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Respiratory > Lung physiology > Flashcards

Lung physiology Flashcards

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1
Q

What are muscles involved in inspiration?

A

Diaphragm- 70% of volume change phrenic C3-5
innervation
External intercostals- lift ribs 2-12
widen thoracic cavity
Scalenes- lift ribs 1&2
Pectoralis major- lift ribs 3-5
Sternocleido.- elevates sternum
Muscles relax to allow passive expiration

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2
Q

What innervates the diaphragm?

A

C3, 4, 5
Phrenic
Keep the diaphragm alive

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3
Q

Function external intercostal?

A

Lift ribs 2-12
Widen thoracic cavity

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4
Q

Function scalenes?

A

Lift ribs 1 and 2

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5
Q

Function pectoralis major?

A

Lift ribs 3-5

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6
Q

Function sternocleidomastoids?

A

Elevate sternum

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7
Q

What occurs to achieve passive expiration?

A

Muscle relaxation

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8
Q

What muscles used during active expiration?

A

Internal intercostals- depress ribs 1-11
Rectus abdominis- depress lower ribes
- compress abdominal organs and diaphragm

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8
Q

What muscles used during active expiration?

A

Internal intercostals- depress ribs 1-11
Rectus abdominis- depress lower ribes
- compress abdominal organs and diaphragm

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9
Q

Define:
PaCO2
PACO2
PaO2
PAO2
PIO2

V’A
V’CO2

A

PaCO2 arterial CO2
PACO2 Alveolar CO2
PaO2 arterial O2
PAO2 Alveolar O2 (~14kPa)
PIO2 Pressure of inspired O2
V’A Alveolar ventilation
V’CO2 CO2 production

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10
Q

What does ‘a’ represent?

A

arterial

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11
Q

What does ‘A’ represent

A

Alveolar

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12
Q

At what point is Hb fully saturated through capillary bed?

A

Fully sat 25% WAY THROUGH

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13
Q

What occurs when hypoxia?

A

Hypoxia
Pulmonary vasoconstriction
Maximise ventilation-perfusion
Optimal gas exchange

Altered posture

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14
Q

How is CO2 transported?

A

Bound haemoglobin
In plasma (dissolved CO2 as HCO3-)

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15
Q

Define Boyle’s law?

A

Boyle’s Law: P1V1=P2V2

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16
Q

How does Boyle’s law apply to ventilation?

A

Inspiritary muscles contract
Thoracic cavity volume increases
Allows air to flow into lungs:
1) increased transpulmonary pressure (Palveolar – Pintraplueral)
2) alveolar pressure lower than atmospheric
3) expiration caused by decreasing transpulmonary pressure
4) ribcage pressing down on lungs
5) alveolar pressure increases above atmospheric
6) air flow out

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17
Q

What limits lung expansion?

A

Compliance- ability stretch and expand
Determined by amount elastic tissue and surface tension in alveoli

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18
Q

What reduces surface tension in alveoli?

A

Surfactant

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19
Q

Define normal pH?

A

7.35-7.45

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20
Q

What is Henderson Hasellback equation for pH?

A

pH = pKₐ + log([A⁻]/[HA])

pH=6.1 + log10([HCO3-]/[0.03PCO2])

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21
Q

Equation for dissociation of CO2?

Study These Flashcards
A

CO2 + H2O to H2CO3 to H+ + HCO3-

22
Q

What enzyme is involved in the dissociation of CO2?

Study These Flashcards
A

Carbonic anhydrase

23
Q

How is pH maintained?

Study These Flashcards
A

CO2 dissociation
renal secretion/reabsorption
protein buffers

24
Characteristics of respiratory acidosis?
Low pH High HCO3- High pCO2
25
What are causes of respiratory acidosis?
Lack respiratory drive Restriction airways Hypoventilation COPD2 Impaired CO2 elimination cause hypercapnia (smaller 6kPA)
26
What compensates respiratory acidosis?
Retention and production HC03- H+ secretion
27
Characteristics of respiratory alkalosis?
High pH Low HCO3- Low CO2
28
What is the cause of respiratory alkalosis?
Hyperventilation, fever Loss CO2 causes hypocapnia H2CO3 converted CO2 meaning less H+ pH raised
29
Define tidal volume?
Volume inhaled/exhaled in normal breath 500ml
30
Define inspiratory reserve?
Max air that can be inhaled minus tidal volume 3L
31
Define expiratory reserve volume?
Mac air that can be exhaled minus tidal volume 1.2L
32
Define residual volume?
Air remaining in lungs after max expiration to prevent collapse 1.2L
33
Define vital capacity?
Max air expired after max inspiration 4.7L (ERV +TV + IRV)
34
Define inspiratory capacity?
Max inhalation after normal tidal expiration 3.5L (IRV + TV)
35
Define functional residual capacity?
Air in lungs after tidal expiration 2.4L (RV+ERV)
36
Define total lung capacity
Total volume of air in lungs after maximal inspiration 5.9L (RV+VC)
37
Define FEV1? Amount?
Forced exp. Volume in 1 second 80% of vital capacity in healthy person
38
Define FVC?
forced vital capacity- max air expired under max force after max inspiration
39
Define PEF?
Peak air flow Highest velocity of air measured during FVC Flow will decrease linearly in healthy person after PEF
40
Define DLCO?
Diffusing capacity of lung for carbon dioxide Measure efficiency gas exchange Known [CO] inhaled, 10 sec breath hold, expired [CO] measured Reduced with COPD
41
What will an airway obstruction cause? (Lung vol) Causes Ratio?
Decreasing FEV1 Increasing RV Increasing TLC FVC similar Ratio FEV1/FVC reduced below 0.7 e.g. COPD, asthma
42
Define airway restriction? Causes? Ratio?
Reduced compliance of lungs Reduce FEV1 and FVC- ratio same Everything else reduced Pulmonary fibrosis
42
Define airway restriction? Causes? Ratio?
Reduced compliance of lungs Reduce FEV1 and FVC- ratio same Everything else reduced Pulmonary fibrosis
43
Label: Tidal volume Inspiratory reserve Expiratory reserve Residual volume Vital capacity Insp. capacity Functional residual capacity Total lung capacity
44
How to calculate vital capacity?
ERV+TV+IRV 4.7L
45
How to calculate inspiratory capacity?
IRV+TV 3.5L
46
How to calculate functional residual capacity?
ERV+VC 2.4L
47
How to calculate total lung capacity?
RV+VC 5.9L
48
State process of inspiration?
Diaphragm- flattens External intercostal muscles- elevate ribs and sternum- extend thoracic Increase volume thoracic cavity- lungs increase Decrease pressure in lungs- Boyles law Pressure higher environment than lungs Air move down pressure gradient
49
Explain process passive expiration?
Relaxation inspiratory muscles Diaphragm- return resting position- reduce thoracic cavity External intercostal relax- depress rib and sternum Decrease volume thoracic cavity- increase pressure Pressure inside lungs greater external environment Air moves out lung Down pressure gradient
50
Explain forced breathing? When used?
Exercise Active inspiration- contraction accessory muscles Scalenes – elevates the upper ribs. Sternocleidomastoid – elevates the sternum. Pectoralis major and minor – pulls ribs outwards. Serratus anterior – elevates the ribs (when the scapulae are fixed). Latissimus dorsi – elevates the lower ribs Increase volume thoracic cavity
51
Outline how active expiration occurs?
Anterolateral abdominal wall – increases the intra-abdominal pressure, pushing the diaphragm further upwards into the thoracic cavity. Internal intercostal – depresses the ribs. Innermost intercostal – depresses the ribs. Decrease volume thoracic cavity

Respiratory (8 decks)

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