respiratory system Flashcards
(121 cards)
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
2
Q
what is the partial pressure of oxygen at rest?
A
PO2=100+-2mmHg
3
Q
what is the partial pressure of CO2 at rest?
A
PCO2=40+-2mmHg
4
Q
what are the two zones that the respiratory system can be split into?
A
- conducting zones
- respiratory zones
5
Q
conducting zones
A
- nose
- pharynx
- larynx
- trachea
- bronchi
- bronchioles
- terminal bronchioles
6
Q
what type of epithelium do the conducting zones have?
A
respiratory epithelium = ciliated pseudostratified columnar epithelium
7
Q
respiratory zone
A
- respiratory bronchioles
- alveolar ducts
- alveaolar sacs
- alveoli
8
Q
what type of epithelium do respiratory zones have?
A
simple squamous epithelium
9
Q
what muscle is responsible for breathing at rest?
A
the diaphragm
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
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
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
13
Q
what is strenuous breathing?
A
respiration during things such as exercise
both inspiration and expiration are active
14
Q
by what & where is pulmonary surfacant produced?
A
by type II epithelial cells
in alveoli
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
16
Q
what happens in the absensce of pulmonary surfacant?
A
- alveoli struggle to resist surface tension and cannot re-expand easily after expiration
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
18
Q
how can you measure O2 saturation?
A
using a pulse oximeter
19
Q
which nerve(s) innervates the diaphragm?
A
phrenic nerve
C3, 4 and 5 (roots of phrenic nerve)
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
21
Q
what is a decrease in PO2?
A
hypoxia
decreased oxygen levels circulating in the bloodstream
22
Q
where are the peripheral chemoreceptors located?
A
- carotid sinus
- aortic arch
23
Q
what receptors are stimulated by a rise in PCO2 levels?
A
central chemoreceptors of the brain
24
Q
what is a rise in PCO2 called?
A
hypercapnia
25
how is an increase in PCO2 corrected?
- stimulation of central chemoreceptors
- signals processed and info passed to neuronal clusters in brainstem -> involved in breathing
- ventilation increases -> levels restored
26
parasympathetic nerves effect on upper airways
- 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
27
which neurotransmitter is involved in the effect of the parasympathetic nerves on the upper airways?
acetylcholine
28
what changes can asthma cause to the airways?
- smooth muscle cell hypertrophy / hyperplasaía & contraction
- oedema
- mucus hypersecretion
- epithelial damage
- infiltration of inflammatory cells / inflammation
- bronchial hyper reactivity
29
what is FEV1?
- 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
30
anabolic pathways
- uses energy
- build complicated molecules from simpler ones
31
catabolic pathways
- release energy
- break complicated molecules down into smaller ones
32
what is STPD?
standard temperature (273K) and pressure (760mmHg) dry
- refers to step where you standardise conditions of a measurement to accurately measure gas volumes
33
why is STPD needed to calculate oxygen utilisation during exercise?
- 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
34
what is the lactate threshold?
- 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
35
what happens when an indivdual passes the lactate threshold?
- 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
36
how to calculate partial pressure?
= fraction of gas (Fgas) in gas mixture x barometric pressure (Pb)
37
total pressure
must equal the sum of partial pressures or tensions of gas
38
what happens to air in airways?
- waremd
- humidified
- becomes saturated with water vapour (at partial pressure & body temp = 47mmHg
39
role of nasal cavities & paranasal sinuses in air movement
- filter
- warm
- humidify air
- detect smells
40
role of pharynx
- conducts air to larynx
- chamber shared with digestive tract
41
larynx role
- protects opening to trachea
- contains vocal cords
42
trachea & bronchi role
- filters air
- traps particles in mucus
- cartilages keep airways open
43
lungs
- responsible for air movement through volume changes during movements of ribs and diaphragm
- include airways and alveoli
44
alveoli
acts as sites of gas exchange between air and blood
45
muscles of inspiration
- the diaphragm
- external intercostals
- sternocleidomastoid
- pectoralis minor
46
muscles of expiration
- internal intercostals
- diaphragm
- abdominals
- quadratus lumbroum
47
diaphragm
major inspiratory, dome shaped muscle
48
quiet breathing inspiration
- active
- diaphragm contracts downward
- pushes abndominal contents outward
- external intercostals: pull ribs outward and upward
49
quiet breathing expiration
- passive
- via elastic recoil
50
strenuous breathing inspiration
- active
- diaphragm contracts stronger
- greater contraction of external intercostals
- insipiratory accessory muscles activated (sternocleidomastoid)
51
strenuous breathing expiration
- active -> push air out to get air in again
- abdominal muscles involved
- internal intercostal muscles oppose external intercostals -> push ribs down and inwards
52
pleural cavity
small space between chest and lung wall
53
functions of upper airways
- humidify -> saturate with water
- warm -> to body temp
- filter air
- conduct air to lungs
54
filtering air
- lining of upper airways with ciliated epithelium
- particles stick to mucous
- mucous moved towards mouth by beating cilia
- stops foreign particles from entering
55
what cells line the upper airways to bronchioles?
pseudo-stratified ciliated columnar epithelium
56
goblet cells
- sit on top of cilia
- produce mucous
57
the respiratory tree
= 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
conducting airways
- bronchi contain cartilage and nonrespiratory bronchioles
- 150mls in volume
59
respiratory airways
- bronchioles with alveoli
- where gas exchange occurs
- 5mm long
- huge s.a.
- hold up to 2500ml
60
what is a respiratory unit?
= gas exchanging unit
- basic physiological unit of lungs
- consisting of respiratory bronchioles, alveolar ducts and alveoli
61
alveoli
- 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
pulmonary artery
- brings deoxygenated blood from rest of body back to lungs
- blood oxygenated in lungs
63
pulmonary vein
takes oxygenated blood from lungs to rest of body cells and tissues
64
type 1 epithelial tissue in alveoli
- 97% of s.a.
- primary site of gas exchange
65
type 2 epithelial tissue in alveoli
- septal cells
- occupy 3% of s.a.
- produce pulmonary surfactant (reduces surface tension)
66
alveolar macrophages
removal of debris
67
why are alveoli perfect for gas exhange?
- large s.a.
- v thin walls
- good diffusion characteristics for faster gas exchange
68
2 blood supplies to the lungs
- pulmonary circulatuion
- bronchial circulation
(- lymphatic system)
69
pulmonary circulation
- 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
pulmonary circulation
brings deoxygenated blood to lung parenchyma
71
lymphatic system
defense and removal of lymph fluid
72
arteries
- thin walled
- highly compliant
- larger diamter
- low resistance
73
alveolar capillary network
- 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
gas gradients
- 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
pulmonary circuit
O2 enters blood
CO2 leaves
76
systematic circuit
O2 leaves blood -> into cells & tissues
CO2 enters blood
77
O2 and CO2 transport
- respiratory & circulatory systems function together
- CO2 from tissues to lungs
- O2 from lungs to tissues
78
gas diffusion
- movemnet of gas via diffusion
79
how does the respiratory system facillitate gas diffusion
- 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
how is oxygen transported?
- dissolved in blood
- bound to haemoglobin (Hb)
81
dissolved O2
- 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
haemoglobin
- 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
oxygen saturation
- 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
how to measure O2 saturation
- pulse oximeters
-> measure ratio of absorption of red and infared ligt by oxyHb and deoxyHb
85
CO2 production
- 200ml CO2/min
- 80 molecules of CO2 expired by lung for every 100 molecules of O2 entering
86
respiratory exchange ratio
ratio of expired CO2 to O2 uptake
normal = 0.8
87
CO2 transport
- 7% dissolved in blood
- 23% bound to Hb
- 70% converted to bicarbonate
88
bicarbonate
- 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
what can affect breathing?
- sleep
- phonation
- emotion
- cardiovascular
- temp
- exercise
90
chemoreceptors
- sensory receptors that detect chemical changes in surrounding environment
- in respiratory system: detect changes in PO2, PCO2, pH in blood
91
peripheral chemoreceptors
- small & highly vascularised
- region of aortic arc & corticoid sinuses
- info sent via glossopharyngael & vagus nerves to nucleus in brainstem (NTS)
92
what do peripheral chemoreceptors detect?
- 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
central chemoreceptors
- clusters of neurons in brainstem
- activated when PCO2 increased or pH decreased
94
action of central chemoreceptors
- 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
hypoxia
a state in which oxygen is not available in sufficient amounts at the tissue level to maintain adequate homeostasis
96
hypercapnia
- when you have too much carbon dioxide (CO2) in your bloodstream
- can be result of hyperventilation
97
mechanoreceptors
- sensory receptors
- detect changes in pressure, movement and touch
- respiratory system: movement of lung and chest wall
98
action of mechanoreceptors
- inflation of lung -> activated -> neural signal sent via vagus nerve to NTS in bainstem -> ventilation adjusted
99
integration of info about breathing in brainstem
NTS: gets info from mechanoreceptors & chemoreceptors -> info processed by brainstem respiratory neurons -> generate rhythm of breathing -> rhythmic signal sent to respiratory muscles
100
respiratory neurons in brainstem
- inspiratory neurons: active during inspiration
- expiratory neurons: active during expiration
- fire at certain phase each time in respiratory cycle
101
respiratory rhythm
- generated in brainstem
- pontine respiratory group
- ventral respiratory group (rhythm generating neurons)
- dorsal respiratory group (NTS)
102
output from brainstem to respiratory muscles
- 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
function of the lungs
- oxygenate blood
- by bringing inspired air in close contact to oxygen-poor blood in the pulmonary capillaries
- promotes efficient gas exchange
104
bronchia
distribute air within lungs
105
control of airway function
regulation of musculature, blood vessles & glands
- afferent pathways: sensory stimuli from lungs -> CNS
- efferent pathways: regulation of muscle contraction
106
afferent pathways
- chemoreceptors and nicireceptors
- respond to exogenous chemicals, inflammatory mediators and physical stimuli
107
efferent pathways
- 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
NANC - non-adrenergic non-cholinergic nerves
- regulate airway function
- intervene in secretion of gases and ions
- relaxons in airways
109
regulation of mucus secretion
- goblet cells & mucous glands
- lowered by smpathetic NS
- increased by parasympathetic NS -> inflammatory mediators & chemical/physical stimuli
110
necessity of mucous
- 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
asthma
- obstructive lung disease
- chronic inflammatory condition with acute exacerbation
- thickening of airways
112
asthma treatment
include bronchodilators & anti-inflammatory agents
113
structural changes in asthma
- smooth muscle cell hypertrophy / hyperplasia & contraction
- thickening of airways
- infiltration of inflammatory cells
- hypersecretion of mucous
- epithelial damage
114
triggers for asthma
- pet dander
- dust mites
- moulds
- pollens
- respiratory infections
- asthma
- cold air
- smoke
- stress
- alc
- aspirin / other dugs
115
asthma diagnosis
- 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
asthma effect on FEV1
- reduced FEV1
- many cells and mediators play part in this
117
early asthma phase
- bronchospasm
- drugs targetting bronchoconstriction
118
late asthma phase
- inflammation
- drugs targetting inflammatory response
119
what are anti-asthmatics
- bronchodilators / relievers
- anti-inflammatory agents / preventors
120
bronchodilators
- relieve muscles surrounding narrowed airways
- beta-2 antagonists e.g. salbutamol
- muscarinic antagonists e.g. ipratropium
- methxlanthines e.g. theophylline
121
anti-inflammatory agents
- glucocorticoids -> inhibit prostanoids, leukotrienes and cytokines
- momntelukast -> cysteinyl leukotriene receptor
- sodium cromoglicate
