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Physiology > Respiratpry Tract 2 > Flashcards

Respiratpry Tract 2 Flashcards

1
Q

What is respiration?

A

The movement of air into and out of the lungs

The principle function of the respiratory system is gas exchange

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2
Q

What are the two types of respiration!

A

Inspiration

Expiration

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3
Q

What are the functions of muscles of respiration? What is the primary muscle of respiration?

A

Muscles of respiration facilitate the changes in the volume and pressure of the thoracic cavity

The diaphragm is the primary muscle of respiration

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4
Q

What happens during quiet respiration?

A

Quiet respiration occurs during resting conditions

  • During quiet respiration the diaphragm facilitates inspiration but e pi ration is passive
  • Forced respiration utilizes accessory muscles of respiration for both inspiration and expiration
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5
Q

What are the muscles of inspiration ?

A
  • Diaphragm
  • External Intercostal
  • Scalene
  • Sternocleidomastoid
  • Serratis anterior
  • Latissimus dorsi
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6
Q

What are the muscles of expiration?

A
  • Internal Intercostal
  • Innermost Intercostal
  • Rectus Abdominis
  • Transverse Abdominis
  • Internal Oblique
  • External Oblique
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7
Q

What is the plural membrane?

A

The visceral pleura is attached to the lung surface

  • The parietal pleura is attached to the chest wall
  • Pleural space/ pleural cavity is found between th3 two layers
  • The pleural space naturally has a negative pressure(subatmospheric) due to the opposing forces of the chest wall and the lungs
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8
Q

Describe the location of function of the respiratory zone

A
  • End of the respiratory tree (respiratory bronchioles, alveolar ducts, and alveolar sacs)
  • Gas-exchange surface
  • Epithelial layer and an extracellular matrix
  • Surrounded by capillaries
  • Surfactant production
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9
Q

Describe the location and function of the conducting zone

A
  • Air flow into and out of the lungs (nose to terminal bronchioles)
  • Heat, hydrate and clean
  • Heat exchange, water vapor pressure equilibration, and remove particulate bond
  • mucociliary bind
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10
Q

Mathematically describe airway resistance and air flow

A

Resistance is the opposition to flow

  • Airflow (Q) = pressure gradient (🔼P)/resistance(R)

R=🔼P/Q

R= 8nl/3.14x r^4

R=resistance

n= viscosity of inspired air

l=length of the airway

r=radius of the airway

The graph shows that there is less resistance at the level of the terminal bronchi, why?

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11
Q

Describe airway resistance and air flow

A

A terminal bronchiole would provide the highest resistance to airflow when considered individually

  • Collectively, the terminal bronchioles has the lowest resistance because of the branching parallel arrangement
  • The highest total resistance is actually in the larger airway
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12
Q

Parasympathetic stimulation and low lung volumes…

A

Increase air resistance

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13
Q

Sympathetic resistance and high lung volumes….

A

Decreased air resistance

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14
Q

Describe the cilia of the conducting zone

A

The cilia lining the airways beat the mucus covering them away from the alveoli, and toward the pharynx (Mucocilliary escalator)

Studies show that ciliary function is inhibited or impaired by cigarette smoke

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15
Q

What is chronic bronchitis?

A
  • Inflammation of the bronchi
  • Commonly caused by cigarette smoking
  • The number of goblet cells may increase and the mucous glands may hypertrophy
  • Cilia movement often is impeded
  • Increased mucous gland secretion and increased viscosity of mucous, leads to coughing and obstruction of air flow
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16
Q

What is Boyle’s law?

A

Pressure and volume of a gas have an inverse relationship, when temperature is held constant

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17
Q

Why does increasing surface area(volume) cause a decrease in pressure?

A

Each wall collision= force applied

Pressure= force per unit area

Therefore increas8ng surface area(volume)= drop in pressure

18
Q

What is recoil?

A

Ability to return to resting volume once stretched

Lung recoil- inward force produced by the elastic properties of the alveoli; acts to collapse the lung

Chest wall recoil pressure (Pcwr)- outward force produced by the chest wall

The lung recoil and the Pcwr oppose each other

19
Q

What is intrapleural pressure (Pip)?

A

The pressure within the pleural cavity

The opposing recoil forces of the chest wall and the lung creates a negative (subatmospheric)Pip

The Pip-5 cm H2O at rest

20
Q

What is alveolar pressure?

A

The pressure within the alveoli

-Pa is 0cm H2O at rest

21
Q

What is trans pulmonary pressure?

A

Difference between Pa and Pip

  • As Ptp increases it causes lung inflation
  • Ptp is 5cm H2O at rest
22
Q

What is atmospheric pressure(Patm)?

A

Pressure exerted by the earth’s atmosphere

-760 mm Hg at sea level

23
Q

Air flow because of pressure gradients…

A

Air flows into the lung when the Pa falls below the Patm

Air moves out of the lungs when Pa becomes greater than Patm

24
Q

What is the pressure during inspiration ?

A

Atmospheric pressure (Patm)= 0

Alveolar pressure (Pa)= 0

Intrapleural pressure(Pip)= -5

Trans pulmonary pressure(PTP)= (Pa)-(Pip)= 0-(-5)= 5

25
Q

How does pressure change in the general lungs during inspiration?

A
  1. Inspiratory muscles contract
  2. Thoracic cavity expands in volume.
  3. Pip decreases from -5 to -8
  4. Trans pulmonary pressure gradient increases (Ptp=Pa-Pip)

Ptp= 0-(-8)=8

  • increased trans pulmonary pressure causes alveolar expansion
  • increased trans pulmonary responsible for inflating the lungs above the resting volume
26
Q

Describe pressure changes in alveoli during inspiration

A
  1. Alveoli increases in volume
  2. Alveolar pressure falls(from 0 to -1)
  3. Air flows in because of the pressure gradient created between the atmosphere and the alveoli
    • During inspiration airflow stops when alveolar pressure again equals atmospheric pressure
27
Q

What are the pressure changes in expiration?

A
  1. Muscles of inspiration relax
  2. Thoracic cavity volume decreases
  3. Pip returns to -5
  4. Ptp decreases
  5. Alveolar volume decreases
  6. Alveolar pressure increases
  7. Air flows out of the lung until alveolar pressure returns to 0
    - Decreased Ptp causes alveolar recoil
28
Q

Describe the Breathing Cycle

A

The thoracic volume increases on inspiration and decreases during expiration

  • The Pip decreases with the increase in thoracic volume seen during inspiration. The opposite is true for expiration
  • Increased airway resistance is encountered dur8ng expiration
  • The Pa decrease on inspiration because of the increase in the alveolar volume. This pressure returns to normal at the end of expiration
29
Q

What is compliance?

A

The measure of distensibility - ease with which the lungs can be stretched ( C= 🔼volume/🔼pressure)

30
Q

What is elastance?

A

Tendency of the lungs to recoil toward its original dimensions; an index of stiffness

31
Q

What is the relationship with compliance and elastance?

A

Compliance is inversely proportional to elastance

Compliance is high at low lung volumes and low at high lung volumes

32
Q

Describe the lung pressure-volume relationship

A

For each increase in trans pulmonary pressure the lung inflates to a new volume

Shape due to forces needed to be overcome:

  1. Airway resistance
  2. Frictional forces
  3. Inertia of air + tissues
  4. Elasticity of lung
33
Q

What are the static compliance challenges in disease states?

A

A. High compliance
-Lung inflates easily and has little elastic recoil
Seen in:
1. Emphysema

B. Low Compliance
Lung is stiff and difficult to inflate

Seen in :

  1. Pulmonary fibrosis.
  2. Surfactant deficiency syndrome
34
Q

Explain emphysema

A

Disintegration of the lung’s elastic framework and destruction of alveolar walls

  • Enlargement of air spaces distal to the terminal bronchioles
  • Signs of air trapping- prolonged expiratory phase, barrel chest, flat diaphragm
  • Commonly caused by cigarette smoking
  • Genetic risk factor- alpha-1-antitrypsin (AAT) deficiency
35
Q

What is surface tension?

A

Property of the surface of a liquid that allows it to act as an elastic sheet

  • Mocules at surface are only attracted from below and with each other
  • As a result the surface of a liquid acts as an elastic sheet
  • Smallest surface area for a given volume in a sphere
36
Q

What is a pulmonary surfactant?

A

Lipoprotein rich in phospholipid (Main component Dipalmitoylphosphatidylcholine)

Secreted by type II cells in the alveolus (type 2 pneumocytes)

Production begins between 24-34 weeks of gestation

37
Q

Wharvare the functions of surfactant?

A
  • Stabilizes alveolar size
  • increase compliance, by reducing surface tension
  • keeps lung dry
38
Q

Effects of surfactant are…

A

Concentration (surface density) dependent-therefore as alveoli shrink- the effective concentration increases and surface tension falls

39
Q

What is the mathematical formula for surface tension?

A

Alveolar lining fluid generates significant tension in the alveoli

T-surface tension

r-radius

P-pressure

P=2T/r

radius and pressure are inversely proportional

40
Q

If it were not for surfactant…

A
  • Small alveoli develop a large pressure; large alveoli develop a smaller pressure
  • So air would flow from the the smaller to larger alveoli
  • Tendency would be for smal alveoli to collapse (atelectasis) and large alveoli to overinflate
41
Q

Summarize infant respiratory distress syndrome (IRDS)

A

Known as respiratory distress syndrome of newborn and surfactant deficiency disorder(SDD)

  • usually affects premature infants
  • underdeveloped lungs - low levels of surfactant
  • Without medical intervention, ventilation failure will ensue
42
Q

What are the classical signs and symptoms of infant respiratory distress syndrome?

A
  • use of accessory muscles of respiration.
  • Cyanosis
  • Hypoxia
  • Tachycardia and Tachypnea

Physiology (36 decks)

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