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Bmsc 208 > Respiratory 4 > Flashcards

Respiratory 4 Flashcards

1
Q

What does high compliance mean

A

Easy to inhale
Hard to exhale
Low elastance

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2
Q

What does low compliance mean

A

Hard to inhale
Easy to exhale
High elastance

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3
Q

What is another important determinant of compliance and lung elastic recoil

A

Surface tension at air water interface of the airways

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4
Q

What is surface tension

A

Measure of force acting to pull a liquids molecules together at an air-water interface

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5
Q

What did Von Neergard find

A

Way easier to inflate if their was liquid
Found fluid lining the inner walls of alveoli

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6
Q

What is structure of alveoli

A

Alveoli wall then liquid layer then air inside

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7
Q

What would happen if alveoli only had water lining walls

A

The pull inward would be so strong alveoli would collapse

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8
Q

Where is fluid found in alveoli

A

Lining the inner walls

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9
Q

What happens when intermolecular force pulls the surface molecules downward

A

The molecules that remain at surface develop opposing force, surface tension

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10
Q

What is surfactant

A

Detergent-like molecule secreted by type II alveolar cells
- 90% phospholipids, 10% proteins

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11
Q

What is role of surfactant

A

Reduce surface tension and disrupt intermolecular bonds
- reduce surface tension to ~25 dynes/cm or less

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12
Q

What are the regions of the surfactant molecules and where do they sit

A

Hydrophilic end stays in water and hydrophobic goes into air
- sit between adjacent water molecules so they can’t form bonds

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13
Q

What are 2 things surfactant does

A
  1. Increases compliances (reduces inward pressure)
  2. Ensures alveoli of all size inflate (smaller have greater concentration of surfactant)
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14
Q

What do alveoli of different radius have in common

A

Same surface tension so there’s equal inward pressure and small ones wont empty into large ones

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15
Q

What ensures two alveoli inflate and have adequate surface area for exchange even when one is blocked or smaller alveolus

A

The rapidly expanding one will put a “brake” on expansion by increasing surface tension and elastic recoil
The slowly expanding one will have less diluted surfactant causing no “brake” in expansion

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16
Q

What is infant respiratory distress syndrome

A

Premature: insufficiency of surfactant production and immaturity of lungs
- alveoli collapse
- prevalence decreases with gestational age
- decrease compliance, increase elastance

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17
Q

Prevention of infant respiratory distress

A

Glucocorticoid injection

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18
Q

Treatment of infant respiratory distress syndrome

A
  • artificial surfactant
  • continuous positive airway pressure (CPAP)
  • intubate
19
Q

Where does 90% of airway resistance occur in healthy individual

A

Trachea and bronchi
- is constant
- smallest total cross sectional area

20
Q

What is airway resistance based on

A

Poiseuille’s equation
Resistance increases when length and viscosity increase
Resistance decreases when increase in radius

21
Q

What is air flow determined by

A

Pressure gradient at start vs end
Resistance (length, viscosity, radius)

22
Q

Factors that affect airway resistance

A
  • length of system: constant
  • viscosity of air: constant (humidity or altitude alter)
  • diameter of airways (constant in healthy)
    - upper airways: physical obstruction (mucus, etc.)
    - bronchioles: bronchoconstriction (parasympathetic, histamine), bronchodilation (CO2, epinephrine)
23
Q

What is the site of variable resistance

A

Bronchioles

24
Q

What is common control of bronchoconstriction/dilation (smooth muscle control)

A
  • paracrine control, CO2 being major one
    High levels = dilation (reduce resistance, get rid of CO2)
    Low levels = constriction
25
Q

What does histamine released from mast cells cause

A

Bronchoconstriction
- large amounts released in response to allergic reaction
- stimulated by irritants and prevent from getting to alveoli

26
Q

How to parasympathetic nerves affect bronchiole smooth muscle

A

Constriction
- activate PLC-IP3 pathways via M3 muscarinic receptor

27
Q

What does not innervate bronchiole smooth muscles

A

Sympathetic nerves

28
Q

What is the PLC-IP3 pathway that cause constriction

A

ACh from postganglionic parasympathetic neurons bind to M3 muscarinic receptors activate G protein complex which activates PLC and converts IP3 and cause release of Ca

29
Q

What are 2 characteristics of asthma

A
  1. Chronic inflammation of airways
  2. Periods of bronchoconstriction/bronchospasm
30
Q

What can oppose bronchoconstriction during infrequent and frequent asthma attacks

A

Infrequent- B2 adrenergic agonist (Inhaler)
Frequent- weekly inhaled corticosteroid

31
Q

What is effectiveness of ventilation determined by

A

Total pulmonary ventilation

32
Q

Total pulmonary ventilation

A

Volume of air moved into and out of the lungs each minute (minute ventilation)

33
Q

What is normal ventilation rate and normal tidal volume

A

12-20 breaths/min
500ml

34
Q

Total pulmonary ventilation calculation

A

Total pulmonary ventilation= ventilation rate x tidal volume
Ex) 12 breaths/min x 500ml= 600 ml/min

35
Q

Is total pulmonary ventilation a good indicator of how much fresh air reaches the alveoli

A

No
- air remains within conducting air space (pharynx, larynx, trachea, bronchi, bronchioles) and does not take part in gas exchange (anatomic dead space)
- ~150ml

36
Q

What is the calculation for alveolar ventilation

A

= ventilation rate x (tidal volume- dead space)
Ex) 12 breaths/min x (500 -150 ml) = 4200 ml/min

37
Q

What is alveolar ventilation

A

Total amount of air making it to alveoli and available for gas exchange in 1 minute

38
Q

At end of inspiration what is dead space filled with

A

Fresh air (150ml)

39
Q

If we exhale 500ml and there’s 150ml of fresh air in dead space what leaves the alveoli

A

350ml leaves alveoli

40
Q

At end of expiration what is dead space full of

A

Stale air from alveoli

41
Q

If we inhale 500 ml of fresh air

A

First 150ml of air in alveoli is stale air from alveoli
Only 350ml of fresh air reaches alveoli
- dead space is full with 150ml of fresh air

42
Q

What kind of breathing can increase alveolar ventilation

A

Slow deep breathing

43
Q

What kind of breathing can decrease the amount of fresh air to the alveoli

A

Shallow and rapid

Bmsc 208 (33 decks)

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