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Physiology Exam 3 > Pulmonary Circulation and Gas Exchange > Flashcards

Pulmonary Circulation and Gas Exchange Flashcards

1
Q

Describe the two circulations of the lungs

A
  1. high pressure; low flow
    - thoracic aorta
    - bronchial arteries
  2. Low pressure; high flow
    - pulmonary artery and branches
    - alveoli
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2
Q

What are the pressures that are in the heart?

  1. Right ventricle systolic
  2. Right ventricle diastolic
  3. Left ventricle systolic
  4. Left ventricle diastolic
A
  1. 25 mmHg
  2. 0-1 mmHg
  3. 120-125 mmHg
  4. 0-5 mmHg
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3
Q

What are the pressures that are in the lung?

  1. pulmonary artery systolic
  2. Pulmonary artery diastolic
  3. Mean pulmonary arterial
  4. mean pulmonary capillary
A
  1. 24-25 mmHg
  2. 8-9 mmHg
  3. 15 mmHg
  4. 7 mmHg
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4
Q

If the left sided of the heart fails, what are the consequences? (basic)

A
  1. increases in blood volume as much as 100%
  2. increases in blood pressure
  3. Mild systemic effect because the systemic blood volume is 9X the volume of the pulmonary
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5
Q

What are the agents that constrict the pulmonary arterioles?

A

norepinephrine
epinepherine
angiotensin 2
prostaglandins

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6
Q

What are the agents that dilate the pulmonary arterioles?

A

Isoproterenol

Acetylcholine

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7
Q

What are the agents that constrict the pulmonary venules?

A

serotonin
histamine
e coli endotoxin

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8
Q

What happens to the blood flow in heavy exercise?

A

The blood flow through the lungs increases to 4x to 7x

  • increases the number of open capillaries to 3X
  • distends all the capillaries and increases the flow rate up to 2x
  • increases pulmonary arterial pressure
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9
Q

What are the 3 blood flow zones?

A

Zone 1: No flow; local alveolar capillary pressure never rises higher than alveolar air pressure
Zone 2: Intermittent flow; only during systole
Zone 3: continuous flow

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10
Q

What happens if the blood supply to one lung is obstructed?

A

The blood flow to the other lung is doubled but the pulmonary pressure is only slightly increased

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11
Q

Describe left sided heart failure

A

Blood begins to dam in the left atrium causing an increase in the left trail pressure from 1-5 to 40-50

this causes the pulmonary arterial pressure to increase which could lead to pulmonary edema

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12
Q

What are the hydrostatic and osmotic forces from the capillaries to the pulmonary interstitial forces?

A
  1. hydrostatic: +7
  2. Interstitial fluid osmotic pressure: (-) 14
  3. Interstitial fluid hydrostatic pressure (-) 8
  4. TOTAL OUTWARD FORCE 29
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13
Q

What are the hydrostatic and osmotic forces from the pulmonary interstitium to the capillaries?

A

Capillary osmotic 28

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14
Q

What is the mean filtration pressure of the lung capillary fluid exchange?

A

1 mmHg

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15
Q

Define and describe pleural effusion

A

Edema of the pleural cavity

Causes: 
blockage of lymph drainage 
cardiac failure 
reduced plasma colloid pressure 
infection
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16
Q

Describe what happens in the event of hypoxia

A

Increase in the pressure of the pulmonary artery

17
Q

Describe what happens in the event of a bronchial obstruction

A

Constriction of vessels supplying the poorly ventilated alveoli

bc. ..
- low alveolar PO2
- drop on pH from CO2 accumulation
- decrease in pH causes vasoconstriction
- decrease in pH produces vasodilation in other tissues

18
Q

What are the factors that affect the rate of gas diffusion in a fluid?

A

-solubility of the gas in the fluid
-cross sectional area of the fluid
-distance through which the gas must diffuse
molecular weight of the gas
-temperature of the fluid

19
Q

What are the two things that control the carbon dioxide concentration in the alveoli?

A
  1. Rate of carbon dioxide excretion

2. alveolar ventilation

20
Q

What are the factors that will determine how rapidly a gas will pass through the respiratory membrane?

A
  • membrane thickness
  • membrane surface area
  • diffusion coefficient of the gas in the substance of the membrane
  • partial pressure difference of a gas between the two sides of the membrane

** ANY factor that increases the membrane thickness to more the 2 or 3 times normal can interfere with gas exchange

21
Q

What is the Va/Q ratio?

A

ventilation-perfusion ratio: alveolar ventilation/blood flow

normal= 0.8

22
Q

In regards to the Va/Q ratio, what happens when Va is 0?

A

There is still perfusion

When Va/Q=0 it is usually due to an airway obstruction

blood gas composition remains unchanged

23
Q

In regards to the Va/Q ratio, what happens when Q is 0?

A

there is still ventilation but there is no gas exchange

When va/Q is infinity, this is usually due to a vascular obstruction

alveolar gas composition remains unchanged because there is no blood contact

Physiology Exam 3 (9 decks)

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