110 terms

Gas Transport

Plasma is
the liquid portion of blood including clotting factors
Most oxygen carried in the blood is
chemically combined with a heme group
its concentration in the blood is decreased by hyperventilation, its accumulation in the blood is associated with a drop in pH, CO2 venous is greater than CO2 arterial
Most CO2 is transported in the blood in the form of
bicarbonate ion
O2 transport in the blood
50% oxygen saturation level of blood returning to the lungs might indicate a higher activity level than normal
Partial Pressure
each gas in a mixture exerts its own pressure as if all the other gases were not present, the pressure a specific gas exerts
Total Pressure
a mixture is the sum of all the partial pressures that make it up
Atmospheric Air
a mixture of oxygen, carbon dioxide, nitrogen and water
21% of gas in the atmosphere is
21% x 760 mm Hg =
p O2 (160 mm Hg)
How does gas diffuse
from areas of high partial pressure to areas of lower partial pressure
Gas acts
independently of other gases in the mixture
Gas dissolve in
Ability to stay in solution is dependent on
partial pressure, solubility coefficient
Solubility coefficient of CO2
high (0.57)
The chief extracellular anion is
The chief intracellular anion is
As dehydration increases, the release of ADH from the posterior pituitary will
The plasma protein concentration of a patient with untreated glomerulonephritis would be expected to be
less than normal
What is a function of atrial natriuretic peptide
it acts to increase blood pressure
Parathyroid hormone acts to
increase plasma calcium levels
7.0 is the normal pH of the
fluid within a typical cell
The addition of a strong acid to the extracellular fluid would result in the increased formation of
Which of the following depends on the presence of electrolytes
membrane polarity, neuromuscular excitability and maintenance of osmotic relations between cells and ECF
Plasma is considered to be
Solubility coefficient of o2 is
low 0.024
Solubility coefficient of N2 is
very low 0.012
The higher the partial pressure and the higher the solubility coefficient the more
the gas will have a tendency to stay in solution
Soft drinks are bottled
under pressure
CO2 remains dissolved
as long as the container is unopened
The term alkaline reserve is used to describe the ___ buffer system
In an attempt to compensate for plasma acidosis
breathing rate and depth will increase
The pH of blood varies directly with
If plasma (aldosterone) increases, Na+ excretion will
If lactic acid is injected iv, then plasma bicarbonate ion level will immediately
Very little atmospheric N2 dissolves in
blood plasma
N2 has low
solubility coefficient
A scuba diver breathes air under
In scuba diving the sum of partial pressures increases as total pressures
PN2 of compressed air is higher than
pN2 in the atmosphere
Increased plasma N2 levels brings on
giddiness, similar to alcohol intoxication (nitrogen narcosis)
Diver returning to the surface slowly allows
dissolved N2 to be eliminated through the lungs
A too rapid ascent
brings N2 out of solution quicker than the lungs can eliminate it
forms gas bubbles in the body tissues
Use of helium-oxygen mixtures instead of air containing N2
reduces dangers of decompression sickness
Carbon dioxide and oxygen for binding sites with the hemoglobin
Oxygen dissociates faster from hemoglobing during exercise
At high altitudes it is difficult to breathe because the air has a lower percentage of oxygen
The PO2 in the pulmonary veins is less than the PO2 in the alveolar air
If the alveolar partial pressure of carbon dioxide were 45 mmHg, carbon dioxide would not readily diffuse into the air
Helium is 40% less soluble than
Hyperbaric Oxygenation
uses pressure to cause more oxygen to dissovle in the blood
Oxygen is adminstered in a chamber at a pressure of
3-4 atmostpheres
HBO is used in treatment of
anaerobic bacterial infections, heart disorders, CO poisoning, gas embolisms, crush injuries, cerebral edema, bone infections, smoke inhalations, burns, asphyxia, vascular insufficiencies and near-drowning
Water will become saturated with
dissolved molecules of the gases with which it is in contact
Then main purpose for cellular oxygen is to provide a means of producing most of the cell energy
In order to maintain homeostasis, chloride ions follow as bicarbonate moves out of the erythrocyte
Within the blood, oxygen is primarily transported ___ while the bulk of carbon dioxide is transported
as oxyhemoglobin, as bicarbonate ions
Wheter oxygen diffuses from the alveoli into the blood or not is dependent upon the partial pressure ___
oxygen in the lungs and in the blood
The respiratory membrane, across which gases diffuse, is very thin and is made up of ___
alveolar cell membrane, capillary membrane and fused basement membranes
CO2 is about 20x more
soluble than O2 at body temperature
p O2 lowered to 100 mm Hg because
of mixture of inspired air witht he volume of old air retained in the anatomical dead space
Volume not exchanged with
inspired air
P CO2 is higher for
the same reasons
Alveolar gas composition
changes little during each respiratory cycle
The most important factor that allows the blood to carry carbon dioxide in high amounts is
carbonic anhydrase
Where is most carbon dioxide transported
as bicarbonate
Has the highest affinity for hemoglobin
Favors a release of oxygen from hemoglobin
decreased pH
At high PO2 levels, where is most oxygen located
Most of the oxygen in the blood is found in the
Which condition is characterized by inflammation and infection involving the alveoli
Where is the highest amount of carbon dioxide found
the arteries entering the lung
What is the normal PO2 of the alveolar air
104 mmHg
What is the normal PCO2 of the capillary blood
45 mm Hg
total alveolar ventilation
2 L
Each alveolar ventilation amounts to only
350 mL to be diluted by the total volume
During exhalation alveolar air
mixes with anatomical dead space air that was not altered by gas exchange
p O2 expired air
120 mm Hg
p CO2 expired air
32 mm Hg
What is the partial pressure of atmospheric oxygen
160 mm Hg
Which is the most abundant gas in the atmosphere
If a person ascended a mountain where the atmospheric pressure was only 500 mmHg, what would the PO2 of the air be, assuming that the air consisted of 21% O2
List the substance that can combine with Hb
O2, CO2, H+, CO
The ___ effect refers to the increased affinity of Hb for CO2 and H+ after O2 unloading
P O2 mixed venous blood
40 mm Hg
P CO2 mixed venous blood
46 mm Hg
Driving force for O2 diffusion
p O2 alveolar air (100 mm Hg) - p O2 of pulmonary arterial blood (40 mm Hg) = 60 mm Hg
Driving force for CO2 diffusion
p CO2 of alveolar air (40 mm Hg) - p CO2 of pulmonary arterial blood (46 mm Hg) = 6 mm Hg
Does CO2 has a much higher solubility and iffusion rate and thus appropriate volumes of CO2 and O2 are exchanged across the alveolar membranes
The ___ effect refers to the reduced affinity of Hb for )2 in the presence of increased CO2 and H+
The primary factor that determines the % Hb saturation is the
The combination of Hb and CO2 is known as carboxyhemoglobin
Hemoglobin, by acting as a storage depot, plasy an important role in permitting the transfer of large quantities of O2 between the blood and surroudnign tissue down PO2 gradietns because the O2 boudn to Hb does not directly contribute tot he blood PO2
In the plateau region of the Hb-O2 curbe, a large decreases in PO2 results in a small decrease in Hb saturation, wheras in the steep portion of the blood and surroudnign tissue down PO2 gradients becasue the O2 bound to Hb does not directly contribute to the blood PO2
Blood gas partial pressures
equilibrate with partial pressures of alveolar air within 1/3 of a seconde that each drop of blood is exposed
Full equilibrium occurs
even with increased blood velocity (exercise)
Extremely short diffusion path
between alveoli and blood
Partial pressure of dissolved gas in systemi arterial blood and alveolar air
might be assumed to be equal
The body's resting O2 consumption is
250 ml per minute O2
During hyperventilation, arterial PCO2 levels decrease because CO2 is blown off more rapidly than it is being produced in the tissue
Carbonic anhydrase is found only in the plasma
At the systematic capillaries, the PO2 is in the range of teh steep portion of the O2 -Hb curve
O2 is much more soluble in blood than CO2 is
The most important factor that determiens the extent to which hemoglobin is satruated with oxygen is the blood PO2
Normal cardiac output
5 L/ min
99% of O2 is carried by
is an oxygen binding iron based protein contained within the RBC
When oxyhemoglobin is fully saturated with oxygen it is
brilliant red
Deoxyhemoglobin has lost one or more of four oxygen molecules
dark red