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physiology final > blood flow and VQ > Flashcards

blood flow and VQ Flashcards

1
Q

Describe the wall thickness and smooth muscle content of pulmonary artery?

A
  • thin walls
  • little smooth muscle
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2
Q

Describe the wall thickness and smooth muscle content of aorta?

A
  • thick walls
  • lots of smooth muscle
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3
Q

pulmonary blood flow is directly proportional to the pressure gradient between pulmonary artery and ?

A

left atrium

  • systemic circulation: P = 100 mmHg
  • pulmonary circulation: P = 15 mmHg
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4
Q

pulmonary blood flow is inversely proportional to

A

resistance of the pulmonary vasculature

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5
Q

regulation of pulmonary blood flow is via alterations in the of arterioles

A

resistance

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6
Q

what is the major factor to regulate pulmonary blood flow

A

PAO2 = PO2 of alveolar gas

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7
Q

what is an adaptive mechanism to reduce BF to poorly ventilated regions

A
  • hypoxic vasoconstriction
    • decrease PAO2
  • assists in directing pulmonary blood flow to other regions of the lung where gas exchange can occur
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8
Q

Is O2 lipid soluble?

A
  • yes, meaning it is very permeable
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9
Q

When PAO2 is < 70 mHg, what happens to vascular smooth muscle cells

A
  • vascular SMC sense the hypoxia -> arteriole vasocontricts -> blood flow to that region falls
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10
Q

When PAO2 is 70-100 mHg, what happens to vascular smooth muscle cells

A

little effect on vascular tone

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11
Q

When PAO2 is normal at 100 mmHg, what happens to vascular smooth muscle cells

A
  • O2 diffuses from alveoli to arteriole
  • smooth muscle arterioles are relaxed and dilated
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12
Q

mechanism of hypoxic vasoconstriction

A
  1. inhibition of nitric oxide production from endothelial cells of vessel walls
  2. hypoxia -> depolarized Vascular Smooth Muscle -> opens voltage-gated CA2+ channels -> increase Ca2+ entry -> contraction
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13
Q

mechanism of nitric oxide

A
  1. nitric oxide is produced from L-arginine by nitric oxide synthase (NOS)
  2. NO activates guanylyl cyclase -> produce cGMP
  3. cGMP directly acts on vascular smooth muscle producing relaxation and vasodilation
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14
Q

describe global hypoxic vasconstriction seen at high altitude

A
  1. decreased PAO2 throughout entire lung
  2. produces a global vasocontriction of pulmonary arterioles and increase in pulmonary vascular resistance
  3. in response to increased resistance -> increase in pulmonary arterial pressure
  4. the increase in pulmonary arterial pressure -> hypertrophy of the RV
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15
Q

describe global hypoxic vasconstriction seen with fetal circulation

A
  • fetus does not breath air, thus mom’s PAO2 > fetus PAO2
  • this results in vasoconstriction, an increase in vascular resistance and decrease in pulmonary blood flow to the fetal lung
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16
Q

Thromboxane A2 is from AA metabolism by whic pathway

A

cyclooxygenase

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17
Q

Thromboxane A2 is produced in response to? and results in?

A
  • produced in response to lung injury
    • from macrophages, leukocytes, and endothelial cells
  • results in vasoconstriction of arterioles and venules
18
Q

Prostacyclin (PGI2) is from AA metabolism by which pathway

A

cyclooxygenase

19
Q

Prostacyclin is produced by ? And results in?

A
  • lung endothelial cells
  • local vasodilation
20
Q

Leukotrienes are from AA metabolism by which pathway

A

lipoxygenase

21
Q

Leukotrienes results in

A
  • vasoconstriction of blood vessels and airways
22
Q

blood flow in the lungs is uneven due to gravity. Which zone has the lowest and highest blood flow?

A
  • zone 1, at apex, has lowest BF
  • zone 3, at base, has highest BF
23
Q

Blood flow to the lung is affected by

A
  • gravity
  • exercise
24
Q

in a patent ductus arteriosis, the PO2 to the Right heart will be increased or decreased and why?

A
  • increased
  • getting oxygenated blood from aorta
25
Q

what type of shunt is patent ductus arteriosis

A
  • left to right
  • does not cuase hypoxemia
26
Q

tetralogy of fallot is what type of shunt

A

right to left shunt

  • Hypoxemia always occurs because a significant portion of CO is not delivered to lungs for oxygenation
27
Q

shunts in tetralogy of fallot

A
  • ventricular shunt: up to 50% of the CO is routed to the LV directly and is not pumped to the lungs
28
Q

can the effects of tetralogy of fallot be corrected by breathing high O2

A

No, shunted blood is NOT going to lungs for oxygenation

29
Q

what is the ventilation/perfusion ratio

A

the ratio of alveolar ventilation to pulmonary blood flow

30
Q

what is the normal value for ventilation/perfusion ratio

A
  • 0.8
  • alveolar ventilation = 80% of pulmonary blood flow
31
Q

ventilation/perfusion ratio is normal when what three factors are normal

A
  1. tidal volume
  2. breathing frequency
  3. cardiac output
32
Q

when ventilation/perfusion ratio is normal, what are the values of PaO2 and PaCo2

A
  • PaO2: 100 mmHg
  • PaCo2: 40 mmHg
33
Q

which zone has the highest ventilation/perfusion ratio

A

zone 1 (apex)

34
Q

which lung zone has the highest PaO2

A

zone 1 (apex)

**organisms that thrive in high O2 (TB) flourish in apex

35
Q

which lung zone has the highest and lowest PaCO2

A
  • zone 1 has lower
  • zone 3 has higher
36
Q

in dead space, what is the value of ventilation/perfusion ratio

A
  • infinity
  • ventilation of lung regions not perfused (V/Q)
  • no gas exchange
37
Q

dead space alveolar gas has the same composition as humidified inspired air. What are the values for PAO2 and PACO2

A
  • PAO2 : 150 mmHg
  • PACO2: 0 mmHg
38
Q

what does a high ventilation/perfusion ratio indicate? Give an example

A
  • high ventilation relative to perfusion
  • blood flow is low
  • pulmonary capillary blood from these regions has
    • high PO2 and low PCO2
  • ex: zone 1 (apex)
39
Q

what does a low ventilation/perfusion ratio indicat? Give an example

A
  • low ventilation relative to perfusion
  • ventilation is diminished
  • pulmonary capillary blood from these regions has
    • low PO2 and high PCO2
  • Zone 3 (base)
40
Q

shunt ventilation/perfusion ratio =

A
  • perfusion of lungs that are not ventilated (e.g. airway obstruction)
  • V/Q = 0
41
Q

pulmonary capillary blood from regions without ventilation due to shunt (airway obstruction) has the same composition as what? Name values

A
  • mixed venous blood
  • PaO2= 40 mmHg
  • PaCO2 = 46 mmHg
  • **this is for the shunted blood only
42
Q

pressure of pulmonary system is ? Pressure of systemic system is ?

A
  • pulmonary: 15 mmHg
  • systemic: 100 mmHg

physiology final (7 decks)

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