Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

CRRAB II- Week 3 > Trachte: Ventilation Perfusion Relationships > Flashcards

Trachte: Ventilation Perfusion Relationships Flashcards

1
Q

What are the causes of hypoxemia?

A
  1. hypoventilation
  2. Diffusion limitation
  3. shunt (left-right)
  4. Ventilation-perfusion mismatch
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are O2 levels in humidified air?

A

150 mmHg

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are O2 levels in the alveoli?

A

100 mmHg

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What happens to O2 in the alveoli if it is being perfused normally? What replenishes oxygen?

A

It’s constantly being REMOVED by blood

Inhalation of fresh air

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the oxygen level in tissues?

A

1-100 mmHg

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is hypoventilation?

A

If O2 is not replenished fast enough in the alveoli–>

alveolar PO2 DECLINES

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What causes hypoventilation?

A

Drugs (opiates)
chest wall damage
paralysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What does hypoventilation do to PCO2?

A

INCREASES PCO2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How do you calculate PCO2?

A

PCO2 = (VCO2/VA) x K

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How do you calculate PAO2?

A

PAO2 = PIO2 – [PACO2/R]

PAO2 is alveolar PO2
PIO2 is inspired air PO2
PACO2 is alveolar PCO2
R is the respiratory quotient (produced CO2/consumed O2)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is R and what is it dependent on?

A

THe respiratory quotient (produced CO2/consumed O2)

Dependent on SUBSTRATE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is R w/ carbohydrate as substrate? w/ FA as substrate?

A

R = 1 with carbohydrate as substrate

R = 0.7 with fatty acid as substrate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How can impaired diffusion result in hypoxia?

A
  1. Reducing the area available for gas exchange

2. Increasing the diffusion distance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Where does a natural shunt occur?

A

Naturally occurs with mixing of O2 depleted blood from the bronchial circulation and a small amount of blood from the thesbian veins of the heart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What else can cause shunts?

A
  1. congenital cardiac abnormalities

2. PDA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How do you calculate shunt flow?

A

Qs/Qt = (CcO2 – CaO2)/CcO2 – CvO2)

17
Q

How do you calculate capillary O2?

A

From PAO2

18
Q

Can 100% O2 correct the hypoxemia resulting from a shunt?

A

NO

19
Q

What are two of the influences on Alveolar PO2?

A

Ventilation and perfusion

20
Q

What is the major cause of hypoxia in lung diseases?

A

Mismatch of ventilation and perfusion

**also affects alveolar PCO2

21
Q

What happens to PO2 and PCO2 if there is no perfusion of a unit but the alveoli are still ventilated?

A

PO2 and PCO2 approach that of inspired gas (150 and 0 mmHg)

22
Q

What happens to PO2 and PCO2 if there IS perfusion but NO ventilation?

A

PO2 and PCO2 approach that of venous blood

40 and 46 mmHg

23
Q

Why do gradations of ventilation-perfusion exist?

A

Because the lung is perfused and ventilated differently in the APEX and BASE

24
Q

What is the ventilation-perfusion ratio in the APEX? What are PO2 and PCO2?

A

HIGH

PO2= 132 mmHg

PCO2= 28 mmHg

25
Q

What is the ventilation perfusion ratio in the base of the lung?

A

LOW

PO2= 89 mmHg
PCO2= 42 mmHg
26
Q

Does pH change from apex to base of the lung? Why?

A

YES

pH is influenced by CO2

27
Q

What affect do ventilation-perfusion mismatches have on PO2 and PCO2?

How do lung diseases affect mismatches?

A

Slight lowering of arterial PO2 <4 mmHg

Slight elevation of PCO2

MUCH MORE DRAMATIC EFFECTS

28
Q

Can hypoxia or hypercapnia be rectified by more rapid breathing?

A

Hypercapnia

29
Q

What is a function of the rate of breathing?

A

CO2 elimination

30
Q

What determines the differences in O2 and CO2 responses to more rapid breathing?

A

Different shapes of their dissociation curves

31
Q

What is the dissociation curve like for CO2?

A

Linear in the physiological range

32
Q

What is the dissociation curve like for O2?

A

sigmoidal and almost flat at the top of the range

33
Q

Why is PCO2 close to normal even in lung disease?

A

B/c alterations in arterial PCO2 will result in more rapid breathing–> this increases the work of breathing

34
Q

How do you assess ventilation perfusion abnormalities?

A

Use the alveolar gas equation to calculate what arterial PO2 should be and compare it w/ what is observed

CRRAB II- Week 3 (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions