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The Nervous System & Respiratory Diseases > Structure of the Lung and the Mechanics of Breathing (L15-16) > Flashcards

Structure of the Lung and the Mechanics of Breathing (L15-16) Flashcards

1
Q

Which structures make up the conducting zone?

A

Trachea to the terminal bronchioles.

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2
Q

Which structures make up the respiratory zone?

A

Respiratory bronchioles to alveoli.

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3
Q

True or false? The luminal diameter of each bronchus is related to number of alveoli at end of each branch.

A

True.

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4
Q

Which bronchiole?

  • first bronchiole along which alveoli appear
  • lined by cuboidal epithelium and have muscular walls
  • function mainly as conducting tubes and account for minimal gas exchange
A

Respiratory bronchiole.

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5
Q

What type of epithelium make up alveoli?

A

Simple squamous.

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6
Q

Describe a Type I Pneumocyte.

6

A
  • Site of gas exchange
  • Covers 95% of the surface area of the alveolar wall but only accounts for 40% of the epithelial cells
  • Flat cells with broad cytoplasmic flaps which are too thin to have organelles
  • Have a perinuclear zone where the clustered organelles and nucleus synthesize products that diffuse into the flaps
  • A layer of basement membrane fuses the alveolar epithelium to the capillary endothelium
  • Susceptible to injury and have no mitotic potential so cannot regenerate
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7
Q

Describe a Type II Pneumocyte.

3

A
  • A rounded cell that covers about 3% of the alveolar surface but accounts for 60% of the epithelial cells
  • Manufacture and release surfactant which reduces the surface tension stabilizing and maintaining all the alveoli in an open position
  • Type II cells are capable of regeneration and replacement of type I cells after injury
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8
Q

Which cell?

  • The major cellular host defence mechanism in the alveolar space
  • They are the only alveolar clearance mechanism for particulate material that has escaped the tracheobronchial filters
  • To leave the lungs these cells must migrate to the nearest bronchiole and exit via the mucocilary escalator or they may pass into the interstitium and exit via the blood vessels or lymph
A

Alveolar Macrophage.

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9
Q

What is a Respiratory acinus?

What does it include?

A
  • Functional respiratory unit of the lung

- Includes all structures from the respiratory bronchiole to the alveolus

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10
Q

What does the parietal pleura cover?

A

The thoracic wall and superior diaphragm.

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11
Q

What does the visceral pleura cover?

A

The external surface of the lung.

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12
Q

What is Intra-alveolar pressure (Intrapulmonary pressure)?

A

Pressure within the alveoli.

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13
Q

What is Intrapleural Pressure?

A

Pressure in the pleural cavity.

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14
Q

The transpulmonary pressure gradient = what?

A

Difference in pressure between intra-alveolar and intrapleural pressures.

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15
Q

When does Pneumothorax occur?

A

When transpulmonary pressure equilibrates resulting in a collapsed lung.

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16
Q

When does a traumatic Pneumothorax occur?

A

When the chest wall is punctured.

17
Q

What is a spontaneous Pneumothorax caused by?

A

By hole in wall of the lung due to congenital defect in connective tissue in alveolar wall.

18
Q

What is compliance a measure of?

A

The change in lung volume accomplished by a given change in the transpulmonary pressure gradient (the force that stretches the lungs).

19
Q

What is Elasticity?

A

The ability to return to initial size after distension.

20
Q

What is the function of surfactant?

A

Lipid component of surfactant lowers surface tension therefore preventing alveolar collapse at end of expiration.

21
Q

How does surfactant work?

A

Reduces attractive forces of hydrogen bonding by becoming interspersed between H2O molecules.

22
Q

What are the benefits of reducing surface tension?

3

A
  • Increases pulmonary compliance - thus reducing the effort (pressure) needed to inflate the lungs
  • Stabilises the alveoli so they do not collapse
  • Allows the alveoli (and thus the lung) to increase & decrease in size at the same rate
23
Q

What is Newborn Respiratory Distress Syndrome (NRDS)?

A

NRDS = premature babies have deficiency in lung surfactant leading to respiratory complications.

24
Q

What are the symptoms of NRDS?

A
  • NRDS is characterised by rapid breathing, nasal flaring, expiratory grunting, cyanosis around lips and nail beds
  • Infants may also develop severe complications e.g. alveolar rupture, pneumothorax, interstitial emphysema, intracranial haemorrhage, retinopathy, hearing and visual handicaps
25
Q

How can you prevent NRDS?

A
  • Treatment with glucocorticoids before delivery

- Speeds up production of surfactant and lung maturation

26
Q

How can you treat NRDS?

A
  • Oxygen with a small amount of continuous positive airway pressure via endotracheal tube
  • Surfactant replacement therapy: can be animal derived or synthetic
27
Q

Modest changes in airway size, to meet the body’s needs, are achieved through the _____ nervous system.

A

Autonomic.

28
Q

Which disease?

  • Characterised by increased airway resistance
  • It is a group of lung diseases including Chronic Bronchitis, Asthma and Emphysema
  • Sufferers have to work harder to breathe: when R is increased a larger pressure gradient is required to maintain a normal airflow
A

Chronic Obstructive Pulmonary Disease (COPD).

29
Q

Factors influencing movement of gases across the respiratory membrane include:?
(3)

A
  • Partial Pressure Gradients
  • Thickness and Surface Area of the Respiratory Membrane
  • Ventilation-Perfusion Coupling
30
Q

Which 3 diseases cause an increase in the thickness of the barrier separating blood and air?

A
  • Pulmonary Oedema
  • Pulmonary Fibrosis
  • Pneumonia
31
Q

What are the 3 causes of VA/Q&raquo_space; 1?

A
  • Pulmonary Embolism (blood clot)
  • Pulmonary Arteritis
  • Necrosis or Fibrosis of capillary bed
32
Q

What does VA/Q&raquo_space; 1 and VA/Q &laquo_space;1 cause?

A

Arterial Hypoxaemia.

33
Q

What are the 3 causes of VA/Q &laquo_space;1?

A
  • Airway Limitation (asthma, chronic bronchitis)
  • Loss of Elastic tissues (emphysema)
  • Lung collapse
34
Q

Over 90% of surfactant = lipid

Main lipid component (40%)=dipalmitoyl phosphatidylcholine (DPPC)

Remaining 10% of surfactant = Proteins: plasma proteins & surfactant proteins- SP-A, SP-B, SP-C and SP-D

What do SP-A and SP-D do?

What do SP-B and SP-C do?

A

SP-A and SP-D - Confer innate immunity as they have carbohydrate recognition domains -Coat bacteria and viruses and promote phagocytosis by macrophages.

SP-B and SP-C - Hydrophobic membrane proteins that increase the rate that surfactant spreads over the surface of the alveoli.

The Nervous System & Respiratory Diseases (15 decks)

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