Intro to Pulmonary Flashcards

1
Q

Structure of the lungs

A

Right: 3 lobes

Left: 2 lobes

Both have 10 segments, and middle right lobe has corresponding 4+5 segment on left upper lobe

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2
Q

Pores of Kohn

A

Fenestrations between alveoli

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3
Q

Channels of Lambert

A

Connection between small bronchioles and alveoli

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4
Q

Channels of Martin

A

Between bronchioles

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5
Q

How do alveoli form during development?

A

Septation

Complete by age 8, then grow

Retinoic acid can induce septation, but not much use in older people with emphysema because septation finished

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6
Q

What is the resistance in the pulmonary blood vessels?

A

Very low resistance in pulmonary blood vessels (1/6 of aorta) in order to get lower pressure in lungs (the lungs can’t stand the high pressure that the body can!)

Also can lower resistance by recruiting more capillaries and putting them in parallel during exercise

P = RQ

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7
Q

Alveolar-capillary membrane

A

Air of alveoli –> alveoli epithelium –> basement membranes of alveoli and capillary are FUSED! –> capillary endothelium –> lumen of capillary

(Normally, when you’re not at alveolar-capillary membrane, have two separate basement membranes with space in between)

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8
Q

Type I alveolar epithelial cells

A

Squamous

Broad, flat, 0.1um thick

93% of alveolar lining membrane

Cannot divide

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9
Q

Type II alveolar epithelial cells

A

Cuboidal

Have microvilli

Located at septal junctions

Secrete surfactant

Can transform into Type 1 cells (responsible for growth and repair)

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10
Q

Type III alveolar brush cells

A

Cone shaped cells

Dense microvilli

Rare, found in central part of acinus

Unknown function, maybe chemoreceptor

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11
Q

Alveolar macrophages

A

Arrive via blood as monocytes

Lie within alveolar lining fluid

Have destructive enzymes to combat infection and scavenge foreign bodies (dust)

Function is impaired by tobacco smoke

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12
Q

Clara cells

A

Non-ciliated

Reside in bronchioles

Contribute to surfactant production

Contain CYP 450 isoenzymes

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13
Q

Mast cells

A

Located in sub-pleural area

Secrete heparin, histamine, other mediators

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14
Q

Interstitial cells

A

Fibroblasts (produce collagen and elastin), myocytes, dendritic cells, neurons (in walls of airways)

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15
Q

Non-respiratory functions of the respiratory system

A

Filtration of particles

Filtration and dissolution of thrombi (microemboli)

Anti-protease

Hormonal (angiotensin I to angiotensin II)

Lipid metabolism (make surfactant)

Acid/base regulation

Immunological protection

Phonation (talking)

Neurotransmitter removal, paracrine removal, histamine release, antioxidase production

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16
Q

Airway zones and generations

A

Conduction, transitional, respiratory zones

Trachea

Main (primary) bronchi (R and L)

Lobar (secondary) bronchi

Segmental (tertiary) bronchi

Bronchioles

Terminal bronchioles

Respiratory bronchioles (alveoli bud off)

Alveolar ducts

Alveolar sacs

17
Q

What happens when you get to generation 16 (end of conducting zone?

A

Bulk flow drives air until generation 16, then cross-sectional area gets huge and diffusion is now mechanism of ventilation

18
Q

Function of conducting zone

A

Humidify, warm, clean, conduct air to respiratory zone

Cilia (until 12th generation) beat to propel mucous viscous layer that captured dust upward –> irritant reflexes in upper airway trigger cough

19
Q

Which chemoreceptors are used by the lungs?

A

Peripheral chemoreceptors in carotid body (NOT aortic arch)

Glossopharyngeal nerve (CN IX) is nerve from carotid bodies, and goes to brainstem

At similar level as CN IX comes into brain, have central chemoreceptors

Sense blood draining lungs

20
Q

What causes negative intrapleural pressure?

A

Opposing elastic recoil properties of lung and chest wall

Lung wants to collapse and chest wall wants to expand

Note: at 55% VC, chest wall at equilibruim, so past this, chest wall actually wants to collapse too

21
Q

Functional residual capacity (FRC)

A

Lung volume at rest/equilibrium when recoil forces of lung and chest wall are equal and opposite

FRC increases if lungs decrease recoil

FRC decreases if lungs increase recoil

22
Q

Inspiration

A

1) Respiratory muscle force expands ribcage
2) Pleural space is virtual, so lung expands
3) Lungs increase elastic recoil
4) Pleural pressure becomes more negative
5) Volume increases so alveolar pressure falls
6) Air flows into lung

23
Q

Expiration

A

PASSIVE PROCESS

1) Respiratory muscles relax
2) Lung elastic recoil pulls ribcage inward
3) Pleural pressure becomes less negative
4) Volume decreases so alveolar pressure rises
5) Air flows out of lung

24
Q

Compliance vs. Elastance

A

Compliance: distensibility; how accommodating; change in voulme per unit distending pressure; V/P

Elastance: stiffness; P/V

Opposites!!

25
Q

Surfactant

A

Reduces surface tension in alveoli by breaking up the attractive forces of water lining alveoli

Lipoprotein material (dipalmitoyl phosphatidylcholine; dipalmitol lecithin)

Synthesized in Type II alveolar cells

26
Q

Advantages of surfactant

A

1) Reduces surface tension/lung recoil and increases compliance
2) Counters tendency for smaller alveoli to empy into larger ones
3) Prevents trasudation of fluid into alveoli from pulmonary capillaries

27
Q

Lung compliance

A

Lungs are not compliant at first because have to get past point where you’ve broken up intermolecular forces and they’re strongest when alveoli are small and molecules are densely packed

Low compliance on the curve is where surface area is increasing faster than surfactant can be added to liquid layer so hard to break up forces.

After enough surfactant added, lung is more compliant the rest of the way up

28
Q

What does gravity do to regional ventilation?

A

Top/apex of lung: pleural pressure LESS, -5; alveoli larger so don’t expand as much because don’t have as far to go

Bottom/base of lung: pleural pressure MORE, -1; alveoli smaller expand more (on steep part of compliance curve too)

More ventilation goes to bottom of the lung