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Physiology and Neuroscience Semester 1 > Lung function > Flashcards

Lung function Flashcards

1
Q

What are the normal conditions for air moving into the lung at rest?

A 
PO2= 100±2 mm Hg, PCO2 = 40±2 mm Hg 
Ventilation:      ~6 L/min 
(~12 breaths/min, 500 ml/breath) 
Gas exchange:  ~ 250 ml/min O2 consumed 
~200 ml/min CO2 expired.
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2
Q

When does ventilation increase?

A

During exercise to maintain blood gas homeostasis

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3
Q

What is the function of the nasal cavities and paranasal sinuses in moving air into lungs?

A

Filter, humidify air and detect smells

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4
Q

What is the function of the pharynx in moving air into the lungs?

A

Conducts air to larynx; a chamber shared with the digestive tract

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5
Q

What is the function of the larynx in moving air into the lungs?

A

Protects opening to trachea and contains vocal cords

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6
Q

What is the function of the trachea in moving air into the lungs?

A

Filters air, traps particles in mucus

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7
Q

What is the function of the bronchi in moving air into lungs?

A

Same functions as trachea

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8
Q

What is the lungs function in moving air into the lungs?

A

Responsible for air movement through volume changes during movements of ribs and diaphragm; include airways and alveoli

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9
Q

What is the function of the alveoli in moving air into lungs?

A

Act as sites of gas exchange between air and blood

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10
Q

Briefly describe diaphragm

A

Major inspiratory, dome-shaped skeletal muscle active during more strenuous breathing

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11
Q

Briefly describe Quiet Breathing

A

Inspiration- active , diaphragm contracts downwards pushing abdominal contents outwards
Expiration- Passive, elastic recoil

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12
Q

Briefly describe Strenuous breathing

A

Inspiration- Active, greater contraction of diaphragm and external intercostals
Expiration- Active, abdominal muscles, internal intercostals muscles oppose external intercostals by pushing ribs down and inwards

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13
Q

Describe the pressure and volume changes from inspiration to expiration

A
  • Beginning of inspiration PA=0 (pressure in lung) because no flow.
  • Inspiratory muscles contract (diaphragm contracts)
  • Thorax expands (upper chest wall extracts, lungs pulled outwards, pressure becomes more negative)
  • Pleural pressure becomes more negative.
  • Increase in transpulmonary pressure (difference between lung and pleural pressure, lung negative, air outside positive so air flows into lung)
  • Lungs expand.
  • PA becomes negative.
  • Air flows into alveoli.
  • Beginning of expiration (stop expanding thorax)
  • Muscles stop contracting.
  • Chest wall moves inwards.
  • Ppl & PL return to pre-inspiration values.
  • Lungs recoil (elastic recoil pressure).
  • Air in alveoli compressed.
  • PA becomes greater than atmospheric pressure.
  • Air flows out of lungs.
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14
Q

What are the major functions of the upper airways?

A

Humidify (saturate with water)
Warm (to body temp)
Filter- upper airways to bronchioles lined by pseudostratified (one layer) , ciliated columnar epithelium

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15
Q

What happens to inhaled particles

A

Stick to mucus, mucus moved towards mouth by beating cilia

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16
Q

What is the respiratory tree?

A

Airways that branch to bronchioles until terminating in a group of alveoli

17
Q

What occurs with each division of the respiratory tree?

A

Increase in number, a decrease in diameter and an increase in surface area
With each division lumen becomes smaller, but more tubes are added on

18
Q

What do conducting airways do?

A

Do not participate in gas exchange

Form anatomic dead space

19
Q

What do Respiratory airways do?

A

Bronchioles with alveoli, where gas exchange occurs ( from terminal bronchioles to alveoli)

20
Q

What is a respiratory unit?

A

Gas exchange unit, basic physiological uni of the lung consisting of respiratory bronchioles, alveolar ducts and alveoli

21
Q

How many alveolar sacs are in an adult?

A

300-400 million

22
Q

What shape and diameter are alveoli?

A

Polygonal in shape, roughly 250 micrometers in diameter

23
Q

What cells make up alveoli?

A

Type 1 and type 2 epithelial cells

24
Q

What innervate alveoli?

A

Blood vessels, this is important for gas exchange

25
Q

How many type 1 epithelial cells are there in the alveoli?

A

Occupy 97% of surface area of alveoli. Primary site of gas exchange, most important

26
Q

How many type 2 (septal cells) epithelial cells are there in the alveoli?

A

Occupy 3% surface area. Produce pulmonary surfactant (reduces surface tension, important for elasticity of lung)

27
Q

How are alveoli perfectly designed for gas exchange?

A
  • Large surface area: roughly 100m2
  • Very thin walls (mean 0.5 micrometers- important for gas exchange)
  • Good diffusion characteristics
28
Q

What are the two different blood supply for the lungs?

A

Pulmonary circulation

Bronchial circulation

29
Q

What is pulmonary circulation?

A

Brings deoxygenated blood from heart to lung and oxygenated blood from lung to heart and then rest of body

30
Q

What is bronchial circulation?

A

Part of systemic circulation, brings oxygenated blood to lung parenchyma
Lymphatic system- defense and removal of lymph fluid

31
Q

Describe the structure of an artery

A

Thin walled (much lower pressure and larger diameters that can deal with higher flow), highly compliant, larger diameter, low resistance (compared to systemic circulation).

32
Q

What is the alveolar capillary network?

A

Gas exchange occurs through dense mesh-like network of capillaries and alveoli.

33
Q

How far is diffusion between alveolar sacs and capillary lumen?

A

Small distance- ideal for gas exchange

34
Q

How long does it take for redblood cells to pass through capillaries?

A

Less than 1 second

35
Q

What are the average gas concentration gradients for the pulmonary and systemic capillary?

A 
Gas Concentration gradients:
Pulmonary Capillary 
Alveolar Air Venous Blood 
PO2 100          40 mmHg 
PCO2 40          46 mmHg 
Systemic capillary 
Tissues    Arterial Blood 
PO2 <46    40 mmHg 
PCO2 >46   40mmHg

Physiology and Neuroscience Semester 1 (21 decks)

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