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+ CAPS 301: Respiratory, Renal, GI, Endocrinology, Reproduction > Respiration: Structure and Function > Flashcards

Respiration: Structure and Function Flashcards

1
Q

What are the steps of external respiration?

A
  1. ventilation between atmosphere and alveoli in lungs
    - O2 enters lungs
    - CO2 exits lungs
  2. gas exchange between air in alveoli and blood in pulmonary capillaries
    - O2 enters blood
    - CO2 exits blood, enters alveoli
  3. blood transports O2 and CO2 between lungs and tissues
  4. gas exchange between blood in systemic capillaries and tissue cells
    - O2 enters tissue cells
    - CO2 exits tissue cells, enters blood
    (tissue cells use O2 to make CO2, H2O, and ATP)
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2
Q

What are the two types of transport/movement of air, blood, and gases?

A
  • bulk transport (long distance)

- diffusion (short distance)

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3
Q

What processes use bulk flow? (2)

A
  • ventilation/breathing

- blood gas transport

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4
Q

What is ventilation/breathing driven by?

A

air pressure gradient

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5
Q

What is blood gas transport driven by?

A

blood pressure gradient – pumped by heart

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6
Q

What process uses diffusion?

A

gas exchange

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7
Q

What is gas exchange driven by?

A

partial pressure gradient of individual gases

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8
Q

What structures do the upper airways consist of?

A
  • nasal passages
  • mouth
  • pharynx
  • larynx (throat)
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9
Q

What structures does the tracheobronchial tree consist of?

A
  • trachea (windpipe)
  • bronchus
  • bronchioles
  • terminal bronchiole
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10
Q

What structures does the chest wall consist of, and associate with?

A
  • ribs + associated muscles
  • dorsal vertebrae
  • diaphragm
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11
Q

What is the diaphragm?

A

key muscle of inspiration, separates abdominal and thoracic cavities

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12
Q

Why does UAW size need to be regulated?

A

negative pressure is generated when drawing air in (breathing), which can cause the UAW to collapse

UAW size needs to be regulated to be kept open for air to be able to continue to be drawn in through them

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13
Q

What are the 3 structures that close during swallowing, and what do they do?

A
  • uvula: inhibits nasal regurgitation
  • epiglottis: inhibits entrance to trachea → directs food into esophagus instead
  • vocal cords: (across laryngeal opening) allows phonation, and prevents aspiration of food into lungs
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14
Q

What controls upper airway patency (keeping it open)?

A
  • 20+ muscles control the position of tissues

- dilator muscles keep airway open during inspiration (controlled by CNS)

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15
Q

What happens during obstructive sleep apnea (OSA)?

A

decrease in genioglossus dilator muscle activity leads to airway obstruction – tongue falls back, which stops airflow to lower airways

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16
Q

What does UAW mucosal lining do?

A

provides heat and humidity to the air you breathe in

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17
Q

Air Conditioning by UAW Mucosal Lining

A

see notes

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18
Q

Where is the isothermal boundary?

A

bifurcation of trachea into bronchi

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19
Q

What are the 2 functional zones of the tracheobronchial tree?

A
  • conducting zone

- respiratory zone

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20
Q

What does the conducting zone do?

A

DRAWS AIR IN

  • bulk transport – requires energy
  • muscle activity alters thoracic volume → changes thoracic pressure relative to atmosphere → drives movement of air (airflow)
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21
Q

What structures of the TBT does the conducting zone consist of?

A

(first half)

trachea
main bronchus
bronchus
bronchiole
terminal bronchiole
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22
Q

What structures of the TBT does the conducting zone consist of?

A

(last half)

respiratory bronchiole
alveolar duct
alveolar sac

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23
Q

What does the respiratory zone do?

A

GAS EXCHANGE

  • diffusion – no energy required
  • individual gases diffuse across alveolar-capillary membrane, driven by partial pressure differences of individual gases
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24
Q

What are the two types of cartilage?

A

trachea cartilage: C-shaped, closed into ring by trachealis muscle

bronchi cartilage: plates interspersed in smooth muscle ring

25
Q

What does cartilage do for airways?

A

airways with cartilage resist collapse

26
Q

What are the bronchioles composed of?

A

mostly smooth muscle with NO CARTILAGE

27
Q

What are the terminal bronchioles?

A

last generation of bronchioles with only conducting function

28
Q

What do respiratory bronchioles do?

A

allow gas exchange across their alveoli

29
Q

What are alveolar ducts?

A

walls covered with alveoli that terminate in alveolar sacs

30
Q

What are 2 other names for alveoli?

A
  • acini

- respiratory zone

31
Q

What are the 3 types of alveolar cells that make up the alveolar epithelium?

A
  • type I: pneumocyte
  • type II: granular pneumocyte / septal cell
  • type III: alveolar macrophage / dust cell
32
Q

What are type I pneumocytes? Describe their structure.

A

cells that line alveoli – flat ‘squamous epithelium’

  • mostly thin
  • thick centre – nucleus
  • covers 95% of alveolar surface area ≈ 80-200 m2
  • 0.1-0.3 microns in width
33
Q

What are type II granular pneumocytes (septal cells)?

A

cuboidal cells that store and produce surfactant

  • lamellar inclusion bodies (typically only seen in lungs and few other structures) stores pulmonary surfactant
34
Q

What is pulmonary surfactant?

A

mixture of lipids and proteins that reduces alveolar surface tension

  • SA reducing agent is diphosphatidylcholine (DPPC)
35
Q

Why is pulmonary surfactant needed?

A

air coming in is moistened, heated, and saturated in water vapour – means that airways (including alveoli) are coated with water, which causes surface tension and may cause lung to collapse

pulmonary surfactant reduces alveolar surface tension to prevent collapse

36
Q

What are type III alveolar macrophages (dust cells)?

A

migratory and phagocytic cells located on extracellular lining of alveolar surface, that defend against foreign particles

37
Q

What is the 0.5 µm air-blood barrier?

A

barrier separating air and blood – distance O2 and CO2 in air has to travel to reach blood in pulmonary capillary

38
Q

Describe the path of O2 from air in alveolus to blood.

A

O2 from air passes through surfactant epithelium (type II) → alveolar epithelium (type I) → travels 0.5 µm through interstitium to pulmonary capillary endothelium → plasma → RBC

39
Q

What are the 2 functions of the alveolar interstitium?

A
  1. joins and supports structural elements by elaborate collagen and elastin fibre system (matrix)
  • more elastin = more stretchy
  • more collagen = more stiff
  • contributes to mechanical characteristics of lung – ie. its compliance, allowing airways to expand during inspiration, and spring back during exhalation
  1. fluid space in series with lymphatic system, which allows excess fluid drainage into lymphatic system
  • excess fluid (plasma) due to high BP that leaks into interstitium will not enter lungs – drained into lymphatic system instead
  • HOWEVER, sometimes if BP is very high, some fluid associated with plasma can get through and overwhelm lymphatic drainage, and fluid will therefore enter alveoli
40
Q

How does the structure of the airway wall change as we move from trachea to alveoli?

A
  • decreasing epithelial height
  • loss of cartilage, smooth muscle, mucous glands
  • decreasing thickness
41
Q

Structural Changes of Airway Wall – Trachea/Bronchus, Bronchiolus, Alveolus

A

Trachea/Bronchus

  • smooth muscle
  • cartilage
  • mucus/surfactant layer
  • columnar cells with villi – moves mucus and surfactant layer
  • cell types without villi – secrete mucus to top
  • glands – secrete mucus to top

Bronchiolus

  • no cartilage
  • decreased epithelial height

Alveolus

  • no smooth muscle
  • no cartilage
  • alveolar epithelium – made of three types of alveolar cells
42
Q

How are particles > 10 µm in diameter cleared from airway?

A
  • filtered and trapped by nasal hairs

- irritant receptors lining nasal passages initiate sneeze reflex

43
Q

How are particles 2-10 µm in diameter cleared from airway?

A
  • mucociliary clearance (MCC) system lines airways proximal to terminal bronchioles
  • irritant receptors in airway lining initiate cough reflex
44
Q

How are particles < 2 µm in diameter (that reach the alveoli) cleared from airway?

A
  • migrating and phagocytic macrophages engulf foreign particles and degrade them
  • non-degradable particles with sharp profiles (ie. silica dust, asbestos fibres) injure alveolar epithelium and alveolar macrophages → damaged macrophages release toxins → inflammation, scar formation (collagen deposition), and pulmonary fibrosis
45
Q

MCC Transport System

A
  1. mucus blanket produced by submucosal glands or goblet cells
  2. metachronal beat synchronization of cilia associated with epithelium of airway move mucus blanket from terminal bronchiole to mouth
    - move mucus through vocal cords into pharynx
    - move mucus blanket from nose to mouth
  3. cough up mucus + any particles stuck to it
46
Q

What are the two layers of the mucus blanket produced in the MCC transport system?

A

GEL mucus: viscous, sticky

SOL: aqueous perciliary (PCL), low viscosity, facilitates stroke of cilia

47
Q

What does impairment of MCC do?

A

↓ airway clearance and ↑ chest infection

48
Q

What are 4 factors that impair MCC?

A
  • cigarette smoking
  • pathogenic microbes
  • primary ciliary dyskinesia
  • cystic fibrosis
49
Q

How does cigarette smoking impair MCC?

A
  • ↓ ciliary length, number, and motility

- ↑ mucus production

50
Q

How do pathogenic microbes impair MCC?

ie. HIV virus, Pseudomonas aeruginosa, and haemophilus influenza bacterias

A

release substances that paralyze and slow ciliary motion

51
Q

How does primary ciliary dyskinesia impair MCC?

A

primary ciliary dyskinesia: (inherited disease) genetic mutations of cilia’s ultrastructure

↓ ciliary motility

airway particle clearance takes 1 week in PCD vs. 12 hrs in healthy non-smokers

52
Q

How does cystic fibrosis impair MCC?

A

cystic fibrosis: (inherited disease) genetic mutation of CFTR – Cl- ion channel involved in H2O and Na+ transport across epithelial, responsible for maintaining mucus osmolarity

↑ mucus viscosity – reduces clearance in lungs and pancreatic ducts

53
Q

What are club cells (Clara cells)?

A

non-ciliated, dome-shaped cells found mostly in terminal and respiratory bronchioles (corridor of functional transition from conducting to respiratory zone of airways)

54
Q

What do club cells (Clara cells) do?

A

secrete variety of products that provide clues to its potential roles:

  • surfactant-like substance – compliance of lungs
  • defence through phagocytic activity engulfing airborne toxins
  • lung remodeling in response to injury/disease – like basal cells, can act as stem/progenitor cells that multiply and differentiate into different epithelial cell types in response to injury
55
Q

Where in the TBT epithelium are ciliated cells found?

A

everywhere – a little more in respiratory zone

56
Q

Where in the TBT epithelium are goblet cells found?

A

conducting zone

57
Q

Where in the TBT epithelium are Clara cells found?

A

mostly in terminal and respiratory bronchioles (corridor of functional transition from conducting to respiratory zone of airways)

58
Q

Where in the TBT epithelium are basal cells found?

A

everywhere – a little more in conducting zone

+ CAPS 301: Respiratory, Renal, GI, Endocrinology, Reproduction (32 decks)

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