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Z YEAR 1 BRS cardiology > Ventilation and gas exchange > Flashcards

Ventilation and gas exchange Flashcards

1
Q

What is minute ventilation?

A

The volume of air expired in one minute or per minute

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2
Q

What is respiratory rate?

A

The frequency of breathing per minute

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3
Q

What is alveolar ventilation?

A

The volume of air reaching the respiratory tone per minute

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4
Q

What is respiration?

A

The process of generating ATP either with an excess of oxygen (aerobic) and a shortfall (anaerobic)

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5
Q

What is anatomical dead space?

A

The capacity of the airways incapable of undertaking gas exchange

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6
Q

What is alveolar dead space?

A

Capacity of the airways that should be able to undertake gas exchange but cannot (e.g. hypoperfused alveoli)

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7
Q

What is physiological dead space?

A

Equivalent to the sum of alveolar and anatomical dead space

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8
Q

What is hypoventilation?

A

Deficient ventilation of the lungs; unable to meet metabolic demand (increase PO2 - acidosis)

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9
Q

What is hyperventilation?

A

Excessive ventilation of the lungs atop of metabolic demands (results in reduced PCO2 - alkalosis)

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10
Q

What is hyperponea?

A

Increased depth of breathing (to meet metabolic demand)

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11
Q

What is hypopnea?

A

Decreased depth of breathing (inadequate to meet metabolic demand)

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12
Q

What is apnoea?

A

Cessation of breathing (no air movement)

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13
Q

What is dyspnoea?

A

Difficulty in breathing

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14
Q

What is bradypnoea?

A

Abnormally slow breathing rate

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15
Q

What is tachypnoea?

A

Abnormally fast breathing rate

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16
Q

What is orthopnoea?

A

Positional difficulty in breathing (when lying down)

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17
Q

How do you calculate minute ventilation? (L/min)

A 
-gas entering and leaving the lungs 
tidal volume (L) x breathing frequency (breaths/min)
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18
Q

How do you calculate alveolar ventilation? (L/min)

A 
-gas entering and leaving the alveoli 
tidal volume (L) - dead space (L)
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19
Q

What factors affect lung volumes and capacities?

A
  1. Body size (height, shape)
  2. Sex (male, female)
  3. Disease (pulmonary/neurological)
  4. Age (chronological, physical)
  5. Fitness (innate, training)
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20
Q

What is the conducting zone in dead space?

A
  • 16 generations
  • No gas exchange
  • Typically 150 mL in adults at FRC
  • Equivalent to anatomicaldead space
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21
Q

What is the respiraotey zone in dead space?

A
  • 7 generations
  • Gas exchange
  • Typically 350 mL in adults
  • Air reaching here is equivalent to alveolar ventilation
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22
Q

What is non-perfused parenchyma?

A
  • Alveoli without a blood supply
  • No gas exchange
  • Typically 0 mL in adults
  • Called alveolardead space
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23
Q

How does the chest wall and lungs act?

A

The chest wall has a tendency to spring outwards, and the lung has a tendency to recoil inwards

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24
Q

What happens at FRC?

A

These forces are in equilibrium at end-tidal expiration (functional residual capacity; FRC), which is the ‘neutral’ position of the intact chest.

25
Q

What are the results in inspiration?

A

Inspiratory muscle effort + chest refill > lung recoil

26
Q

What are the results in expiration?

A

Chest recoil < lung recoil + expiratory muscle efforts

27
Q

What are the lungs surrounded by?

A

by a visceral pleural membrane

28
Q

What is the inner surface of the chest wall covered by?

A

a parietal pleural membrane

29
Q

Whats in the plural cavity?

A
  • The pleural cavity (the gap between pleural membranes) is a fixed volume and contains protein-rich pleural fluid
  • The chest wall and lungs have their own physical properties that in combination dictate the position, characteristics and behaviour of the intact chest wall
30
Q

What is a heamo-thorax?

A

Intrapleural bleeding

31
Q

What is a pneumothorax?

A

Perforated chest wall (could also be caused by a punctured lung)

32
Q

What drives flow?

A

Pressure gradients

-Normal breathing is ‘negative pressure breathing’

33
Q

What are negative and positive transmural pressures?

A

-Transmural pressures
(Pinside – Poutside)
-A negative transrespiratory pressure will lead to inspiration
-A positive transmural pressure leads to expiration

34
Q

What are shorthands?

A 
Patm = atmospheric pressure
Ppl = intrapleural pressure
Palv = alveolar pressure
PTT = Transthoracic pressure
PTP = Transpulmonary pressure
PRS = Transrespiratory System pressure
35
Q

What is the inspiratory muscle forces?

A
  1. The effect of the diaphragm is like a syringe
    - A pulling force in one direction
  2. The effect of the other respiratory muscles is like a bucket handle
    - An upwards and outwards swinging force
36
Q

What is dalton law?

A

Pressure of a gas mixture is equal to the sum (Σ) of the partial pressures (P) of gases in that mixture

37
Q

What is fick law?

A

Molecules diffuse from regions of high concentration to low concentration at a rate proportional to the concentration gradient (P1-P2), the exchange surface area (A) and the diffusion capacity (D) of the gas, and inversely proportional to the thickness of the exchange surface (T)

38
Q

What is Henry law?

A

At a constant temperature, the amount of a given gas that dissolves in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid

39
Q

What is boyle law?

A

At a constant temperature, the volume of a gas is inversely proportional to the pressure of that gas

40
Q

What is Charles law?

A

At a constant pressure, the volume of a gas is proportional to the temperature of that gas

41
Q

What happens as air passes down respiratory tract?

A

WARMED, HUMIDIFIED, SLOWED and MIXED as air passes down the respiratory tree

42
Q

What is total O2 delivery at rest?

A

16mL-min-1

43
Q

What is resting VO2?

A

Resting V̇O2 is approx. 250 mL·min-1 so obviously relying on dissolved oxygen alone is not conducive with life.

44
Q

What do haemoglobin monomers consist of?

A

Haemoglobin monomers consist of a ferrous iron ion (Fe2+; haem- ) at the centre of a tetrapyyrole porphyrin ring connected to a protein chain (-globin); covalently bonded at the proximal histamine residue

45
Q

What type of proteins is Hb?

A

Allosteric

46
Q

What is cooperatively?

A

As one O2 joins to haemoglobin becomes easier for other O2 to join
(from tense low affinity to relaxed high affinity)

47
Q

What happens with foetal haemoglobin?

A

Greater affinity than adult HbA to ‘extract’ oxygen from mothers blood in placenta

48
Q

What happens for myoglobin?

A

Much much greater affinity than adult HbA to ‘extract’ oxygen from circulating blood and store it.

49
Q

How is O2 transported?

A

O2 transported in solution (~2%) or bound to Hb (~98%)

50
Q

How is CO2 transported?

A

CO2 transported in solution, as bicarbonate (HCO3-) and as carbamino compounds (e.g. HbCO2)

51
Q

What shape is Oxygen dissociate curve?

A

sigmoid shaped

52
Q

What shape is carbon dioxide dissociated curve?

A

is almost linear

53
Q

What causes downward shift?

A

anaemia

54
Q

What causes Left shift?

A
  1. Decrease temp
  2. Alkalosis
  3. Hypocapnia
  4. Decrease 2,3 DPG
    ↑pH, ↓PCO2, ↓temp and ↓2,3-DPG
    (= Increased affinity as O2 binds at a lower pO2)
55
Q

What causes right shift?

A
  1. Increased temperature
  2. Acidosis
  3. Hypercapnia
  4. Higher 2,3 DPG
    ↓pH, ↑PCO2, ↑temp and ↑2,3-DPG
    (Bohr effect)
56
Q

What causes upward shift?

A

polycythaemia

57
Q

What is the affinity of myoglobin?

A

VVVV greater affinity than adult haemoglobin to extract oxygen from circulating blood and store it

58
Q

Describe the oxygen dissociation curve

A
  • When the PO2 is low is when O2 is off-loaded and when Hb has a lower affinity of the O2
  • But once the first O2 binds then the others bind easier
  • When the PO2 is high is when O2 is taken up by Hb

Z YEAR 1 BRS cardiology (10 decks)

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