Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Semester 3 - respiratory > 2. Lung Mechanics and Ventilation > Flashcards

2. Lung Mechanics and Ventilation Flashcards

1
Q

Define ventilation.

A

Process of inspiration and expiration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Define tidal volume.

A

Volume of air which enters and leaves the lungs with each breath (during quiet breathing)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Which muscles are used during inspiration in quiet breathing?

A

Diaphragm and intercostal muscles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Which muscles are used during expiration in quiet breathing?

A

None, muscles of inspiration relax. Passive process, no energy is used.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Define respiration

A

the exchange of oxygen and carbon dioxide across a membrane either in the lungs or at the cellular level

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How is breathing controlled?

A
  • Breathing is rhythmic and involuntary

* Neurones in respiratory centre of brain automatically generate impulses to inspiratory muscles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is intrapulmonary pressure

A

Pressure inside lungs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe the mechanism of quiet inspiration

A
  • diaphragm and external intercostal muscles contract(active)
  • diaphragm flattens and ribcage moves upwards and out
  • expansion of thoracic cavity (and lungs)
  • ↑thoracic and lung volume and ↓pressure (relative to atmospheric pressure)
  • Moves air into airways (lung)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe the mechanism of quiet expiration

A
  • diaphragm and external intercostal muscles relax(passive)
  • reducing size of thoracic cavity and lungs
  • ↓thoracic and lung volume and ↑ pressure (relative to atmospheric pressure)
  • Moves air out of airways (lung)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Why do lungs have tendency to collapse in?

A

Have natural elastic recoil (and surface tension of alveoli generate an inwardly directed force that favour small volumes.)
• Especially with increased stretch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is responsible for holding lungs against chest wall without ‘physical’ attachment?

A

The pleural fluid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How does the pleural fluid keep the lungs against the chest wall?

A

Creates surface tension between the 2 layers of pleura, which creates a pleural seal between the lung and the thoracic wall. holds outer surface of lung to inner surface of chest

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the result of the pleural fluid holding lungs against chest wall ?

A

So lungs expand with the thoracic cavity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the resting expiratory level?

A

State of equilibrium in the respiratory system. At the end of quiet expiration, lung is subject to 2 equal and opposing forces.

  • state when we have just expired and before we start inspiring
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the forces acting on the lung during the resting expiratory level?

A

Inwards: lungs elastic recoil (and surface tension) generate INWARDLY directed force.

Outwards: muscles and various connective tissues associated with the rib cage also have elasticity. At rest, these elastic elements favour OUTWARD movement of the chest wall. Diaphragm also pulls down

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

describe why the lung collapses and why the chest wall pulls out

A
  • Lungs collapse inwards (lung elastic recoil)
  • Chest wall pulls “out” (chest elastic recoil)
  • Forces are equal and opposite so balance out (=no movement chest wall)
  • Tendency to always want to return to this resting state (like an elastic band or spring
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How does inspiration disturb the equilibrium of the two forces?

A

Muscles contract to allow the chest wall and diaphragm to overcome inward pull of the lung recoil

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How does expiration disturb the equilibrium of the two forces?

A
  • Muscles stop contracting
  • Chest wall &diaphragm no longer overcome inward pull of lung recoil
  • Return to resting expiratory level
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What kind of pressure exists in the interpleural space and why?

A

Negative pressure, due to elastic recoil of lung pulling visceral pleura inward and chest wall pulling parietal pleura outward

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

At what point is the interplueral pressure the most negative?

A

Intrapleural pressure is negative throughout expiration and inspiration (becomes more negative up until end of inspiration)

21
Q

When is intra pulmonary pressure positive and negative?

A

negative in inspiration

positive in expiration

22
Q

what holds the visceral and parieatl pleura together?

A

pleural seal

23
Q

What would happen if the pleural seal was broken?

A

chest wall would go outwards and lung would collapse in

24
Q

Define inspiratory capacity.

A

Max amount of gas that can be inspired after a normal expiration.
Tidal vol + Inspiratory reserve vol

25
Q

Define functional residual capacity.

A

Volume of air in lungs at the end of quiet expiration.

Expiratory reserve vol + residual vol

26
Q

Define expiratory reserve volume?

A

the extra volume you can breath out

27
Q

define residual volume

A

the air still left in lungs after expiration

28
Q

define inspiratory reserve volume

A

the volume of air you can breathe in above normal inspiration level

29
Q

Define vital capacity

A

amount of air that can be expired after maximal inspiration

Tidal vol + inspiratory reserve + expiratory reserve

30
Q

Define Total Lung Capacity

A

Vital Capacity + Residual Volume

31
Q

Define anatomical dead space.

A

The volume of the conducting respiratory passageways (area in and around the nose, pharynx, larynx, trachea, and bronchial tree) which fills with inspired air, but never contributes to gas exchange in the alveoli.

32
Q

What helps Forced Inspiration and Expiration?

A

accessory muscles

33
Q

what are the accessory muscles of inspiration?

A

Sternocleidomastoid
Scalene muscles
Serratus anterior
Pectoralis major

34
Q

what are the accessory muscles of expiration?

A

Internal intercostals

Abdominal wall muscles

35
Q

When are accessory muscles used?

A

Used during exercise but also when diseases affect the lungs

36
Q

What does the fluid surrounding alveoli create and what is the effect of it?

A

Surface tension of fluid limits expansion of the alveoli

• Decreases compliance making it difficult for alveoli (and therefore lungs) to expand

37
Q

What substance helps increase compliance of alveoli and how?

A

Surfactant
• has detergent properties
• Acts to disrupt interaction between fluid molecules on alveolus surface…reducing surface tension

38
Q

What produces surfactant?

A

secreted by type II pneumocytes in lungs

39
Q

when is surfactant more effective?

A

more effective at disrupting surface tension when its molecules are closer together (i.e. around smaller alveoli)

40
Q

describe the effectiveness of surfactant in smaller alveoli

A

• Smaller alveoli surfactant molecules closer together
• More effective at disrupting surface tension of fluid
• Reduced surface tension
• Reducing surface tension in smaller alveoli prevents
pressure rising (within the alveolus) as a result of
the smaller volume…

41
Q

describe the effectiveness of surfactant in largeralveoli

A

• Larger alveoli surfactant molecules spread further apart
• Less effective at disrupting the surface
tension
• Surface tension ↑ as alveoli increase in size i.e. as lungs expand [hence forced inspiration harder than quiet inspiration]

42
Q

How does surfactant stabilise the lungs?

A
  • Due to surfactant, surface tension in larger alveoli&raquo_space;smaller alveoli - effectively surfactant ‘diluted’ in larger alveoli
  • Thus, pressure inside the bigger alveoli stays high despite it being bigger
  • i.e. pressure does not drop despite increased ‘volume’ of the alveolus, as the increased pull ‘inwards’ from the surface tension counters this
  • If pressure remains high in bigger alveoli, keeps pressures equal to smaller alveoli
  • Prevents collapsing of small alveoli into big alveoli
43
Q

What are 3 functions of surfactant?

A
  1. Increases lung compliance by reducing surface tension of alveolar fluid
  2. Stabilises the lungs, by preventing small alveoli collapsing into big ones
  3. Prevents the surface tension in alveoli creating a suction force which can cause transudation fluid from pulmonary capillaries into the alveoli
44
Q

When is surfactant produced?

A

> 25 weeks

45
Q

What is respiratory distress syndrome?

A

a condition seen in premature babies, particularly those less than 30 weeks old, due to the lack of surfactant

46
Q

What does air need to overcome as it passes through airways?

A

resistance to flow

47
Q

Which tubes have the greatest resistance to air flow individually?

A

Tubes with smaller diameter have greatest ristance

48
Q

How is the resistance of the small tubes overcome?

A
  • Numerous airways running in parallel

* Compensates for increase in their ‘individual’ resistance

Semester 3 - respiratory (20 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions