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BRS Term 2 > Ventilation and gas exchange (29) > Flashcards

Ventilation and gas exchange (29) Flashcards

1
Q

What is minute ventilation?

A

the volume of air expired in 1 minute/ 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 zone per minute

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4
Q

What is respiration?

A

the process of generating ATP either aerobically or anaerobically

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5
Q

What is anatomical dead space?

A
  • the capacity of airways incapable of undertaking gas exchange (nose/mouth to terminal bronchioles)
  • ‘conducting zone’ (16 generations)
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6
Q

What is alveolar dead space?

A
  • the capacity of the airways that should be able to undertake gas exchange but cannot (e.g. alveoli w/out blood supply)
  • ‘non perfused parenchyma’
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7
Q

What is physiological dead space?

A

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

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9
Q

What is hyperventilation?

A

excessive ventilation of the lungs above metabolic demand

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10
Q

What is hyperpnoea?

A

increased depth of breathing (to meet metabolic demand)

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11
Q

What is hypopnoea?

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

What distinguishes lung volumes and capacities?

A
  • volumes are discrete sections of the graph and DON’T overlap
  • whereas capacities are the SUM of 2 or more volumes
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18
Q

What is inspiratory reserve volume?

A

the additional amount of air that can be inhaled after a normal inspiration (tidal volume)

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19
Q

What is tidal volume?

A

the lung volume representing the normal volume of air displaced between normal inhalation and exhalation w/ no extra effort

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20
Q

What is expiratory reserve volume?

A

the amount of extra air exhaled during a forceful breath out

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21
Q

What is residual volume?

A

the amount of air that remains in a person’s lungs after fully exhaling

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22
Q

What is functional residual capacity?

A

the amount of gas left in the lungs after normal expiration

23
Q

What is inspiratory capacity?

A

the volume of air that can be inspired following a normal, quiet expiration (tidal volume+inspiratory reserve volume)

24
Q

What is vital capacity?

A

the maximum amount of air a person can expel from their lungs after a maximum inhalation (inspiratory reserve + tidal volume + expiratory reserve)

25
Q

What is the equation for minute ventilation?

A

tidal volume X breathing frequency

L/min

26
Q

What is the equation for alveolar ventilation?

A

(tidal volume - dead space) X breathing frequency

27
Q

What factors affect lung volumes and capacities?

A
  • body size (height, shape)
  • sex
  • fitness
  • age
  • disease
28
Q

What is non-perfused parenchyma?

A
  • alveoli without a blood supply
  • no gas exchange
  • alveolar dead space
29
Q

What reversibly increases anatomical dead space?

A
  • ventilator

- snorkel

30
Q

What reversibly decreases anatomical dead space?

A
  • tracheostomy

- cricothyrocotomy

31
Q

How is inspired gas modified in the airways?

A

warmed, humidified, slowed and mixed w/ air already in there

32
Q

What are the different types of haemoglobin?

A
  • Hb A (98%): Hb a + Hb b
  • Hb A2 (2%): Hb a + Hb d
  • Hb F (fetal): Hb a + Hb y
33
Q

What is the allosteric behaviour of haemoglobin (cooperative binding)?

A
  • Hb without oxygen has v. low affinity for oxygen
  • when oxygen binds–> conformational change in protein structure–> greater affinity for oxygen
  • inc. each time an oxygen binds
  • tense–> relaxed (as O2 binds), opens up a binding site for 2,3-DPG–> pushes Hb into tense state, causing some O2 to be ejected
34
Q

What is the P50?

A

the partial pressure at 50% HbO2 saturation

35
Q

What causes a rightwards shift of the oxygen dissociation curve?

A
  • metabolic activity- inc. in temperature
  • acidosis (Bohr effect)
  • hypercapnia (inc. CO2)
  • inc. 2,3-DPG

rightwards shift causes inc. release of oxygen (unloading) e.g. in muscles, or placenta

36
Q

What causes a leftwards shift of the oxygen dissociation curve?

A
  • low temperature
  • alkalosis
  • hypocapnia (dec. CO2)
  • dec. 2,3-DPG
  • fetal haemoglobin (bc needs greater affinity for oxygen than adult HbA to ‘extract’ it)
  • myoglobin (v. steep bc oxygen store)

inc. affinity/loading e.g. in lungs

37
Q

What causes a downwards shift of the oxygen dissociation curve?

A

less Hb, so less total O2 in blood, but HbO2 saturation still high
e.g. anaemia–> impaired oxygen-carrying capacity

38
Q

What causes an upwards shift of the oxygen dissociation curve?

A

polycythaemia, so inc. Hb in blood–> inc. oxygen-carrying capacity

39
Q

How does carbon monoxide affect the oxygen dissociation curve?

A
  • downwards and leftwards shift

- bc dec. capacity and inc. affinity

40
Q

How is carbon dioxide transported (3 ways)?

A
  • CO2 from respiration moves into blood from tissues
  • reacts (non-enzymatically) w/ water to form carbonic acid (H2CO3)
  • H2CO3 dissociates into H+ and HCO3- (most transported as bicarbonate)
  • also CO2 moves into erythrocyte and combines w/ water using carbonic anhydrase enzyme–> inc. rxn rate
  • HCO3- moved out of erythrocyte and Cl- moved in
  • also CO2 binds to Hb (amine ends of globin chains)–> HbCO2
  • protons in RBC bind to Hb
41
Q

What is the Haldane effect?

A
  • property of Hb
  • deoxygenated blood can carry more CO2 at any given pressure i.e. veins
  • and oxygenated blood has. a reduced capacity for CO2 i.e. arteries
42
Q

What is pulmonary transit time?

A

amount of time that the blood is in contact w/ respiratory exchange surface
0.75s- how long it takes for O2 to equilibrate between plasma and alveoli

43
Q

Why will increased tidal volume increase the concentration of dissolved oxygen in blood?

A

deeper breathing will increase the ‘refresh rate’ of air at the gas exchange surface

44
Q

Why will uncontrolled type 1 diabetes shift the oxygen dissociation curve to the right?

A

may lead to diabetic ketoacidosis–> acidity shifts curve to right

45
Q

Why is there greater of ventilation the lungs at the bottom?

A

alveoli are completely contracted so not much needed for them to expand

46
Q

How do pressure gradients drive flow?

A
  • high pressure–> low pressure
  • inspiratory effort expands alveoli, decreasing its pressure, so air flows in until pressures equilibriate
  • removing inspiratory effort, pressure inc., pushing air out
47
Q

What is transmural pressure?

A

Pinside - Poutside

N.B. +ve transmural pressure leads to expiration

48
Q

What is the chest wall relationship?

A
  • lung tissue naturally recoils inwards and ribcage naturally recoils outwards
  • chest recoil= lung recoil
  • inspiratory muscle effort + chest recoil > lung recoil–> results in inspiration
  • expiratory muscle effort + lung recoil > chest recoil–> results in expiration
49
Q

What is a haemothorax?

A

vessel bleeding inside pleural cavity–> compresses lung- less space for lung to expand

50
Q

What is a pneumothorax?

A

puncture of chest wall or lung, allowing air into intrapleural space

51
Q

What is negative pressure breathing?

A

lowering Palv below Patm to create -ve pressure gradient

e.g. normal breathing

52
Q

What is positive pressure breathing?

A

increasing Patm above Palv, forcing air into lungs

e.g. ventilator, mouth to mouth

53
Q

What is transrespiratory system pressure?

A

Prs= Ralv - Patm

N.B. a -ve transrespiratory pressure will lead to inspiration

BRS Term 2 (36 decks)

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