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Cardiorespiratory Biology > Work of ventilation 2 > Flashcards

Work of ventilation 2 Flashcards

1
Q

non elastic work in breathing

A

frictional/resistive work

force to overcome air-flow resistance - force to move air through airways

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2
Q

airway resistance definition

A

the impedance of air flow through the tracheobronchial tree as a result of friction of gas molecules
Very important contribution to the work of breathing

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3
Q

when is airway resistance present

A

during both inspiration and expiration

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4
Q

what does increased airway resistance require

A

greater pressure gradient to drive airflow and result in the same tidal volume of approximately 500 ml

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5
Q

2 main components to determine the airway resistance

A 
Diameter of the airway (cross sectional area) and distance air has to travel
Lung volume
Bronchial smooth muscle tone
Thickness of mucous lining and submucosa
Mucus layer
flow type/pattern - laminar or turbulent
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6
Q

driving pressure

A

pressure difference between mouth and alveoli

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7
Q

hagen-poiseuille law relates to

A

Relates flow rate (volume transported per time unit) to airway radius and to distance the air is transported

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8
Q

flow rate

A 
(V/t) = ΔP π r4/ 8 η l
ΔP = Driving Pressure; r = Radius; η = viscosity; l = Length
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9
Q

what law is used to express airway resistance

A

hagen-poiseuille law

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10
Q

resistance definition

A

the ratio between the driving pressure and the associated flow rate.

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11
Q

resistance formula

A

Resistance (R) = ΔP/V/t = 8ηl /πr4

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12
Q

if airway radius is reduced to 50% by how much is the resistance increased

A

increased 16 fold

1/(0.5)4*

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13
Q

is the resistance in trachea or bronchioles higher and why

A

bronchioles have smaller radius than trachea but a more of them than trachea - overall the airway widens
resistance in trachea is higher than bronchioles

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14
Q

as the airway resistance decreases ..

A

lung volume increases

increases airway diameter

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15
Q

what contributes to the diameter airways of trachea and bronchi

A

cartilage prevent collapse

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16
Q

what contributes to the airway diameter in the small bronchi and bronchioles

A 
no supporting cartilages 
pull of surrounding tissue
innervated smooth muscle
small diameter easily obstructed
offer little resistance
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17
Q

what features of the lungs in the walls of the airways contribute to the airway diameter

A

Smooth muscle tone

Thickness of mucosa/submucosa

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18
Q

what features in the lumen of the airway contribute to the airway diameter

A

mucus

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19
Q

what intrinsically controls the smooth muscle tone

A

chemical mediators - mast cell degranulation (via release of histamine) and inflammatory mediators lead to bronchoconstriction

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20
Q

when CO2 is raised it leads to

A

bronchodilation

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21
Q

when CO2 is lowered it leads to

A

bronchoconstriction

22
Q

factors influencing secretions

A

Secretions of seromucous glands and goblet cells that line respiratory system

23
Q

where are the seromucous glands and goblets cells

A

5-10 μm thick, inner layer more watery to allow ciliary action and upper layer more viscid to trap particles

24
Q

seromucous glands and goblet cells are controlled by what category of the CNS

A

by parasympathetic nervous system reflexes and local chemical stimulation

25
Q

activities of seromucous glands and goblet are increased in

A

bronchitis

26
Q

activities of seromucous glands and goblet are decreased in

A

atropine

27
Q

how does turbulence affect air flow resistance

A

increase airflow resistance

28
Q

how is reynolds number expressed in straight tubes

A 
R = 2rvd/η
r = Radius; v = velocity; d = Fluid density; η = Fluid viscosity
29
Q

what promotes turbulences

A

high velocities and large diameters

30
Q

turbulence in airway can lead to

A

Empty Nose Syndrome/paradoxical obstruction

31
Q

why don’t turbulences occur in bronchioles

A

velocities are low and diameters are small

32
Q

sites of airway resistance

A

greatest resistance in large airways

1/2 in nose, pharynx and larynx

33
Q

where does 80% of airway resistance occur

A

Below larynx –in trachea and main bronchi

34
Q

where does less than 20% of airway resistance occur

A

in bronchioles

35
Q

how is asthma caused

A

lung inflammation

36
Q

how is asthma treated and explain the treatments mechanism

A

Treat with bronchodilators and corticosteroids
Bronchodilators relax bronchial smooth muscle and widen airways
Corticosteroids reduce inflammation and reduce secretions

37
Q

chronic obstructive pulmonary disease examples

A

chronic bronchitis

emphysema

38
Q

how is chronic bronchitis affect work of ventilation

A

excess production of mucus
increased flow work
leads to cough, production of sputum

39
Q

how is chronic bronchitis treated

A

cessation of smoking, antibiotics (if bacterial), bronchodilators

40
Q

how does emphysema impact work of ventilation

A

Loss of elastic tissue due to uncontrolled action of proteolytic enzymes
loss of elastic work

41
Q

how is emphysema treated

A

Treat by cessation of smoking, avoiding irritants, lung transplant

42
Q

pulmonary fibrosis

A

Formation of excess fibrous connective tissue in the lung.

Restrictive lung disease, reduces compliance

43
Q

causes of pulmonary fibrosis

A

Idiopathic
Inhalation of pollutants (coal dust, asbestos)
Certain medications (bleomycin)
Disease (Sarcoidosis)

44
Q

treatment of pulmonary fibrosis

A

Immune supressive agents (corticosteroids)
Oxygen supplementation (improves QOL)
Lung transplantation

45
Q

what is the difference between obstructive and restrictive respiratory disease

A

Obstructive - interfere with MOVEMENT of air, increase FLOW- RESISTIVE work, no effect on ELASTIC work, decrease FEV1, NOT FVC
Restrictive - Interfere w/ ABILITY to EXPAND LUNGS, increases ELASTIC work, NO EFFECT on FLOW- RESISTIVE work, decrease FEV1 AND FVC

46
Q

determinants of airway diameters

A

lung volume
bronchial smooth muscle tone
thickness of mucous lining and submucosa
mucus layer

47
Q

what features outside the airway contribute to the airway diameter

A

radial traction of elastic tissue

pressure from lymph nodes

48
Q

smoking can cause goblet cell hyperplasia which subsequently causes increased mucus production. What effect would this have on the work of breathing.

A

increases flow resistive work

49
Q

how do we know if turbulence occurs in reynolds number

A

if reynolds number is greater than approx. 2000

50
Q

how does the hagen poiseuille equation relate to another law

A

resistance = driving pressure/ flow rate

ohm’s law resistance = voltage / current

Cardiorespiratory Biology (25 decks)

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