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SK299 > Topic 7 > Flashcards

Topic 7 Flashcards

1
Q

What is meant by the term “external respiration”?

A

The exchange of gases between the blood and the external environment

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2
Q

The average adult takes how many breaths per minute and exchanges more than how many litres of air per day?

A
  • 12 - 18

* 8000

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3
Q

Which structures form the upper respiratory tract?

A
  • The nasal cavities
  • The pharynx
  • The larynx
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4
Q

The walls of the bronchi contain what?

Why?

A
  • Cartilage

* To prevent their collapse

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5
Q

What is the smallest division of the bronchi?

A

Terminal bronchioles

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6
Q

What are the pleura?

A

Thin membranes which line fluid-fillid cavities between the lungs and the inside of the thoracic (chest) wall

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7
Q

What structure does the base of each lung rest on?

A

The diaphragm

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8
Q

What are cardiac impressions?

A

The grooves on each lung which the heart sits within

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9
Q

What are the structures of the conduction zone of the respiratory system?

A
  • The nasal passages
  • The pharynx
  • The larynx
  • The bronchi
  • The bronchioles
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10
Q

How many times do the terminal bronchioles further divide, and into what?

A
  • Seven

* Respiratory bronchioles, alveolar ducts, alveolar sacs

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11
Q

What are the holes in the walls of the alveolar sacs called?

A

Alveolar pores

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12
Q

In an adult human, roughly how large is the respiratory surface?

A

140 sq m / the size of a tennis court

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13
Q

Why is the respiratory surface so large?

A

To increase capacity to exchange CO2 and O2

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14
Q

In which structures within the lungs does CO2/O2 exchange occur?

A
  • The respiratory bronchioles
  • Alveolar ducts
  • Alveoli
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15
Q

What is haemoglobin?

A

A globular, iron-containing protein present in red blood cells which binds oxygen and transports it to tissues

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16
Q

What are the steps of the flow of air from the conduction zone through to the respiratory zone?

A
  • Air is taken in through the nasal cavities
  • Air passes down the pharynx, past the epiglottis and into the larynx
  • From the larynx, air travels into the trachea and into the bronchi
  • Air moves through the terminal bronchioles into the respiratory bronchioles
  • Air passes into the alveolar ducts and into the alveolar sacs
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17
Q

What are the muscles of respiration?

A
  • Diaphragm

* Intercostal muscles

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18
Q

Which nerve innervates the diaphragm?

Where in the brain does that nerve originate?

A
  • The phrenic nerve

* The medulla

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19
Q

Where do the intercostal nerves receive their neuronal inputs from?

A

The thoracic nerves of the spinal cord

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20
Q

What type of muscle surrounds the bronchi and bronchioles?

A

Smooth muscle

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21
Q

During which part of respiration are the external intercostal muscles most active?

A

Inhalation

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22
Q

During which part of respiration are the internal intercostal muscles most active?

A

Forced respiration

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23
Q

A _______________ is the reason that air is drawn into and forced out of the lungs?

A

Pressure gradients

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24
Q

Is expiration a passive or active process?

A

Passive

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25
Q

What is the mechanism by which the ribcage, diaphragm and lung tissues return to their pre-inspiratory positions?

A

Elastic recoil

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26
Q

Put in broad terms, what are the factors which can regulate pulmonary ventilation?

A
  • Pressure gradients
  • Surface tension
  • Airway resistance
  • Lung compliance
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27
Q

What is meant by the term “compliance” in reference to lungs?

A

The ease with which the lungs and pleura expand and contract based on changes in pressure

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28
Q

What is airway resistance?

A

The friction that is generated when the air passes along the structures in the conduction and respiratory zones

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29
Q

What does Boyle’s law state?

A

That at a constant temperature, an increase in pressure causes a proportional decrease in volume

PV = k

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30
Q

In physiology, how is a unit of pressure conventionally measured?

A

Millimetres (mm) of mercury (Hg) - mmHhg

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31
Q

What does mmHg refer to?

A

The height of a column of mercury attached to an instrument which detects pressure

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32
Q

How many Pa is 1 mmHg equivalent to?

A

133 Pa

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33
Q

At sea level, the atmospheric pressure on Earth is about what?

A

760 mmHg

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34
Q

Describe the process of inhalation and exhalation in regards to pressure

A
  • During inhalation, the volume of the lungs increases and the pressure inside the lungs decreases below that of atmospheric pressure
  • This creates a pressure gradient which draws air into the lungs
  • During exhalation, the lungs return to their original size and pressure in the lungs rises compared with atmospheric pressure and air moves out
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35
Q

What is meant by the term “partial pressure”?

A

The pressure that one component of a mixture of gases would exert if it were alone in a container

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36
Q

How is partial pressure calculated?

A

By multiplying the percentage of the particular gas in the atmosphere by the total atmospheric pressure

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37
Q

What is the notation used to represent partial pressure?

A

An italicised ‘P’

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38
Q

What is meant by the term “surface tension”?

A

Chemical forces that hold liquids in their smallest surface area possible

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39
Q

What shape are the alveoli?

A

Round

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40
Q

In which direction does surface tension put pressure on the inside of the alveolus?

A

Inwards

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41
Q

How does the lung combat the surface tension of water to ensure that the alveoli can expand with each breath?

A

Cells within the alveoli secrete surfactant

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42
Q

What is a surfactant?

A

A phospholipid substance which breaks the surface tension of water by attaching to the water molecules and preventing them from interacting with each other

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43
Q

What is the surface tension in the alveolus reduced to thanks to the surfactant?

A

Near-zero levels

44
Q

What kind of effect can insufficient surfactant production cause?

A

Breathing difficulties

45
Q

What is compliance (with regard to lungs)?

A

The ease with which the lungs and pleura expand and contract based on changes in pressure

46
Q

What is the effect of low lung compliance on the pressure gradient needed to get lungs to expand and contract?

A

It means that a higher than normal pressure is needed

47
Q

What is the outcome of high lung compliance?

A

The lungs move in response to small changes in pressure which makes exhalation difficult because the elastic recoil is decreased

48
Q

High lung compliance is a characteristic of which disease?

A

COPD - chronic obstructive pulmonary disease

49
Q

Is the airflow resistance in a bronchiole higher or lower than in a bronchus?

A

Higher - the radius of a bronchiole is smaller than that of a bronchus. A smaller radius equals higher resistance

50
Q

How is lung capacity calculated?

A

From the volume of air that is exchanged during normal and forceful breathing

51
Q

With regards to breathing, what does resting tidal volume refer to?

A

The amount of air entering or leaving the lungs in a single normal breath

52
Q

What is the resting tidal volume of an average adult?

A

About half a litre

53
Q

What is inspiratory reserve volume?

A

The air you take when you take an extra deep breath

54
Q

What is expiratory reserve volume?

A

The extra volume you breathe out when you breathe out for as long as you can after a normal intake of breath

55
Q

What is the average inspiratory volume for an adult?

A

About 2 to 3 litres

56
Q

What is the average expiratory reserve volum for an adult?

A

About 1 litre

57
Q

What is “vital capacity”?

A

The sum of the tidal, inspiratory and expiratory volumes

58
Q

What is “total lung capacity”?

A

The sum of all the volumes, including the residual volume

59
Q

What does total lung capacity represent?

A

The maximum amount of air that the lungs can hold

60
Q

What is “residual volume”?

A

The amount of air left in the lungs in addition to the expiratory reserve volume

61
Q

What is “tidal volume”?

A

The amount of air entering or leaving the lungs in a single resting breath

62
Q

What is spirometry?

A

The test used to measure lung function

63
Q

What is “forced vital capacity” (FVC)?

A

The total volume of air that can be forcefully blown out

64
Q

What is “peak expiratory flow” (PEF)?

A

The maximum rate at which air is forcefully expired (litres per second)

65
Q

What is “forced expiratory volume” (FEV1)?

A

The amount of air that is forcibly blown out within the first second of a spirometry test

66
Q

What values are used to evaluate lung function?

A

The FEV1 (forced expiratory volume) and FVC (forced vital capacity) ratio

67
Q

What is the average FEV1/FVC (forced expiratory volume/forced vital capacity) ratio in healthy individuals?

A

0.8 - meaning that 80% of total volume of air is blown out within the first second (of a spirometry test)

68
Q

What biological/physiological factors can affect normal lung function?

A
  • Age
  • Height
  • Ethnicity
  • General fitness
69
Q

What happens to lung function with age in both men and women?

A

It decreases

70
Q

How is most O2 carried in the blood?

A

By erythrocytes which contain haemoglobin (Hb)

71
Q

What is haemoglobin formed of?

A

It is a protein which is formed of four polypeptide chains called globins

72
Q

What are the names of the two types of polypeptide chains which form haemoglobin?

A
  • Alpha

* Beta

73
Q

What is a haem group?

A

A small non-protein structure

74
Q

What are the molecules in the centre of a haem group?

A

An iron ion (FE2+), which binds to one O2 molecule

75
Q

How many O2 molecules can one Hb molecule carry

A

Four

76
Q

What is oxyhaemoglobin?

A

Haemoglobin which is bound to oxygen molecules

77
Q

What does oxyhaemoglobin do?

A

It transports oxygen from blood vessels in the lungs to the cells in the rest of the body

78
Q

Where in the lungs does oxygenation of haemoglobin occur?

A

In the capillaries surrounding the alveoli of the lungs

79
Q

What is the type of relationship which governs the binding of O2 to Hb?

A

Positive cooperativity

80
Q

What is positive cooperativity?

A

When the change in shape of the first subunit makes easier the binding of substrate to the second unit

81
Q

What form of Hb is predominant in the blood carried by the pulmonary arteries?

A

Deoxyhaemoglobin - pulmonary arteries carry CO2-rich blood, therefore deoxyhaemoglobin will be the predominant form of Hb in these vessels

82
Q

What is the binding and dissociation of O2 to and from haemoglobin dependent on?

A

The PO2 (partial O2 pressure)

83
Q

What does the term “affinity” refer to?

A

The strength of binding between two particles or proteins. Low affinity means the particles can be easily separated; high affinity means the binding is strong

84
Q

Does the binding of O2 to Hb have high or low affinity?

A

Low - this is why O2 is easily transferred to tissues

85
Q

During exercise, what happens to muscle cells?

A

They become more active and produce more CO2 and heat, which increases the acidity and content of the haemoglobin protein 2,3-diphosphoglyceric acid (DPG)

86
Q

With regards to oxygen saturation, what is P50?

A

A representation of haemoglobin-oxygen affinity

87
Q

What is the normal P50?

A

26.7 mmHg

88
Q

When CO2 levels are low, does the affinity of haemoglobin for oxygen increase or decrease?

A

Increase

89
Q

What are the biological factors which affect the affinity of Hb binding of O2?

A
  • CO2
  • Acidity
  • 2,3-DPG
  • Exercise
  • Temperature
90
Q

What is the Bohr effect?

A

The decrease in the oxygen affinity of haemoglobin in the presence of high pH or high CO2. It manifests as a right-shift in the Oxygen-Haemoglobin Dissociation Curve

91
Q

The chemical reaction between water and CO2 generates what?

A
  • Bicarbonate

* Hydrogen protons

92
Q

Do hydrogen ions increase or decrease the pH of a solution?

A

Decrease

93
Q

What is the acid which is formed when carbon dioxide combines with water in the erythrocytes?

A

Carbonic acid

94
Q

The reaction between carbon dioxide and water is facilitated by which enzyme?

A

Carbonic anhydrase

95
Q

What does carbonic acid dissociate into?

A
  • A bicarbonate ion

* A proton

96
Q

What is the chloride shift?

A

The process where chloride ions move into erythrocytes from the blood in order to balance its charge

97
Q

What is carbaminohaemoglobin?

A

Haemoglobin which is bound to carbon dioxide

98
Q

In the alveoli, binding of O2 to HbH+ (protonated haemoglobin) results in what?

A

The release of free H+ ions

99
Q

What is the Haldane effect

A

The influence of oxygen on haemoglobin transport of carbon dioxide

100
Q

Which gas greatly reduces the capacity of blood to carry O2?

A

Carbon monoxide - because the affinity for Hb is higher than the affinity oxygen

101
Q

The replacement of which amino acid disrupts the structure of haemoglobin and causes sickle cell anaemia?
What amino acid replaces it?

A
  • Glutamic acid

* Valine

102
Q

How is sickle cell denoted?

A

HbS

103
Q

Why do the erythrocytes change shape in sickle cell anaemia?

A

Because glutamic acid normally helps Hb retain its shape

104
Q

How long do sickled cells live in comparison to normal erythrocytes?

A

20 days instead of 120 days

105
Q

If you were heterozygous for the HbS (sickle cell) allele, will you develop sickle cell anaemia?

A

No - you would have one mutated allele, and one normal allele. Sickle cell is recessive, therefore two mutated alleles must be present

106
Q

What are thalassaemias?

A

A group of recessive disorders which cause anaemia due to the decreased/absent synthesis of a globin chain of haemoglobin

107
Q

How many alleles is disease susceptibility to thalassaemias dependent on?

A

Four

SK299 (15 decks)

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