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Physiology > Pulmonary Physiology > Flashcards

Pulmonary Physiology Flashcards

1
Q

What are the main functions of the lungs?

A
  1. Deliver oxygen to cells, remove CO2
  2. pH balance -> CO2/HCO3 buffer (carbonic anhydrase)
  3. Warm and humidify the air
  4. Filter the airways
  5. Defense -> Mast cells and goblet cells exert immune responses and mucus, prostaglandin, heparin, histamine release in response to pathogens, foreign materials
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2
Q

What is bronchiectasis?

A

-Remodeling, thickening of walls of large airways from recurrent infection that reduces airflow, harder to move mucus, and promotes infection

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3
Q

What are some factors that can decrease compliance of the lung?

A

Stiff lung/fibrosis

Volume of the lung

Surfactant

Obesity

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4
Q

In emphysema, what would the would PA02 be compared to normal? How about Pa02?

A

PA02 would be normal or low (air can get in but destruction of alveoli means less surface area for gas exchange)

Pa02 would be low

DLCO reduced

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5
Q

In fibrotic lung disease, what would the PA02 and Pa02 be compared to normal?

A

PA02 would be normal or low

Pa02 would be low

DLCO reduced

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6
Q

What are conditions that would cause a decrease in Pa02?

A

Obstructive lung disease
Restrictive lung disease
Hypoventilation
Decrease in diffusion
High altitude
R to L shunt

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7
Q

In PFT what would be characteristics of obstructive lung disease?

A

Increase in TLC, RV
Decrease in FEV1/FVC
Decrease in DLCO (emphysema)

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8
Q

In PFT what would be characteristics of restrictive lung disease?

A

Decrease in TLC, RV
FVC <75%

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9
Q

What are normal lung volumes?

A
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10
Q

The following is a graph of just maximum expiratory airflow of three patients. The red curve represents a healthy 25 year old male. Which curve (blue or green) represent a patient with obstructive lung disease and which curve represents a patient with restrictive lung disease?

Where is the TLC?
Where is the RV?

A

Green - Obstructive
Red - Restrictive

TLC - A
RV - C

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11
Q

Closing capacity is what? When does it increase/decrease?

A

Closing capacity = closing volume + residual volume

Increases
Age
Smoking

Decreases
Laying down
Anesthesia
Obesity

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12
Q

How do you calculate pulmonary ventilation (VT) “Minute Ventilation”

A

Minute Ventilation = vent. rate X tidal volume

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13
Q

How do you calculate alveolar ventilation (VA)?

A

VA = vent rate X (tidal volume - dead space)

Normal = 4.2L/min

V<strong>A</strong> (L/min) = 0.863mmHg*L/ml X [VC02 (ml/min) / PAC02 (mmHg)]

Volume of C02 expired/min = 200ml/min (normal)

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14
Q

A patient has a dead space of 150 ml, functional residual capacity of 3 L, tidal volume of 650 ml, expiratory reserve volume of 1.5 L, a total lung capacity of 8 L, respiratory rate of 15 breaths/min. What is the alveolar ventilation?

a. 5 L/min
b. 7.5 L/min
c. 6 L/min
d. 9 L/min

A

7.5L/min

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15
Q

A patient’s normal tidal volume is 500 ml with a dead space of 100 ml. The metabolism of CO2 is 200 ml/min. The respiratory rate is 10 breaths/min. The patient is then placed on a ventilator for surgery and the tidal volume is 1000 mls with similar metabolism. The machine has an additional dead space volume of 100 mls with a rate of 10 breaths/min.

What is the PACO2 for this patient after ventilation?

a. 100 mm Hg
b. 50 mm Hg
c. 25 mm Hg
d. 12.5 mm Hg
e. 5 mm Hg

A

c. 25 mm Hg

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16
Q

How do you calculate net filtration pressure?

A

Net filtration pressure = (PC - PIS) - (OC - OIS)

If net + = fluid moves from capillary -> interstitial space

If net - = fluid moves from interstitial space -> capillary

17
Q

What is atmospheric P02?

A

760mmHg (21%) = 160mmHg

18
Q

How do you calculate the Fi02 coming into the trachea?

A

Pi02 = Fi02 * (Patm - PH20)

PH20 = 47mmHg (water vapor pressure)

19
Q

Calculating PA02

A

PA02 = [Fi02 * (Patm - PH20) - (PACO2/RQ)]

RQ = ratio of total C02 production to 02 consumption (C02/02)
Sugars = 1
Lipids = 0.7
Proteins = 0.8
Mixed = 0.8 (normal diet)
20
Q

What does the A-a gradient tell you? How do you calculate it?

A

A-a gradient helps you diagnose the reason for hypoxemia

A-a = [Fi02 * (Patm - PH20) - (PACO2/0.8)] - Pa02

Normal = <10mmHg

Large A-a = Diffusion issue

21
Q

What are normal hemoglobin values for men and women? How do you calculate the amount of 02 bound to hemoglobin?

A

Normal blood contains 15g Hg/dl (men) or 14g Hg/dl (women)

1 g Hg can bind 1.34 ml O2

Amount of 02 bound to hemoglobin = total Hg (g/dl) x 1.34 ml (02/g Hg) x S02

22
Q

What do every 20mmHg P02 in the oxyhemoglobin saturation curve correlate to percent saturation of hemoglobin?

23
Q

What is the Bohr effect? What causes a rightward shift on the oxyhemoglobin curve?

A

Bohr effect -> decrease in oxygen affinity of hemoglobin in response to decreased blood pH resulting from increased CO2

Rightward Shift
“Good for unloading 02”
Increase in temperature
Metabolic acidosis (H+)
Increase in BPG
Increase in CO2

24
Q

What are the three ways C02 is carried in blood?

A

Dissolved in plasma- 7%
Bound to Hemoglobin- 23% (carbamino hemoglobin)
In the form of bicarbonate (HCO3-)- 70%

25
Q

What is the haldane effect?

A

Haldane effect -> the promotion of carbon dioxide dissociation that results from the oxygenation of hemoglobin

26
Q

The dorsal respiratory group controls what? What are the afferent nerves that innervate them?

A

Normal breathing
Inspiration

Vagus and glossopharyngeal

27
Q

The ventral respiratory group mainly controls what?

A

Expiration
Inspiration in times of high demand

28
Q

The _________ center inhibits the dorsal respiratory group

The _________ center activates the dorsal respiratory group

A

The pneumotaxic center inhibits the dorsal respiratory group

The apneustic center activates the dorsal respiratory group

29
Q

Central chemoreceptors respond to what?

A

Changes in CO2 and H+ (indirectly)
Play a larger role in respiration than peripheral in the short term
Stimulate the respiratory center

Location: Medulla Oblangata (ventral)

30
Q

What activates peripheral chemoreceptors?

A

O2, H+, C02
Activates respiratory centers to increase or decrease respiration

_Location_: Carotid body (Glossopharyngeal)
 Aortic body (Vagal)
31
Q

How are pheripheral chemoreceptors activated by low P02?

A

They respond to low P02 (<60mmHg) but cells can also be stimulated by high H+ and C02

32
Q

What do irritant stimuli to the lungs cause?

A

Nociceptors are stimulated and sensory neurons (afferent vagal) elicit bronchoconstriction (vagal efferents), cough, tachypnea

33
Q

What is the hering breuer reflex?

A

When the lung is over inflated and it stimulates stretch receptors (vagal afferents) that inhibit inspiration at the dorsal inspiratory group (DRG)

34
Q

Cause of Cystic fibrosis? Characteristics?

A

CFTR gene mutation (normally functions as a Cl- channel)
Autosomal recessive disease (1:2,500 caucasian; 1:25 carriers in caucasian)

Characteristics:

  • Faulty CFTR results in thick mucus
  • Causes obstruction and infections
  • Salty sweat
  • Problems absorbing fats, fat soluble vitamins
35
Q

What does a faulty CFTR gene do in the lung epithelia?

36
Q

What does the CFTR 508F deletion cause?

A

Abnormal channel folding and does not even reach the membrane

Most common CF mutation (66-70% of affected)

37
Q

What does the CFTR R117H substitution cause?

A

Channels don’t open properly but still have some function

38
Q

Treatments for CF?

A

Hypertonic saline
Vest
Tobi
Pulmozyme
Antibiotics
Prednisone

39
Q

What are two new CF drugs and what do they do?

A

Lumacaftor -> Helps CFTR folding

Ivacaftor -> Helps channel conductance

Physiology (17 decks)

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