Week 5 Respiratory Flashcards
1
Q
what cells compose the alveolar surface
A
Type 1 alveolar cells
Type 2 alveolar cells
fibroblasts
capillaries
pericytes
macrophages
immune cells
2
Q
function of type 1 alveolar cells
A
95% of alveolar surface, facilitate gas exchange
3
Q
function of type 2 alveolar cells
A
5% of alveolar surface; secrete surfactant and aid repair
4
Q
function of fibroblasts
A
ECM production, facilitate repair
5
Q
what are the capillaries of the lungs
A
consists of endothelial cells and pericytes
6
Q
function of pericytes
A
enigmatic cells, solicit various functions
7
Q
function of macrophages
A
phagocytotic ‘engulfing’ of particulate matter
8
Q
function of immune cells
A
includes T cells, B cells and dendritic cells
9
Q
what are alveolar macrophages
A
-reside in the mucous layer
-responsible for the clearance of apoptotic cells and cellular debris
10
Q
Describe the pulmonary circulation
A
RV–>Pulmonary trunk–>Pulmonary arteries–>Smaller arteries–>arterioles –>capillaries–>venules–>smaller veins–>pulmonary veins–>Left atrium–>LV
11
Q
How do pulmonary arteries respond to hypoxia
A
-constrict in response to alveolar hypoxia
-this diverts blood to better ventilated areas of lung, synchronising perfusion and ventilation
12
Q
pulmonary arteries vs bronchial arteries
A
-pulmonary arteries and veins are vasa publica, public vessels that are responsible for transport to the lung and gas exchange
-however, bronchial vessels are vasa privata, private vessels that supply lung parenchyma (eg SM, CT,)
13
Q
features of the bronchial arteries
A
-originate from the thoracic aorta and 3rd right intercostal artery
-in 1/3 of instances, bronchial veins drain into the azygos (right) vein and hemi-azygos or intercostal veins (left)
-in 2/3 of instances, blood from the peripheral bronchial arteries drains into the pulmonary veins
14
Q
Features of inspiration
A
-diaphragm contracts
-the external intercostals contract
-the rib cage and sternum moves up and out
-the lungs and chest wall expand
-increase in intrathroacic volume
-decrease in intrathoracic pressure
-air moves from environment into lungs (high to low)
15
Q
Features of expiration
A
-the diaphragm relaxes
-the internal intercostals contract
-the chest wall and lungs contract
-the sternum and rib cage moves down and in
-decrease in intrathroacic pressure
-decrease in intrathoracic volume
-air moves from lungs into environment (high to low)
16
Q
Describe the lymph drainage of the lungs
A
lung lymph –> lymph (upper)–> ipsilateral lymph nodes –> paratracheal lymph nodes –> bronchomediastinal trunks –> right lymphatic duct
OR
lung lymph –> lymph (lower)–> inferior lymph nodes –> paratracheal lymph nodes –> bronchomediastinal trunks –> right lymphatic duct
17
Q
outline the normal cough reflex
A
-irritant enters respiratory tract, contacting respiratory epithelium
-innervation of vagal sensory fibres in pharynx, trachea and bronchi
-input via higher order centres–>sensory fibres end in nucleus of solitary tract (NTS in brain stem)
-CPG motor neurons
-VRG motor neurons
-innervation of respiratory muscles (diaphragm, intercostals, intrinsic larangyeal and abdominal muscles)
-forceful expiration against closed glottis (cough)
18
Q
list the causes of sputum
A
-respiratory infections
-GORD
-bronchitis
-allergies
19
Q
how do respiratory infections cause sputum production
A
viruses, bacteria, and other pathogens cause inflammation and increased mucus production in the airways as a defence mechanism
20
Q
how does GORD cause sputum production
A
stomach acid can reach the airways, leading to irritation, inflammation and excess mucous production
21
Q
how does bronchitis cause sputum production
A
long term irritation from smoking, pollutants, or infection causes chronic inflammation of bronchi, resulting in excess mucous production
22
Q
how do allergies cause sputum production
A
allergens trigger an immune response that includes inflammation and excess mucous production in the respiratory tract
23
Q
what is pulmonary ventilation
A
inflow and outflow of air between the atmosphere and alveoli
24
Q
what is diffusion
A
movement of oxygen and carbon dioxide between the alveoli and pulmonary circulation
25
what is gas transport
transport of oxygen and carbon dioxide in the blood stream
26
what is gas exchange
exchange of gases within body tissue
27
Whats Boyles law
-pressure of gas is inversely proportional to its volume
28
Outline features of air flow
-air flows from high pressure to low pressure
-increasing lung volume results in negative alveolar pressure, air inflow, expansion of chest wall pulls outwards on the lungs, creating more negative pleural pressure
-relaxation of diaphragm and elastic recoil of lungs results in positive alveolar pressure, air outflow and pleural pressure decreases back to baseline
29
what is lung compliance
-'stretchiness of lungs'
= change in volume/change in pressure
30
factors that impact compliance
-elastic forces of the lungs and elastic forces caused by surface tension
-lung is more compliant during inspiration compared to expiration, due to difficulty inflating alveoli
31
what is surface tension
-tension of the surface film of a liquid, caused by attraction of particles in the surface layer
-in the lungs surface tension causes alveoli to collapse
32
features of the pleura
-double layered membrane
-outer parietal pleura, attaches to the chest wall, diaphragm and mediastinum
-inner visceral pleura adheres closely to surface of lungs
-pleural pressure is negative to create a vacuum between lung surface and thoracic cavity
33
role of diaphragm
primary respiratory muscle, contracts to increase thoracic volume during inhalation and relaxes to decrease thoracic volume during exhalation
34
role of external intercostals
elevate ribs during inhalation, aiding in expanding chest cavity
35
role of internal intercostals
depress the ribs during forced exhalation, assisting in decreasing thoracic volume
36
role of sternocleidomastoid
accessory muscle involved in elevating the sternum and aiding in deep inhalation
37
define quiet breathing
normal, rhythmic inhalation and exhalation during rest or light activities primarily driven by the diaphragm and external intercostal muscles
38
define forced breathing
active, intense inhalation and exhalation involving additional respiratory muscles to meet increased oxygen demands during strenuous activities or when additional ventilation is needed
39
whats Tidal volume (TV)
the amount of air inhaled or exhaled during normal breathing
40
what is Inspiratory reserve volume
the additional air that can be forcibly inhaled beyond tidal volume
41
what is expiratory reserve volume
the additional air that can be forcibly exhaled beyond tidal volume
42
what is total lung capacity
maximum volume of air the lungs can hold, sum of all lung volume (including residual volume)
43
what is residual volume
the air remaining in the lungs after forceful exhalation
44
what is inspiratory capacity
total volume of air that can be inhaled after a normal exhalation (TV + IRV)
45
what is functional residual capacity
volume of air remaining in the lungs after normal exhalation (RV + ERV)
46
what is forced vital capacity
the maximum amount of air that can be exhaled after a maximal inhalation (IRV + TV + ERV)
47
Describe how pressure, volume, flow and resistance are related
V= QR
Volume = flow x resistance
"airflow is inversely proportional to resistance"
48
state pleural pressure during inspiration and expiration
-negative pleural pressure during inspiration
-negative pleural pressure during expiration
49
state alveolar pressure during inspiration and expiration
-negative alveolar pressure during inspiration
-positive alveolar pressure during expiration
50
define work of breathing
refers to the energy expenditure required to overcome the resistance and compliance of respiratory system during ventilation
51
define transmural pressure
the pressure difference across a structures wall, determining its distension or collapse
52
define trans pulmonary pressure
the pressure difference between alveolar and pleural pressure, maintain lung expansion (needs to be +)
53
define lung compliance
measure of the lungs ability to stretch and expand in response to applied pressure, typically during inhalation
-change in lung volume per unit change in transpulmonary pressure
54
how does compliance link to pressure
high lung compliance indicated the lungs can easily expand with little pressure, whereas low compliance suggests stiffness or resistance
55
x and y axis for pressure volume loop
x = pressure
y =volume
56
key features of pressure volume loop
-lung compliance is directly related to slope
-in compliant lung, the graph demonstrates a steep slope, indicating small increase in pressure leads to significant increase in lung volume
-less complaint lung has a flatter slope
-hysterisis present (inflation curve differs to deflation curve)
57
list the factors that provide resistance to air flow
airway resistance
pulmonary resistance
chest wall resistance
58
how does airway resistance impact air flow
the resistance encountered by air moving through the airways, influenced by airway diameter and the smooth muscle tone in bronchi and bronchioles
59
how does pulmonary resistance impact air flow
the overall resistance to airflow within the lungs, incorporating airway resistance, lung tissue elasticity, and the viscoelastic properties of the lung parenchyma
60
how does chest wall resistance impact air flow
the resistance from the chest wall and diaphragm during breathing, influenced by muscle tone, rib cage stiffness, and the compliance of the thoracic cavity
61
define surface tension
the force exerted by the cohesive properties of water molecules at the interface between the air and fluid lining the alveoli, which creates a tendency for alveoli to collapse
62
what is the role of pulmonary surfactant
a mixture of lipids and proteins secreted by type II alveolar cells into the alveolar surface, its primary role is to reduce surface tension, thereby decreasing work of breathing and preventing alveolar collapse (atelectasis)
63
what regulates surfactant release and synthesis
mechanical stretching of alveoli and hormonal signals eg cortisol
64
describe the role of surface tension in the elastic recoil of the lung
-contributes to the forces that drive lung deflation, surface tension drives deflation and surfactant drives inflation
65
define elastic recoil
the tendency of the lungs to return to their original shape and size after being stretched, driven by elastic forces and surface tension
66
compare and contrast the pulmonary and systemic circulation
-In SC veins carry deO2blood towards the heart vs in PC veins carry o2blood toward the heart
-In SC arteries carry O2 blood vs in PC arteries carry deO2 blood
-In SC arteries and veins travel adjacently vs in PC arteries travel with airways, veins travel with septa
-In SC arteries have thicker walls vs in PC arteries have thinner walls
-In SC arteries are highly elastic vs in PC arteries are less elastic
-in SC pressure change (12 to 5 at capillaries) vs in PC pressure change (100 to 12 at arterioles)
67
List the regional differences in blood flow of lungs
-when upright, blood flow in lower parts of lungs>apex
-Zone 1: lack of blood flow as alveolar pressure is higher than venous and arterial pressure
-Zone 2: blood flow occurs in systole but not diastole, as arterial pressure is higher than alveolar pressure (but alveolar pressure is still greater than venous)
-Zone 3:constant supply of blood flow as arterial AND venous pressure is higher than alveolar pressure
68
factors impacting PVR
-endothelin 1 increases PVR
-Histamine increases PVR
-Catecholamines increase PVR
-NO decreases PVR
-adenosine decreases PVR
69
what is PVR
refers to the resistance that blood faces when flowing through the blood vessels in the lungs
-impacted by vessel width
70
Features of internal respiration
Location: Body tissues
Process: Gas exchange between blood in systemic capillaries and tissues.
Oxygen: Moves from blood to tissues.
CO2: Moves from tissues to blood, carried back to lungs.
Purpose: Deliver oxygen to cells, remove CO2.
71
Features of external respiration
Location: Lungs
Process: Gas exchange between alveoli and blood in pulmonary capillaries.
Oxygen: Moves from alveoli to blood.
CO2: Moves from blood to alveoli, then exhaled.
Purpose: Oxygenate blood, remove CO2.
72
Describe the principle of gas diffusion
-net movement of gas molecules from a. region of high to low partial pressure
-partial pressure = product of total pressure and fractional concentration of gas
73
what factors influence O2 dissociation
-increase H+ (lower pH)
-increased temperature
-increased CO2
74
what is Bohr effect
increased H+ and CO2, promotes offloading of O2 in the peripheral tissues (where PCO2 is high) and promotes O2 loading in the lungs (where PCO2 is low)
75
what is a left shift in the O2-Hb dissociation curve
-increased affinity for O2
-decreased PCO2
-decreased [H+]
-decreased temp
-decreased 2-3 DPG
76
what is a right shift in the O2-Hb dissociation curve
-decreased affinity for O2
-increased PCO2
-increased [H+]
-increased temp
-increased 2-3 DPG
77
describe the diffusion of oxygen at the lungs
-alveoli have a standard PO2 of 104 mmHg
-pulmonary capillary carrying deoxygenated blood has a PO2 of 40 mmHg
-Thus, as blood enters pulmonary circulation, its PO2 increases significantly, hence oxygenating blood via diffusion between the capillary and alveolus
78
describe the diffusion of oxygen at tissues
-oxygen supply to tissues follows a similar principle, arterial ends of capillaries have PO2 of 95, the interstitial tissue has a PO2 of 40 and the intracellular solution a PO2 of 23
-hence, oxygen diffuses from the arterial end to intracellular space via interstitial space, oxygenating the tissue
79
PCO2 and PO2 at arterial capillary
PCO2=40 mmHg
PO2=95 mmHg
80
PCO2 and PO2 at interstitial cells
PCO2=45 mmHg
PO2=45 mmHg
81
PCO2 and PO2 at intracellular space
PO2= 23mmHg
PCO2=46 mmHg
82
PCO2 and PO2 at Venous capillary cells
PO2=45 mmHg
PCO2=45 mmHg
83
how is oxygen transported in the body
-via Hg (97-98%)
84
how is carbon dioxide transported in the body
-dissolved state (5-10%)
-As bicarbonaten ion ,HCO3 (70%)
-As carbaminohaemoglobin (CO2Hb) (20-25%)
85
Describe the Haldane effect
greater binding of oxygen with haemoglobin increases the release (offloading) of CO2, thus, CO2 release is promoted when venous blood is arterialised
86
what is Fick's law of diffusion
rate of gas transfer is proportional to the product of diffusing capacity across a membrane (size of membrane) and the pressure gradient
87
Define diffusing capacity
the net rate of gas transfer for a partial pressure gradient of 1 mmHg
88
What factors affect diffusing capacity
membrane SA
membrane diffusion barrier
Gas uptake
89
How does membrane SA impact diffusing capacity
-body size (height)
-lung volume
-ventilation/perfusion
ALL impact diffusion capacity
90
How does membrane diffusion barrier impact diffusing capacity
-Pulmonary congestion '
-interstitial oedema
-membrane thickening
91
How does gas uptake impact diffusing capacity
-Hb capacity
-capillary transit time
92
Describe the process of gas exchange at lungs and tissues
Pressure gradients drive gas exchange:
Partial pressure of oxygen (PO2) is higher in the alveoli (about 100 mmHg) than in the blood (about 40 mmHg), so oxygen moves into the bloodstream.
Partial pressure of carbon dioxide (PCO2) is higher in the blood (about 45 mmHg) than in the alveoli (about 40 mmHg), so carbon dioxide moves into the alveoli to be exhaled.
*same partial pressure values at tissues and same movement ; however, occurs between blood and tissues instead
93
describe regional mismatches to v/q in lungs
In an upright individual, the base of the lungs receives more blood flow due to gravity. This matches well with the greater ventilation in the lower regions, optimizing gas exchange. In contrast, the apex receives less blood flow, and despite being well-ventilated, the V/Q ratio is higher, meaning less efficient gas exchange.
94
what is the v/q ratio
measure of the efficiency of gas exchange in the lungs
95
what factors influence regional ventilation
-gravity
-anatomical expansion (base of lungs larger)
-lung compliance (base more compliant)
-breathing pattern
96
what factors influence regional perfusion
-gravity
-hypoxic pulmonary vasoconstriction (redirection)
-pulmonary vascular structure
-lung volume
97
identify the primary features of the respiratory centre
dorsal respiratory group
ventral respiratory group
pontine respiratory group
98
function of dorsal respiratory group
inspiratory neurons responsible for timing respiratory cycle (inspiration)
99
function of ventral respiratory group
neurones that influence both inspiration and expiration
100
function of pontine respiratory group
includes the pneumotaxic centre (shortens inspiration) and apneustic centre (prolongs inspiration)
101
what are the three predominant receptors in lungs
-slow adapting stretch receptors (SASR)
-rapidly adapting stretch receptors (RASR)
-vagal C fibre nociceptors
102
function of SASR
predominantly in the airways, acts as a lung volume sensor
103
function of RASR: rapidly acting stretch receptors
located in superficial mucosa, stimulated by changes in tidal volume ,breathing frequency and lung compliance
104
function of vagal C fibre nociceptors
free never endings found in bronchi and pulmonary capillaries, stimulated by oxidative stress, inflammation or inhaled irritants
105
Outline the chemical control of respiration
-CO2 passes BBB, increasing PCO2 within CSF, pH decreases, H+ can't penetrate BBB
-CO2--> carbonic acid, dissociates into H+ and bicarbonate ion
-respiratory activity is varied based on CO2 levels
106
where are peripheral chemoreceptors located
aortic arch
carotid body
107
what are peripheral chemoreceptors sensitive to
PO2, PCO2, H+
108
how is information sent from the aortic arch to medullary respiratory neurons
vagus nerve
109
how is information sent from the carotid body to medullary respiratory neurons
glossopharyngeal nerve
110
function of J receptors
located near pulmonary capillaries, respond to capillary changes, stimulation leads to tachypnoea
111
describe chest wall reflex
activated by receptors in the chest muscles, joints and skin; prevent over inflation or sudden deflation of lung (includes hering breur and deflation reflex)
112
describe lung reflexes
activated by irritant and stretch receptors in lung tissues; detect harmful particles and chemicals; activate coughing and bronchoconstriction; assist in maintaining overall tidal volume
113
outline hering breur reflex
-inflated lung
-activation of stretch receptors
-impulses generated
-inhibition of inspiratory centre
-expiration reduces lung inflation
114
outline deflation reflex
-extreme lung deflation (pneumothorax)
-activation of compression receptors
-impulse generated
-stimulation of respiratory centre
-rapid respiration attempt to restore lung volume
115
explain the homeostatic control of respiration and how the body responds to correct hypoventilation and hyperventilation
Hypoventilation triggers increased ventilation to correct hypercapnia and hypoxia, while hyperventilation leads to a reduction in ventilation to correct hypocapnia.
116
Explain how the respiratory system is involved in the regulation of acid-base balance.
An increase in PCO₂, as seen in hypoventilation, leads to respiratory acidosis, while a decrease in PCO₂, as seen in hyperventilation, results in respiratory alkalosis.
117
How does the body respond to exercise hyperpnea
-aerobic exercise
-metabolic acidosis and stress on muscles
-acidosis detected by chemoreceptors, muscle stress detected by proprioceptors
-initiation of respiratory centres
-hyperventilation
-expulsion of CO2
118
list the types of PFT
-spiromtery
-single breath diffusing capacity of carbon monoxide (DLCO)
-subdivisons of lungs volume
119
describe spirometery
Spirometry is a common pulmonary function test used to measure lung function, specifically the amount (volume) and speed (flow) of air a person can inhale and exhale.
120
describe DLCO
Measures the lung's ability to transfer gas from inhaled air to the bloodstream.
121
How is spirometery conducted
Preparation: The patient is seated or standing, with their nose clipped and lips sealed around a mouthpiece.
Initial Test: They fully inhale, then forcefully exhale until empty, followed by a rapid inhalation.
Repetition: This process is repeated 3 to 8 times.
Bronchodilator Test: After administering a bronchodilator, the test is repeated 20 minutes later to assess lung function changes.
122
what is forced expiratory volume1
maximum amount of air that can be expelled in one second
123
what is forced vital capacity
maximum amount of air that can be expired in one breath
124
what is peak expiratory flow
fastest speed at which air is expired
125
what is mid forced expiratory flow
averaged flow rate between 25% and 75% of FVC
126
what is forced expiratory time
time taken for FVC to become completely expired
127
Obstructive ventilatory defects findings on spirometery
-decreased FEV
-decreased or normal FVC
-decreased FEV1/FVC
128
Restrictive ventilatory defects findings on spirometery
-decreased or normal
FEV
-decreased FVC
-increased or normal
FEV1/FVC
129
examples of obstructive respiratory conditions
-asthma
-emphysema
-chronic bronchitis
-foreign bodies
130
examples of restrictive respiratory conditions
congestion
kyphoscolisosis
pleural effusion
fibrosis
ILD
Pulmonary fibrosis
sarcoidosis
131
Describe the significance of bronchodilator response in the obstructive pattern
The bronchodilator response is used to determine if airway obstruction is reversible. After administering 200 µg of salbutamol post-spirometry, a 10% or greater improvement in FEV1 or FVC indicates reversibility, which is key in diagnosing conditions like asthma.
132
Describe steps in lung dilution
1. The patient inhales a helium-oxygen mixture with a known helium concentration.
2. The helium mixes with lung gases until equilibrium is reached, ensuring even distribution in the lungs.
3. The patient exhales the mixture, and the spirometer measures the helium concentration in the exhaled breath.
4. Comparing the initial and exhaled helium concentrations allows calculation of lung volume and other pulmonary parameters.
133
reduced DLCO indicates
-less Hb available for CO binding
-anaemia, PE, emphysema
134
elevated DLCO indicates
-more Hb available for CO binding
-polycythaemia, erythrocytosis
135
how does CAD lead to dyspnoea
-CAD
-stenosis/occlusion
-MI
-reduced oxygen to myocardium
-damage to heart
-reduced CO
-inadequate circulation of oxygenated blood
-increased workload of breathing
-dyspnoea
136
how does cardiomyopathy lead to dyspnoea
-cardiomyopathy
-heart enlargement/stiffening
-reduced CO
-inadequate circulation of oxygenated blood
-increased workload of breathing
-dyspnoea
137
how does anaemia lead to dyspnoea
-anaemia
-decreased RBC count
-reduced Hg
-reduced oxygen capacity
-insufficient oxygen delivery tissue and cells
-reduced oxygen availability at the lungs
-dyspnoea
138
how does COPD lead to dyspnoea
-COPD
-inflammation leads to narrowed airways
-obstructed flow of air in/out lungs
-reduced oxygen uptake
-reduced oxygen availability at lungs
-dyspnoea
139
how does asthma lead to dyspnoea
-asthma
-bronchoconstriction
-reduced airway diameter, reduces oxygen intake
-increased work of breathing
-dyspnoea
140
how does pneumonia lead to dyspnoea
-pneumonia
-inflammation and fluid buildup in the lungs
-reduced gas exchange capacity
-inadequate circulation of oxygenated blood
-increased workload of breathing
-dyspnoea
141
how does valvular disease lead to dyspnoea
-valvular disease
-stenosis/regurgitation
-increased pulmonary pressure puts strain on the right heart
-RV becomes weakened
-less blood to the lungs
-inadequate circulation of oxygenated blood
-increased work of breathing
-dyspnoea
(RV dysfunction can eventually lead to decreased venous return and decreased preload hence causing left sided failure which leads to pulmonary congestion)
142
how does inflammation of the pericardium lead to dyspnoea
-inflammation of the pericardium
-fluid build up (pericardial effusion)
-reduced contractility of the heart
-reduced CO
-inadequate circulation. of oxygenated blood
-increased workload of breathing
-dyspnoea
143
control of ventilation using peripheral chemoreceptors
-peripheral chemoreceptors in aortic arch--> vagus nerve--> medullary respiratory neurons--> changes to pulmonary ventilation (dependent on CO2) and decreased metabolism if chronic
-peripheral chemoreceptors in aortic arch--> glossopharngyeal nerve--> medullary respiratory neurons--> changes to pulmonary ventilation (dependent on CO2) and decreased metabolism if chronic
144
control of ventilation using central chemoreceptors
-central chemoreceptors of the brain and spinal chord
-medullary respiratory neurons
-changes to pulmonary ventilation and decreased metabolism if chronic (decreases CO2 produced)
145
systematic approach to interpret spirometry results
-if FEV/FVC is low then it has to be obstructive
-if FEV/FVC is high then it could be restrictive, but only if the FVC is less that LLN
