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Physiology And Pharmacology Of Systems > Introduction to the respiratory system and lung mechanics > Flashcards

Introduction to the respiratory system and lung mechanics Flashcards

1
Q

Definition of internal respiration

A

Exchange of cases between blood, interstitial fluid and cells

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2
Q

Definition of external respiration

A

Exchange of gases (O2, CO2) between blood and the external environment

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3
Q

Definition of pulmonary ventilation

A

Physical movement of air into and out of the lungs.

Movement of air needs pressure gradient to be generated along the airways

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4
Q

Definition of functional residual capacity

A

Volume of lung at end of a normal expiration

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5
Q

Definition of transmural pressure

A

Pressure differences between the inside compartment minus the outside compartment

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6
Q

Definition of respiratory cycle

A

Single cycle of inhalation and exhalation

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7
Q

Definition of tidal volume

A

Amount of air moved in 1 cycle (500ml)

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8
Q

Definition of dead space

A

Airway volume with no gas exchange

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9
Q

Definition of dyspnoea

A

Breathlessness

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10
Q

Definition of elastic resistance

A

Resistance to stretch of lung tissues and air liquid interface lining alveoli

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11
Q

Definition of airway resistance

A

Resistance due to friction between layers of flowing air and between the air and airway walls

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12
Q

Definition of compliance

A

∆V/∆P, the measure of elastic resistance (stiffness)

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13
Q

What is the difference between external and internal respiration

A

Internal
Exchange of gases between blood, interstitium and cells

External
Exchange of gases between blood and lungs

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14
Q

Describe step 1 of inspiration

-muscle contraction (obligate and accessory)

A

Inspiratory muscles contract => expands cage

Obligate

  • ext intercostals
  • diaphragm
  • scalenes

Accessory
-sternocleidomastoid

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15
Q

Describe step 2 of inspiration

-how does cage expansion affect the pleural cavity

A

Cage expands => pulls on the pleural cavity => pleural cavity pressure gets more -ve => lungs expand

PC starts -ve due to natural cage recoil out and lung recoil in

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16
Q

Describe step 3 of inspiration

-how does the change in Ppl affect the Pl

A

Pl gets more +ve => holds lungs open => Pa becomes more -ve

Pl = -Pa – Ppl
Pl starts +ve due to both recoils in equilibrium => lungs held open

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17
Q

Describe step 4 of inspiration

-how does the change in Pa affect the movement of gas

A

More +ve Pl => more -ve Pa

As Pa is more negative than Pb => bulk air flow into lung

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18
Q

Describe step 1 of expiration

-muscle contraction (obligate and accessory)

A

Expiratory muscles contract => shrinks cage

Obligate

  • Int intercostals
  • Passive process

Accessory

  • RA, EO, IO, TA
  • Chest wall, limb girdle muscles
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19
Q

Describe step 2 of expiration

  • pleural cavity
  • what can happen in forced expiration
A

PC becomes more +ve => lungs recoil

PC can become +ve if expiration is forced

20
Q

Describe step 3 of expiration

  • how does the change in Ppl affect the Pl
  • what happens in end expiration
A

Pl pressure becomes more -ve => lungs recoil => Pa increases

At the end of expiration, Pl is +ve to keep the lungs open

21
Q

Describe step 4 of expiration

-how does the change in Pa affect bulk air flow

A

Pa is more +ve than Pb => bulk air flow out of lungs

22
Q

What happens in a pneumothorax

A

Chest wall punctured => Ppl = Pb

Lung recoils in, cage recoils out

23
Q

What is the respiratory cycle?

What is the typical tidal volume

A

Single cycle of inhalation and exhalation

Tidal volume, amount of air moved in 1 cycle = 500ml

24
Q

What is the tidal volume at rest for a typical person

A

500ml

25
Q

What is the vital capacity for a typical person

A

5500ml

26
Q

What is the inspiratory reserve volume for a typical person

A

3300ml

27
Q

What is the expiratory reserve volume for a typical person

A

1700ml

28
Q

What is the inspiratory capacity for a typical person

A

3800ml

29
Q

What is the total lung capacity in a typical person

A

7300ml

30
Q

What is the functional residual capacity in a typical person

A

3500ml

31
Q

What is the residual volume for a typical person

A

1800ml

32
Q

What is dead space (Vd)

A

Airway volume with no gas exchange

33
Q

What is anatomical dead space

What volume of the lung makes up anatomical Vd

A

All except alveoli and respiratory bronchioles

150ml

34
Q

What is physiological dead space
How much physiological dead space is normally present in a healthy individual
How much physiological dead space is present in others?

A

Anatomical plus areas with dysfunctional gas exchange
Normally in healthy people, PVd=AVd

In others PVd=AVd + AlvVd

35
Q

What volume does the alveoli take up in the lung is a typical person

A

3000ml

36
Q

What volume of blood is present in the pulmonary capillary beds

A

70ml

37
Q

What is the rate of total ventilation in a typical person

How would you calculate this value

A

7500ml/min

7500 = 15 x 500

38
Q

What is the typical frequency of ventilation

A

15/mins

39
Q

What is the rate alveolar ventilation

How would you calculate this value

A

5250ml/min

5250 = 7500 - (15 x 150)

40
Q

What is the rate of pulmonary blood flow

What is the rate of alveolar ventilation

A 
PBF = 5000ml/min
AV = 5250ml/min
41
Q

What are the sources of resistance in breathing and what equations are they determined by

If R increases, what can happen?

Why is high resistant flow dangerous in asthma

A

Elastic resistance of lung

  • Inverse of compliance = ∆V/∆Pl
  • If compliance low => R is high

Airway resistance

  • R = Pa-Pb/F
  • Determined by F = r4 , R = 1/r4, R = 8VL/πr4
  • Increased flow, sharp bends (decreased r) => turbulent flow => increased R and noise

Can lead to dysnpoea

If airway r too small => can’t generate noise => ominous silent wheeze

42
Q

Where are the main sites of airway resistance in the lungs

A

Nose, larynx, pharynx
3rd gen bronchi
More distal bronchi have high R, but net R is low due to parallel flow

43
Q

What factors can affect the airway in airway resistance

SM tone

  • Bronchodilation
  • Bronchoconstriction

Inflammation

A 
SM tone
Bronchodilation
-CO2
-NANC (VIP NO)
-B2 agonists

Bronchoconstriction

  • Histamine, prostaglandins
  • NANC (SP, neurokinins)
  • Ach M3 due to irritants

Inflammation
-gland hypertrophy => mucus prod

44
Q

What factors can affect the pressure across the airway wall in airway resistance

A

Normally, Pl = -ve to keep lungs open

However in forceful expiration, Pl can become +ve => dynamic compression of gen 3-4 bronchi

45
Q

What are the effects off effort on expiratory flow

A

Dynamic compression occurs in forceful expiration
-Effort independent

Occurs in everyone, more likely in those with higher airway resistance

Physiology And Pharmacology Of Systems (22 decks)

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