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HUBS192 > RESPIRATORY PHYSIOLOGY > Flashcards

RESPIRATORY PHYSIOLOGY Flashcards

1
Q

how does pressure gradient alter during inhalation and exhalation?

A
  • inhalation: lung volume increase –> pressure inside lung decrease –> pressure outside greater than inside –> air rushes into lungs
  • exhalation: opposite to above
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2
Q

what is intrapulmonary pressure?

A

pressure inside the lungs

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3
Q

what are the 2 opposing forces that must be overcome to take a breath?

A
  • stiffness of the lungs
  • resistance of the airways to the lungs
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4
Q

what does it mean by saying stiff lungs? example?

A
  • stiff lung = lung with low compliance –> need more work to expand the lungs
  • pulmonary fibrosis
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5
Q

what causes stiff lungs?

A
  • thickening and scarring of the alveolar membranes
  • can arise from chronic inflammation or exposure to industrial chemicals
  • lack of surfactant
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6
Q

what is surface tension at the lungs?

A
  • tendency of a fluid surface to occupy the smallest possible surface area
  • must overcome surface tension at the lungs to expand it
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7
Q

what causes surface tension at the lungs?

A
  • alveoli are lined with fluid that exert surface tension
  • walls of alveoli are very thin –> enhancing the effect of surface tension
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8
Q

what is surfactant? what does surfactant do to the lungs? how does it work?

A
  • surfactant, produced by type II pneumocytes with major constituents is phospholipid
  • surfactant helps lungs expand easier by lower surface tension
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9
Q

how does surfactant lower the surface tension?

A

reduces attractive forces between fluid molecules lining alveoli

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10
Q

what is airway resistance through the respiratory tract?

A

exert force (friction) on air when air move from outside to the alveoli

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11
Q

where is most of the resistance to airflow arise in?

A

bronchi

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12
Q

the _____1______ airways like terminal and respiratory bronchioles contribute very little to _____2_______ due to _______3_______ ________4________

A

1: small
2: airway resistance
3: high
4: cross sectional area

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13
Q

what is the compliance equation?

A

compliance = difference in V/difference in P

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14
Q

what is used to measures volume inspired/exhale and determine how big a breath you can take?

A

spirometer

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15
Q

what is tidal volume?

A

volume of air move in and out during normal quiet breath

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16
Q

what is inspiratory reserve volume?

A

extra volume that can be inhaled over and above the tidal volume

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17
Q

what is expiratory reserve volume?

A

extra volume that can be exhaled voluntarily after completion of a normal, quiet respiratory cycle

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18
Q

what is residual volume?

A

volume remaining in lungs after maximal exhalation

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19
Q

what is minimal volume

A

volume remaining in lungs if they collapsed

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20
Q

what is vital capacity, what made up vital capacity?

A
  • volume of air that can be move in an out of your lungs
  • inspiratory reserve + tidal + expiratory reserve
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21
Q

what is total lung capacity and what made up it?

A
  • total volume in lungs when it is filled to max
  • vital capacity + residual volume
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22
Q

what is inspiratory capacity and what made up it?

A
  • total volume of air that can be inspired from rest
  • tidal + inspiratory reserve
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23
Q

what is functional residual capacity and what made up it?

A
  • volume remaining in lungs after normal exhalation
  • residual + expiratory reserve
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24
Q

what is FEV1 in spirometry trace?

A

forced expiratory volume in 1 second

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25
Q

what is FVC in spirometry trace?

A

forced vital capacity

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26
Q

what is a normal number for FEV1/FVC ratio

A

80% (<0.7 indicates airways obstruction –> increase airway resistance)

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27
Q

what is obstructive lung disease?

A
  • narrowing/obstruction of airway which increase airway resistance
  • asthma, chronic bronchitis, emphysema (COPD)
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28
Q

what is restrictive lung disease?

A
  • reduced the ability to expand the lungs due to reduced lung compliance (fibrosis) or insufficient surfactant release
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29
Q

what does PEF mean? what does a low PEF indicates?

A
  • PEF = peak expiratory flow
  • low PEF indicates obstructive lungs disease
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30
Q

what is an inhaled bronchodilator and what does it use for?

A
  • helps relax the smooth muscle in airway
  • used to determine if any airway narrowing is reversible such as in asthma or not reversible such as with chronic obstructive pulmonary disorder (COPD)
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31
Q

what does low PEF after inhaled bronchodilator indicates?

A

COPD

32
Q

what is dead space mean in respiratory?

A

some of the inhaled air never gets to the alveoli so cannot gas exchange

33
Q

equation for respiratory minute volume?

A

Ve = Vt x f
- Ve = respiratory minute volume (L/min)
- Vt = tidal volume (L/breath)
- f = respiratory rate (breaths/min)

34
Q

why is alveolar ventilation important?

A

because it show the true amount of air that gets into the alveoli

35
Q

alveolar ventilation equation?

A

Va = (Vt - Vd) x f

36
Q

state Dalton’s Law, what does that mean?

A
  • in a gas mixture (air in this case), each gas exerts its own individual pressure called a partial pressure
  • the pressure of a mixture of gas = the sum of the pressures of each individual gas
37
Q

what are the 2 forms of oxygen transport in blood?

A
  • dissolve in plasma
  • bind with RBCs
38
Q

state Fick’s Law of Diffusion

A

gases move across the membranes between the alveoli and the capillaries by diffusion

39
Q

what determines the rate of diffusion?

A
  • surface area of the membrane
  • thickness of the membrane
  • pressure difference between the 2 sides
40
Q

Fick’s Law of Diffusion equation?

A

F = (A/T) x D x (P1 - P2)
- F = amount flowing
- A= surface area
- T = thickness
- D = diffusion constant
- P1 - P2 = pressure difference

41
Q

what does diffusion constant depend on?

A
  • gas solubility and its molecular weight
  • e.g. CO2 diffuse about 20x faster than O2 due to higher solubility of CO2
42
Q

what is emphysema?

A
  • a disease characterised by dilation of the alveolar spaces and destruction of the alveolar walls
  • example of a COPD
  • since the surface area is reduced, there is less contact between air and capillaries –> the flow is greatly reduced
43
Q

to ensure an effective gas exchange, the distance between alveolar air and blood is _______________

A

very small

44
Q

how does pulmonary fibrosis affect gas exchange?

A
  • thickening and scarring of the alveolar membranes –> increase thickness –> decrease flux
45
Q

in the P1 - P2 in Fick’s Law equation, what does P1 indicate and what does P2 indicate?

A

P1 = pressure alveolar (PA)
P2 = pressure arterial (Pa)

46
Q

what does PAO2 depends on?

A
  • partial pressure of oxygen in inspired air
  • alveolar ventilation
  • oxygen consumption - blood oxygen
47
Q

what happens to oxygen in venous blood during rest and exercise?

A
  • rest - low activity –> reduced oxygen consumption –> higher level of oxygen in venous blood
  • exercise = high activity –> increase oxygen consumption –> lower level of oxygen in venous blood
48
Q

how does the amount of oxygen in venous blood during exercise assist the gas exchange?

A

body extract more O2 from blood –> when blood came back to lung and contact alveoli, PAO2 much greater than PaO2 –> much greater P difference –> greater flux –> draw more O2

49
Q

PACO2 depends on?

A
  • partial pressure of CO2 in inspired air
  • alveolar ventilation
  • carbon dioxide production
50
Q

what does oxygen-haemoglobin curve show?

A

the percentage of haem unit bound with oxygen

51
Q

in the oxygen-haemoglobin saturation curve, what is y-axis and what is x-axis?

A

y-axis = oxyhaemoglobin (%saturation)
x-axis = PO2 (mmHg)

52
Q

what is the shape of the oxy-haemoglobin curve?

A

sigmoidal

53
Q

what is the value for PO2 and %oxy-saturation for blood entering systemic, blood leaving peripheral tissues, in active muscle and in partial pressure

A
  • blood entering systemic: 98% saturated and around 100mmHg
  • blood leaving peripheral tissues: 75% saturated and 40 mmHg
  • in active muscle tissue: 20% saturated and below 20mmHg
  • partial pressure where O2 is 50% saturated
54
Q

why is the the upper part of the sigmoidal curve is flat?

A

buffer/safety zone where we can tolerate a dramatic reduction of partial pressure before haemoglobin begins desaturated

55
Q

why can we observe a steep part of the curve at lower PO2

A

helps with loading of Hb in lungs and unloading of O2 to the tissues

56
Q

_____1______ changes in PO2 result in ____2______ changes in amount of O2 bound to haemoglobin

A

1: small
2: large

57
Q

what does Bohr effect mean?

A

the shifting of the binding curve

58
Q

what cause left shift of the binding curve?

A
  • O2 decreased affinity for haemoglobin
  • lower plasma pH
  • higher temperature
  • increased in PCO2 (because increase in CO2 means increase in H+ means reduce pH)
  • increase in BPG (2,3-biphosphoglycerate)
59
Q

what is BPG and what does it do?

A

RBC glycolysis by-product that shift the oxygen-haemoglobin curve to the left

60
Q

what cause right shift of the binding curve?

A
  • O2 increased affinity for haemoglobin
  • higher plasma pH
  • decrease in temperature
  • decrease in CO2
61
Q

what does exercise cause to alter the binding curve?

A

exercise causes pH to drop and temperature to rise in skeletal muscle –> right shift

62
Q

what are the 3 forms of CO2 transport?

A
  • dissolved in plasma (7%)
  • as bicarbonate HCO3- (70%)
  • combined with proteins as carbamino compounds (23%)
63
Q

how much CO2 diffuse into bloodstream?

A

93%

64
Q

within the 93% CO2 diffused in the bloodstream, what 2 things can it do?

A
  • 23% of this binds to haemoglobin as HbCO2
  • the other 70% is converted to carbonic acid by the activity of enzyme carbonic anhydrase
65
Q

is the formation of carbonic acid reversible?

A

yes

66
Q

what happens to the carbonic acid once it is formed?

A

immediately dissociate into a hydrogen ion and a bicarbonate ion

67
Q

what does the H+ from dissociated carbonic acid do?

A

bind to haemoglobin forming HbH+

68
Q

what does the bicarbonate ion from dissociated carbonic acid do? what is the process called?

A
  • move into plasma in exchange for chlorine
  • chloride shift
69
Q

where is our respiratory centre located? what are the 3 groups of neurons (from highest to lowest) here? what are the 3 groups referred to as?

A
  • Medulla obloganta
  • 3 groups: inspiratory center of the dorsal respiratory group (DRG), ventral respiratory group (VRG), and pre-botzinger complex
  • respiratory rhythmicity centers
70
Q

where does DRG and VRG send signals to?

A
  • DRG: to diaphragm and external intercostal muscles
  • VRG: to accessory respiratory muscles
71
Q

what does the pre-botzinger complex do?

A

generates respiratory rhythm

72
Q

briefly describe the control of breathing

A

sensors send afferent signals –> central controller (medulla) then medulla sends efferent signals to effectors (respiratory muscles)
–> form a cycle to maintain O2 and CO2 exchange at a ‘normal’ rate

73
Q

central chemoreceptors are located in ____1_______, they are sensitive to _____2_____ but not to _____3_____ of blood and they respond to _______4_______

A

1: medulla
2: PCO2
3: PO2
4: pH change

74
Q

peripheral chemoreceptors located in ____1____ and ______2______ bodies, they mainly respond to ____________3____________ and have a limited respond to ________4_____________, especially, they _______5______ responding

A

1: carotid
2: aortic
3: changes in arterial PO2
4: changes in PCO2
5: rapidly

75
Q

which receptors are the most important in determining respiratory activity?

A

carbon dioxide receptors

76
Q

as the lungs inflate/deflate, they send _______1______ from _______2_______, the brain then send _____3_______ preventing them from stretching too far away
receptors also detect _____4______ for brain to send ______3______ that triggers sneeze or cough

A

1: afferent input
2: stretch receptors
3: efferent output/signal
4: irritation

HUBS192 (23 decks)

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