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A1. ME2521 RESP > WEEK 1: LUNG PHYSIOLOGY > Flashcards

WEEK 1: LUNG PHYSIOLOGY Flashcards

1
Q

Describe the main anatomical features of the airways and gross anatomical features of the lung

A
  • URT: nasal cavity (warming and moisture), pharynx, epiglottis (tracheal fold), larynx (voice box)
  • LRT: Trachea, bronchus, left and right lungs, alveoli (basic cellular unit)
  • pleural cavity
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2
Q

• Identify the different classes of airways and the two types of alveolar cells

A

Conducting airway: cleans and moistens, nose->bronchioles
Non-conducting airway: respiratory units for gas exchange, respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli

T1 alveolar cell: site of gas exchange (adjacent to capillary)
T2 alveolar cell: excrete surfactant

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3
Q

List the functions of the respiratory system

A

gas exchange
acid-base balance
protection from infection
communication

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4
Q

the difference between pulmonary and systemic circulation

A

PULM

  1. deoxygenated blood and CO2 from heart to lungs (pulm art.)
  2. oxygenated blood from lungs to heart (pulm vein)

SYSTEMIC

  1. o2 to cells (arteries)
  2. co2 from cells to heart (veins)
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5
Q

Identify points of gas exchange between the respiratory and cardiovascular systems

A
  1. alveolar level at alveoli

2. cellular level at capillaries

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6
Q

Understand why, and how, resistance to air flow varies across the respiratory tree

A

HIGHER RESISTANCE at Higher level: wider lumen but less if not singular path
LOWER RESISTANCE at Lower levels: smaller lumen exponential paths

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7
Q

Steady state net volume gas exchange

A

250 ml/min O2

200 ml/min CO2

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8
Q

Lung Volumes

A
  1. TIDAL: normal shallow inspiration 500ml
  2. INSPIRATORY RESERVE VOLUME: extra air inwards w/ exert. on top of TIDAL 3L
  3. EXPIRATORY RESERVE VOLUME: extra air outwards w/ exert 1.1L
  4. RESIDUAL VOLUME: air we cannot voluntarily exhale 1.2L (prevent alv collapse + continual gas exchange) 1.2L
  5. DEAD SPACE VOLUME: volume in conducting airway 150ml
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9
Q

Lung Capacities

A
  1. VITAL CAPACITY: max air exhaled after deep inhalation 4.6L LFT
  2. FUNCTIONAL RESIDUAL CAPACITY: volume of air in lungs at end of normal expiration 3L
  3. INSPIRATORY CAPACITY: IRV + TV
  4. TLC
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10
Q

Describe the anatomy of the pleural cavity

A
  • per lung, doubles at hilum
  • thin pleural cavity, 3ml of fluid
  • visceral (lung)
  • parietal (ribs)
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11
Q

Describe the relationship between the parietal and visceral pleura and why this is important for inflation and deflation of the lung

A

cohesive fluid action between pleural membrane facilitates changes in lung shape aswell as maintaining positive transpulmonary pressure.

  • prevent elastic recoil upon exhalation
  • reduces friction allows gliding of ribcage and lungs
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12
Q

tracheal deviation

A

visible sign in CXR indicative of (tension) pneumothorax pushing nearby structures + heart = reduced cardiac output hypotension, raised JVP

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13
Q

Describe how the muscles of respiration act to increase and decrease thoracic volume

A
  1. DIAPHGRAGM CONSTRICTS (phrenic), FLATTENS,
    ↑thor. vol
    ↓ pressure
    +ext. intercostal musc, scalenes, sternocleidomastoids
    *ribcage up
  2. DIAPHGRAGM RELAXES (phrenic stops), DOME
    ↓ thoracic volume
    ↑ pressure
    + inter. intercostal mus., abdominal muscles
    * ribcage down
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14
Q

Relate Boyle’s law to the mechanics of breathing, inspiration and expiration

A

PRESSURE EXERTED BY GAS INVERSELY PROPORTIONAL TO VOLUME therefore VOL & THUS PRESSURE CHANGES MUST FAVOUR LAW OF PARTIAL PRESSURE OF DIFFUSION

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15
Q

Respiration and changes to airways

A
  1. INSPIRATION ↑thor. vol
    ↑DIAMETER | ↓RESISTANCE
  2. EXPIRATION compression and ↓thor. vol
    ↓DIAMETER ↑RESISTANCE
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16
Q

State the mechanical factors that affect respiratory minute volume.

A

MINUTE VOLUME = TIDAL x RR
“quantity of air moved into and out of the lungs in a minute and dictates CO2 elimination from alveoli.”

• intrapleural pressure
-VE, 
• intrathoracic/alveolar pressure
RELATIVE TO P.atmos.
• transpulmonary pressure 
\+ve, DIFFERENCE BETWEEN P.alv. + P.ip.
17
Q

Explain why intrapleural pressure is always less than alveolar pressure.

A
  1. opposing pleural membranes
  2. inspiration = ↑vol of pleural cav d/t parietal away from visceral
  3. -ve pressure

*more -ve at apex d/t gravity

18
Q

State the role of pulmonary surfactant and the Law of Laplace

A

P = 2T/r
P required to keep alveoli open

  • surfactant ↓2T = equalising P in small and large alveoli
  • smaller = ↓r = ↑P
  • surfactant more diluted = less effective in larger alveoli
19
Q

Define the term compliance the factors that affect this

A

Change in volume relative to change in pressure; stretchability
high & healthy: large change in vol = small changes therefore easy to revert back!

  • elasticity
  • surface tension
  • airway resistance
20
Q

IRDS

A

inability/inefficient surfactant prod (thyroid hormones + cortisol) by 36w. alveolar collapse. GREATER WORK.

21
Q

Understand the functional difference between pulmonary and alveolar ventilation

A
  1. PULMONARY (MINUTE) VENTIL. = Total mvmnt of. air in/out lungs
  2. ALVEOLAR = Fresh air to alveoili available for gas exchange
  • 150ml dead space ‘stale’ air of TIDAL expirated air
  • 350ml fresh air on INSPIRATION
22
Q

Normal values for alveolar and arterial gas partial pressures

A
  1. paO2 13.3kPA / 100mmHg
    > diluted from atmos160mmHg d/t deadspace; residual volume; water vapor dilution; equilibrium with blood

pCO2 5.3kPA / 40mmHg
>hypo: high pCO2 stimulates breathing @. 11mmHg

  1. pAO2 ≥40mmHg; pCO2 ≥ 46mmHff
23
Q

factors that influence diffusion of gases across the alveoli

A
  • pp gradient
  • gas solubility
  • SA
  • thickness of membrane
  • distance
24
Q

REMEMBER!

A

CO2 solubility greater than O2’s = ↑diffusionrateCO2

25
Q

EMPHYSEMA impact on gas exchange

A

↓SA=exchange = (exhalation d/t loss of elasticity)

  1. PaO2 LOW
  2. PAO2 NORM/LOW
  3. PCO2 HIGH

= OBSTRUCTIVE (COPD) (air flow)

26
Q

FIBROSIS impact on gas exchange

A

↓COMPLIANCE + ↑DISTANCE (inspiration)

  1. PaO2 LOW
  2. PCO2 HIGH

= RESTRICTIVE (lung expansion)

27
Q

ASTHMA impact on gas exchange

A

↑resistance = ↓ventilation (bronchioconstriction)
1. PO2 LOW

= OBSTRUCTIVE (obstruct air flow)

28
Q

PULM OEDEMA impact on gas exchange

A

↑distance ↑fluid pull hypertension = poor diffusion
1. PaO2 LOW

= RESTRICTIVE (lung expansioon)

29
Q

LFT

A

spirometry
static = exhaled vol only
dynamic = time taken to exhale certain volume measured

> FEV1 (4L) / FVC (5L) = 80%

30
Q

OBSTRUCTIVE DISEASE LFTs

A

↓FEV1 = ↑time
↓FVC = ↓air = ↓vol
>80%

  • ~↑FRC d/t retention
  • FEV1 greatly affected
31
Q

RESTRICTIVE DISEASE LFTs

A

↓FEV1 = ↓air expired
↓FVC
NORMAL RATIO

A1. ME2521 RESP (13 decks)

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