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BDS Stage 1 > Respiratory System > Flashcards

Respiratory System Flashcards

To stay awake

1
Q

What are some common respiratory conditions?

A 
Asthma
Emphysema
Cystic Fibrosis
Chronic Bronchitis
COPD (Chronic obstructive pulmonary disease)
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2
Q

What are the main functions of the respiratory system?

A 
Gas exchange (atmosphere + blood) (blood + tissue)
Regulation of body pH (CO2 release)
Vocalisation 
Protection
Synthesis of hormones
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3
Q

What forms the upper respiratory tract?

A

Nasal Cavity
Pharynx
Vocal Cord
Larynx

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4
Q

What is the function of the upper respiratory tract?

A

Warm
Humidify
Filter
Vocalise

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5
Q

What is asthma?

A

Respiratory condition caused by inflammation and spasms of the bronchioles. Usually triggered due to hypersensitivity.

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6
Q

What is emphysema?

A

Air sacs of the lungs are damaged and enlarged. Common in smoking and causes breathlessness

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7
Q

What is cystic fibrosis?

A

Production of thick mucus which leads to the blockade of bronchi, often results in respiratory infection.

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8
Q

What forms the lower respiratory tract?

A

Trachea
Bronchi
Bronchioles
Alveoli

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9
Q

What are the functions of the lower respiratory tract?

A

Conduct Air
Stabilise conductive airways
Regulate flow
Gas Exchange

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10
Q

What keeps the trachea open?

A

U-shaped cartilage rings and the trachealis muscle.

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11
Q

What important reflex does the trachealis muscle facilitate?

A

Coughing

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12
Q

What keeps the bronchi open?

A 
Cartilage Rings (Upper)
Plates (Lower Parts)
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13
Q

What is the function of goblet cells?

A

Secrete mucus to coat the respiratory tract

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14
Q

What is the function of ciliated cells?

A

Sweep mucus upwards to the pharynx, to be swallowed

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15
Q

What is the combined function of goblet and ciliated cells called?

A

The mucociliary escalator

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16
Q

What is the structure of Bronchioles?

A

Small diameter

Smooth muscle walls

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17
Q

How are bronchioles diameter regulated?

A 
Histamines constrict bronchioles
Parasympathetic NS (Acetylcholine induce bronchoconstriction)
Sympathetic NS (Noradrenaline induces bronchodilation)
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18
Q

What is the structure of Alveoli?

A

Single cell width
Side facing capillaries - ‘leaky’ for gas exchange
Supporting side - Elastic fibres (collagen IV) , robust

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19
Q

What blood vessels supply the respiratory zone

A 
Pulmonary Artery (deoxygenated blood)
Capillary Network (Increases gas exchange)
Pulmonary Vein (oxygenated blood)
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20
Q

What is the respiratory zone?

A

Consists of the ends of the bronchioles, alveoli and the vessels that support them.

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21
Q

How many types of Alveolar cells are there?

A

2-
Cell Type I (gas exchange)
Cell Type II (Production of surfactant)

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22
Q

What does surfactant do?

A

Reduces surface tension and prevents alveoli from collapsing

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23
Q

What are the pores of Kohn?

A

They allow for intra-alveolar ventilation

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24
Q

What do macrophages do related to the alveoli?

A

They protect from small particles and ingest degraded surfactant

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25
Q

Which part of the respiratory tract has the highest resistance?

A

The bronchi

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26
Q

What does flow rate ely on?

A

Viscosity of the gas
Airway resistance
Flow pattern (turbulence)

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27
Q

What conditions can increase resistance?

A

Inflamed airways,

Increased mucus secretion

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28
Q

What is a ‘shunt’?

A

When blood from the bronchiolar artery draining into pulmonary circulation.

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29
Q

What membrane lines the thoracic wall?

A

The parietal pleura

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30
Q

What membrane lines the surface of the lungs?

A

Visceral Pleura

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31
Q

Why is intrapleural pressure less than atmospheric cavity?

A

As the lungs and chest wall are pulling away from each other.

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32
Q

What is boyle’s law?

A

If volume increases, pressure will decrease

P1 x V1 = P2 x V2

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33
Q

How does standing upright help breathing?

A

Gravity facilitates the diaphragm lowering.

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34
Q

What is lung compliance?

A

How easily the lung can be inflated and emptied

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35
Q

How do you calculate compliance?

A

Change in volume/change in pressure

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36
Q

What affects lung compliance?

A

The elasticity of the lung

Surface tension in the alveoli

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37
Q

How is lung compliance limited?

A

As the college fibres have limited length

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38
Q

What is the law of LaPlace?

A

P =2T/r

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39
Q

What does a spirometer do ?

A

monitors the volume of air inspired and expired usually done under quiet breathing and no time restraitnts

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40
Q

What is a lung volume ?

A

A single difference

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41
Q

What is a lung capacity ?

A

the sum of 2 or more lung volumes

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42
Q

What is tidal volume ?

A

volume of air that moves during a single inspiration or expiration (500 ml)

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43
Q

What is inspiratory reserve volume ?

A

Additional air you inspire on top of tidal volume

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44
Q

What is expiratory reserve volume ?

A

Amount of air forcefully exhaled at the end of normal expiration

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45
Q

What is residual volume ?

A

the volume of air remaining in the respiratory system after maximum exhalation

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46
Q

What is vital capacity ?

A

inspiratory reserve volume + expiratory reserve volume + tidal volume

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47
Q

What is total lung capacity ?

A

vital capacity + residual volume

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48
Q

What is functional residual capacity ?

A

Expiratory reserve volume + residual volume

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49
Q

What are dynamic measurements ?

A

they assess the time taken to exhale a certain volume of air

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50
Q

What is FEV ?

A

forced expired volume

How fast air leaves the airways in 1 second

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51
Q

What is FVC ?

A

Forced vital capacity

the defined amount of air that can be forcibly exhaled from the lungs after taking the deepest breath possible

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52
Q

What are the characteristics of restrictive lung disease ?

A

FVC reduced

FEV close to normal

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53
Q

What are the characteristics of obstructive lung disease ?

A

FEV reduced

FVC close to normal

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54
Q

What is a pneumothorax?

A

Presence of air in the cavity between the lung and the thoracic cavity.

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55
Q

What factors affect gas exchange?

A

Sufrace area
Thickness of the membrane
Concentration gradient
Solubility of the gas

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56
Q

What is meant by the term dead space?

A

Airways that are ventilated but not designed for gas exchange (perfusion)

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57
Q

What is the consequence of dead space on alveolar air?

A

When breathing in ‘used’ air, remaining from previous expiration, re-enters the alveolar space and ‘dilutes’ the fresh air.

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58
Q

What does the fowlers method measure?

A

Anatomic dead space

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59
Q

What does dalton’s law state?

A

The total pressure of a gas mixture is equal to the sum of partial pressures of the individual gases

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60
Q

How do you calculate diffusion capacity?

A

Rate of gas transfer from lung to blood/ driving partial pressure

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61
Q

How does emphysema affect gas exchange?

A

Destruction of alveoli means less surface area for gas exchange

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62
Q

How does asthma affect gas exchange?

A

Increased airway resistance decreases airway ventilation

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63
Q

How does pulmonary oedema affect gas exchange?

A

Fluid in interstitial space increases diffusion distance.

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64
Q

What are the boundaries of the thorax ?

A

posteriorly - thoracic vertebrae
laterally-ribs
anteriorly - sternum

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65
Q

How many thoracic vertebrae are there ?

A

12

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66
Q

What are the features of a typical thoracic verebra ?

A

body-heart shaped
spinous process-long and slender
articular process - on the body for the rib above
costovertebral facets - these are the superior and inferior demi facets
costotransverse facets - facets on the transverse processes

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67
Q

What are the features of a rib ?

A

head- facets for articulation with the demi facets in the vertebra
neck - enlarged bit is the crest
Tubercle - between the neck and the body - articulates with the facets on the transverse processes
Costal groove - on the internal inferior surface in which the neurovascular bundle runs
pit - joins to the costal cartilages

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68
Q

What are the 3 parts of the sternum ?

A

the manubrium , body and the xiphoid process

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69
Q

What are the 3 notches on the manubrium of the sternum ?

A

sternal notch
clavicular notch
notches for the costal cartilages of the first rib

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70
Q

What is the structure between the manubrium and the body of the sternum ?

A

the angle of louis or the sternal angle

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71
Q

What type of joint is the angle of louis ?

A

Symphysis

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72
Q

What structures bind the thoracic inlet ?

A

body of the first thoracic vertebra
1st rib
manubrium of the sternum
roofed by pleura

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73
Q

What does the thoracic inlet transmit ?

A 
trachea
oesophagus 
carotid artery 
subclavian arteries 
internal jugular veins 
brachial veins 
vagus nerve 
phrenic nerve
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74
Q

What are the boundaries of the thoracic outlet ?

A

body of the 12th vertebra
lower ribs
xiphoid cartilage
closed by the diaphragm

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75
Q

What does the thoracic outlet transmit ?

A 
oesophagus 
dorsal aorta 
inferior vena cava
vagus nerve
phrenic nerve
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76
Q

What are costovertebral joints ?

A

articulations between the facets on the head of the rib and the facts on demi facets on the vertebra

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77
Q

What type of joints are the costovertebral joints ?

A

synovial - depression and elevation

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78
Q

What are the costotransverse joints ?

A

articulations between the facets on the transverse processes and the tubercle of the rib

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79
Q

What are costochondral joints ?

A

joints between the costal cartilages and the distal ends of the ribs
synchondroses

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80
Q

What are chondrosternal joints ?

A

between costal cartilages and the sternum

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81
Q

What are interchondral joints ?

A

between the costal cartilges

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82
Q

What is the type of joint between the manubrium and the first rib ?

A

Synchondrosis

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83
Q

What type of action do ribs perform ?

A

lever action

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84
Q

What happens to the ribs in ventilation ?

A

they elevate causing an increase in thoracic dimensions

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85
Q

How do the a-p and transverse diameters increase ?

A

anterior rib ends rise and protrude more

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86
Q

What are the precise movements of ribs 3 and 6 ?

A

elevation occurs by rotation at the neck - increasing a-p dimensions

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87
Q

What are the precise movements of ribs 7 and 10 ?

A

elevation occurs by sliding outwards and backwards increasing transverse dimensions

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88
Q

What are the intercostal muscles ?

A

the external
the internal
the innermost

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89
Q

What do the external intercostal muscles do ?

A

pass from rib to rib in an anteroinferior direction

they elevate the ribs in inspiration

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90
Q

What do the internal intercostal muscles do ?

A

pass from rib rib in perpendicular to the external intercostal muscles - they depress the ribs in inspiration

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91
Q

What do the innermost intercostal muscles do ?

A

the internal and the innermost muscles are separated by the neurovascualr bundles - intercostal arteries , nerves and veins - VAN

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92
Q

What is the thoracic cavity divided into ?

A

the right and left pleural cavities

the mediastinum

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93
Q

What do the pleural cavities contain and what are they lined with ?

A

they contain the lungs and are lined with pleura

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94
Q

What are the 2 types iof pleura ?

A

parietal

visceral

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95
Q

What is the parietal pleura ?

A

covers the inner aspect of the pleural cavity

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96
Q

What is the visceral pleura ?

A

covers the lungs

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97
Q

What is between the parietal and the visceral pleura ?

A

the pleural cavity - contains the pleural fluid

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98
Q

What is the costodiaphragmatic recess ?

A

a space between the lungs and the diaphragm created by the pleura

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99
Q

What are the fissures in the left lung ?

A

the oblique fissure creates the upper and lower lobes

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100
Q

What are the fissures of the right lung ?

A

the horizontal and the oblique fissures create the upper middle lower lobes

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101
Q

What is the depression found in the left lung ?

A

the cardiac notch to contain the heart

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102
Q

What is on the mediastinal aspect of each lung ?

A

the hilum of the lung - entrance for blood vessels and the tubes

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103
Q

What are the structures found in the hilum ?

A

primary bronchus
2 pulmonary veins
pulmonary artery
bronchial arteries - associated with the primary bronchus

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104
Q

What are the differences between the right and left primary bronchi ?

A

the right primary bronchus is wider and more vertical - more likely to find foreign bodies lodged in here

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105
Q

What are the 4 surfaces of the heart ?

A

apex
diaphragmatic surface
costal surface
mediastinal surface

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106
Q

Where can you find the intercostal NV bundle ?

A

running in the costal grooves of the ribs

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107
Q

Where does the intercostal nerve arise from ?

A

primary ramus of a thoracic spinal nerve

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108
Q

What are the branches of the descending aorta in the thorax ?

A

the posterior intercostal arteries and paired pericardial, oesophageal and bronchial arteries.

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109
Q

What is a bronchopulmonary segment ?

A

a segment of lung tissue with its own bronchus and blood supply which acts independent of other segments - can be removed without causing damage

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110
Q

Which branches of the subclavian artery provide an arterial supply to the thorax ?

A

internal thoracic artery and the costocervical trunk

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111
Q

What type of joints are formed between the head of the rib and the demifacets ?

A

synovial

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112
Q

How does the head of the rib articulate with the vertebra ?

A

the head of the rib articualtes with the same thoracic vertebra and the one above - form a full circle from the demi facets

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113
Q

What do ribs 11 and 12 lack ?

A

a transverse facet

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114
Q

What do the intercostal nerves supply ?

A

they supply the intercostal muscles and the skin supplying the space between the ribs

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115
Q

What is the origin of the sympathetic fibres found in the intercostal nerves ?

A

the ganglia of the sympathetic chain

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116
Q

Where do the fleshy fibres of the diaphragm insert ?

A

into the central tendon

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117
Q

What is the morphology of te diaphragm ?

A

double domed

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118
Q

What type of muscle is the diaphragm ?

A

skeletal muscle

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119
Q

What are the 2 recesses assocaited with the diaphragm ?

A

costomediastinal reccess

costodiaphragmatic reccess

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120
Q

Where is the costodiaphragmatic recess ?

A

within the lung

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121
Q

Where is the costomediastinal recess ?

A

between the parietal pleura and the costal pleura

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122
Q

What are the attachments of the diaphragm ?

A

sternal
costal
verterbral
lumbocostal arches

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123
Q

What is the sternal attachment of the diaphragm ?

A

Xiphoid process

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124
Q

What is the costal attachment of the diaphragm ?

A

lower 6 costal cartilages

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125
Q

What are the vertebral attachments of the diaphragm ?

A

left and right cruae and lumbocostal arches

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126
Q

What are the right and left crue ?

A

they are the parts of the diaphragm that arise from the vertebrae

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127
Q

Where does the right crus arise from ?

A

arises from L1-L3 and some fibres form around the oesophageal opening

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128
Q

Where does the left crus arise from ?

A

from L1-L2

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129
Q

What are the types of lumbocostal arches ?

A

median and lateral

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130
Q

What are the 3 diaphragmatic apertures ?

A

caval
oesophageal
aortic

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131
Q

What is the aortic aperture ?

A

T12 Passes between the fibres of the 2 crura

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132
Q

What is the oesophageal apertures ?

A

made from the fibres of the right crura

T10

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133
Q

What is the caval opening ?

A

the inferior vena cava passes through this opening in the central tendon at T8

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134
Q

What passes through the caval hiatus ?

A

the inferior vena cava

right phrenic nerve

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135
Q

What passes through the oesophageal hiatus ?

A

oesophagus

right and left vagus nerves

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136
Q

What passes through the aortic hiatus ?

A

descending aorta
thoracic duct
azygous vein
sympathetic chains

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137
Q

What is the motor innervation of the diaphragm ??

A

the anterior ramii of C3-C5 that form the phrenic nerve

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138
Q

What is the sensory innervation of the diaphragm ?

A

centrally - phrenic nerve

laterally - lower 5 intercostal nerves

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139
Q

What are the functions of the diaphragm ?

A 
ventilation-regulation of thoracic pressure 
micturition 
parturition
daefacation 
lifting
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140
Q

What does the anterior abdominal wall consist of ?

A

1 central vertical muscle which is rectus abdominis

3 flat lateral muscles - internal oblique , external oblique and transversus abdominis

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141
Q

What is the transversalis fascia ?

A

a layer of fascia found depp to the transversus abdominis

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142
Q

What are the attachments of the rectus abdominis ?

A

attaches between the ribs and the pubic bone

3 transverse tendinous bands that join to the linea alba

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143
Q

What are the attachments of the external oblique ?

A

Arises from the lower 8 ribs and inserts into the linea alba , pubic bone , inguinal ligament and iliac crest
runs inferomedially

144
Q

What are the attachments of the internal oblique ?

A

Runs superomedially

Arises from below the pelvis and iliac crest and inserts into the costal margin and the linea alba

145
Q

What are the attachments of the transversus abdominis ?

A

Arises from the lower 6 ribs and lumbar fascia , iliac crest and the inguinal ligament and inserts into the linea alba

146
Q

What is the innervation of the muscles of the anterior abdominal wall ?

A

T7-L1 intercostal nerves which run between internal oblique and transversus abdominis

147
Q

What are the functions of the muscles of the anterior abdominal wall ?

A

trunk movements
abdominal pressure regulation
expiration - accessory muscles

148
Q

How much blood do the lungs receive per minute?

A

5l/min

149
Q

How much air do the lungs receive per minute?

A

5l/min

150
Q

Why is interpleural pressure less than atmospheric pressure?

A

Because the lungs and chest wall pull away from each other.

151
Q

What challenges does the pulmonary circulation face?

A

The right ventricle can’t generate high pressure.

152
Q

How does the pulmonary circulation overcome its challenges?

A

The vascular resistance in the pulmonary circulation is 1/10th that of the systemic circulation.

153
Q

How can you assess ventilation and perfusion in the lungs?

A

Insert a radioactive compound into airspaces of the lung and into veins of the lung.
‘Mismatch’ of compounds highlights areas where either ventilation or perfusion is affected.

154
Q

What does V/Q stand for?

A

Ventilation/Perfusion ratio.

155
Q

What can cause a high V?Q?

A

High alveolar O2 caused by vasodilation

Low alveolar CO2 caused by bronchoconstriction

156
Q

What is hypoxic pulmonary vasoconstriction (HPV)?

A

This is when small arteries in the lungs constrict in hypoxic conditions. This redirects blood flow to well ventilated regions increasing V/Q

157
Q

How is HPV linked to birth?

A

In utero the lungs aren’t ventilated, therefore after birth when O2 reaches the lungs HPV is lifted and perfusion greatly increases

158
Q

What is COPD?

A

Chronic obstructive pulmonary disease

159
Q

How is HPV linked to COPD?

A

In COPD ventilation in certain areas are low.
This trigger HPV.
Resistance increases, Pulmonary BP increases which could lead to right ventricular heart failure

160
Q

What is venous admixture?

A

When blood passes through the lung without being properly oxygenated

161
Q

What can cause venous admixture?

A

Anatomical Shunt - Blood bypasses the lungs through an anatomical channel

Low V/Q - When there is more blood in capillary than can be fully oxygenated (tumours, oedemas)

162
Q

What are the risk of high levels of oxygen?

A

High levels may reduce ventilation and cause CO2 retention causing the pH to fall
Relatively little CO2 will enter the alveoli, this ay cause the alveoli to collapse

163
Q

What is the direction of movement of Rectus Abdominis ?

A

downwards

164
Q

What is the direction of movement of transversus abdominis ?

A

medially

165
Q

What is the direction of movement of external oblique ?

A

inferomedially

166
Q

What is the direction of movement of Internal oblique ?

A

Superiomedially

167
Q

What is the solubility of oxygen?

A

3ml/l

168
Q

What is the consumption of O2 at rest?

A

250 ml/min

169
Q

FUCK THE ITALIANS!!!!

A

GO ESKIMOS

170
Q

What is the required cardiac output to match consumption and solubility (without haemoglobin)?

A

84litres/minute

171
Q

What would the heart rate be without haemoglobin?

A

Around 1200 beats/min

172
Q

With haemoglobin what is the solubility of O2?

A

200ml/l

173
Q

What is the over capacity of oxygen transport?

A

Under normal CO (5l) there is 4x over capacity

174
Q

What is the structure of adult haemoglobin?

A

2 alpha subunit
2 beta subunits
4 haem groups

175
Q

What is the structure of foetal haemoglobin?

A

2 alpha subunits

2 delta subunits

176
Q

What % of erythrocyte mass is Hb?

A

Around 33%

177
Q

Why do males have higher Hb % than females?

A

As androgens cause vasoconstriction.

178
Q

Where does CO2 bind to haemoglobin?

A

The N-terminus of Hb

179
Q

Why does the initial binding of 02 to a haem group promote further binding?

A

It forms an allosteric change in structure which promotes further binding.

180
Q

What is 2-3 DPG (Diphosphoglycerate)?

A

Produced in RBC’s, increases offload of oxygen to tissues at low P(O2)

181
Q

What is important about Foetal Hb?

A

It has a higher affinity for oxygen than the maternal hb, this means it ‘steals’ oxygen from the mother blood.

182
Q

What is Anoxia?

A

Complete deprivation of oxygen

183
Q

What is hypoxia?

A

Reduced oxygen supply

184
Q

What is cyanosis

A

02 saturated haemoglobin is purple. Reduced saturation causes bluish discolouration of the skin and mucous membranes

185
Q

What is Hypercapnia?

A

Increased levels of CO2

186
Q

How is CO2 spread in the body?

A

7% is soluble
23% is bound to Hb
70% is found in Bicarbonate

187
Q

Why is bicarbonate important?

A

It is an important buffer in the blood

188
Q

What is the Bohr effect?

A

Protons reduce Hb’s affinity for O2

189
Q

What is the haldane effect?

A

CO2 reduces Hb’s affinity for O2

190
Q

What are the main goals of the respiratory system ?

A

ensure alveolar ventilation is sufficient to maintain gas pressure
adapt ventilation to physiological or metabolic need
integrate ventilation with non respiratory activities

191
Q

What do peripheral chemoreceptors sense ?

A

mainly oxygen

192
Q

What are the 2 locations of the peripheral chemoreceptors ?

A

aortic bodies and the carotid bodies

193
Q

How much of the response to oxygen to peripheral chemoreceptors mediate ?

A

100%

194
Q

How much of the response to carbon dioxide do central chemorecepetors mediate ?

A

15%

195
Q

Are peripheral or central chemoreceptors quicker at responding to carbon dioxide ?

A

peripheral

196
Q

What potentiates the oxygen response ?

A

low pH and high co2

197
Q

Where does the sensory information go ?

A

respiratory centre in the medulla

198
Q

How does sensory info from the aortic bodies get to the respiratory centre ?

A

vagus nerve

199
Q

How does sensory info get from the carotid bodies to the respiratory centre ?

A

glossopharyngeal nerve

200
Q

What are type 1 glomus cells ?

A

peripheral chemoreceptors located in carotid bodies and aortic bodies

201
Q

What are type 2 glomus cells involved in ?

A

support

202
Q

What are the characteristics of glomus cells ?

A

well perfused - able to detect changes in oxygen quickly

high metabolic rate - any drops in oxygen are detected

203
Q

Is there a high intensity of signal transmission when you remove oxygen ?

A

yes - via the glossopharyngeal nerve

204
Q

Is there a higher rate of ventilation or lower when co2 increases and pH drops ?

A

higher - more signla transmission via the glossopharyngeal nerve

205
Q

How is a low oxygen level detected ?

A 
low oxygen in the blood 
potassium channels close 
cell depolarises 
voltage gated calcium channels open 
calcium entry 
exocytosis of dopamine vesicles 
binding of dopamine receptors 
signals to medullary centres to increase ventilation via glossopharyngeal
206
Q

At what pressure of oxygen does ventilation start to become responsive to low O2 ?

A

60 mmHg

207
Q

What is the effect of decreasing oxygen as well as carbon dioxide on the ventilatory response ?

A

potentiates the response - slope become steeper as both stimuli come together to stimulate the ventilatory response

208
Q

What is the main parameter for the ventilatory response ?

A

carbon dioxide

209
Q

What is the blood-brain barrier impermeable to ?

A

bicarbonate and protons

210
Q

What easily diffuses across the blood-brain barrier ?

A

carbon dioxide

211
Q

What happens to c02 in the cerebral capillaries ?

A

co2 diffuses across the BBB into the CSF where the reaction with water (catalysed by carbonic anhydrase) turns into carbonic acid and then protons and bicarbonate

212
Q

What happens to the protons ?

A

they are detected by the central chemoreceptors

signals sent to respiratory control centre and there is increased ventilation to counter act

213
Q

Where are the central chemoreceptors located ?

A

in the venterolateral surface of the medulla and are bathed in CSF

214
Q

What does an increase in Co2 do to ventilation ?

A

linear response

215
Q

At what level of c02 is there no change in ventilation ?

A

30 mmhg

216
Q

What happens if oxygen and carbon dioxide levels are both decreased ?

A

the 2 stimuli potentiate other - oxygen and carbon dioxide have synergic effects

217
Q

What effect does acidosis have on the ventilation rate ?

A

there is a higher ventilation rate - steeper slopes representing more sensitivity - the proton and the carbon dioxide response potentiate one another to produce a bigger change in ventilation

218
Q

What happens during sleep or a narcotic overdose ?

A

there is a reduced sensitivity to oxygen (right shift)

higher tolerance of co2

219
Q

What happens in heroin overdose ?

A

less response to carbon dioxide
forget to breathe
autonomous activity not stimulated enough

220
Q

What happens in the instance of ‘death in shallow water’ ?

A

hyperventilation reduces pCO2 (30 mmhg-no response) and a moderate increase in oxygen
the ventilatory drive is reduced and the oxygen deficit is overruled so ventilation decreases - die due to o2 deficit

221
Q

Where are peripheral chemoreceptors located ?

A

carotid bodies and aortic arch

222
Q

What do peripheral chemoreceptors sense ?

A

pH co2 and O2

223
Q

What is the relative speed of peripheral chemoreceptors ?

A

relatively quick

224
Q

Where are central chemoreceptors located ?

A

floor of the 4th ventricle bathed in CSF

225
Q

What do the central chemoreceptors sense ?

A

c02

226
Q

`What is the relative speed of central chemoreceptors ?

A

relatvely slow

227
Q

What provides the major ventilatory drive for central chemoreceptors ?

A

carbon dioxide

228
Q

What are the advantages of using a carbon dioxide based system ?

A

carbon dioxide production is related to oxygen consumption
Carbon dioxide production is related to pH
Linear relationship - Carbon dioxide changes are buffered by changes in pH

229
Q

What are the 3 types of receptors related to vagal afferent reflexes ?

A

slowly adapting pulmonary stretch receptors
rapidly adapting pulmonary receptors (irritant)
J receptors

230
Q

Where are the stretch receptors located ?

A

large airways and the visceral pleura

231
Q

What do the stretch receptors detect ?

A

stretch detected by thoracic cavity expansion

232
Q

What is the effect of activating the stretch receptors ?

A

signals are sent to he respiratory centre when expanded enough to terminate inspiration and limit tidal volume
extedn expiration

233
Q

What is an exmaple of the use of stretch receptors ?

A

herring-breuer reflex

234
Q

Where are peripheral chemoreceptors located ?

A

carotid bodies and aortic arch

235
Q

What do peripheral chemoreceptors sense ?

A

pH co2 and O2

236
Q

What is the relative speed of peripheral chemoreceptors ?

A

relatively quick

237
Q

Where are central chemoreceptors located ?

A

floor of the 4th ventricle bathed in CSF

238
Q

What do the central chemoreceptors sense ?

A

c02

239
Q

`What is the relative speed of central chemoreceptors ?

A

relatvely slow

240
Q

What provides the major ventilatory drive for central chemoreceptors ?

A

carbon dioxide

241
Q

What are the advantages of using a carbon dioxide based system ?

A

carbon dioxide production is related to oxygen consumption
Carbon dioxide production is related to pH
Linear relationship - Carbon dioxide changes are buffered by changes in pH

242
Q

What are the 3 types of receptors related to vagal afferent reflexes ?

A

slowly adapting pulmonary stretch receptors
rapidly adapting pulmonary receptors (irritant)
J receptors

243
Q

Where are the stretch receptors located ?

A

large airways and the visceral pleura

244
Q

What do the stretch receptors detect ?

A

stretch detected by thoracic cavity expansion

245
Q

What is the effect of activating the stretch receptors ?

A

signals are sent to he respiratory centre when expanded enough to terminate inspiration and limit tidal volume
extedn expiration

246
Q

What is an exmaple of the use of stretch receptors ?

A

herring-breuer reflex

247
Q

Where are rapidly adapting (irritant) pulmonary receptors found ?

A

underneath airway epithelium at bifurcations

248
Q

What do rapidly adapting pulmonary receptors (irritant) detect ?

A

flow (rate of change)

249
Q

When are rapidly adapting receptors most active ?

A

when a person inhales noxious substances

250
Q

Where are pulmonary C fibre (J receptors) found ?

A

juxtapulmonary capillaries

251
Q

When are J receptors triggered ?

A

when the lung is diseased - pulmonary eedema and the release of histamine

252
Q

What type of breathing pattern is triggered with the J receptors ?

A

aponea followed by rapid shallow breathing

253
Q

What are the 2 neurogenic control systems ?

A

voluntary and involuntary

254
Q

Which part of the brain initiates voluntary control ?

A

cerebral cortex

255
Q

Where are the signals from the voluntary control system sent ?

A

respiratory centre in the medulla

256
Q

What produces the response in the voluntary control system ?

A

respiratory muscles

257
Q

Inhibitory and excitatory neurones display what ?

A

reciprocal innervation - they are mutually inhibitory

258
Q

The voluntary and involuntary systems are ….

A

independent of one another and can be overrriden

259
Q

What do both the voluntary and involuntary systems require ?

A

descending pathways - alpha motoneurones to the respiratory muscles and descneding pathways

260
Q

Which muscle system controls the muscles of respiratory ventialtion ?

A

somatic motor system

261
Q

What does the Autonomic nervous system control ?

A

smooth muscle contraction and secretion

262
Q

Where are the 2 respiratory centres ?

A

in the pons and the medulla

263
Q

What is the role of the pons ?

A

modulation

264
Q

What is the role of the medulla ?

A

the medulla is the site of the rhythmic respiratory centre and it generates the automatic breathing pattern

265
Q

What is the medulla made of ?

A

2 groups of neurones - the DRG and the VRG

266
Q

What does the DRG do ?

A

generates the inspiration firing pattern and hence the inspiratory drive
output via the phrenic nerve activates respiratroy muscles and initiates inspiration

267
Q

What does the VRG do ?

A

mainly expiratory neurones (at the ends)

some inspiratory neurones are found in the pre-botzinger complex

268
Q

What is the pre-botzinger complex ?

A

found in the VRG centrally

a rhythm generator - cells within it generate the basic rhythm

269
Q

Destruction of the VRG and the DRG leads to ?

A

immediate and permanent termination of automatic respiration

270
Q

During inhalation what is the activity of inspiratory neurones , phrenic nerve and the external intercostal nerves ?

A

inspiratory neurones fire
phrenic nerve increases activity
external intercostal nerves fire

271
Q

During exhalation what is the activity of the phrenic , expiratory neurones and internal intercostal neurones ?

A

expiratory neurones fire
reduced activity of the phrenic and the external intercostal
internal intercostal neurones fire

272
Q

What is cheyne-stokes respiration ?

A

deeper and faster breathing followed by apnea

273
Q

What causes cheyne-stokes respiration ?

A

over and under correction of pC02 due to increased transit time between the lung and the carotid body

274
Q

The conducting airways are .. ?

A

ventilated but not perfused

275
Q

The conducting airways are known as ?

A

dead space - no gas exchange takes place

276
Q

Why does some air enter the respiratory system but not reach the alveoli ?

A

because part of each breath remains in the airways like the trachea and the bronchi

277
Q

What is the anatomic dead space ?

A

the volume of the conducting airways (150 ml)

278
Q

What is the alveolar dead space ?

A

the volume of air in the alveoli that is ventilated but not perfused due to V/Q mismatch

279
Q

What is the physiologic dead space ?

A

anatomic air space + alveolar dead space

280
Q

In animals how big is the anatomic dead space ?

A

1/3 of tidal volume

281
Q

What happens in the dead space at the end of inspiration ?

A

the anatomic dead space is filled with fresh air at the end of inspiration (150)

282
Q

What happens in the dead space during expiration of tidal volume ?

A

the first exhaled air comes out of the dead space
150 ml comes out the dead space
350 ml is left in the alveoli

283
Q

What happens to the dead space at the end of expiration ?

A

it is filled with stale air

284
Q

If you inhale 500 ml of air what happens ?

A

the dead space is filled with air (150)so this goes to the alveoli- so only 350 actually reaches the alveoli

285
Q

How can we measure anatomic dead space ?

A

using fowlers method

286
Q

Describe fowlers method ?

A

one breath of pure oxygen (any gas that doesnt contain nitrogen)
gas that doesnt take place in alveolar gas exchange is exhaled first and the alveoalr air

287
Q

What does henrys law state ?

A

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

288
Q

What is the order of solubility of co2 , o2 and n2 ?

A

CO2 > O2 > N2

289
Q

Oxygen being poorly soluble is compensated by the fact that ?

A

it has a large pressure gradient

290
Q

What compensates for the low c02 pressure gradient ?

A

the high solubility of carbon dioxide

291
Q

How is diffusion capacity optimised in the lungs ?

A

the shape of type 1 alveoalr cells

fused basement membranes

292
Q

What does diffusion capacity measure ?

A

the amount of gas travelling from the alveolar dead space to the blood

293
Q

How do you calculate diffusion capacity ?

A

rate of gas transfer from lung to blood / driving partial pressure

294
Q

What does diffusion capacity depend on ?

A

solubility of the gas

295
Q

When is Diffusion capacity impaired ?

A

in respiratory diseases

296
Q

Which parts of the lung are poorly perfused and why ?

A

apex due to limited force of contraction of the right ventricle

297
Q

What does the efficiency of the lung depend on ?

A

diffusion and perfusion

298
Q

What happens in a perfusion limited scenario ?

A

there is not enough blood to carry away thr gas transferred
rapid transfer of gas between the alveolus and the blood
equilibrium is reached before the end of the capillary bed

299
Q

Which molecules are perfusion limited ?

A

n20 and 02

300
Q

What happens in a diffusion limited scenario ?

A

slow transfer of gas across the blood and alveolus interface
equilibrium is not reached in transit time

301
Q

The lung receives how much blood from the cardiac output ?

A

5L / min

302
Q

How can we measure ventilation using Xe 133 ?

A

Xe 133 is inhaled and it distributes evenly in the alveolar space
radiograph shows that the apex is fainter showing that it is well ventilated

303
Q

What is the normal ventilation/perfusion ratio ?

A

1 (5/5)

304
Q

At the beginning of inspiration intrapleural pressure is what ?

A

-3 mmhg

305
Q

As inspiration proceeds what do the pleural membranes and lungs do ?

A

they follow the expanding rib cage

306
Q

Why is intrapleural pressure less than atmospheric pressure ?

A

because the lungs and chest wall pull away from each other

307
Q

What effect does gravity have on the alveoli ?

A

the weight of the lung means that alveoli at the base are compressed whilst alveoli at the top are distended

308
Q

Where are ventilation and perfusion efficient ?

A

at the base rather than the apex

309
Q

What happens at the apex ?

A

perfusion and ventilation are low

the alveoli are distended so they squeeze the capillaries and ventilation > perfusion

310
Q

If ventilation is high at the apex what does this mean ?

A

there is a low amount of co2 and therefore a high pH

311
Q

What happens at the base of the lung ?

A

volume is higher
V/Q in favour of perfusion
low hydrostatic pressure to overcome
po2 is lower and pco2 is higher - lower pH

312
Q

How can we assess ventilation and perfusion ?

A

Xe 133

313
Q

How can we measure ventilation using Xe 133 ?

A

Xe 133 is inhaled and it distributes evenly in the alveolar space
radiograph shows that the apex is fainter showing that it well ventilated

314
Q

How can we measure perfusion using Xe 133 ?

A

Xe 133 is injected and leaves the blood quickly as it is poorly soluble - via the lungs
radiograph shows that apex is poorly perfused

315
Q

How would a pulmonary embolus appear on a Xe radiograph ?

A

embolus blocks perfusion - no gas transfer - no stain

316
Q

What is the pattern of blood flow from the base to the apex ?

A

blood flow decreases from the base the apex

317
Q

What is the response of the lung to a high V/Q ?

A

vasodilation - increase blood flow to remove co2

bronchoconstriction- reduce air flow so that V and Q are matched

318
Q

What is the response of the lung to a low V/Q ?

A

bronchodilation - increase oxygen and remove carbon dioxide as there is a lot of perfusion
hypoxic pulmonary vasoconstriction - allows more oxygen to enter the blood as it lowly ventilated

319
Q

Hypoxic pulmonary vasoconstriction occurs where ?

A

pulmonary arterioles

320
Q

What happens in the systemic circulation during hypoxic conditions ?

A

vasodilation

321
Q

What type of response is hypoxic pulmonary vasoconstriction ?

A

local

322
Q

What is HPV independent of ?

A

autonomic nervous system

323
Q

What is HPV still responsive after ?

A

sympathectomy
vagotomy
chemoreceptor destruction

324
Q

How is an oxygen disbalance sensed in smooth muscle cells ?

A

cells sense a disbalance between ATP and ADP
moreADP means low o2
ADP to AMP to AMP kinase
affects membrane potential via a voltage gated channel
allows calcium to enter via voltage gated channels

325
Q

How is the V/Q mismatch balanced again ?

A

reduction in oxygen supply to the alveolus
reduced oxygen gradient into the blood
blood not fully oxygenated
pulmonary capillary constriction
blood supply rediced in the hypoxic region and diverted to the well oxygenated areas

326
Q

Why is there a lower pressure of oxygen in the pulmonary capillaries compared to the arteries ?

A 
anatomical shunt (blood from systemic arterioles drains directly into pulmonary veins)
V/Q mismatch
327
Q

What is venous admixture ?

A

occurs when the blood passes through the lung withour being oxygenated properly

328
Q

What can left ventricular heart failure lead to ?

A

increase in pulmonary pressure due to backlog
hydrostatic pressure/oncotic pressure balance disturbed
water is trapped - pulmonary odema

329
Q

What happenns in asthma ?

A

bronchoconstriction - harder to exhale

330
Q

What happens in emphysema ?

A

surrounding tissue doesn’t support bronchioles - bronchioles collapse

331
Q

What are the dangers of giving oxygen ?

A

the o2 dissociation curve predicts that even at higher o2 concentrations not much more H b is saturated
increased o2 reduces ventilation
causes co2 retention
acidosis
all the o2 may enter the elveoli whilst co2 doesnt leave the blood - ateclasis

332
Q

How does ventilation change with work rate ?

A

ventilation increases linearly with work rate

333
Q

What happens when peak oxygen consumption has been reached ?

A

body reverts to glycolysis to get more energy

334
Q

What are the changes to ventilation during exercise ?

A

increase in tidal volume
increase in ventilation rate
increased diffusion capacity
increased recruitment of capillaries for GE

335
Q

Why does arterial pH continue to drop even when carbon dioxide levels drop ?

A

lactic acid production

336
Q

What stimulates pulmonary ventilation in exercise ?

A

motor cortex
proprioceptors and the muscle spindle
lung stretch receptors
increase in K concentration due to repolarisation

337
Q

What is the most adaptive response to low O2 ?

A

hypoxic response
low o2 detected by peripheral chemoreeptors in the aortic body and the carotid bodies
signal to the respiratory centre in the medulla
causes hyperventialtion

338
Q

What are the consequences of hyperventilation ?

A 
blows off extra co2 
increase in pH leading to alkalosis 
increases affinity for 02 
decrease in c02 reduces the ventilatory drive 
mediated by central chemoreceptors
339
Q

How is pulmonary oedema caused at high altitude ?

A

low 02 triggers HPV
this increases pulmonary pressure
disturbs the balance between oncotic and capillary pressure
leads to fluid

340
Q

What is the long term adaptation to high altitude ?

A

bicarbonate is transported out of the CSF
this reduces the pH of the CSF
resets central chemoreceptors and makes them more sensitive to co2
increase ventilatory drive

341
Q

What takes care of the bicarbonate concentrations in the blood ?

A

kidney

342
Q

What doe ssutained hypoxia trigger ??.

A

the release of 2,3 DPG
shape of the o2 dissociation curve moves to the right
leads to a lower affinity for 02 so that it is readily released in the tissues

343
Q

How is 02 carrying capacity increased at high altitude ?

A

hypoxia stimulates erythrocyte production
EPO is released from the kidneys
haemopoiesis in the bone marrow
50% increase in RBC levels

344
Q

What are the consequences of having higher RBCs levels in the blood ?

A

increased viscosity of blood

heart has to pump harder

345
Q

What leads to frostbite and gangrene ?

A

peripheral vasoconstriction in lower temperatures

reduces the circulation of blood

346
Q

What are the short term changes to high altitude ?

A

increased pulmonary pressure
promotes recruitment of more capillaries
number and size of mitochondria increase - more aerobic metabolism

347
Q

What are the long term changes to high altitude ?

A

body develops more capillaries in response to high altitude - increases oxygen diffusion

348
Q

What are the early changes in response to high altitude ?

A

increased ventilation
increased HR
increased 2,3 DPG

349
Q

What are the later changes to high altitude ?

A

increased RBCs

350
Q

If the diameter of a bronchiole is halved , the flow drops by a factor of ?

A

16

pouiselles law

351
Q

Lung compliance is ?

A

change in volume/ change in pressure

352
Q

Which disease increases lung compliance ?

A

emphysema

353
Q

Average arterial co2 pressure is ?

A

40 mmHg

354
Q

Average arterial o2 pressure is ?

A

100 mmHg

355
Q

What balances the V/Q mismatch ?

A

hypoxic pulmonary vasoconstriction

356
Q

What do peripheral chemoreceptors sense ?

A

02 below 60 mmHg

BDS Stage 1 (39 decks)

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