Section 5 Lecture 3 Flashcards by Tedman McMahon

True or False? Inspiration is active at all lungs volumes.

F. not for FRC

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When does expiration because active?

exercise, cough, vomiting, ling disease that increases airway resistance, speaking and singing

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True or False? The more a muscle stretches the more force it can generate.

F. more stretch = less force

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What results if the recoil > chest wall force?

FRC decreases

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What results if the muscles of contraction are weak/

FRC decreases (why? I would think it would increase)

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an instrument for measuring changes in volume in lungs:

plethysmograph

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What can lead to premature airway closure?

plethysmograph > helium (?)

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Transpulmonary pressure is aka:

transmural pressure

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Transpulmonary pressure =

alveolar - pleural pressures

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P (w) is:

Transmural pressure across the chest wall

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P (w) =

pleural - barometric pressure

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P (rs) (respiratory system) =

transmural pressure surrounding lungs + transmural pressure across chest wall OR alvelor - barometric pressure

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What does a spirometer tracing show?

lung volumes and capacities

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FRC =

residual volume + ERV

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Vital capacity =

ERV + Tidal volume + IRV

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Inspiratory capacity =

Tidal volume + IRV

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Avg tidal volume:

500 mL

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Avg IRV:

3000 mL

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Avg ERV:

1100 mL

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Avg vital capacity:

4600 mL

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Pulmonary volumes, men vs. women:

5800 vs. 4200 (the graph was for a man)

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Primary determinants of lung volume:

sex, age, height (20% variability)

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Avg RV/ TLC ratio:

25%

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Elevated RV/ TLC ratio secondary to RV elevation:

obstructive pulmonary diseases (chronic bronchitis)

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Elevated RV/ TLC ratio secondary to TLC decrease:

restrictive lung diseases (pulmonary fibrosis)

Factors affecting the RV/ TLC ration:

elastic recoil of lung, compliance, muscle strength of inspiratory muscles, recoil of the chest wall

How is FRC affected if the chest wall muscles are weak?

FRC decreases, lung elastic recoil > chest wall muscle force

How is FRC affected if there is an airway obstruction?

FRC increases (premature airway closure)

How are measurements of RV and TLC taken?

body plethysmography or helium dilution

C(1) X V(1) =

C(2) X (V(1) + V(2)

P(1) (this is pressure before inspiration) X V (V is FRC) =

P(2) (V - delta v) (P(2) is pressure after inspiration)

True or False? Less than half of the FVC is exhaled during FEV(1).

F More than half, about 3/4

Average FEV1/FVC ratio:

3L/4L = 75%

What factors decrease FEV(1) /FVC ratio?

decrease muscle strength, increases airways resistance, increases lungs compliance

What causes the increase in resistance in emphysema?

smooth muscle constriction and mucus plugging of the airways

Which lungs volumes increases and which decrease in emphysema?

increase: V, FRC, and TLC, decrease: VC and FEV

FEV(1)/FVC ratio in patient with emphysema

1L/3L (33%)

How are FEV and FVC related?

FEV = 1/ FVC

Peek expiratory flow rate occurs around how many liters of air expired?

1 L

What % of VC is expired at the peek expiratory flow rate?

25%

True or False? Recoil of the lungs increases in inspiration.

FEF from 15-75% is called:

Mid maximal expiratory flow (MMEF)

How will increasing R affect the FEF?

decrease (R = resistance?)

Lungs compliance =

delta V/ delta P

Compliance must be corrected for:

changes in lungs volume

Diseases that cause a reduction in compliance:

emphysema, obstructive pulmonary fibrosis or restrictive diseases

What kind of flow occurs in the small airways?

laminar flow

Velocity in airways =

P(pi)(r^4)/8nl

R =

delta P/V

delta P/V =

8nl/(pi)(r^4)

Are the small airways in parallel or series?

parallel

Factors contributing to airway resistance:

resistance decreases with lung volume, conductance, density of inspired gas, neural control of airway, irritants, and agents

Conductance =

1/Resistance

How is the density of inspired gas affected by pressure?

increases pressure, increases density

True or False? Lung volume resistance increases as lung volume decreases.

F. resistance decreases as lung volume decreases

Stimulation of what increases resistance due to airway constriction via smooth muscle?

efferent vagal nerves

List agents that can contribute to airway resistance:

histamine, acetylocholine, throboane A(2), prostoglandin F(2), and leukotrienes due to allergens and viral infections

Effect of the postganglionic neurotransmitter Norepinephrine on airway resistance:

inhibits constriction, stimulation of sympathetic

Maximum inspiratory flow is __ dependent.

effort (1/2 TLC and RV)

Does force increase or decrease with lung volume?

decrease

Does recoil pressure increase or decrease with lung volume?

increase

Does resistance increase or decrease with lung volume?

decrease

True or False? Expiratory flow resistance is effort-dependent.

F. effort-independent

When does compression of the airways occur?

P outside > P inside

Crackles are caused by:

the "popping open" of small airways and alveoli collapsed by fluid, exudate, or lack of aeration during expiration.

what are the inherent mechanical properties of the lung?

elastic and flow resistance forces

OABCD:

elastic resistance

AECF:

non elastic resistance

AECB:

non elastic resistance during inspiration

ABCF:

non elastic resistance during expiration

What % of total body O2 gas flow does the body normally require?

2-5%

The expired flow rate can be increased up to:

15-20% of total body O2 gas flow