Flashcards
Respiratory 1
Cards in this deck (197)
- 1Describe the nose?Most superior portion of the respiratory tract
- Warms inspired air (0.25 seconds of contact)
- Humidifies air
- Filters inspired air of pathogen using cilia to trap particulates
- Defence function - cilia take inhaled particles backwards to be swallowed - 2What are the nasal meatuses?Superior meatus: Has olfactory epithelium, olfactory nerve penetrates into superior meatus through pores in the cribform plate - sphenoid sinus drains here
Middle meatus: more sinuses drain here (inc maxillary)
Inferior meatus: nasolacrimal duct drain her e - 3What lines the nose?The anterior nose opens into the enlarged vestibule which is skin lined and has stiff hairs
The surface area of the nose is doubled by turbinates - 4Describe the paranasal sinuses?- Pneumatised areas of the frontal, maxillary, ethmoid and sphenoid bones
- Arranged in pairs
- 5Define: pneumatised?A bone that is hollow or contains many air cells
- 6Describe the frontal sinuses?- Within the frontal bone
- Lie of the orbit
- Innervataion: opthalamic division (V1) of the trigeminal nerve (CNV) - 7Describe the maxillary sinuses?- Located within the body of the maxilla
- Pyramidal in shape
- Innervation: Maxillary division (V2) of the Trigeminal nerve (CNV)
- Base: Lateral wall of the nose
- Apex: Zygomatic process of the maxilla
- Roof: follow of orbit
- Floor: alveolar process
Open into the MIDDLE MEATUS - 8Describe the ethmoid sinuses?- Between the eyes
- Labyrinth of air cells
- Innervation: Opthalamic (V1) and Maxillary (V2) branches of the trigeminal nerve (CNV)
- Open into middle meatus - 9Describe the caverous sinuses?Contians caroitd artery, ocularmotor nerve (CNIII), trochlear (CNIV), trigeminal (CNV) and abductens (CNVI)
- 10Describe the sphenoid sinusMedial to the canervous sinus
Inferior to optic canal, dura and pituarty gland
Empties into the sphenoethomoidal recess, lateral to the attachment of the nasal septum
- Innervation: Opthalmic (V1) branch of the trigeminal nerve (CNV) - 11What is the pharynx?A fibromuscular tube which takes filtered air to the larynx
Lined with squamous and columnar ciliated epithelium
Extends from the base of the skull to C6 - 12What epithelium lines the pharynx?Nasopharynx = pseudostratified, cilitated columnar epithelium (same as nasal cavity)
Oropharynx and laryngopharynx = Non keratinising squamous epithlium - 13What is the valvular function of the larnyxPrevents liquid and food from entering the lungs
- 14Describe the structure of the larynx?- Rigid structure
- Consists of 9 CARTILAGES
(6) Paired = Cuneiform, Corniculate and Arytenoid
(3) Unpaired = Epiglottis, thyroid and cricoid - 15How are the vocal chords changed?The arytenoid cartilages rotate on the cricoid cartilage to change vocal chords
- 16What innervates the larynx?Vagus Nerve (CNX)
Superior laryngeal and Recurrent laryngeal nerve - 17What does the superior laryngeal nerve innervate?Divides into the internal (sensation) and external (motor)
External innervated the cricothyroid muscle - 18What does recurrent laryngeal nerve innervate?Provides motor innervation for ALL larynx muscles apart from the cricothyroid muscles
- 19Where does the left recurrent laryngeal nerve run?Runs laterally to the arch of the aorta, loops UNDER the aortic arch and ascends between the trachea and oesophagus
- 20Where does the right recurrent laryngeal nerve run?Loops underneath the right subclavian artery, then runs up the plane between the trachea and oesophagus
- 21What could a tumour/ulcer on or near the reccurent laryngeal nerve cause?Hoarse voice
- 22What is the main function of the lungs?Gaseous exchange
- 23What is the area of gas exchange PER lung20m2
40 m2 for both lung s - 24What is minute volume?The volume of air inhaled /exhaled in a minute
Approx 5 litres - 25What is cardiac output?Volume of blood pumped out by the heart a minute
5 litres per minute - 26Where is the trachea?Extends from the larynx to the carina
C6 to T5 - 27Describe the trachea?Oval in cross section
Semicircular hyaline cartilages (C shaped cartilages increase flexibility)
Pseudo-stratified, ciliated, columnar epithelium
Goblet cells
Upper trachea is more mobile than distal trachea - 28Describe the main bronchi?- Consist of left and right main bronchus
- Sharp division at the carina - 29Which bronchus is more vertically disposed and why?The RIGHT main bronchus is more vertically disposed
Therefore more risk of trapping things and choking
Related to the right pulmonary artery
1.2 to 5cm - 30Describe the left main bronchus?Comes off at more of an angle
5cm
Related to the aortic arch - 31What do the lobar bronchi supply?Right: upper lobe, middle lobe and lower lobe THEREFORE 3 divisions
Left: upper lobe and lower lobe
THEREFORE 2 divisions - 32How many segmental branches are there?Right = 10 branches
Left = 8 branches - 33What is the organisation of bronchi?Main bronchi
Lobar bronchi
Segmental bronchi
Terminal bronchioles
Respiratory bronchioles
Alveolar ducts
Alveoli - 34Describe the alveoli?Type I pneumocytes
Type 2 pneumocytes
Alveolar macrophages
Basement membrane
Membrane is 1 micron thick
Columnar ciliated epithlium - 35What innervates the lung?The PULMONARY PLEXUS lies between each hilum, it receives innervation from both right and left vagus nerve
AND T2 - T4 ganglia of the sympathetic trunk - 36What innervates bronchodilation and bronchocontriction?Bronchodilation = sympathetic input from sympathetic trunk
Bronchoconstriction = parasympathetic input from the vagus nerve - 37Which lung is larger and why?Right lung is large that the left due to the the silhouette of the heart
- 38Describe the lung pleura?2 main layers of mesodermal origin one cell thick, both continuous with eachother at the lung root
VISCERAL: applied to the lung surface - only has autonomic innervation
PARIETAL: applied to the internal chest - has pain sensation via phrenic nerve - 39Describe the blood supply of the lungs?Pulmonary and Bronchial circulations
PULMONARY :
The left and right pulmonary arteries run from the right ventricle
BRONCHIAL :
17 orders of branching
Bronchus and pulmonary arteries run together via the bronchiovascular bundle
Pulmonary veins run on their own - 40What is transpulmonary pressure?Difference in pressure between the inside and outside of the lung
Alveolar pressure - intrapleural pressure - 41What is interpleural pressure?The pressure in the pleural space
Also known as the inter thoracic pressure - 42What is alveolar pressure?Air pressure in the pulmonary alveoli
- 43What initiates inspiration?A neurally induced contraction of the diaphragm and the external intercostal muscles located between the ribs
- 44What is the most important muscle during normal quiet breathing?The diaphragm
- 45What innervates the diaphragm?The phrenic nerve, which arises from C3, C4 and C5
- 46Describe inspiration?1. The diaphragm contracts causing its dome to move downwards thereby enlarging the thorax increasing its volume
2. Simultaneously, the activation of the motor neurones in the intercostal nerves to the EXTERNAL intercostal muscles causes them to contract, up and out movement, further increasing in thoracic volume
3. As the thorax expands, the intrapleural pressure is being lowered and the transpulmonary pressure is becoming more positive = resulting in lung expansion as TP is larger than elastic recoil
4. The lung expansion results in alveolar pressure becoming negative
5. Inwards airflow
6. At the end of inspiration, the chest wallk is no longer expanding but yet to start passive recoil, glottis open so
alveolar pressure = atmospheric pressure
Since elastic recoil balanced by transpulmonary pressure - 47Describe expiration? at rest1. At the end of inspiration, the motor neurones to the diaphragm and external intercostal muscles decrease their firing so that muscles can relax, diaphragm ASCENDS decreasing thoracic volume
2. As they relax, the lungs and chest walls start to passively collapse due to to elastic recoil because muscle relaxation increases intrapleural pressure decreasing transpulmonary pressure so it is less than the elastic recoil
3. As the lungs become smaller the air in the alveoli becomes temporarily compressed resulting in an increase in alveolar pressure resulting in outwards air flow - 48Describe the characteristics of expiration at rest vs. forced?Expiration at rest is passive relying only on the relaxation of the external intercostal muscles and diaphragm and the elastic recoil of the lungs
On certain occurs e.g. excercise the expiration of larger volumes of air is required and resulting in forced expiration which involves the contraction of the internal intercostal muscles - 49Describe forced expiration?1. On top of the actions mentioned in expiration at rest, the internal intercostal muscles also contract as do the abdominals
2. This results in the ribs moving downwards and inwards - actively decreasing thoracic volume, abdominal contraction increases intra-abdominal pressure more thereby forcing the relaxed diaphragm further up into the thorax
3. Resulting in a greater volume of air being expelled - 50Why is there the greatest resistance in the trachea?Because although bronchioles are small, when you add them all up they have a much GREATER surface area therefore providing much less resistance
- 51Define: Dead space?The volume of air not contributing to ventilation
Anatomically theres around 150mls in the alveoli and 25mls in the lungs
So 175 mls of dead space in total - 52Where does gas exchange take place?Between the alveoli and capillaries
- 53What is bulk flow?Net movement down a concentration gradient due to the random motion of individual molecules
- 54What allows O2 and CO2 movement in the airways?Bulk flow
This requires a large surface area with minimal distance for gases to move across as well as adequate perfusion of blood - 55How many alveoli are there per lung?300 milllion
- 56How many capillaries per alveolus?1000
An individual RBC may come into contact with multiple alveoli - 57What are the 7 layers that gases must diffuse through? Alveoli to cappilaries?1. Alveolar epithelium
2. Tissue interstitium
3. Capillary endothelium
4. Plasma layer
5. Red cell membrane
6. Red cell cytoplasm
7. Haemoglobin binding - 58Describe ventilation perfusion matching? V/QEach alveolus is capable of receiving CO2 from, and supplying oxygen to the pulmonary capillary blood
To be most efficient, the correct proportion of alveolar airflow (ventilation) and capillary blood flow (perfusion) shows to be available - 59Describe ventilation perfusion mismatch?The main effect of ventilation perfusion mismatching is that the partial pressure of oxygen is decreased in the systemic arterial blood
In healthy people there is naturally some ventilation perfusion inequality - 60Why is there naturally some V/Q mismatch in healthy people?Gravitational effects
One effect of upright posture is increased filling of the blood vessels at the bottom of the lung due to gravity - contributing to the difference in blood flow distribution in the lung
This explains why the PO2 is roughly 5mmHg higher than in arterial blood - 61What are the extremes that can cause V/Q mismatch?1. The may be ventilated alveoli but no blood supply at all due to a blood clot
2. There may be adequate blood flow through areas of lung but no ventilation due to a collapsed alveoli - 62What else can cause V/Q mismatch?Disease, regional changes in lung compliance, airway resistance and vascular resistance
- 63What is a local homeostatic response to V/Q mismatch?- Hypoxic pulmonary constriction
- Local bronchoconstriction - 64Describe hypoxic pulmonary constriction?A decrease in ventilation within a group of alveoli and nearby blood vessels leads to vasoconstriction
Diverting blood away from the poorly ventilated area
This effect is unique to the pulmonary arterial vessels since in systemic circulation the opposite would occur
Ensures that blood flows away from diseases areas and towards well ventilated - 65Describe local bronchoconstriction?If there is a local decrease in blood flow within a lung region due to e.g. a small blood clot in a pulmonary arteriole
The local decrease in blood flow will mean there is less systemic CO2 in the area, resulting in a decreased partial pressure of CO2
This will cause bronchioconstriction to divert air to areas with better perfusion - 66PaCO2?arterial CO2
- 67PACO2?Alveolar CO2
- 68PaO2arterial O2
- 69PAO2Alveolar O2
- 70PIO2Pressure of Inspired O2
- 71VA?Alveolar ventilation
- 72VCO2?CO2 Production
- 73Describe the structure of haemoglobin?- Four subunits bound together
- Subunits consist of a haem and a polypeptide together
- This means a single haemoglobin can bind to 4 oxygen molecules because each haem can have one oxygen - 74What is the reaction between oxygen and haemoglobin?O2 + Hb ⇄ HbO2
Thus haemoglobin can exist as deoxyhaemoglobin and oxyhaemoglobin - 75Describe the oxygen dissociation curve?Sigmoid shaped because of the four haemoglobin subunits
The reactions of the four subunits occurs sequentially with each combination facilitating the next one - 76At what partial pressure of oxygen is the haemoglobin 90% saturated?60 mmHg
From this point onwards a further increase in the partial pressure of oxygen produces only a small increase in oxygen binding
The curve plateaus - 77Why is the plateau important and higher O2 pressures?In situations such as high altitude with pulmonary disease, a moderate reduction in alveolar O2 partial pressure and thus arterial partial pressure
O2 is decreased from the normal value of 100 to 60mmHg, total quantity of O2 carried by haemoglobin would only decrease by 10%
The plateau provides and excellent safety factor so that even a significant limitation of lung function still allows almost normal oxygen saturation of haemoglobin - 78What does an increase in temperature do to the oxygen dissociation curve?Shifts it RIGHT
Haemoglobin has less affinity for oxygen
Easier to get rid of CO2
Temperature is increased because of the heat produced by tissue metabolism - 79What happens to the oxygen dissociation when there is a decrease in pH or increased acidity?Shifts it RIGHT
Haemoglobin has less affinity for oxygen
pH is decreased because of the elevated CO2 partial pressure and the release of metabolically produced acids (lactic) - 80How does carbon monoxide effect the oxygen dissociation curve?Carbon monoxide has a 200 times greater affinity for the oxygen binding sites on haemoglobin than O2
For this reason, it reduces the amount of oxygen that combines with haemoglobin
Shifts the curve LEFT - 81Describe the relationship between arterial CO2 and alveolar ventilation?The partial pressure of arterial CO2 is inversely related to alveolar ventilation
PaCO2 ⇄ kV̇ CO2 / V̇A - 82What are the three ways that CO2 is carried in the blood?1. Bound to haemoglobin (23%)
CO2 + Hb ⇄ HbCO2
2. Plasma dissolved (10%)
3. As bicarbonate/HCO3- (60-65%) - 83How is CO2 carried as bicarbonate?
- 84What enzyme catalyses the formation of H2CO3?Carbonic anhydrase
- 85What happens to the carbonic acid as soon as it is formed in the RBC?It dissociates into HCO3- and H+ and then the HCO3- moves out of the RBC into the plasma via a transporter
This transporter exchanges on HCO3- for at chloride ion to maintain electroneutrality within the erythrocyte and the plasma - 86Why is venous blood only slightly more acidic than arterial blood?The H+ binds to deoxyhaemoglobin since deoxyhaemoglobin has a greater affinity for H+
Only a small amount of H+ generated in the blood remains free
This is why venous blood is only slightly more acidic than arterial blood - 87What happens chemically as the venous blood enters the lungs?Deoxyhaemoglobin becomes converted to oxyhaemoglobin
In that conversion, H+ is released and picked up in the tissues
H+ reacts with HCO3- to form carbonic acid
Broken down to CO2 and H2O by carbonic anhydrase and the CO2 is diffuses to the alveoli to be expired - 88Why is there net diffusion of CO2 from blood to the alveoli?Because when blood reaches the longs the partial pressure of CO2 in the blood is higher than alveolar CO2 so there is a net diffusion
- 89What is the usual pH of blood>7.4
7.35 - 7.45 - 90How is balance of pH maintained in the body?Balance is maintained by mechanisms that generate, buffer and eliminated acids and bases
Most body acids and bases are weak - 91What are the three main buffering systems of body fluid pH?1. Intra and extracellular buffers
2. The lungs eliminating CO2
3. Renal HCO3- absorption and H+ elimination - 92Describe respiratory acidosis?When a person HYPOventilates, there is inadequate ventilation of the alveoli meaning that CO2 cannot be excreted and expired adequately
The partial pressure of CO2 increases thereby resulting in more carbonic acid being produced and thus increased H+ concentration - 93Describe respiratory alkalosis?When a person is HYPERventilating, this would decrease arterial partial CO2 pressure and thus H+ concentration resulting in respiratory alkalosis
- 94What is the Henderson-Hasselbalch equation?pH=6.1* + log10([HCO3-]/[0.03*PCO2])
It is the dissociation constant for the bicarbonate buffer system
0.03*PCO2 = estimate of H2CO3
0.03 = the blood CO2 solubility co-efficient - 95What is Dalton's Law?The pressure exerted by each gas in a mixture of gases is independent of the pressure exerted by the other gases
This is because the gas molecules are so far apart that they do not affect each other
Each gas in a mixture behaves as if there are no other gases presnt
So the total pressure of the mixture is simple the sum of the individual pressures (pp) when are directly proportional to its concentration - 96What Boyle's Law?The pressure of a fixed amount of gas in a container is inversely proportional to the containers volume
P1V1 = P2V2 - 97What is Henry's Law?The amount of gas dissolved in a liquid is proportional to the partial pressure of that gas with which the liquid is in equilibrium with
At equilibrium the partial pressures of the gas molecules and the liquid and gaseous phases must be identical - 98What is the alveolar gas equation?PAO2 = PiO2 - PaCO2/R
R - the respiratory exchange ratio which is the ratio between the amount of CO2 produced in the metabolism and oxygen used - 99Describe the relationship between pressure, flow and resistance?Pressure = flow x resistance
- 100What is the law of Laplace?Describes the relationship between pressure (P), surface tension (T) and the radius of on an alveolus (r)
P = 2T/r - 101What is lung compliance? (Cl)The change in lung volume caused by a given change in transpulmonary pressure
The greater the lung compliance, the more readily the lungs are expanded - 102What are the determinants of lung compliance?- Stretchability of the lung tissues
- Surface tension of the air water interface - 103How does the stretchability of lung tissues determine lung compliance?A thickening and thus a loss in the stretchability of the lungs connective tissues results in a decreased lung compliance
- 104How does the surface tension from air water interfaces determine lung compliance?The surface of the alveolar cells are moist, thus alveoli are effectively air filled sacs lined with water
At an air water interface the attractive forces between the water molecules known as surface tension, make the water lining like a stretch ballon
Thus the expansion of the lungs requires energy to not only stretch the connective tissue but also to overcome the surface tension of the water layer lining the alveoli - 105How is the surface tension of water overcome in the lungs?The type II pneumocytes in the alveoli produce a surfactant which markedly reduced the cohesive forces between the water molecules on the alveolar surface
This surfactant lowers the surface tension which in turn increases the lung compliance making it easier to expand the lungs - 106What would happen if these was no surfactant in the lungs?In pure water the surface tension is so great that eventually lung expansion wouls require exhausting muscular effort resulting in lung collapse
- 107When does the amount of surfactant decrease?When breaths as small and constant
However a deep breath stretches the type II pneumocytes stimulating the secretion of surfactant - 108What is Inspiratory Reserve Volume? IRVThe amount of air in excess tidal inspiration that can be inhaled with maximum effort
- 109What is Expiratory Reserve volume? ERVThe amount of air in excess tidal expiration that can be exhaled with maximum effort
- 110What is Residual Volume? RVThe amount of air remaining in the lungs after maximum expiration, keeps alveoli inflated between breaths and mixes with fresh are on inspiration
- 111What is vital capacity? VCThe amount of air that can be exhaled with maximum effort after maximum inspiration
ERV + TV + IRV
Used to asses the strength of the thoracic muscles as well as pulmonary function - 112What is functional residual capacity? FRCThe amount of air remaining in the lungs after normal expiration
RV + ERV - 113What is Inspiration Capacity? ICThe maximum amount of air that can be inhaled after a normal tidal expiration
TV + IRV - 114What is the Total Lung Capacity? TCThe maximum amount of air that the lungs contain
RV + VC - 115What is Tidal Volume? TVThe amount of air inhaled or exhaled in one normal breath
Usually around 500ml per breath - 116What is FEV1?Forced Expiratory Volume in one second
In which a person take a maximal inspiration and then exhales maximally as fast as possible
The important value is the FRACTION of the total forced vital cap in one seocnd - 117What fraction of vital capacity can be exhaled in one second in healthy individuals?80% of the vital capacity
- 118Describe the procedure measuring FEV1?1. Breath in total lung capacity
2. Exhale as fast as possible in one second
3. Volume produced is the forced vital capacity for 1 second - 119Describe the FEV6 graph?Flow is greatest at the start of expiration however it declines linearly with volume
- 120What is FEF25?Flow at point when 25% of total volume to be exhaled has been exhaled
- 121When would an FEV1 be considered normal or low?If the result is 80% or greater than the predicted value then it is considered normal
If the FEV1 is lower than 80% then it is low - 122What is FVC, and what is a considered normal for FVC?Forced vital capacity
80% of predicted vital capacity is considered normal
Low FVC = airways restriction - 123What are the indicators of airways restriction?If the ratio of FEV1/FVC is high i.e normal but the FVC is low
This is airway restriction - 124What are the indicators of airways obstruction?If the ratio of FEV1/FVC is below 0.7
This is airway obstruction - 125What is the diagnosis? Measured values FEV1 = 1.8 FVC = 3.3 Predicted values FEV1= 2.94 FVC 3.70Ratio of measured values = 1.8/3.3= 0.55 which is low
Look at predicted values
FEV1 1.8/2.94 = 61% low
FVC 3.3/3.7 = 89% normal
Low ratio, Low FEV, Normal FVC =
AIRWAYS OBSTRUCTION - 126What is the diagnosis? Measured values FEV1 = 1.1 FVC = 1.2 Predicted values FEV1= 3.6 FVC = 4.55FEV1/FVC ratio = 1.1/1.2 = 92% normal
Look at predicted values
FEV1 = 1.1/3.6 = 31%
FVC = 1.2 / 4.55 = 26%
Normal ratio, Low FEV1, Low FVC =
AIRWAYS RESTRICTION - 127How is inspiration initiated in the lungs?Inspiration is initiated by a burst of action potentials in the spinal motor neurons to inspiratory muscles like the diaphragm
Vagus nerve arises from C3, C4 and C5 for the diaphragm - 128Where does control of breathing reside?Control of breathing resides primarily in the neurons in the medulla oblongata, the same area of the brain that controls the major cardiovascular control centres
- 129What are the two main anatomical components of the medullary respiritory centre?Dorsal Respiratory Group: These primary fire during inspiration and have input to the spinal motor neurons that active respiratory muscles involved in inspiration
Ventral Respiratory Group: Respiratory rhythm generator is located in the pre Botzinger complex of the neurons in the upper part of the VRG - 130What does the Ventral respiratory group contain?Contains expiratory neurons that appear to be most important when large increases in ventilation are required e.g. during strenuous physical activity
- 131What is the respiratory rhythm generator composed of?Pacemaker cells and a neural network that acting together set the basal respiratory rate
During quiet breathing the respiratory rhythm generator activates inspiratory neurons in the VRG that depolarise the inspiratory spinal motor neurons - 132What does the apneustic centre do?An area of the lower pons called the apneustic centre is thought to be involved in fine tuning the output of the inspiratory neurones of the medulla by continuing to active the inspiratory neurone it inhibit expiration
- 133What can override the apneustic centre?The pneumotaxic centre
- 134What is the pneumotaxic centre?Regulates and on occasion can override the apneustic centre
It is also known as the pontine respiratory group in the upper pons and it acts to smooth the transition between inspiratory and expiration
It is also thought to be involved in switching off inspiratory neurons to prevent hyperinflation allowing expiration - 135What are the receptors of the nose, nasopharynx and larynx?Chemo and mechanoreceptors
Some appear to sense and monitor flow
Stimulation of these receptors appear to inhibit the central controller i.e. medullary respiratory centre - 136What are the receptors of the pharynx?Has receptors that appear to be activated by swallowing - respiratory activity stops during swallowing protecting against the risk of aspiration of food or liquid
- 137Describe Slowly Adapting Stretch Receptors? SASRsMyelinated
Maintain a persistant or slowly decaying receptor potential during constant stimulus - imitating action potentials for the duration of the stimulus
Found in airway smooth muscle and activated by lung distension
High activity inhibits further inspiration and inhibits further inspiration thus beginning expiration
If inflation is maiting they slowly adapt to low frequency firing - 138Describe Rapid Adapting Stretch Receptors? RASRsMyelinated
Generate a receptor potential and action potentials at the onset of a stimulus but very quickly cease responding
Found between airway epithelial cells
Activated by lung distension and irritants
Produce a brief burst of activity and high activity causes bronchoconstriction
Might be involved in the cough reflex - 139Describe C fibres and J receptors?Non myelinated
Found in either the capillary walls or the interstitium
Stimulated by an increase in lung interstitial pressure causes by the collection of fluid in the interstitum
Such an increase can occur during the vascular congestion cause by PE or left ventricular heart failure
Activity results in rapid breathing, shallow breathing, bronchoconstriction, cardiovascular depression and a dry cough
In addition, J receptors gives rise to the sensation of pressure in thickest and dyspnea - 140What is the interstitum?Pulmonary interstitium is a collection of support tissues within the lung that includes the alveolar epithelium, pulmonary capillary endothelium, basement membrane, perivascular and perilymphatic tissues.
- 141What are the pulmonary stretch receptors?Slowly adapting stretch receptors
Rapidly adapting stretch receptors
C fibres and J receptors - 142What are the most important inputs for automatic control of ventilation at rest?Peripheral (arterial) chemoreceptors
Central chemoreceptors - 143Describe the locations of the peripheral chemoreceptors?Located high in the neck at the bifurcation of the common carotid arteries and in the thorax on the arch of the aorta
Carotid = carotid bodies
Aorta = aortic bodies
In both locations they are quite close to but distinct from the arterial baroreceptors and are in intimate contact with the arterial blood - 144Describe the function of the composition of the peripheral chemoreceptors?Composed of specialised receptor cells stimulated by:
- decrease in PaO2
- Decrease in pH (increase in H+)
Type II cells are located here and on detection of hypoxia release stored neurotransmitters that stimulate the carotid sinus nerve
These provide excitatory input to the medullary inspiratory neurons - 145What is the predominant peripheral chemoreceptor?The carotid body input
- 146When are the peripheral chemoreceptors stimulated?They are not sensitive to small reductions in arterial partial O2 pressure, it is only when the partial pressure of O2 comes close to 60mmHg where haemoglobin is close to 90% saturated when the peripheral chemoreceptors really begin to dire
- 147Describe the effects of carbon monoxide on the peripheral chemoreceptors?CO does not effect the amount of O2 that can dissolve in the blood therefore does not alter the oxygen diffusion capacity of the lung, the arterial pressure is unaltered meaning that there is not increase peripheral chemoreceptor output
- 148Describe the location and action of the central chemorecepotr?Located in the medulla
Provides excitatory synaptic input to the medullary inspiratory neurons
Stimulated by a decrease in pH of the brains CSF however HOWEVER since blood brain barrier is readily impermeable to H+ this is poorly reflected
However, CO2 diffuses readily into the CSF and blood partial CO2 pressure can influence CSF pH enabling central chemoreceptors to detect H+ changes - 149What would a very small change in arterial PaCO2 result in?Very small increases in the arterial PaCO2 pressure causes a marked reflex in ventilation
The reflex mechanisms controlling ventilation prevent small increases in arterial partial CO2 pressure to a much greater degree than they prevent equivalent decrease in arterial O2 pressure - 150What is ventilatory drive sensitive to?Ventilatory drive is extremely sensitive to changes in arterial partial CO2 pressure of blood entering the brain
- 151What would happen if there is an increase in arterial CO2 pressure?If there is an increase in the PaCO2 then some of the extra CO2 will diffuse into the CSF and react with H2O resulting in more H+ ions enabling the central chemoreceptors to detect the pH change and increase ventilation by stimulation the medullary inspiratory neurons
- 152What accounts for most of the increased ventilation stimulation?Central chemoreceptors account for 70% of increase ventilation
- 153Describe hypoxia?Defined as a deficiency of oxygen at the tissue level
The most common type of hypoxia is hypoxic hypoxia or hypoxemia which is where the PaO2 is reduced - 154What are the most common causes of hypoxia?1. Hypoventilation
2. Diffusion impairment
3. Shunting
4. Ventilation perfusion mismatch - 155Describe hypoventilation?Results in an increased PaCO2
Failure to ventilate the alveoli quickly
Causes by muscular weakness, obesity, loss of respiratory drive (e.g. morphine) - 156Describe diffusion impairment?Results from the thickening of the alveolar membranes or a decrease in their surface area
Causes the blood PaO2 and the PAO2 to fail to equilibrate
Caused by pulmonary oedema, anaemia, interstitial fibrosis - 157Describe shunting?An anatomical abnormality of the cardiovascular system that causes mixed venous blood to bypass the ventilated alveoli passing rom the right side of the heart to the left side e.g. ventricular septal defect (VSD) - Eisenmenger's Syndrome
- 158Describe ventilation perfusion mismatch?Most common cause of hypoxemia
Occurs in chronic obstructive pulmonary disorder and many other lung diseases
Arterial partial CO2 pressure may by normal or increased depending on how much ventilation is reflexively stimulated
Can be caused by a pulmonary embolism, asthma, pneumonia and pulmonary oedema - 159What is hypercapnia?Carbon dioxide retention and increased arterial partial CO2 pressure
Principally caused by hypoventilation
Can sometimes be caused by ventilation perfusion mismatch depending on how much ventilation is reflexively stimulated - 160Describe type 1 respiratory failure?pO2 is low
pCO2 is low or normal
1 change = low pO2 then normal/low pCO2
Pulmonary embolism (type of V/Q mismatch) causes type 1 - 161Describe type 2 respiratory failure?pO2 is low
pCO1 is high
2 changes = low pO2 + high pCO2
Hypoventilation causes type 2 - 162Describe the vascular physiology of the lungs?There are two circulations in the lungs: the pulmonary circulation and the bronchial circulation
PULMONARY CIRCULATION:
- Main circulation
- From right ventricle
- Receives 100% of cardiac output
- Red cell transit time 5 seconds
- Surfacea area for gas exchange 50 to 100 m2
- 280bn capillaries and 300m alveoli
BRONCHIAL CIRCULATION:
- Receives 2% of bronchial circulation n - 163Describe the differences in pulmonary v.s. systemic circulation?PULMONARY:
- Vessel wall is thin
- Minor muscularisation
- No need for redistribution
SYSTEMIC:
- Vessel wall is thick
- Significant muscularisation
- Redistribution is required
- MUCH higher pressure - 164Describe the parasympathetic regulation of the airways?Neurotransmitter: Acetylcholine
Innervates via: Vagus nerve
Innervates: vasculature, glands and airways in lungs
Intrinsic tone of the airways is governed by the parasympathetic system
Ach interacts with muscarinic cholinergic receptors on the muscle to provide a general level of intrinsic muscle tone - 165What type of nerve releases acetylcholine?Acetylcholine is released by both the sympathetic and parasympathetic but in the lungs, ACh is primary released by parasympathetic
- 166Describe the sympathetic regulation of the airways?Neurotransmitter: Noradrenaline
Innervates via: sympathetic trunk
Innervates: Vasculature and glands - does not directly influence the airways - 167How does the sympathetic system indirectly influence the airways?Sympathetic activation causes NAd to be
released to the adrenal glands and can
result in the release of adrenaline (from
adrenal medulla) which in turn binds to
beta-2-adrenoreceptors on muscles of
the airways and subsequently results in
bronchoDILATION - thus this is the
indirect effect of the sympathetic system
on the airways - 168What are the different types of receptors in the lungs?- Cholinergic receptors
- Nicotinic receptors
- Muscarinic receptors
-Adrenergic receptors (alpha and beta) - 169Describe cholinergic receptors ?- Neurons that release Ach are called cholinergic neurons
- Neurons associated with Ach system degenerate in people with Alzheimers disease - 170Describe nicotinic receptors?- Respond to Ach as well as nicotine
- Stimulated by both sympathetic and parasympathetic but predominantly parasympathetic
- Found in post ganglionic neurons and at neuromuscular junctions
- Contains a ligand gated channel that is permeable to both Na+ and K+ ions but since Na_ has a larger electrochemical driving force the net effect of opening these channels is depolarisation - 171Describe muscarinic receptors?- ACh receptors that form G coupled receptor complexes
- Parasympathetic
- Many types: M1,M2 M3, M4 and M5
- M3 plays an important role in that airways - 172Describe the action of the M3 receptor?1. ACh binds to M3 receptor
2. Receptor couples with Gq protein
3. Gq protein activates phospholipase C (PLC)
4. Phospholipase C catalyses the breakdown of a plasma membrane phospholipid to a DAG and IP3
5.DAG acts as a second messenger and actives a family of proteins known as protein kinase C (PKC)
6. IP3 binds to the ligand gated Ca2+ receptors located on the endoplasmic reticulum in the bronchial cells which open when IP3 is bound to them, resulting in Ca2+ release stimulating BRONCHOCONSTRICTION - 173What are the different types of adrenergic receptors?Neurons that release NAd are called adrenergic:
Alpha = alpha 1 and alpha 2
Beta = Beta -1 (heart) Beta-2 (lung) Beta-3 (adipose) - 174How do the alpha receptors act?Alpha-1: Acts postsynaptically to either stimulate or inhibit the activity of different types of K+ channels
Alpha-2: Acts presynaptically to inhibit noradrenaline release - 175How to beta-2 receptors act?G Coupled Protein Receptor
1. Ad or NAd binds to the receptor
2. Receptor couples with Gs protein
3. Gs protein activitates Gs protein
4. Adenyl cyclase the catalyses the conversion of cytosolic ATP to cyclic 3'5'adenosine monophosphate or cAMP
5. cAMP acts as a second messenger then diffuses in the lung resulting in a decrease in calcium concentration as well as other effect e.g. activating PKA resulting in BRONCHODILATION - 176What do beta-2 receptors cause?Bronchodilation
- 177What are the types of receptor ligand?Agonist
Antagonist - 178Describe the action of an agonist receptor ligand?Agonist: a compount that binds to the receptor and activates it, demonstrating both affinity and efficacy
- 179Describe the action of an antagonist receptor ligand?Antagonist: a compount that blocks the effect of an agonist by competing with a chemical messenger for its binding site
It does not active signalling normally thus blocking its action - it has affinity by zero efficacy - 180How does affinity determine wither or not a ligand acts as an agonist or antagonist?Affinity is shown by BOTH agonists and antagonists
Affinity is the degree to which a particular messenger binds to its receptor and is determined by the affinity of the receptor for the messenger
A receptor with a high affinity will bind at lower concentrations than a receptor of low affinity - 181How does efficacy determine weather or not a ligand acts as an agonist or antagonist?Describes how well a ligand activates a receptor
High efficacy agonist: large change in receptor shape upon binding
Low efficacy agonist: small change in receptor shape when binding
Antagonist: No conformational change to receptor shape when binding - 182What are some of the agonists for receptors?Muscarine binds to the muscarinic acetylcholine receptor
Nicotine binds to the nicotinic acetylcholine receptor - 183What are some of the antagonists for receptors?Atropine binds to muscarinic acetylcholine receptor
Used to help people poisoned with marine - 184How are symptoms in asthma and COPD alleviated?Asthma and COPD results in difficulty breathing due to inflammation
To alleviate symptoms bronchodilators are given to increase bronchoconstriction
Muscarinic antagonists are allow given to block bronchodilaton - 185What beta agonists are used in asthma and COPD?Beta agonists increase bronchodilaton
Short acting (around 4 hours): Salbutamol and terbutaline
Long acting (around 12 hours): Salmeterol and formoterol - 186What muscarinic antagonists are used in asthma and COPD?Muscarinic antagonists want to decrease bronchoconstriction
Short acting (around 4 hours): Ipratropium
Long acting (around 12 hours): Tiotropium - 187Summarise the parasympathetic influence on the respiratory system?Neurotransmitter: Acetyl Choline
Receptor: Muscarinic 3 (M3)
Effect: Constriction - 188Summarise the sympathetic influence on the respiratory system?Neurotransmitter: Noradrenaline, which acts on the adrenal glands to release adrenaline
Receptor: Beta-2-adrenoreceptor
Effect: Dilation - 189What is epithelium?Tissues composed of cells that line the cavities and surfaces of structures throughout the body
Lies on top of connective tissue - the two layers are separated by a basement membrane - 190Describe the respiratory epithelium?Ciliated Pseudostratified Columnar Epithelium
- Serves to moisten and protect the airways
- Also function as a barrier to potential pathogens
- Prevents tissue infection and tissue injury by action of the muscocilary escalator - 191How do glands help defend lungs?The various skin glands, salivary glands and lacrimal glands secrete antimicrobial chemicals such as:
Antibodies
Lysozymes - destroys bacterial cell walls
Lactoferrin - prevents bacteria obtaining iron - 192What are the non immune host defence mechanisms?Epithelium (Respiratory)
Surface defence mechanisms e.g. glands and mucous
Physical defence mechanisms e.g. coughingand sneezing - 193What are the surface defence mechanisms?Glands secreting antimicrobial chemicals
Mucus
Chemical barriers from respiratory epithelium including anti fungal and antimicrobial peptides - 194Describe coughing?A cough is an explosive expiration that provides a normal protective mechanism for clearing the tracheobronchial tree of secretions and foreign material
A cough may be initiated voluntarily or reflexively - 195Describe the action of coughing?When the receptors are stimulated, the medullary inspiratory neurons reflexively cause a deep inspiration (2.5L)
The epiglottis closes and the vocal chords shut tightly to entrap air within the lung
Abdominal muscles contract forcefully pushing against the diaphragm
Internal intercostal muscles also contract forcefully
Pressure in the lungs rises to 100mmHg or more
Markedly postive intrathoracic pressure causes narrowing of the trachea
Vocal cords and epiglottis suddenly open widely
The large differential pressure between airways and atmosphere coupled with tracheal narrowing expels air at velocities ranging from 75 to 100 mph - 196Describe mucus?Airway mucous is a viscoelastic gel containing water, carbohydrate, proteins and lipids
It is a secretory product of the goblet cells of the airway surface epithelium and submucosal glands
Protects epithelium from foreign lateral and fluid loss
Transported via mucociliary escalator that constantly moves mucus by cilia beating in directional waves
Consists of a superficial gel later and a liquid (surfactant) layer that bathes cilia - 197Describe epithelial injury?Infections caused by viruses often target specific epithelial cells whereas bacterial are less specific
Following an injury to the airway epithelium, the epithelium can carry out a fully repair i.e it regenerates itself
This is due to the fact that epithelium exhibits a level of functional plasticity and when this goes wrong it can result in pulmonary disease
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- PHASE 1 MED (Cardiovascular and Respiratory ) Flashcards on Respiratory 1, created by Erin Dunn on 28/01/2019.
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