Respiratory Physiology Part 3 Flashcards

1
Q

if transmural pressure is positive

A

expanding pressure on the lung

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2
Q

if transmural pressure is negative

A

collapsing pressure on the lung

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3
Q

At rest of breathing cycle

A
  • diaphragm at equilibrium
  • alveolar pressure = atmospheric pressure
  • no airflow b/c no pressure difference
  • intrapleural space is negative
  • FRC
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4
Q

During Inspiration of breathing cycle

A
  • diaphragm contracts
  • lung volume increases
  • pressure in lung decreases
  • intrapleural space becomes more negative
  • dynamic compliance
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5
Q

Halfway through inspiration of breathing cycle

A

alveolar pressure falls below atmospheric

this drives airflow into lung until atmospheric pressure = 0

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6
Q

expiration of breathing cycle

A
  • alveolar pressure becomes positive

- air flows out & returns to FRC

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7
Q

Forced expiration of the breathing cycle

A
  • contraction of expiration muscles raises intrapleural pressure
  • if transmural pressure is positive the airways and lungs will remain open
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8
Q

patients with emphysema forced expiration

A
  • airways can collapse
  • lung compliance increases
  • alveolar & airway pressure lower than normal
  • resistance increases (expiration more difficult)
  • expire more slowly
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9
Q

O2 in gas exchange

A

alveolar gas into pulmonary capillary

delivered to tissues

systemic capillary blood into cells

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10
Q

CO2 in gas exchange

A

delivered from the tissue to venous blood to pulmonary capillary blood

alveolar gas to be expired

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11
Q

Dalton’s Law of Partial Pressure

A

the partial pressure of gas in a mixture of gases is the pressure that gas would exert if it occupied the total volume of the mixture

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12
Q

barometric pressure

A
sume of partial pressures
O2
CO2
N2
H2O
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13
Q

percentages of gases in dry air at barometric pressure

A

O2 = 21%

N2 = 79%

CO2 = 0%

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14
Q

since air is humidified in the airways, the water pressure is ___

A

obligatory and equal to 47 mmHG at 37 degrees

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15
Q

Henry’s Law for Concentration of Dissolved Gases

A

used to convert the partial pressure of gas in the liquid phase to the concentration of gas in the liquid phase

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16
Q

at equilibrium, the partial pressure of a gas in the liquid phase =

A

the partial pressure in the gas phase

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17
Q

diffusion of gases - fick’s law

A

transfer of gases that occurs by simple diffusion

18
Q

rate of transfer by diffusion is directly proportional to

A

driving force
diffusion coefficient
surface area available for diffusion

19
Q

rate of transfer by diffusion is inversely proportional to

A

the thickness of membrane barrier

20
Q

the driving force for diffusion of a gas is the ___

A

partial pressure difference of the gas across membrane

21
Q

the diffusion coefficient of gas is a combination of ___

A

usual diffusion coefficient and the solubility of gas difusion

22
Q

gas concentration

A

dissolved gas + bound gas + chemically modified gas

23
Q

dissolved gas

A

contribute to partial pressure

24
Q

N2 as a dissolved gas

A

can only be carried in dissolved form and is never bound or chemically modifies

25
bound gases
O2, CO2, and CO are bound to proteins in blood
26
chemically modified gas
CO2 --> HCO3 in RBC by action carbonic anhydrase
27
gas transport in the lungs
Mixed venous enters the pulmonary capillary Oxygen is added to pulmonary capillary blood CO2 is removed from it by transfer across the alveolar/capillary barrier Systemic arterial blood leaves the pulmonary capillary
28
dry inspired air
PO2 = 160 mmHg
29
Humidified tracheal air
air saturated w/ water vapor O2 reduced No CO2 humidified air enters alveoli
30
alveolar air
O2 decreases (going in blood) CO2 increases (enters alveolar air)
31
mixed venous blood
blood entering pulmonary capillary - blood returned from tissue to heart
32
systemic arterial blood
blood that leaves pulmonary capillary that has been oxygenated
33
diffusion-limited gas exchange
total amount of gas transported across alveolar-capillary barrier that is limited by diffusion process
34
perfusion limited
total amount of gas transported across alveolar/capillary barrier is limited by blood flow
35
how to increase the amount of gas transported?
increase blood flow
36
oxygen is carried in 2 forms
dissolved | bound to hemoglobin
37
dissolved oxygen
insufficient to meet the demands of the tissues needs hemoglobin
38
oxygen bound to Hgb
98% of total O2 content is reversibly bound Hgb
39
4 subunits of Hgb
4 molecules of O2 per molecule of Hgb
40
The O2 content of blood is primarily determined by
Hgb and the O2 binding capacity of hgb
41
amount of O2 delivered to tissues is determined by
blood flow and O2 content of blood ( dissolved O2 + O2-Hgb)
42
CO2 is carried in blood in 3 forms
- dissolved CO2 - carbaminohemoglobin (CO2 bound to hemoglobin) - bicarbonate (CO2)