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RES149
Study Guide questions
86
Anatomy
Undergraduate 2
01/20/2009

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Term
What is the term that describes the movement of gas between the lungs and the body tissues?
Definition
Diffusion
Term
Diffusion gradient - Area where highest PO2 is found
Definition
Air
Term
Diffusion gradient - Area where lowest PO2 is found
Definition
Cells
Term
Diffusion gradient - Area where highest CO2 is found
Definition
Cells
Term
Diffusion gradient - Area where lowest CO2 is found
Definition
Air
Term
What is PAO2
Definition
partial pressure of oxygen
Term
What is the alveolar air equation
Definition
PAO2=FIO2x(PB-47) - (PACO2 / 0.8)
Term
Explain the pulmonary diffusion gradients
Definition
For gas exchange to occur between the alveoli and pulmonary capillaries, a difference in partial pressures (P1-P2) must exist
Term
What is the normal value for PO2 of venous blood returning to the lungs from the right side of the heart
Definition
40 mmHg
Term
What is the normal value for PCO2 of venous blood returning to the lungs from the right side of the heart
Definition
46 mm Hg
Term
How much faster does Carbon dioxide diffuse across the alveolar-capillary membrane than does oxygen and why
Definition
20 times faster, because of its much higher solubility in plasma
Term
What is the P50
Definition
A quantification of the measurement of variations in the affinity of Hb for oxygen
Term
What is the P50 a partial pressure of
Definition
Oxygen at which the Hb is 50% saturated, standardized to a pH level of 7.4.
Term
What is a normal P50 value
Definition
26.6 mm Hg
Term
WHat conditions cause the HbO2 curve to the right
Definition
conditions that cause a decrease in Hb affinity for oxygen
Term
What conditions cause the HbO2 curve to the left
Definition
conditions that cause an increase in Hb affinity for oxygen
Term
Define the Haldane Effect
Definition
The more oxygen that is bound to a hemoglobin molecule, the less carbon dioxide will bind to that molecule.
Term
What is the important thing to remember about the Haldane Effect
Definition
It causes the blood to pick up carbon dioxide better in areas of low oxygen and vice versa
Term
What is the Bohr Effect
Definition
The fact that pH alters the bonding of oxygen to hemoglobin
Term
Describe the Bohr Effect and its influence on the HbO2 Dissociation Curve
Definition
Changes in pH causes a shift in the curve. As the H ion concentration increases, which makes the pH more acidic, which alters the bonding of oxygen to hemoglobin, and therefore shifts the curve to the right
Term
With regard to the Bohr Effect, which shifts the curve to the right, how is it physiologically significant that an alkaline pH will cause a left shift of the curve?
Definition
as blood pH at the tissue is more acidic than at the lungs, so oxygen is more readily unloaded to the tissues. blood pH changes are the strongest of factors that will shift HbO2 curve
Term
What cause a right shift in Dissociation Curve
Definition
Decreased affinity, more tissue oxygenation, increased H+ (lower pH), Increased PCO2, Increased temperature, Increased 2.,3 DPG - If you live RIGHT you'll go UP to heaven
Term
What cause a left shift in Dissociation Curve
Definition
Increased affinity, less tissue oxygenation, Decreased H+ (higher pH), Decreased PCO2, Decreased temperature, Decreased 2,3 DPG
Term
What factors contribute to an increased in hemoglobin's (Hb) affinity for O2
Definition
acute alkalosis, decreased PCo2, Decreased temperature, low levels of 2,3 DPG, carboxyhemoglobin, methemoglobin, abnormal hemoglobin
Term
What factors contribute to a decrease in hemoglobin's (Hb) affinity for O2
Definition
Acute acidosis, High CO2, Increased temperature, high levels of 2,3 DPG, abnormal hemoglobin
Term
What is the normal value of the arterial oxygen content of combined O2 (1.34x 15 x SO2)
Definition
19.5 ml/dl
Term
What is the normal value of the venous oxygen content of combined O2 (1.34 x 15 x so2)
Definition
14.7 ml/dl
Term
What is the normal value of the arterial oxygen content of dissolved O2 (PO2 x 0.003)
Definition
0.3 ml/dl
Term
What is the normal value of the venous oxygen content of dissloved O2
Definition
0.1 ml/dl
Term
WHat is the normal value of the total arterial oxygen content
Definition
19.8 ml/dl
Term
What is the normal value of the total venous oxygen content
Definition
14.8 ml/dl
Term
What is the formula for the total oxygen content of blood
Definition
CaO2 = (0.003x PO2) + (Hbtot x 1.34 x So2)
Term
Calculate the total oxygen content if Po2 is 100 mm Hg, containing 15g/dl and Hb that is 97% saturated with O2
Definition
CaO2 = (0.003 x 100 mmHg) + (15 g/dl x 1.34 x 0.97) = CaO2 19.8 ml/dl
Term
Cite the primary indicator of hypoventilation
Definition
High PaCO2
Term
What is the amount of oxygen dissolved in the plasma represented by
Definition
the arterial oxygen tension PaO2 - to convert from oxygen tension (partial pressure) to oxygen content in ml/dl, multiply by 0.003 since .003 ml of oxygen will dissolve in one ml of plasma at a temperature of 37 celcius and one torr of ambient pressure. paO2 x 0.003 = CaO2!
Term
Blood carries oxygen in what two forms
Definition
small amount exists in simple physical solution, dissolved in plasma and erythrocyte intracellular fluid; majority is carried in a reversible chemical combination with Hb (hemoglobin) inside the RBC
Term
Hemoglobin saturation formula
Definition
SaO2 = [HbO2/total Hb] x 100
Term
Calculate the hemoglobin saturation where HbO2 of 15 g/dl Hb of which 7.5g was HbO2
Definition
Sao2 = [7.5/15]x100=50%
Term
Identify the hemoglobin saturation of the arterial blood that correlates with a PO2 of 65 mmHg
Definition
The HbO2 dissociation curve is shaped in a way such that the flat upper part of teh curve representing the normal operating range for arterial blood, minor changes in PaO2 of this flat portion, have little effect. Therefore 65mmHg PO2 is still 90%
Term
What is Fick Formula for calculating Cardiac Output (both Qt and C.O.)
Definition
Qt = VO2 / [C (a-v) O2 x 10]
Term
Calculate the following using Fick Formula for cardiac output; factor of 10 converts ml/dl to ml/L. Given a normal VO2 of 250 ml/min and a normal C (a-v)O2 of 5 ml/dl
Definition
Qt = 200 ml/min/ (5 ml/dl x 10) ; Qt = 250 ml/min / 5 ml/dl; AT = 5.0 L/min
Term
compare CO affinity to Hb compared to O2
Definition
CO is more than 200 times greater than it is for oxygen. Even extremely low concentrations of CO represent a loss in carrying capacity. CO with Hb shifts the HbO2 curve to the left furhter impeding oxygen delivery.
Term
What is looked at as the primary measure of ventilation
Definition
PaCO2 = partial pressure of arterial carbon dioxide
Term
How is CO2 transported in the blood and what are the percentages of each
Definition
1) dissolved in plasma and erythrocyte intracellular fluid - 8%; 2)chemically combined with protein - 12%; 3) Ionized as bicarbonate -80%
Term
How is carbonic acid classified
Definition
it is the only volatile acid of physiologic significance in the body. A volatile acid is one that is in equilibrium with a dissolved gas
Term
What is the primary blood gas component maintained by acid-base balance
Definition
CO2
Term
WHat are normal blood gas ranges
Definition
pH 7.35-7.45; PaCO2 35 - 45 torr; HCO3- 22-25 mEq/L; PaO2 80-100 torr
Term
What are the organs responsible for acid excretion in the body
Definition
lungs and kidneys
Term
what is the amount of time it takes for the lungs to remove acid from the body vs the time it takes the kidneys to excrete acid
Definition
compared with the ability of the lungs to change blood pco2 in seconds, the renal process is slow requiring hours to days
Term
what is the respiratory and what is the metabolic acid-base components
Definition
CO2 is respiratory and HCO3- is metabolic
Term
Define buffer solution
Definition
resists changes in pH when an acid or a base is added to it. Buffer solutions are mixtures of acids and bases. The acid component is the H+ cation, formed when a weak acid dissociates in solution. The base component is the remaining anion portion of the acid molecule , known as the conjugate base.
Term
what is the henderson-hasselbach equation
Definition
pH=6.1 = log [hco3/pco2x.03
Term
with regard to the henderson-hasselbach equation, what is the normal HCO3 to CO2 ratio
Definition
pH of 7.4 = 20:1 ratio of bicarb to CO2
Term
identify primary events that cause respiratory acidosis and respiratory alkalosis
Definition
hypoventilation causes respiratory acidosis, hyperventilation causes respiratory alkalosis
Term
describe the process of compensation
Definition
in hypoventilation (respiratory acidosis) the kidneys restore the pH to normal by reabsorbing HCO3, compensatory renal response to hyperventilation (respiratory alkalosis) is urinary eliminatin of HCO3. if a metabolic process lowers or raises HCO3 the lungs compensate by hyperventilation (eliminating CO2) or hypoventilation (retaining CO2) restoring the pH to near normal
Term
WHat are the two ways metabolic acidosis occurs
Definition
fixed (nonvolatile) acid accumulation in the blood or an excessive loss of HCO3 from the body
Term
what regulates the volatile acid content of the blood (CO2) whereas what controls the fixed acid concentration of the blood
Definition
the lungs regulate the volatile acid content of the blood (CO2) whereas the kidneys control the fixed acid concentration of the blood
Term
The larger an acid's equilibrium constant, what happens with regard to H+
Definition
the more the acid molecule dissociates and yields H+
Term
What happens in the open bicarbonate buffer system
Definition
H+ is buffered to form the volatile acid H2CO3 which is exhaled into the atmosphere as CO2
Term
What happens in the closed nonbicarbonate buffer system
Definition
H+ is buffered to form fixed acids which accumulate in the body
Term
What is the difference between bicarbonate buffers and nonbicarbonate buffers
Definition
bicarbonate buffers can buffer only fixed acids, but nonbicarbonate buffers can buffer both fixed and volatile acids
Term
How do the kidneys respond to hypoventilation and how to they respond to hyperventilation
Definition
hypoventilation by reabsorbing bicarbonate, hyperventilation by excreting bicarbonate
Term
how do the lungs respond to metabolic acidosis, alkalosis
Definition
acidosis by hyperventilating, alkalosis hypoventilating
Term
PaCO2 abnormalities characterize which type of acid-base disturbance vs. HCO3 abnormalities
Definition
PaCO2 is respiratory; bicarb is metabolic
Term
WHat does hypochloremia do to the acid-base balance
Definition
forces the kidneys to excrete increased amounts of H+ and K+ to reabsorb Na+, causing alkalosis and hypokalemia
Term
What does hypokalemia do to the acid-base balance
Definition
forces the kidneys to excrete increased amounts of H+ to reabsorb Na+ causing alkalosis
Term
Define hypoxia
Definition
When oxygen delivery falls short of cellular needs
Term
Describe the V/Q ratio and cite its normal value
Definition
ventilation perfusion ratio; an ideal ratio of 1.0 indicates that ventilation and perfusion are in perfect balance. High V/Q indicates that ventilation is greater than normal, perfusion is less than normal or both. A low V/Q ratio means ventilation is less than normal perfusion is greater than normal, or both
Term
What is a shunt
Definition
blood flow but no ventilation; venous blood bypasses ventilated alveoli and mixes with freshly oxygenated arterial blood, resulting in what is called a venous admixture
Term
What is the most common cause of hypoxemia in patients with respiratory diseases
Definition
v/q imbalance
Term
how can hypoxemia from v/q imbalance be differentiated from hypxemia caused by shunting
Definition
apply the following 50/50 rule: If the oxygen concentration is more than 50 (%) and teh PaO2 is less than 50 mmHg, significant shunting is present; otherwise the hypoxemia is mainly caused by a simple V/Q imbalance
Term
Define anemic hypoxia
Definition
when the blood cannot carry enough oxygen, even when enough O2 gets from the lungs to the blood
Term
What is the result of hemoglobin deficiency on oxygen delivery
Definition
hemoglogin carries the vast majority of oxygen, while blood plasma carries very little. if hemoglobin is unable to carry oxygen, the CaO2 will be greatly decreased and the patient will be hypoxic
Term
What does the movement of gases between the lungs and the tissues depnd mainly on?
Definition
diffusion
Term
What does the alveolar PCO2 vary directly with and inversely with
Definition
varies directly with carbon dioxide production and inversely with alveolar ventilation
Term
How is alveolar PO2 computed
Definition
using alveolar air equation
Term
With a constant FIO2, what does the alveolar PO2 varies inversely with
Definition
the alveolar PCO2
Term
What is the normal alveolar PO2
Definition
100 mmHg, with a mean alveolar PCO2 of approximately 40 mmHg
Term
What does normal mixed venous blood PO2 and PCO2
Definition
PO2 40 mmHg; PCO2 46 mmHg
Term
What must be in balance for pulmonary gas exchange to be effective
Definition
ventilation and perfusion must be in balance
Term
Why is pulmonary gas exchange less than perfect
Definition
because of normal anatomic shunts and V/Q imbalances
Term
In disease, what is the range of V/Q ratio
Definition
ranges from zero (perfusion without ventilation or physiologic shunting) to infinity (pure alveolar dead space)
Term
How does blood carry oxygen
Definition
small amount in physical solution, greater amount carried in combination with erythrocyte Hb
Term
What is hemoglobin saturation the ratio of
Definition
oxyhemoglobin to total Hb expressed as a percentage
Term
What are the two ways metabolic acidosis occurs
Definition
1) fixed (nonvolatile) acid accumulation in the blood 2) an excessive loss of HCO3- from the body
Term
What are some examples of the two types of metabolic acidosis
Definition
fixed acid accumulation example is a state of low blood flow in which tissue hypoxia and anaerobic metabolism produce lactic acid. The resulting H+ accumulate and react with HCO3- lowering blood HCO3-. Bicarbonate loss example is severe diarhea in which large stores of HCO3- are eliminated from the body, also causing nonrespiratory acidosis.
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