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Medicine - Year 1 - Term 2 > W1 - Respiratory Physiology (1-3) > Flashcards

W1 - Respiratory Physiology (1-3) Flashcards

1
Q

Name the 4 functions of the respiratory system

A

Gas exchange
Acid base balance
Protection from infection
Communication

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2
Q

Blood pH is regulated at what pH?

A

7.4

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3
Q

When we speak, are we inhaling, exhaling or both?

A

Exhale only

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4
Q

Provide the equation of life

A

Nutrients + O2 = ATP + Waste

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5
Q

Integration from what two things determine the ability to deliver fuel to cells and remove waste?

A

Integration from CVS
Integration from resp system

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6
Q

Name the 2 types of respiration and where they occur

A

Cellular/internal respiration in peripheral tissues

External respiration in lungs

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7
Q

Cellular/Internal respiration releases energy via which two processes?

A

Glycolysis

Oxidative phosphorylation

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8
Q

Oxidative phosphorylation requires which two things?

A

O2

External respiration

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9
Q

External respiration releases energy from what?

A

Glucose

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10
Q

Exercise causes working muscle to demand more energy. What 2 changes does it lead to in the body?

A

Increase rate and depth of breathing

Increase HR and force of contraction

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11
Q

Name the places Exchange I, II and III occur

A

Exchange I: between atmosphere and lung

Exchange II: between lung and blood

Exchange III: between blood and cells

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12
Q

In steady state, net volume of gas exchanged in lungs is equal to net volume of gas exchanged in tissues. How much ml per min?

A

250 ml / min of O2

200 ml / min of CO2

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13
Q

Describe the difference between pulmonary and systemic circulation in terms of location, CO2 and O2

A

Pulmonary - heart and lungs
Systemic - whole body

Pulmonary - deliver CO2 to lungs
Systemic - collect CO2 from tissues

Pulmonary - collect O2 from lungs
Systemic - deliver O2 to tissues

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14
Q

Which artery in the body carries deoxygenated blood and which vein carries oxygenated blood? In terms of definitions, why do these arteries/veins go against the norm?

A

Pulmonary artery/vein

Artery - carries blood away from heart
Vein - carries blood to heart

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15
Q

What is standard adult respiration rate and what is max during exercise?

A

12-18 breaths per min

40-45 max during exercise

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16
Q

Name the 7 main anatomical regions of the airways

A

Nose
Pharynx
Epiglottis
Trachea
Larynx
Lung
Bronchus

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17
Q

What is the function of the epiglottis?

A

Close during eating/drinking to prevent aspiration

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18
Q

Roughly how many times does the bronchi divide to become alveoli

A

Around 25x

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19
Q

What is the function of the larynx? What’s the lay term for larynx?

A

Contains vocal cords which vibrate to produce sound

Lay term is voice box

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20
Q

Name 2 reasons why it’s more comfortable to breathe through the nose rather than mouth. Why?

A

Nose warms and moistens air

Due to huge surface area to volume ratio

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21
Q

Where is the jugular notch and sternal angle? What’s inferior to the sternal angle?

A

If you run your fingers over your sternum, you find the jugular notch

About 2-3 fingers down is the sternal angle

Below is the trachea dividing into the 2 primary bronchi

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22
Q

Why are the lungs soft and spongy?

A

Thousands of tiny hollow air sacs

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23
Q

What 6 areas can be found in the upper respiratory tract?

A

Pharynx
Vocal cords
Oesophagus
Nasal cavity
Tongue
Larynx

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24
Q

What 3 areas can be found in the lower respiratory system? What 3 things surround them?

A

Trachea
Bronchi
Lungs

Surrounded by: ribs, spine, diaphragm

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25
Q

How many lobes, fissures and secondary bronchi do our right lung have? What about left?

A

Right: 3 lobes, 2 fissures, 3 secondary bronchi

Left: 2 lobes, 1 fissure, 2 secondary bronchi

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26
Q

What’s the name of the fissure found in both the right and left lung? What’s the name of the fissure only found on the right?

A

Right and left: Oblique fissure

Right only: Horizontal fissure

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27
Q

What 2 ways help us determine the right from left bronchus? Why is it clinically relavent?

A

R is wider
R has more vertical trajectory

Aspirated foreign bodies are more likely to get stuck in R

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28
Q

Define anatomical dead space

A

Air in trachea and bronchioles, where walls are too thick for gas exchange

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29
Q

Name the 6 anatomical regions from windpipe to terminal point in lung

A

Larynx
Trachea
Primary bronchus
Secondary bronchus
Bronchiole
Alveoli

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30
Q

Where does gas exchange occur

A

Alveoli in lungs

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31
Q

Define patency and name the feature that maintains it

A

Airway is open and air flows freely

Provided by semi-rigid tubes in airway, created by C-shaped rings of cartilage

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32
Q

The bronchiole does not have C-shaped rings of cartilage. How is patency maintained?

A

Physical forces in thorax

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33
Q

What 2 things surround alveoli?

A

Elastic fibres
Network of capillaries

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34
Q

Does expiration need energy? What happens to alveoli?

A

It is passive and so does not need energy

The inspiration muscles stop contracting and energy in elastic fibres is released, squeezing alveoli to force air out

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35
Q

What are type 1 and type 2 alveolar cells?

A

Type 1 - gas exchange occurs here. More common. Capillaries are only abutted to type 1

Type 2 - secrete surfactant

36
Q

What type of immune cell can be found near alveoli?

A

Macrophages - important since site is not sterile

37
Q

Explain the relationship between airway diameter, resistance and the sympathetic nervous system

A

The smaller the airway, the less resistance due to a larger surface area. As airways merge, there are more particles in proportionally less space, causing resistance

Sympathetic nervous system causes bronchial smooth muscle relaxation
- Relaxation increases diameter = decreases resistance
- Contraction decreases diameter = increases resistance

38
Q

Bronchial smooth muscle relaxation is caused by what binding to what receptors?

A

Adrenaline/noradrenaline binding to beta-2 receptors

39
Q

What is the surface area of the alveoli? What value is total lung capacity?

A

Surface area: 80m2
Volume: 2 x 3l lungs

40
Q

Most resistance to air flow happens in what areas of the lungs? What is the cross-section area?

A

Trachea, primary and smaller bronchi - between 0-11 divisions. They have a cross-section area of 2.5cm

41
Q

In what 2 ways is residual volume beneficial?

A

Prevents alveoli from completely collapsing, which would require a lot of energy to “reboot”

Allows gas exchange between breaths

42
Q

Define inspiratory capacity. What two values make it? What is the normal value?

A

Inspiratory capacity - normal air in the lungs after inspiration

Tidal volume + Inspiratory Reserve Volume = Inspiratory Capacity

Usually it’s 2.8 litres

43
Q

How many litres is total lung capacity? Which two values is it made of?

A

6 litres

Vital capacity + residual volume = total lung capacity

44
Q

Define tidal volume and give its typical value

A

Tidal volume is the air we breathe in and out

It’s around 500 ml

45
Q

Define functional residual capacity. What two things is it made of and what’s the typical value?

A

Functional residual capacity is the total left in lungs after expiration

Expiratory reserve volume + residual volume = functional residual capacity

It’s 2.3 litres

46
Q

Define inspiratory reserve volume and provide a value

A

Taking a big breath, e.g. exercise

3 litres

47
Q

Define expiratory reserve volume and provide a value

A

Big breath out

Roughly 1 litre

48
Q

Define vital capacity and the three values that make it

A

Deep breath in then pushing as much air out as possible

Tidal volume + Inspiratory Reserve Volume + Expiratory Reserve Volume = Vital Capcity

49
Q

Define residual volume and provide a value

A

Air you can’t voluntarily remove

Around 1.2 litres

50
Q

What is FEV1FVC?

A

Fraction of forced vital capacity expired in 1 second

51
Q

Define dead space volume and provide a value

A

The volume of gas occupied by the conducting airways which is not available for exchange.

150 ml

52
Q

Each lung is surrounded by a continuous pleural membrane. Name the two aspects and give their locations

A

Parietal membrane - stuck to ribs and diaphragm

Visceral membrane - stuck to surface of lungs including all fissures

53
Q

Define hilum and its relevance for the membrane

A

The hilum of the lungs are where lungs connect to the major airway entering/leaving lungs, pulmonary artery and vein

It’s where the parietal membrane doubles back on itself to become the visceral membrane (or vice versa!)

54
Q

Boyle’s Law

A

The pressure exerted by a gas is inversely proportional to its volume

P = 1/V

55
Q

Dalton’s Law

A

The total pressure of a gas mixture is the sum of the pressures of individual gasses

56
Q

Charles Law

A

The volume occupied by a gas is directly related to absolute temperature

v = T

57
Q

Henry’s Law

A

The amount of gas dissolved in a liquid is determined by the pressure of the gas and its solubility in liquid

58
Q

Where is intrapleural fluid? What 3 functions does it serve? How many ml is it?

A

Between visceral and parietal membranes

  1. Allow membranes to glide over each other
  2. stops separation which allows for lung expansion during isnpiration
  3. prevents recoil of lungs and too much chest wall expansion during expiration

3ml in each lung

59
Q

Relate Boyle’s law of the mechanics of breathing, inspiration and exparation

A

Breathing occurs because the thoracic cavity changes volume

Based on Boyle’s law:
Increased volume = decreased pressure
Decreased volume = increased pressure

Gasses always move from high pressure to low pressure

60
Q

Which muscles do we use during inspiration, heavy inspiration, expiration and heavy expiration?

A

Normal Inspiration: External intercostal muscles, diaphragm

Heavy Inspiration: Scalene Muscles, Sternocleidomastoid muscles (and above)

Normal Expiration: None - its passive

Heavy Expiration: Internal intercostal, abdominal muscles

61
Q

Describe the action of the diaphragm, thoracic volume and airways during inspiration and expiration

A

Inspiration: Diaphragm contracts, thoracic volume increases, airways are pulled open

Expiration: Diaphragm relaxes, thoracic volume decreases, airways are compressed

62
Q

What 2 metaphors are used to describe the action of the ribs during breathing?

A

Pump handle motion - increases anterior-posterior dimension of the rib cage

Bucket handle motion - increases lateral dimension of rib cage

63
Q

Name the 3 pressures in the thoracic cavity and whether they’re positive or negative in healthy lungs compared to atmospheric pressure

A

Intrathoracic pressure - pressure in thoracic cavity. Positive/negative

Intrapleural pressure - pressure in pleural cavity. Negative

Transpulmonary pressure - alveolar pressure minus intrapleural pressure. Negative

64
Q

Explain why intrapleural pressure is always less than alveolar pressure

A

Intrapleural pressure is less than atmospheric pressure and becomes more negative during inspiration, due to expansion between the parietal and visceral pleura. If intrapleural pressure were higher than alveolar pressure, inspiration would be difficult or the lung could collapse.

65
Q

What 4 mechanical factors affect respiratory minute volume?

A

Airflow between atmosphere and alveoli: Proportional to pressure difference (Patm - PA) and inversely proportional to airway resistance (F = (Patm- PA)/R)

End of unforced expiration: Stable lung and thoracic cage dimensions with opposing elastic forces.

Lung’s attempt to recoil vs. chest wall’s attempt to move outward creates subatmospheric intrapleural pressure and transpulmonary pressure.

Airway resistance majorly determined by airway radii, impacting airflow at varying pressure differences.

66
Q

What makes surfactant?
What is it? Is it more effective in smaller or bigger alveoli?

What 4 functions does it have?

A

Type II alveolar cells
Detergent-like fluid
More effective in small alveoli as surfactant molecules come closer together so are more concentrated

Functions:
-Reduces surface tension, reducing tendency of alveoli to collapse
-Increases lung compliance
-Reduces lung’s tendency to recoil
-Makes work of breathing easier

67
Q

In the foetus, when does surfactant production occur? What 2 hormones stimulate it? What may premies suffer due to a lack of surfactant?

A

25-36 weeks in utero
Thyroid and cortisol
Infant Respiratory Distress Syndrome (IRDS)

68
Q

What is the Law of LaPlace?

A

Pressure = 2 x surface tension / radius

Pressure is greater in smaller alveoli. Surfactant reduces surface tension. Pressure is equalised in larger and smaller alveoli

69
Q

Define compliance

A

Change in volume relative to change in pressure, i.e. how much does volume change for any given change in pressure. It’s stretchability or distensibility (not elasticity. People with emphysema have compliant but not elastic lungs)

70
Q

Define high compliance and low compliance

A

High compliance - large increase in lung volume for small decrease in ip pressure. It’s good if accompanied by high elasticity

Low compliance - small increase in lung volume for large decrease in ip pressure. You have to work hard to get air into lungs. Can be caused by fibrosis

71
Q

What 3 factors affect compliance?

A

Age - as we get older compliance decreases
Fibrosis
Surfactant - surfactant reduces surface tension which reduces likelihood of alveolar collapse

72
Q

Define ventilation, pulmonary ventilation and alveolar ventilation

A

Ventilation - movement of air in and out of lungs

Pulmonary ventilation - total air movement into/out of lungs

Alveolar ventilation - fresh air getting to alveoli, therefore available for gas exhange

73
Q

In what unit are pulmonary ventilation and alveolar ventilation measured?

A

L/min

74
Q

Describe the impact of dead space on alveolar ventilation

A

Breathing is only around 70% efficient - the rest of the air is stuck in dead space and can’t participate in gas exchange

If we reduce TV and keep dead space the same, dead space is a bigger proportion of lung space. So for someone anxious, breathing is around 50% efficient.

If we increase TV and keep dead space the same, dead space is a smaller proportion of lung space. So for someone chill, breathing is around 80% efficient.

75
Q

Is someone anxious likely to be hypoventilating or hyperventilating? What about someone chilled out? Which is more efficient? Which is more common in a clinical setting?

A

Anxious - hypoventilating
Chilled - hyperventilating
(contrary to popular belief)

Hyperventilation is more efficient

Hypoventilation is more common than hyperventilation as hyperventilation requires consciously overcoming the brain telling you there’s no CO2 to get rid of

76
Q

Air is roughly what % nitrogen, oxygen and CO2?

A

79% nitrogen
21% oxygen
0.03% carbon dioxide

77
Q

Define partial pressure. Whose law does it derive from?

A

The pressure of a gas in a mix of gases is equivalent to the % of that particular gas in the entire mixture multiplied by the pressure of the whole gaseous mixture

From Dalton’s Law

78
Q

What are the PO2 and PCO2 values in mmHg and kPa for the ideal man?

A

PO2
100 mmHg
13.3 kPa

PCO2
40 mmHg
5.3 kPa

79
Q

Does the ideal PO2 and PCO2 rise or fall if hypoventilating (anxious)? How about chilled (hyperventilating)?

A

Hypoventilating
PO2 falls
PCO2 rises

Hyperventilating
PO2 rises
PCO2 falls

80
Q

Describe how pressure-volume varies between apex and base of lung. How would this differ for a patient lying down?

A

At base, the volume change is greater for a given change in pressure

Alveolar ventilation is greater at the base and lower at the apex

Compliance is lower at apex due to more inflation at FRC. At base lungs are slightly compressed by diaphragm so more compliant on inspiration

Small changes in intrapleural pressure brings about large change in volume at base compared with apex

If patient is lying down, they’ll have more compliance and ventilation at the back of the lung compared to the front

81
Q

Define the following abbreviations used to describe partial pressure of gasses in alveoli, systemic arteries and veins

A
a
ṽ
P
PaO2
PACO2

A

A - alveolar
a - arterial blood
ṽ - mixed venous blood (pulmonary artery or large veins in body)
P - partial pressure
PaO2 - partial pressure of oxygen in arterial blood
PACO2 - partial pressure of CO2 in alveolar air

82
Q

What do the pulmonary artery and vein carry?

A

Pulmonary artery - carries deoxygenated blood to lungs
Pulmonary vein - carries oxygenated blood away from lungs

83
Q

What do bronchial arteries carry? What % of left heart output is it? Where and via what does blood drain to?

A

Bronchial arteries carry oxygenated blood to lung tissues from systemic circulation. Comprises 2% of left heart output. Blood drains to left atrium via pulmonary veins

84
Q

How does pulmonary circulation work for gas exchange?

A

L & R pulmonary arteries from right ventricle. Entire cardiac output from RV. Supplies the dense capillary network surrounding alveoli and returns oxygenated blood to left atrium via pulmonary vein. It’s a high flow, low pressure system: (24/10mmHg vs 120/80mmHg)

85
Q

What 5 factors affect the rate of diffusion across a membrane?

A
  • Partial pressure gradient (directly proportional)
  • Gas solubility since CO2 is more soluble in water than O2 (directly proportional)
  • Available surface area (directly proportional)
  • Thickness of membrane (inversely proportional)
  • Distance as it’s most rapid over short distances
86
Q

Define obstructive and restrictive lung disease

A

Obstructive - obstruction of air flow, especially on expiration

Restrictive - restriction of lung expansion leading to loss of lung compliance

87
Q

Describe why the line showing inspiration and line showing expiration are not super-imposed on a pressure-volume relationship and compliance graph

A

Inspiration requires a greater change in pressure (from FRC) to reach a particular lung volume.

During expiration, volume is maintained. This is because:
- Overcome lung inertia during inspiration
- Overcome surface tension during inspiration
- During expiration compression of the airways means more pressure is required for air to flow along them

Medicine - Year 1 - Term 2 (13 decks)

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