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EXCI 259 > Ch. 38 Pulmonary Ventilation > Flashcards

Ch. 38 Pulmonary Ventilation Flashcards

1
Q

What 2 (human) systems are used for respiration?

A
  1. Breathing system

2. Circulatory system

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2
Q

What are the 4 major functions (steps / stages) of respiration?

A
  1. Pulmonary ventilation: inflow and outflow of air between atmosphere and lung alveoli
  2. Diffusion of O2 and CO2 between alveoli and blood (“cross-over”)
  3. Transport of O2 and CO2 in blood and body fluids to and from tissue cells
  4. Regulation of ventilation and other facets
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3
Q

Inspiration and expiration is a mechanical process which has what type of relationship between volume and pressure?

A

An inverse relationship – therefore, if there is an increase in the volume, there is a decrease in the pressure.

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4
Q

The volume of the chest cavity can be modified in what two ways?

A
  • VERTICALLY: DOWNWARD or UPWARD MOVEMENT of thorax floor to LENGTHEN or SHORTEN chest cavity
  • ANTERO-POSTERIORLY: ELEVATION or DEPRESSION of the ribs to INCREASE or DECREASE the DIAMETER of the chest cavity
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5
Q

List the muscles of inspiration:

A

Vertical ( increase): Diaphragm

Antero-posterior (increase):

  • External intercostals (mainly)
  • Parasternal intercostals
  • Anterior serrati
  • Scaleni (in deep breath)
  • Sternocleidomastoid (in deep breath)
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6
Q

List the muscles of expiration:

A

At rest (quiet breathing):

RELAXATION of diaphragm and external intercostals leads to passive recoil of lungs and chest cage

During exercise (heavy breathing):

  • Elastic forces are not powerful enough to cause rapid expiration
  • Elastic recoil PLUS CONTRACTION of ABDOMINALS (vertical) and INTERNAL intercostals (antero-posterior) to REDUCE VOLUME – using muscles of respiration increasing pressure, decreasing volume, helps push air out.
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7
Q

How many muscles contract during expiration?

A

NONE. They are at rest!

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8
Q

Describe the function of the diaphragm during the respiratory cycle.

A

Inspiration, diaphragm (and external intercostals etc.) CONTRACT; increasing the volume and affecting the pressure (decreasing) until Expiration occurs and the diaphragm RELAXES, decreasing volume and increasing pressure until inspiration occurs again and so on…

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9
Q

What is the overview of the ventilatory cycle at rest (normal quiet breathing)?

A
  • Inspiration:
  • Diaphragm and external intercostals CONTRACT
  • Ribs lift up and out, thorax floor lowers
  • Volume of thorax increases
  • Intrapulmonary pressure decreases (below atmospheric pressure)
  • Atmospheric air moves INTO pulmonary system
  • Pressure gradient between lung and atmosphere equilibrates
  • Expiration:
  • Diaphragm and external intercostals RELAX
  • Diaphragm recoils > raises thorax floor
  • Lungs and ribs recoil to original position
  • Thorax volume decreases
  • Intrapulmonary pressure increases Forcing air OUT
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10
Q

What is the overview of the ventilatory cycle during exercise?

A
  • Inspiration:
    Accessory muscles :
    parasternal intercostals, anterior serrati, scaleni, sterno
  • Assist to Lift ribs and clavicles vertically and TRANSVERSALLY
  • Allows for large INCREASE in TIDAL volume during exercise

Expiration:

  • Becomes ACTIVE / forced movement
  • Internal intercostals contract > pull ribs down and in
  • Abdominal muscles contract > increase abdominal pressure, forcing
  • Diaphragm up INTO thorax
  • Increases VENTILATORY AIRFLOW so pulmonary ventilation can increase GREATLY without a dramatic increase in breathing frequency
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11
Q

What statement properly describes the lung?
A. The lung is a hard and porous structure
B. The lung is a soft, non-porous structure
C. The lung is an elastic structure
D. The lung is mostly made of collagen

A

ANSWER: C – the lung is an elastic structure

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12
Q

How is the lung attached to the inside of the chest cavity?

A

There are no attachments between lung and chest walls except at its hilum (entry and exit point of structures).

  • The lung floats in thoracic cavity surrounded by thin layer of pleural fluid
  • Continual suction of excess fluid into lymphatic channels maintains slight suction between visceral and parietal layers of pleura
  • Lungs float but are held to chest as if GLUED, but well lubricated and can SLIDE freely as chest expands and contracts.
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13
Q

True or False?

Pleural space can be considered a Dynamic Environment?

A

ANSWER: TRUE

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14
Q

What is dead space ventilation?

A

The air travels through certain respiratory passages without any gas exchange, like the nose, the trachea and the pharynx.

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15
Q

What is physiological dead space?

A

The space air travels for gas exchange. E.g. alveoli

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16
Q

What is anatomical dead space?

A

The space air travels without gas exchange

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17
Q

Which way does air flow? From High to low pressure? Or from Low to high pressure?

A

Form high to low pressure

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18
Q

What is pleural pressure?

A

The pressure of the fluid in the pleural space

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19
Q

What happens to pleural pressure during inspiration?

A
  • Slightly negative (for suction to maintain open lungs)
  • Normal Ppl at beginning of inspiration = -5 cm H2O
  • Normal inspiration > expansion of chest > more negative pressure
  • -7.5 cm H2O
  • During expiration, events reversed
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20
Q

What happens to pleural pressure during expiration?

A
  • Lungs are at negative pressure -7.5 cm H2O
  • Normal expiration > diaphragm relaxes, chest recoils, less negative pressure
  • -5 cm H2O : Normal Ppl
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21
Q

What is alveolar pressure?

A

The pressure of air inside the alveoli of the lung

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22
Q

What happens to alveolar pressure during inspiration?

A
  • Zero reference: when glottis open / no air in or out – pressures are equal with atmosphere
  • Normal Palv= 0 cm H2O
  • Palv falls below atm. Pressure >/= inward flow of air
  • Palv decreases to >/= -1 cm H2O
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23
Q

What happens to alveolar pressure during expiration?

A
  • Expiration

- Palv increases to + 1 cm H2O

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24
Q

What is Transpulmonary pressure (Ptran)? What does it measure

A

Also called the “recoil pressure” is the difference between Palv and Ppl. It measures the elastic forces in the lungs.

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25
Q

What is compliance of the lung?

A

The extent to which the lungs will expand for each unit increase in transpulmonary pressure (if enough time to reach equilibrium).

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26
Q

What is average compliance of the lung for the normal adult?

A

200 ml /cm H2O of Ptran; the normal lung expands and fills with 200 ml of air volume for every 1 cm H2O increase in Ptran (if enough time allowed… 10 – 20 sec.)

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27
Q

Are the compliance curves of the lung the same during inspiration and expiration?

A

No.
The characteristics of the compliance diagram are determined by the elastic forces of the lungs.

  1. Elastic forces of the lung tissue
  2. Elastic forces caused by surface tension of the fluid that lines the Inside walls of the alveoli and other lung air spaces.
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28
Q

What determines the elastic forces of the lung tissue (4)?

A

Elastic forces of the lung tissue are determined mainly by elastin and collagen fibers that areinterwoven among the lung parenchyma

When lungs expand these fibres stretch

Force that acts to resist distention / inflation

Account for about 1/3 of total elastic forces for returning lung to natural state

29
Q

What causes the elastic forces of the lung tissue (4)?

A

Elastic forces caused by surface tension of the fluid that lines the Inside walls of the alveoli and other lung air spaces.

Caused by attraction between alveolar lining fluid and the air in the alveoli

Force that acts to resist distention / inflation

Account for 2/3 of total elastic forces

30
Q

Principle of Surface Tension:

A

When water forms a surface with air, the water molecules on the surface of the water have an especially strong attraction for one another and the water surface is always trying to contract (e.g. raindrops helfdl together by tight contractile membrane of water molecules

On inner surface of alveoli:

–> Water surface is attempting to contract; results in attempt to force air out of alveoli through bronchi; alveoli try to collapse and end up causing elastic contractile force of the entire lungs: surface tension elastic force

31
Q

What are some factors that affect surface tension (2)?

A
  • Effect of surfactant on surface tension; REDUCES surface tension from 1/12 to ½ the surface tension of pure water
  • Effect of Alveolus Radius on Pressure Caused by Surface Tension; Laplace Law: The smaller the alveolus the greater the alveolar pressure caused by surface tension

P = 2x surface tension (T) / radius of alveolus (R)

32
Q

What is surfactant?

A

Surfactant is a detergent like substance produced from type II alveolar epithelial cells. It reduces the surface tension of water and thus PREVENTS COLLAPSE OF THE ALVEOLI

33
Q

If the lungs were not present in the thorax, would muscular effort still be required to expand the thoracic cage?

A

YES. muscular effort is still required to expand the thoracic cage.

34
Q

When discussing the compliance of the Total pulmonary system, what and how is it measured?

A

The total pulmonary system compliance is the lungs and the thoracic cage.

2x Pressure needed to inflate total pulmonary system than to inflate lungs alone therefore, the entire pulmonary system is about ½ the compliance that that of the lungs alone.

(110 ml – system, 200 ml Lungs)

35
Q

The Work of Breathing can be divided into 3 parts:

A
  1. Compliance or elastic work (work required to expand lungs against lung and chest elastic forces)

compliance work= (∆V×∆P_PL)/2

  1. Tissue resistance work ( work required to overcome viscosity of chest wall structures, small % of total work)
  2. Airway resistance work (work required to overcome airway resistance to movement of air into the lungs; e.g. during heavy breathing Great volumes of airflow through bronchi at high velocities  requires greater % of airway resistance work to overcome increased airway resistance.
36
Q

What are the energy requirements of Pulmonary ventilation during quiet respiration?

A

3-5% of total energy expenditure

1 MET = 3.5 ml O2 / kg/ min, 3 % MET = 0.03 x 3.5 = .105 O2/ kg/ min

37
Q

What are the energy requirements of pulmonary ventilation during heavy exercise?

A

Work of breathing increases up to 50-fold –> 5.25 O2 / kg/min

38
Q

How can airway RESISTANCE or PULMONARY compliance lead to an INCREASE in work in breathing?

A

By increasing resistance (obstructive) or decreasing compliance (restrictive) will increase the work of breathing.

39
Q

How can increasing the work of breathing (when a person has an obstructive or restrictive pulmonary disease) become an exercise-limiting factor?

A

Either increasing airway resistance (obstructive) or decreasing pulmonary compliance (restrictive) leads to increase in work of breathing -> The Ability to provide enough energy to respiratory muscles for breathing can become an exercise-limiting factor.

40
Q

What type of respiratory disease is emphysema (obstructive or restrictive)?

A

OBSTRUCTIVE

41
Q

What type of respiratory disease is Asthma (obstructive or restrictive)?

A

OBSTRUCTIVE

42
Q

What type of respiratory disease is Pulmonary Fibrosis (obstructive or restrictive)?

A

RESTRICTIVE

43
Q

What is the function of the upper airways? (And what does that include?

A

The upper airways;
- Nose, sinuses, pharynx, larynx

Serve as conduction airways for MOVEMENT of air toward lower airways
Main role;
o	Warm, humidify, and filter inhaled air
Other role;
o	Smell, swallowing, phonation
44
Q

How is air distributed to the lungs?

A

Air is distributed to the lungs by way of the trachea, bronchi and bronchioles

45
Q

How are bronchioles kept open?

A

Bronchioles are not prevented from collapsing by the rigidity of their walls (like the trachea ) but, by transpulmonary pressures (PTRAN) that expand the alveoli. Alveoli expand thus bronchioles also expand / enlarge.

46
Q

How does mucus and cilia clear airways (trachea, bronchi and bronchioles)?

A

About 1 L mucus secreted / day lining airways (goblet cells)

  • -> Traps small particles
  • -> Contains antibacterial enzyme (lysozyme)  destructs bacteria imprisoned by mucus
  • -> Mucus directed toward pharynx (cilia) eliminated by deglutition or spit
  • -> Cold weather; cilia slow down, mucus accumulates in nasal cavity and drips
47
Q

How is cough reflex triggered?

A

Trachea has sensitive membrane
Substance passes through larynx at carina – cough reflex to expel it

**When unconscious reflex not active – do not administer fluids.

48
Q

Where is greater resistance found in the airways?

A

Greater resistance to airflow found in the larger bronchi and bronchioles than in the smaller ones and there are less.

49
Q

In some diseases – the smaller bronchioles play a greater role in determining airflow resistance… why? (3)

A
  1. Muscle contraction in their walls
  2. Edema occurring in the walls
  3. Mucus collecting in the lumens of the bronchioles
50
Q

Can you identify RV, ERV, IC, IRV, VT, TLC and FRC on a spirogram?

A

Residual volume: The volume remaining in the lungs at the end of the most forceful expiration(1.2L)

Expiratory Reservation Volume: The maximum volume of air that can be expired after the end of normal VT (1.1L)

Inspiratory Capacity: The maximum amount of air that can be inspired following normal expiration (3.5L)

Tidal Volume: The volume of air inspired and expired with each normal breath (500 ml)

Total Lung Capacity: The amount of air in the lungs at the end of a maximal inspiration (5.8 L)

Functional Residual Capacity: The amount of air remaining in the lungs after a normal expiration (2.3 L)

Vital Capacity (VC): The maximum amount of air that can be expired following a maximal inspiration (4.6 L)

51
Q

How is FRC calculated?

A

FRC= ERV+RV { RV cannot be expired into spirometer; therefore, the helium dilution test is used and FRC = (Ci/Cf-1)Vi

52
Q

How is IRV calculated?

A

IRV= IC-VT

53
Q

What important physiological variables can we obtain from a spirometry test?

A

IRV,ERV, VT (?)

54
Q

What are the main expiratory flow rates? (3)

A
  1. FVC: Forced Vital Capacity; Total amount of air than can forcibly be blown out after full inspiration ,reported in liters and % of predicted value
  2. FEV1: Forced Expiratory Volume in 1 Second; Amount of air that can forcibly be blown out in the first second of an FVC maneuver, reported in liters and % of predicted value . Along with FVC, considered one of the primary indicators of lung function
  3. FEV1/FVC; ratio of FEV1 (in liters) over FVC (in liters) reported as absolute ratio (e.g. 0.8) or as % (e.g. 80%)
    * *** WILL be HIGH if airways are NORMAL

– Also dependent on age, gender and height

55
Q

What is spirometry?

A

Simple method of measuring volume movement of air into and out of the lungs

56
Q

Which lung volume cannot be measured through forced inspiratory / expiratory maneuvers?

A

RV (Residual volume)

57
Q

What are other methods to determine FRC, RV and TLC?

A
  1. Gas dilution techniques
    • Helium dilution method
    • Nitrogen washout
  2. Radiographic determination
    • Qualitative only
  3. Body plethysmography
    • Common in respiratory care settings
58
Q

What is minute ventilation (VE)?

A

Total amount of air moved through the respiratory passages per minute.
VE = VT (tidal volume) * fB (Breathing frequency or RR)

e.g. for Young Healthy male:
VE = 500 ml/ breath x 12 breath / min= 6000 ml / min = 6 L / min

59
Q

VA = Alveolar Ventilation

What does VA represent?

A

The rate at which new air reaches areas for gas exchange; alveoli, alveolar sacs, alveolar ducts, and respiratory bronchioles

60
Q

Are VE (Minute Ventilation) and VA (Alveolar ventilation) interchangeable?

A

No. They are different. VA is contained in or part of the measurement of VE

61
Q

What happens to a person’s VO2 and VCO2 during exercise?

A

Consumption increase : More IN (VENTILATION) and more CO2 OUT (VENTILATION)

62
Q

What must increase during exercise in order to meet metabolic demand of O2?

A

VENTILATION

63
Q

True or False:

VO2 increases faster than VE (Minute ventilation) does .

A

FALSE. VE increases faster than VO2 does.

64
Q

What is the normal response to progressive exercise in regards to minute ventilation (VE)?

A

Increases linearly with VO2 until threshold – then increase out of proportion to VO2
Early rise resulting from increase in tidal volume (VT and breathing frequency
As intensity increases, VT tens to level of and increases in VE are due to increases in frequency. (increases 3-4-fold from rest)

65
Q

Controversial term for ventilatory threshold?

A

Anaerobic threshold

66
Q

How is ventilatory threshold often defined?

A

Ventilatory threshold is often defined as BREAKPOINT in VE / VO2 relationship

67
Q

Where is does the ventilatory threshold typically occur in sedentary individuals?

A

At 50-60% VO2 max (wide range 35-80% VO2max)

68
Q

What is the most common non-invasive method of assessment?

A

Modified V-slope method

EXCI 259 (2 decks)

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