a
function of the integrity of the alveolar-capillary membrane itself.
Diffusion Limited
A strictly diffusion-limited test gas such as ____ _____ is used to measure the diffusion capacity of the lung.
Carbon Monoxide
Carbon Monoxide (CO) is used to measure diffusion capacity due to its high affinity for _____
Hemoglobin
Carbon Monoxide (CO) affinity for hemoglobin is ____ times greater than O2
210 times greater
As clinically performed, the single-breath CO test measures the amount (in
milliliters) of CO that diffuses across the alveolar-capillary membranes during a
___ second breath-holding period after first inhaling a known concentration of
CO.
10 second
Normal ranges for the single-breath CO test
20-30 mL/min/mm Hg
Normal DLCO in healthy young man under resting conditions
21 mL/min/mm Hg
Most O2 in the blood is bound to hemoglobin inside the ______
erythrocyte
Hemoglobin allows whole blood (plasma plus cellular components) to carry ____ mL/dL of O2 per 100 mL of blood if PaO2
= 100 mm Hg and Hb concentration = 15 g/dL.
20
Hemoglobin allows whole blood to carry _____ times more than the capacity of plasma alone.
67 times more
Binds 4 molecules of O2
Hemoglobin Molecule (HbA)
Hb combined with oxygen
Oxyhemoglobin (HbO2)
Not bound with oxygen
Deoxyhemoglobin
Means that a hemoglobin molecule either is bound to four O2 molecules or is bound to none.
Cooperative binding
At sea level, ___% of Hb in arterial blood are oxygenated
97%
At sea level, 97% of Hb in arterial blood are oxygenated, and ____% are
unoxygenated.
2.5%
Normal SaO2
97.5% at a normal PaO2
Normal SvO2
75% at a partial pressure of oxygen in mixed venous blood (PvO2)
low O2 content, yet can be 100% saturated.
Low Hb
normal O2 content, yet can have low saturation.
High Hb
Normal Hb level
12-15 g/dL
Normal arterial-venous content difference
At 15 g/dL and 100% saturation, hemoglobin’s oxygen carrying capacity is
15 x 1.34 = 20.1 mL oxygen.
- Mixed venous blood (PvO2
) at 75% saturation carries
0.75 x 20.1 = 15.1 mL/dL. - This equates to an arterial-venous content difference ≈ 5 mL/dL
Normal cardiac output
5 L/min
Represents the partial pressure at which
hemoglobin is 50 percent saturated with oxygen
P50
Provides a means of quantifying the hemoglobin’s affinity (willingness to bond) with oxygen
P50
Normal P50 (Remember this!!!)
27 mm Hg under perfect conditions.
Formula for oxygen content
CaO2 = ([Hb] x 1.34 x SaO2) + (PaO2 x 0.003)
Factors affecting O2 delivery (O2
DEL) to the tissues (Remember this!!!)
- Hb concentration
- Arterial Hb saturated with O2
- Cardiac output
The cardiopulmonary system delivers ____ mL of O2 to the tissues each minute at rest.
1000 mL
Blood transfusion to improve O2
delivery is needed when the Hb amount drops to this level
- Hb <7 g/dL
The movement of HCO3 creates an electropositive environment inside the RBC, as K+ and Na+ can’t follow HCO3 due to the RBCs membrane impermeability to positive ions. This is known as….
Hamburger Phenomenon (Chloride Shift)
During a Chloride Shift (Hamburger Phenomenon), all reactions involving CO2
are _____ in the lungs.
Reversed
CO2 is a byproduct of
oxidative (aerobic) metabolism
Body tissue produces = ___ mL/min of CO2
at rest each minute. (Remember this!!!)
200
At the tissue level, the _____ _____ occurs as hemoglobin’s affinity for CO2
increases as O2 dissociates from it and moves into the tissues.
Haldane Effect
Haldane effect = ____ in Hb affinity for CO2
Increase
At the alveolar level, the ____ ____ occurs when the uptake of oxygen
facilitates hemoglobin’s release of CO2
Haldane Effect
Haldane effect = _____ affinity in Hb for CO2
Decreased
At the tissue level, the _____ _____occurs when carbaminohemoglobin has a
decreased affinity for oxygen as CO2
combines with Hb this enhances the release of O2 to the tissues.
Bohr Effect
Bohr effect = _____ in Hb affinity for oxygen.
Decreased
At the alveolar level, the _____ ____ occurs as Hb affinity for oxygen increases
due to the offloading of CO2 into the alveoli.
Bohr Effect
Bohr effect = ____ in Hb affinity for oxygen.
Increase
CO2 reacts with water to form…
carbonic acid (H2CO3)
The fundamental characteristic of an acid is its release of ____ into a solution.
H+
Although CO2 is not technically an acid CO2
is treated as an acid in the body because of resulting ____ produced.
H+
Pathways for CO2 transported in the plasma (3)
- Carbamino compounds
- Dissolved CO2
- Bicarbonate
Pathways for CO2 transported in the red blood cells
- Bicarbonate
- Dissolved CO2
- Carbamino
CO2 is carried in the following three forms in the plasma and erythrocyte:
- Dissolved CO2
- HCO3
- Protein compounds (carbamino compounds)
According to _____ ______, the amount of CO2 dissolving in plasma is proportional
to the PCO2 to which the plasma is exposed.
Henry’s Law
Henry’s Law states that CO2
in the gaseous phase establishes _____ with CO2 in the aqueous state
Equilibrium
Blood pH normal range
7.35 - 7.45.
Blood pH becomes more _____ as the ratio decreases.
Acidic
Blood pH becomes more _____ as the ratio increases.
Alkaline (Basic)
In the plasma, the ratio of HCO3 and H2CO3 is normally maintained at…
20:1
90% of CO2 diffuses into the _____ rather than remaining in the plasma.
Erythrocyte
The reaction between CO2
and HCO3 is _____ x faster in RBC than in plasma (Remember this!!!)
13,000 X Faster
Cardiac Output: O2 delivery is ___ x body’s resting requirement (Remember this!!!!)
4x
