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Body Systems > Week 10 - Anatomy & Mechanics Of Breathing > Flashcards

Week 10 - Anatomy & Mechanics Of Breathing Flashcards

1
Q

Describe the anatomy of the lungs

A
  • located in thorax
  • extend from neck to diaphragm
  • has 3 surfaces
    Diaphragmatic surface (base) - sits on diaphragm
    Costal surface - lies adjacent to ribs
    Mediastinal surface - faces the mediastinum (inwards)
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2
Q

Describe the anatomy of the right lung

A
  • wider and shorter than left lung
  • has three lobes (superior, middle, inferior)
  • has 2 fissures (oblique, horizontal)
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3
Q

Describe the anatomy of the left lung

A
  • narrower and longer than right lung
  • two lobes (superior + inferior)
  • one fissure (oblique)
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4
Q

What is the lung hilum?

A
  • located on mediastinal surface
  • area where pulmonary vessels, bronchi, bronchial vessels, lymphatics and nerves enter / leave the lung
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5
Q

What are some physical properties of the lungs?

A

Compliance (distensibility)
- the ability of the lungs to expand
- affected by :
- connective tissue structures of lungs
- level of surfactant
- mobility of the thoracic cage

Elasticity
- elastic tissue allows lung expansion during inspiration + recoil during expiration

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6
Q

What is the difference between the visceral and parietal pleura?

A
  • visceral pleura adheres directly to the lung
  • parietal pleura attaches to the thoracic wall and diaphragm
  • pleural cavity = potential space between parietal and visceral layers - contains thin layer of serous fluid
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7
Q

What are the functions of the pleura?

A
  • reduce friction during breathing
  • creates a pressure gradient which assists in ventilation
  • compartmentalises lungs - reduces infection spread
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8
Q

What 3 elements make up the bony thorax?

A
  • sternum
  • ribs (12 pairs)
  • thoracic vertebrae (12)
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9
Q

What 3 elements make up the sternum?

A
  • manubrium
  • body
  • xiphisternum
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10
Q

What are the 3 types of intercostal muscle?

A
  • external intercostal muscle
  • internal intercostal muscle
  • innermost intercostal muscle

(IM’s span the spaces between ribs - intercostal spaces)

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11
Q

What is the difference in fibre direction between external and internal intercostals?

A

Externals - fibres run downwards and forwards
Internals - fibres run downwards and backwards

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12
Q

Describe some features of the diaphragm

A
  • separates thorax from abdomen
  • Innervated by phrenic nerve
  • fibrous pericardium fused to central tendon
  • openings for inferior vena cava, oesophagus + aorta
  • attatched to xiphisternum, costal margin, 11th + 12th ribs, and lumbar vertebrae
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13
Q

What is the difference between inspiration and expiration?

A
  • Inspiration = movement of air into lungs, caused by intrapulmonary pressure being lower than atmospheric pressure
  • expiration = movement of air out of lungs, caused by intrapulmonary pressure being higher than atmospheric pressure
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14
Q

how can thoracic volume be changed?

A

Altering:
- vertical diameter
- anterior posterior (AP) diameter
- transverse diameter

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15
Q

How do you alter vertical diameter of lungs?

A
  • contraction of diaphragm increases vertical diameter
  • relaxation of diaphragm decreases vertical diameter
  • diaphragm sort of like an elastic band - when contracted, goes flat and tight - when relaxed, goes loose and curves upwards
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16
Q

How do you alter AP + transverse diameters?

A
  • elevate ribs to increase AP + transverse diameters
  • lower ribs to decrease AP + transverse diameters
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17
Q

What are the muscles of quiet inspiration?

A
  • external intercostals
  • diaphragm
18
Q

What are the muscles of quiet expiration?

A

Passive process - diaphragm and intercostal muscles relax

19
Q

What are the muscles involved in forced inspiration?

A
  • pectoralis (major + minor)
  • sternocleidomastoid
  • serratus anterior
  • scalenes
20
Q

What are the muscles involved in forced expiration?

A
  • inner intercostal
  • rectus abdominis
  • external oblique
  • transversus abdominis
  • internal oblique
21
Q

What is respiration?

A
  • exchange of gases (O2 & CO2) between atmosphere, blood, and cells
22
Q

What are the 3 steps of respiration?

A
  • pulmonary ventilation - inspiration and expiration of air between atm and lungs
  • external (pulmonary) respiration - exchange of gases between alveoli and blood in pulmonary capillaries
  • internal (tissue) respiration - exchange of gases between blood & tissue cells - cells use oxygen for respiration and generate CO2
23
Q

What is Boyle’s Law?

A

When the temperature of a gas is constant, the pressure of the gas varies inversely with volume

E.g. if volume halves, pressure doubles (if temp is the same)

24
Q

What is intraplueral pressure?

A
  • pressure within pleural cavity
  • created by elastic recoil of lungs
25
Q

what is lung (pulmonary) compliance?

A

The ease with which the lungs can be expanded
- depends on 3 factors:
- elasticity of lung tissue - connective tissue structure
- mobility of chest wall
- surface tension

26
Q

What is elasticity of lung tissue?

A
  • measure of elastic recoil
  • measure of lung volume changes resulting from a given pressure change
  • calculated by equation
    Compliance = dV / dP
    ( dV = difference in volume, dP = difference in pressure)
    Units = litres/cmH2O)
27
Q

How does surface tension affect lung compliance?

A
  • the greater the surface tension, the lower the compliance (makes inspiration more difficult)
28
Q

How does pulmonary surfactant affect surface tension?

A
  • greatly reduces surface tension, which in turn increases compliance
  • equalises pressure differences between small + large alveoli
29
Q

What is neonatal respiratory distress syndrome?

A
  • lack of surfactant secretion in premature babies
  • causes reduced compliance, cause alveoli to collapse upon exhalation
  • 50% die without rapid treatment
30
Q

How is airway resistance measured?

A
  • forced vital capacity (FVC) + forced expiratory volume in 1 second (FEV1)
  • FVC = forcibly breathing out vital capacity
  • FEV1 = the volume of air expired in 1 second
31
Q

What is the function of a spirometer?

A

To measure lung volumes and capacities
E.g. tidal volume, vital capacity, etc

32
Q

What is tidal volume? (TV)

A
  • volume of air inhaled or exhaled in one quiet breath
  • males = 500mls, female = 500mls
33
Q

What is expiratory reserve volume? (ERV)

A
  • the amount of air the can be forcibly exhaled after a normal tidal volume exhalation
  • males = 1000mls, female = 700mls
34
Q

What is inspiratory reserve volume? (IRV)

A
  • the amount of air that can be forcibly inhaled after a normal tidal volume inhalation
  • males = 3300mls, females = 1900 mls
35
Q

What is residual volume? (RV)

A
  • air remaining in lungs after maximum expiration
  • males = 1200mls, females = 1100mls
36
Q

What is vital capacity? (VC)

A
  • the maximum amount of air that can be expired after a maximum inspiratory effort
    VC = TV + IRV + ERV
    Males = ~4800ml, female = ~4200ml
37
Q

What is inspiratory capacity (IC)

A
  • the maximum amount of air that can be inspired after a normal expiration
  • IC = TV + IRV
38
Q

What is functional residual capacity? (FRC)

A
  • the volume of air remaining in the lungs after a normal tidal expiration
  • FRC = RV + ERV
39
Q

What is the total lung capacity? (TLC)

A
  • the maximum amount of air contained in the lungs after a maximum inspiratory effort
  • TLC = TV + IRV + ERV + RV
  • males = 6000ml, females = 4200ml
40
Q

What is the difference between pulmonary and alveolar ventilation?

A
  • pulmonary volume includes all air inhaled - however, for every 500ml tidal volume, 150ml doesn’t reach alveolar exchange surfaces
  • due to air in ‘dead space’ - air that doesn’t participate in gas exchange
41
Q

How is alveolar ventilation calculated?

A

Respiratory rate x (TV - anatomical dead space)

E.g. 12 x (500 - 150) = 4.2 litres min-1

Body Systems (11 decks)

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