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respiratory system Flashcards

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1
Q

why do we breathe?

A
  • maintain blood gas homeostasis
  • ensure CO2 and O2 levels in blood are optimal to fuel body
  • get rid of waste
  • coupled with cellular respiration
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2
Q

what is the partial pressure of oxygen at rest?

A

PO2=100+-2mmHg

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3
Q

what is the partial pressure of CO2 at rest?

A

PCO2=40+-2mmHg

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4
Q

what are the two zones that the respiratory system can be split into?

A
  • conducting zones
  • respiratory zones
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5
Q

conducting zones

A
  • nose
  • pharynx
  • larynx
  • trachea
  • bronchi
  • bronchioles
  • terminal bronchioles
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6
Q

what type of epithelium do the conducting zones have?

A

respiratory epithelium = ciliated pseudostratified columnar epithelium

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7
Q

respiratory zone

A
  • respiratory bronchioles
  • alveolar ducts
  • alveaolar sacs
  • alveoli
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8
Q

what type of epithelium do respiratory zones have?

A

simple squamous epithelium

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9
Q

what muscle is responsible for breathing at rest?

A

the diaphragm

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10
Q

what are the mechanics of inhaling during quiet breathing / breathing at rest?

A
  • inspiration part is an active process
  • diaphragm contracts downward
    allows lungs to expand & push abdominal contents downwards
  • external intercostal muscles pull the ribs outward and upwards -> helps increase space in thoracic cage -> gives lungs more space to expand
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11
Q

what are the mechanics of exhaling during quiet breathing / breathing at rest?

A
  • this is a passive process -> expiration is driven by the elastic recoil of the muscles
  • this recoil causes the muscles to force air (CO2) back out of lungs and causes lungs to deflate
  • this reduces the space within the thoracic cage & it returns to its resting state
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12
Q

how does exercise affect respiration?

A
  • greater contraction of the diaphragm and the external intercostal muscles
  • other accessory muscles also activated during this time
  • active: these muscles are activated to help with expiration and the internal intercostal muscles oppose external intercostals
  • do this by pushing the ribs downwards and inwards
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13
Q

what is strenuous breathing?

A

respiration during things such as exercise
both inspiration and expiration are active

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14
Q

by what & where is pulmonary surfacant produced?

A

by type II epithelial cells
in alveoli

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15
Q

what is the purpose of pulmonary surfacant?

A
  • helps line the surfaces of the alveoli to reduce surface tension
  • allows alveoli in lungs to easily expand and deflate as needed for respiration
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16
Q

what happens in the absensce of pulmonary surfacant?

A
  • alveoli struggle to resist surface tension and cannot re-expand easily after expiration
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17
Q

what is oxygen saturation? SaO2

A
  • amout of oxygen molecules bound to haemoglobin relative to the max amount that they can bind
  • each Hb can bind 4 O2
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18
Q

how can you measure O2 saturation?

A

using a pulse oximeter

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19
Q

which nerve(s) innervates the diaphragm?

A

phrenic nerve
C3, 4 and 5 (roots of phrenic nerve)

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20
Q

what would happen after a decrease in PO2 involving the peripheral chemoreceptors?

A
  • if reduction in arterial blood -> peripheral chemoreceptors are stimulated
  • when stimulated -> send neural signals to the nucleus tractus solitarius in brainstem
  • these stimulate an increase in ventilation via the rhythm generating neurons in the ventral respiratory group of neurons
  • overall: restore PO2 levels
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21
Q

what is a decrease in PO2?

A

hypoxia
decreased oxygen levels circulating in the bloodstream

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22
Q

where are the peripheral chemoreceptors located?

A
  • carotid sinus
  • aortic arch
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23
Q

what receptors are stimulated by a rise in PCO2 levels?

A

central chemoreceptors of the brain

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24
Q

what is a rise in PCO2 called?

A

hypercapnia

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25
Q

how is an increase in PCO2 corrected?

A
  • stimulation of central chemoreceptors
  • signals processed and info passed to neuronal clusters in brainstem -> involved in breathing
  • ventilation increases -> levels restored
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26
Q

parasympathetic nerves effect on upper airways

A
  • nerves derived from Vagus (X) nerve (the bronchioles)
  • can cause mild to moderated bronchoconstriction
  • also involved in mucus production when stimulated by irritants -> narrowed airways in asthma
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27
Q

which neurotransmitter is involved in the effect of the parasympathetic nerves on the upper airways?

A

acetylcholine

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28
Q

what changes can asthma cause to the airways?

A
  • smooth muscle cell hypertrophy / hyperplasaía & contraction
  • oedema
  • mucus hypersecretion
  • epithelial damage
  • infiltration of inflammatory cells / inflammation
  • bronchial hyper reactivity
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29
Q

what is FEV1?

A
  • a measurement of an individuals forced expiratory volume in the first second
  • the amount of air that can be forced from the lungs in the first 1 second
  • important = helps indicate the health of the airways and if they are very narrowed or not
  • those with asthma have lower values
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30
Q

anabolic pathways

A
  • uses energy
  • build complicated molecules from simpler ones
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31
Q

catabolic pathways

A
  • release energy
  • break complicated molecules down into smaller ones
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32
Q

what is STPD?

A

standard temperature (273K) and pressure (760mmHg) dry
- refers to step where you standardise conditions of a measurement to accurately measure gas volumes

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33
Q

why is STPD needed to calculate oxygen utilisation during exercise?

A
  • because temperature and pressure of gases can change depending on the environmental conditions
  • if standardise them, can be comparable to other values taken at other times
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34
Q

what is the lactate threshold?

A
  • the point where blood lactate starts to accumulate above resting levels during exercise of increasing intensity
  • good indicator of an athlete´s potential for endurance exercise
  • reflect aerobic and anaerobic energy systems
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35
Q

what happens when an indivdual passes the lactate threshold?

A
  • level of lactate in blood increases (increased H+)
  • H+ in blood is buffered by bicarbonte forming carbonic acid -> dissociated into H2O and CO2
  • causes increase in pulmonary CO2 whihc can cause minute respiration to rise
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36
Q

how to calculate partial pressure?

A

= fraction of gas (Fgas) in gas mixture x barometric pressure (Pb)

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37
Q

total pressure

A

must equal the sum of partial pressures or tensions of gas

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38
Q

what happens to air in airways?

A
  • waremd
  • humidified
  • becomes saturated with water vapour (at partial pressure & body temp = 47mmHg
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39
Q

role of nasal cavities & paranasal sinuses in air movement

A
  • filter
  • warm
  • humidify air
  • detect smells
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40
Q

role of pharynx

A
  • conducts air to larynx
  • chamber shared with digestive tract
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41
Q

larynx role

A
  • protects opening to trachea
  • contains vocal cords
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42
Q

trachea & bronchi role

A
  • filters air
  • traps particles in mucus
  • cartilages keep airways open
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43
Q

lungs

A
  • responsible for air movement through volume changes during movements of ribs and diaphragm
  • include airways and alveoli
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44
Q

alveoli

A

acts as sites of gas exchange between air and blood

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45
Q

muscles of inspiration

A
  • the diaphragm
  • external intercostals
  • sternocleidomastoid
  • pectoralis minor
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46
Q

muscles of expiration

A
  • internal intercostals
  • diaphragm
  • abdominals
  • quadratus lumbroum
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47
Q

diaphragm

A

major inspiratory, dome shaped muscle

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48
Q

quiet breathing inspiration

A
  • active
  • diaphragm contracts downward
  • pushes abndominal contents outward
  • external intercostals: pull ribs outward and upward
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49
Q

quiet breathing expiration

A
  • passive
  • via elastic recoil
50
Q

strenuous breathing inspiration

A
  • active
  • diaphragm contracts stronger
  • greater contraction of external intercostals
  • insipiratory accessory muscles activated (sternocleidomastoid)
51
Q

strenuous breathing expiration

A
  • active -> push air out to get air in again
  • abdominal muscles involved
  • internal intercostal muscles oppose external intercostals -> push ribs down and inwards
52
Q

pleural cavity

A

small space between chest and lung wall

53
Q

functions of upper airways

A
  • humidify -> saturate with water
  • warm -> to body temp
  • filter air
  • conduct air to lungs
54
Q

filtering air

A
  • lining of upper airways with ciliated epithelium
  • particles stick to mucous
  • mucous moved towards mouth by beating cilia
  • stops foreign particles from entering
55
Q

what cells line the upper airways to bronchioles?

A

pseudo-stratified ciliated columnar epithelium

56
Q

goblet cells

A
  • sit on top of cilia
  • produce mucous
57
Q

the respiratory tree

A

= conducting airways + respiratory airways
- airways branch into smaller, more numerous bronchioles
- terminate in a group of alveoli
- each division = increase in number, decrease in diameter, increase in s.a.

58
Q

conducting airways

A
  • bronchi contain cartilage and nonrespiratory bronchioles
  • 150mls in volume
59
Q

respiratory airways

A
  • bronchioles with alveoli
  • where gas exchange occurs
  • 5mm long
  • huge s.a.
  • hold up to 2500ml
60
Q

what is a respiratory unit?

A

= gas exchanging unit

  • basic physiological unit of lungs
  • consisting of respiratory bronchioles, alveolar ducts and alveoli
61
Q

alveoli

A
  • 300-400million alveolar sacs
  • polygonal in shape
  • composed of T1 and T2 epithelial cells
  • air filled
  • thin walls
  • covered by capillaries
  • allow for gas exchange
62
Q

pulmonary artery

A
  • brings deoxygenated blood from rest of body back to lungs
  • blood oxygenated in lungs
63
Q

pulmonary vein

A

takes oxygenated blood from lungs to rest of body cells and tissues

64
Q

type 1 epithelial tissue in alveoli

A
  • 97% of s.a.
  • primary site of gas exchange
65
Q

type 2 epithelial tissue in alveoli

A
  • septal cells
  • occupy 3% of s.a.
  • produce pulmonary surfactant (reduces surface tension)
66
Q

alveolar macrophages

A

removal of debris

67
Q

why are alveoli perfect for gas exhange?

A
  • large s.a.
  • v thin walls
  • good diffusion characteristics for faster gas exchange
68
Q

2 blood supplies to the lungs

A
  • pulmonary circulatuion
  • bronchial circulation
    (- lymphatic system)
69
Q

pulmonary circulation

A
  • brings deoxygenated blood from heart to lungs
  • oxygenated blood from lung to heart & rest of body
  • total blood vol = 500mls (10%)
  • blood volume increases with exercise
70
Q

pulmonary circulation

A

brings deoxygenated blood to lung parenchyma

71
Q

lymphatic system

A

defense and removal of lymph fluid

72
Q

arteries

A
  • thin walled
  • highly compliant
  • larger diamter
  • low resistance
73
Q

alveolar capillary network

A
  • gas exchange between dense mesh-like network of capillaries and alveoli
  • type 1 alveolar epithelial cell, capillary endothelial cell & basement membrane
  • ideal environment for gas exchange
  • rbc pass through capillaries in less than 1 second -> enough time for CO2 and O2 exchange (O2 binds to haemoglobin)
74
Q

gas gradients

A
  • gases move down their concentration gradients
  • similar volume of CO2 and O2 move each minute
  • O2 has a greater pressure gradient than CO2
  • CO2 more diffusible
75
Q

pulmonary circuit

A

O2 enters blood
CO2 leaves

76
Q

systematic circuit

A

O2 leaves blood -> into cells & tissues
CO2 enters blood

77
Q

O2 and CO2 transport

A
  • respiratory & circulatory systems function together
  • CO2 from tissues to lungs
  • O2 from lungs to tissues
78
Q

gas diffusion

A
  • movemnet of gas via diffusion
79
Q

how does the respiratory system facillitate gas diffusion

A
  • large s.a
  • large partial pressure gradients (high to low)
  • gases with advantageous diffusion properties
  • specialised mechanisms for O2 and CO2 transport between lung and tissues
80
Q

how is oxygen transported?

A
  • dissolved in blood
  • bound to haemoglobin (Hb)
81
Q

dissolved O2

A
  • measured clinically in arterial blood sample
  • only small % dissolved
  • amount of O2 dissolved in blood proportional to partial pressure
  • not adequate for body requirements even at rest
82
Q

haemoglobin

A
  • major O2 transport molecule
  • found in red blood cells
  • made of 4 heme groups joined to globin protein
  • each heme group has iron in reduced ferrous form -> site of O2 binding
  • 280 million
  • binding & dissociation of O2 with Hb in milliseconds -> so short bc rbc only in capillaries for 1 second
  • O2 binding to Hb is reversible
83
Q

oxygen saturation

A
  • each Hb can bind 4 O2
  • O2 saturation = amount of O2 bound to Hb relative to max amount that can bind
  • 100% sat = all heme groups of Hb bound to O2 (4O2)
84
Q

how to measure O2 saturation

A
  • pulse oximeters
    -> measure ratio of absorption of red and infared ligt by oxyHb and deoxyHb
85
Q

CO2 production

A
  • 200ml CO2/min
  • 80 molecules of CO2 expired by lung for every 100 molecules of O2 entering
86
Q

respiratory exchange ratio

A

ratio of expired CO2 to O2 uptake
normal = 0.8

87
Q

CO2 transport

A
  • 7% dissolved in blood
  • 23% bound to Hb
  • 70% converted to bicarbonate
88
Q

bicarbonate

A
  • The bicarbonate ion present in the blood plasma is transported to the lungs
  • there it is dehydrated back into CO2
  • CO2 released during exhalation
89
Q

what can affect breathing?

A
  • sleep
  • phonation
  • emotion
  • cardiovascular
  • temp
  • exercise
90
Q

chemoreceptors

A
  • sensory receptors that detect chemical changes in surrounding environment
  • in respiratory system: detect changes in PO2, PCO2, pH in blood
91
Q

peripheral chemoreceptors

A
  • small & highly vascularised
  • region of aortic arc & corticoid sinuses
  • info sent via glossopharyngael & vagus nerves to nucleus in brainstem (NTS)
92
Q

what do peripheral chemoreceptors detect?

A
  • decreases in PO2 (hypoxia)
  • stimulated by a reduction in aterial PO2 -> neural signals sent from carotid and aortic bodies to NTS -> ventillation increases to restore PO2 levels
93
Q

central chemoreceptors

A
  • clusters of neurons in brainstem
  • activated when PCO2 increased or pH decreased
94
Q

action of central chemoreceptors

A
  • increase in arterial PCO2 -> cc stimulated -> signal processed -> info passed to neural clusters in brainstem involved in breathing -> increase ventilation to restore PCO2 levels
95
Q

hypoxia

A

a state in which oxygen is not available in sufficient amounts at the tissue level to maintain adequate homeostasis

96
Q

hypercapnia

A
  • when you have too much carbon dioxide (CO2) in your bloodstream
  • can be result of hyperventilation
97
Q

mechanoreceptors

A
  • sensory receptors
  • detect changes in pressure, movement and touch
  • respiratory system: movement of lung and chest wall
98
Q

action of mechanoreceptors

A
  • inflation of lung -> activated -> neural signal sent via vagus nerve to NTS in bainstem -> ventilation adjusted
99
Q

integration of info about breathing in brainstem

A

NTS: gets info from mechanoreceptors & chemoreceptors -> info processed by brainstem respiratory neurons -> generate rhythm of breathing -> rhythmic signal sent to respiratory muscles

100
Q

respiratory neurons in brainstem

A
  • inspiratory neurons: active during inspiration
  • expiratory neurons: active during expiration
  • fire at certain phase each time in respiratory cycle
101
Q

respiratory rhythm

A
  • generated in brainstem
  • pontine respiratory group
  • ventral respiratory group (rhythm generating neurons)
  • dorsal respiratory group (NTS)
102
Q

output from brainstem to respiratory muscles

A
  • brainstem neurons produce rhythmic output -> neural signals sent to spinal cord -> phrenic nerve exits spinal cord at C3-5
  • phrenic nerve innervates diaphragm
  • nerve exiting thoracic spinal cord innervate intercostal muscles
103
Q

function of the lungs

A
  • oxygenate blood
  • by bringing inspired air in close contact to oxygen-poor blood in the pulmonary capillaries
  • promotes efficient gas exchange
104
Q

bronchia

A

distribute air within lungs

105
Q

control of airway function

A

regulation of musculature, blood vessles & glands

  • afferent pathways: sensory stimuli from lungs -> CNS
  • efferent pathways: regulation of muscle contraction
106
Q

afferent pathways

A
  • chemoreceptors and nicireceptors
  • respond to exogenous chemicals, inflammatory mediators and physical stimuli
107
Q

efferent pathways

A
  • parasympathetic nerves -> bronchoconstriction (upper airways) & mucous secretion (acetlycholine)
  • sympathetic nerves -> dont innervate airway smooth muscle (blood vessels and glans, noradrenaline)
  • inhibitory non-adrenergic non-cholinergic (NANC) nerves relax airway smooth muscles
  • excitatory NANC nerves -> cause neuroinflammation bc of tachykinin release
108
Q

NANC - non-adrenergic non-cholinergic nerves

A
  • regulate airway function
  • intervene in secretion of gases and ions
  • relaxons in airways
109
Q

regulation of mucus secretion

A
  • goblet cells & mucous glands
  • lowered by smpathetic NS
  • increased by parasympathetic NS -> inflammatory mediators & chemical/physical stimuli
110
Q

necessity of mucous

A
  • line lungs
  • protect epithelial cells
  • capture pathogens
  • provide liquid - fluid interface that would help exchange of O2 between blood vessels and air
  • in asthma = overproduction
111
Q

asthma

A
  • obstructive lung disease
  • chronic inflammatory condition with acute exacerbation
  • thickening of airways
112
Q

asthma treatment

A

include bronchodilators & anti-inflammatory agents

113
Q

structural changes in asthma

A
  • smooth muscle cell hypertrophy / hyperplasia & contraction
  • thickening of airways
  • infiltration of inflammatory cells
  • hypersecretion of mucous
  • epithelial damage
114
Q

triggers for asthma

A
  • pet dander
  • dust mites
  • moulds
  • pollens
  • respiratory infections
  • asthma
  • cold air
  • smoke
  • stress
  • alc
  • aspirin / other dugs
115
Q

asthma diagnosis

A
  • spirometry
    FVC: forced (expiratory) vital capacity -> persons maximal expiration following full inspiration
    FEV1: forced expiration volume in 1 second

FEV1: > 75% normal
< 3 seconds in people without asthma

116
Q

asthma effect on FEV1

A
  • reduced FEV1
  • many cells and mediators play part in this
117
Q

early asthma phase

A
  • bronchospasm
  • drugs targetting bronchoconstriction
118
Q

late asthma phase

A
  • inflammation
  • drugs targetting inflammatory response
119
Q

what are anti-asthmatics

A
  • bronchodilators / relievers
  • anti-inflammatory agents / preventors
120
Q

bronchodilators

A
  • relieve muscles surrounding narrowed airways
  • beta-2 antagonists e.g. salbutamol
  • muscarinic antagonists e.g. ipratropium
  • methxlanthines e.g. theophylline
121
Q

anti-inflammatory agents

A
  • glucocorticoids -> inhibit prostanoids, leukotrienes and cytokines
  • momntelukast -> cysteinyl leukotriene receptor
  • sodium cromoglicate

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