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physiology IV > oxygen transport > Flashcards

oxygen transport Flashcards

1
Q 
what are the effects of the following factors on the O2 disassociation curve:
increased PCO2
decreased pH
fetal Hg
increased 2,3 DPG
increased temperature
A

increased PO2, decreases pH, 2,3-DBG and increased temp all shift curve to right
fetal hg has a L shifted curve

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2
Q

what does fetal Hg have a left shifted curve

A

because it doesn’t have beta subunits

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3
Q

where does 2,3 DPG bind on hemoglobin?

A

the beta subunit

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4
Q

the bohr effect is referring to the effects of what to stimuli?

A

increased PCO2 and decreased pH

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5
Q

what does a curve shifted to the Right mean?

A

higher oxygen disassociation

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6
Q

can we measure the rate of O2 usage by the tissues?

A

not directly

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7
Q

what are the two ways oxygen can go after being delivered to the tissues?

A

it can be used by the tissues or it can be taken up by the venous blood

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8
Q

what is the equation of the rate of delivery of O2 to the tissues?

A

oxygen content in the blood x cardiac output

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9
Q

what characterizes stagnant hypoxia?

A
  • normal arterial partial pressure and concentration of O2
  • decreased venous oxygen partial pressure and concentration
  • cardiac output is decreased
  • Extraction is increased
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10
Q

what characterizes hypoxic hypoxia?

A

decreased partial pressure and concentration of O2 in both the arteries and veins while the extraction stays normal

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11
Q

what is the main cause of stagnant hypoxia

A

CHF

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12
Q

what are some causes of hypoxic hypoxia?

A

high altitude
diffusion problems
hypoventilation

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13
Q

what characterizes histotic hypoxia? when can this occur?

A
  • Normal partial pressure and concentration in arteries of O2
  • Increased partial pressure and concentration of O2 in the veins
  • Because extraction is reduced
  • This can occur when there is poisoning of tissue metabolism by heavy metals, cyanide or other toxins
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14
Q

what characterizes anemic hypoxia?

A
  • Normal partial pressure of O2 but decreased O2 concentration
  • Decreased venous partial pressure and concentration
  • Normal extraction
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15
Q

what characterizes CO poisoning?

A
  • Results from substitution of CO for oxygen bound to Hg
  • CO takes up the O2 binding sites
  • Minor effect: left shift of the oxygen dissociation curve
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16
Q

describe the correlation of smoking with CO

A

Cigarette smoke contains up to 4% CO which can result in 5-10% reduction in O2 transport capacity

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17
Q

Where is the pneumotaxic center/ pontine respiratory group located?

A

In the pons….the nucleus parabrachialis medialis and the Kolliker fuse nucleus

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18
Q

Where is the DRG located?

A

Bilaterally in the nucleus of the tracts solitaries

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19
Q

What does the DTS consist of mostly?

A

Inspiratory neurons

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20
Q

Where is the VRG located?

A

Bilaterally in the retro facial nucleus, the nucleus ambiguous, and the nucleus retroambifualis

21
Q

What type of neurons does the VRG primarily consist of?

A

Inspiratory and expiratory neurons

22
Q

What is the Botzlinger complex?

A

A cluster of expiratory neurons in the VRG that generate pacemaker activity associated with the respiratory rhythm

23
Q

What is the function of the pontine respiratory group?

A

Fine tune the resp pattern

24
Q

No respiration is a characteristic of what level transaction?

A

Level IV

25
Q

Irregular, gasping breathing is a characteristic of what level transaction?

A

Level III

26
Q

Slower frequency and larger tidal volumes with lower infrequency breathing is characteristic of what level transaction?

A

Level II

27
Q

Normal breathing is characteristic of transaction at what level?

A

Level I

28
Q

When does apneusis occur?

A

Is occurs when there is a transaction at level II and the vagus is cut. It is characterized by longer inspiration phases ans short passive expirations.

29
Q

What happens when there is both a transaction at level I and the vagus is cut?

A

Increased tidal volume with decreased frequency, but rhythmic breathing

30
Q

Describe Cheyenne-stokes respiration

A

Abnormal form of breathing pattern characterized by altering periods of hypernea and apnea. You see this in injuries to the brain.

31
Q

Describe cluster breathing (biot’s respiration)

A

Abnormal form of breathing associated with stroke, head trauma, pressure or a lesion in the lower pontine region of the brainstorm.

Take a few breaths and then stop, repeating this cycle.

32
Q

Describe ataxic breathing

A

Characterized by completely irregular series of inspirations and expirations with irregular pauses and increasing periods of apnea

33
Q

Why do the capillary partial gas pressures equilibrate with the alveolar, and not the other way around?

A
  • The alveolar compartment has much more volume than the capillaries
34
Q

What happens to DLCO in severely anemic patients?

A
  • ventilation rate is increased, and cardiac output is increased since there is not enough O2 in the blood —>DLO2 is actually increased
  • however there is a decrease of hemoglobin (due to the anemia) so it appears that DLCO is decreased
35
Q

Is dissolved oxygen alone enough to meet the metabolic demands of the body?

A

N0o0o this is why hemoglobin exists

36
Q

Define extraction?

A

Difference between the percent of O2 in arterial blood minus the percent in venous blood

37
Q

What is P50=?

A

26 mmHg

This means at 50% saturation of hemoglobin

38
Q

At PaO2=100 mmHg, what percent of hemoglobin is saturated? What percent of the total blood volume is this?

A

98.5% bound to hemoglobin

20% of total volume

39
Q

At Pao2=40 mmHg,what percent of hemoglobin is saturated? What percent of the total blood volume is this?

A

75% saturated hemoglobin

40
Q

What is the normal extraction percentage from arterial to venous blood of O2?

A

4-5%

41
Q

Why is the extraction of O2 such a small number?

A

It occurs at the plateau of the sigmoid dissociation curve – cooperative binding

42
Q

How many molecules of O2 does one hemoglobin bind?

A

4 molecules of O2

43
Q

How is the dissociation curve shifted for venous blood?

A

To the right since pH is lower

44
Q

What is the function of the plateau in the oxygen dissociation curve?

A

It permits toleration for hypoxemia

-ensures constant O2 content despite wide variations in PO2

45
Q

How is the oxygen dissociation curve shifted in polycythemia?

A

Up

-hematocrit and therefore the percent of O2 of the volume of the blood is increased to 30%

46
Q

How is the oxygen dissociation curve shifted in anemia?

A

Down

-hematocrit is decreased

47
Q

How does P50 change in polycythemia or anemia?

A

It does not change

48
Q

How does hypoxia influence the amount of hemoglobin?

A

It upregulates EPO mRNA and protein synthesis

-increases the amount of erythrocytes and therefore hemoglobin

physiology IV (40 decks)

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