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Carbon dioxide transport and V/Q
quiz review
59
Medical
Undergraduate 1
12/09/2014

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Cards

Term
How much O2 do the tissues produce at rest each minute?
Definition
250 mL
Term
How much CO2 do the tissues produce at rest during a minute?
Definition
200 mL
Term
How is CO2 transported from the tissues to the lungs?
Definition
Plasma

RBC
Term
How many different mechanisms are there for CO2 transport?
Definition
6

3 in plasma

3 in RBC
Term
How is CO2 transported in the plasma?
Definition
Carbamino compound

Bicarbonate

Dissolved CO2
Term
How much a percent of the CO2 that dissolves in the plasma chemically combines with an amino group and forms carbamino compound?
Definition
1%
Term
How much percent of the CO2 that dissloves in the plasma ionizes as HCO3?
Definition
5%
Term
When CO2 is dissolved in the plasma, what percentage accounts for the total CO2 released at the lungs?
Definition
5%
Term
Dissolved CO2 in the intracellular fluid account for what percentage of CO2 released at the lungs?
Definition
5%
Term
What percentage of CO2 combines with Hb to form carbamino-Hb?
Definition
21%
Term
When CO2 combines with carbamino Hb what happens to the O2 that is released by this reaction?
Definition
Available for tissue metabolism
Term
When CO2 is transported from the tissue cells to the lungs in HCO3 form, what percentage is that?
Definition
60-70%
Term
The major portion of dissolved CO2 that enters the RBC is converted to
Definition
HCO3
Term
How is dissolved CO2 converted into HCO3?
Definition
Hydrolysis
Term
What is the hydrolysis reaction for dissolved CO2 to convert into HCO3?
Definition
CO2 leaves the tissue and enters plasma

PP of CO2 increases in plasma of venous blood which causes increase diffusion of CO2 into RBC

H2O combines with CO2 and forms H2CO3

Enzyme increases the reaction(carbonic anhydrase)

Hb releases O2 to tissues while HCO3 is forming

RBC is saturated with HCO3, causing diffusion into plasma and combo with Na

HCO3 leaves RBC and CL moves in(CL shift)

HCO2 and CL are increased in RBC(H2O causes RBC to swell in venous blood)
Term
Whats the ratio of HCO2 and H2CO3 in the plasma?
Definition
20:1
Term
Whats the purpose of the HCO3 and H2CO3 ratio in the plasma?
Definition
To keep the pH within normal range
Term
When CO2 is eliminated at the lungs is the venous CO2 greater or less than the alveolar CO2?
Definition
Greater
Term
What is the carbon dioxide dissociation curve?
Definition
The direct relationship between PCO2 and CO2 in the blood
Term
What can also effect the CO2 dissociation curve?
Definition
Level of Hb saturation
Term
What happens when the Hb is 97% saturated with O2 verses Hb being 75% saturated?
Definition
There is less CO2 content for any given PCO2
Term
What is the haldane effect?
Definition
When deoxygenated blood enhances the loading of CO2 and oxygenated blood enhances the unloading of CO2
Term
What do hydrogen ions effect?
Definition
Cells metabolic function
Term
What is the pH maintained by?
Definition
Buffer systems of blood and tissues

Ability of respiration to eliminate CO2

Renal ability o regulate excretion of hydrogen and reabsorb bicarb
Term
What keeps the pH happy?
Definition
Lungs and kidneys
Term
Anything acute means
Definition
The kidneys are not there and the pH has been changed
Term
What causes metabolic acidosis?
Definition
Increase in non volatile acids in the blood
Term
What causes an increase in non volatile acids in the blood?
Definition
Lactic acidosis

Ketoacidosis

Renal failure

Severe diarrhea
Term
What causes metabolic alkalosis?
Definition
Removal of stomach acids

Hypokalemia

Hypochloremia

Massive doses of steroids

Diuretics

Increased deliverance of NaHco3
Term
If respiratory acidosis persists what happens to the kidneys?
Definition
They retain bicarb
Term
Renal compensation is rarely complete, what happens to the pH?
Definition
It wont fully return to 7.4
Term
The extent of renal compensation is ID'd from
Definition
Base excess
Term
How much is aveolar ventilation?
Definition
4 L/min
Term
What is ventilation?
Definition
Mechanical movement of air in and out of the lungs.

Mechanism by which O2 is carried from the atmosphere to the alveoli and which CO2 is carried from the lungs to the atmosphere
Term
What the ratio of ventilation blood flow(V/Q)?
Definition
4:5 or 0.8
Term
What plays a key role in V/Q variance?
Definition
Lung zones
Term
What is PAO2 dependant on?
Definition
The amount of O2 entering the alveoli (V)

O2 removal by capillary blood flow(Q)
Term
The PACO2 is determined by
Definition
The CO2 that diffuses into the alveoli from the capillary blood

CO2 removal from the alveoli by means of ventilation
Term
What causes an increased V/Q ratio?
Definition
Increase in ventilation

Decrease in perfusion
Term
What is perfusion?
Definition
Passing of blood or fluid through a vascular bed
Term
What is a shunt?
Definition
Perfusion with out ventilation
Term
What is dead space?
Definition
Ventilation without perfusion
Term
What happens during V/Q increase?
Definition
PAO2 rises

PACO2 falls
Term
In what lung zone is an increased V/Q present?
Definition
Zone 1

Upper lung zone
Term
During increased V/Q the PO2 is BLANK and PACO2 is BLANK
Definition
High

Low
Term
Why does the PACO2 decrease during increased V/Q?
Definition
Because it is washed out of the alveoli faster than it can be replaced by venous blood
Term
Why does the PAO2 increase during increased V/Q?
Definition
Because it does not diffuse into the blood
Term
How does a decreased V?Q ratio develop?
Definition
Decrease in ventilation

Increase in perfusion
Term
Why does the PAO@ decrease during a V/Q decrease?
Definition
Because O2 moves out of the alveolus and into the pulmonary capillary bed faster than it is replenished by ventilation
Term
Why does the PACO2 increase during V/Q decrease?
Definition
Beacause it moves out of the capillary bed and into the alveolus faster than it washed out of the alveolus.
Term
Where is a decreased V/Q ration present?
Definition
Lower lung zones
Term
What is internal inspiration?
Definition
Gas exchange between capillaries and cells
Term
What is the respiratory quotient?
Definition
Ratio between volume of O2 consumed and volume of CO2 produced
Term
How is the RQ represented?
Definition
RQ=VCO2/VO2

RQ=200/250=0.8
Term
What is respiratory exchange ratio(RR)?
Definition
Quantity of O2 and CO2 exhanged during a period of 1 minute

(Under normal conditons the RR= RQ)
Term
What are some disorders that increase V/Q ratio?
Definition
Pulmonary emboli

Decreased cardiac output

Partial/complete obstruction of the pulmonary artery/arterioles

Pressure on the pulmonary vessels

Destruction of the pulmonary vessels
Term
It is an increased V/Q ratio or called by the term
Definition
Dead space
Term
Decreased V/Q ratio or what other term is it called?
Definition
Shunt
Term
What causes decreased V/Q ratio?
Definition
Obstructive lung disorders

Restrictive lung disorders

Hypoventilation from any cause
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