Respiration Flashcards
What are the components of the upper respiratory tract?
Nose, pharynx and larynx
What are the components of the lower respiratory tract?
Trachea, bronchus, lungs
What are the 3 parts of the pharynx
Nasopharynx, oropharynx, laryngopharynx
What components of the pharynx are exposed to both air and food?
Oropharynx and laryngopharynx
What part of the pharynx is only exposed to air?
Nasopharynx
What is the surface area of the lungs, and what is it comparable to?
100m2, half the size of a tennis court
What system is the pharynx apart of?
Digestive & respiratory
What travels down the pharynx?
Air and food
What closes the nasopharynx when swallowing?
Soft palate
What 2 things are essential for efficient gas exchange?
Small diffusion distance between air and blood
Large surface area
Approximately how many breaths are taken at rest per min?
~10/min
What is the diffusion distance between the air in the lungs and blood?
0.5 micrometers (1/15th of a RBC)
Approximately how many litres of air does 1 breath contain?
1/2 a litre
What is respiration?
Exchange of gases
What is ventilation?
The mechanical movement of air in and out (breathing)
What are the 3 types of respiration?
External, internal and cellular
What is external respiration?
Exchange of gasses in the lungs across pulmonary capillaries
What does the ventilatory pump include?
The diaphragm, rib cage and associated muscles
What is internal respiration?
Exchange of gasses between blood in systemic capillaries and systemic tissues
What is cellular respiration?
The process by which individual cells gain energy
What is the primary role of the conducting part of the respiratory system?
Conduct air and prepare it for exchange by warming, cleaning, and humidifying it
What is the primary role of the respiratory part of the respiratory system?
Gas exchange
What are the 2 functional parts of the respiratory system?
Conducting and respiratory
What are the conducting airways?
Nasal cavities, pharynx, larynx, trachea, bronchi and bronchioles
What are the respiratory airways in the respiratory part of the system?
Respiratory bronchioles, alveolar ducts and sacs, and the alveoli themselves
What is the process by which cilia clear the conducting airways?
Mucociliary clearance
How often do cilia beat?
10-15 times per second
What are the 3 requirements for air in order for gas exchange?
Clean, warm (37 degrees), saturated with water
In which direction do cilia beat?
Towards the throat
How is blood warmed in the nasal cavity?
The very rich blood supply under the epithelium
What are the 3 bones in the nasal cavity called, and what do they form?
Turbinate bone forms conchae (superior, middle and inferior)
What is the purpose of the Choncae?
Increase surface area (to maximise warming and humidifying)
Swirl air around to create turbulence, throwing particles onto mucous layers
Describe the lining of the conducting airways
Pseudostratified ciliated columnar epithelium, goblet cells, basal cells
What do paranasal sinuses do?
Lighten face and add resonance to voice
What is the temperature of the air by the time it reaches the throat?
~32 degrees
What part of the respiratory system slows air down?
Nasal cavity
What do seromucous glands secrete and why?
Secrete a watery product to help humidify and filter air
What do goblet cells secrete and why?
Secrete a mucin to help humidify and filter air
Why is an infection in the lower respiratory tract more dangerous than the upper respiratory tract?
Because it is closer to the blood supply
What are the 2 sources of mucous in the respiratory tract?
Mucous glands and Goblet cells
What are nose hairs also known as?
Vibrissae
What are the overall 3 main functions of the nose?
- Warm, moisten and filter air
- Detect olfactory stimuli
- Modify speech vibrations
What is the name of the bone where the olfactory receptor cells are located?
Cribriform plate
Name the order of the branches in the respiratory tree
Trachea -> main stem bronchi -> lobar bronchi -> segmental bronchi -> smaller bronchi -> bronchioles -> terminal bronchioles -> respiratory bronchioles -> alveolar ducts -> alveolar sacs
How many generations of branching are there in the airways?
28
What angle do branches branch off at?
37 degrees
What is the main purpose of the branching in the respiratory tract?
Increase surface area
How long and wide is the trachea?
12cm long, about as wide as a thumb
What 2 things decrease as you go further down the respiratory tract?
Tube diameter and epithelial height
What is the shape of the cartilage in the trachea?
C shaped ring
What does the cartilage in the trachea do?
Protect the trachea and keep it open
What is the widest tube in the respiratory tract?
Trachea
What is the name of the muscle connecting the ends of the incomplete cartilage rings in the trachea?
Trachealis muscle
What is the role of the trachealis muscle?
Narrow diameter of the trachea - possibly involved with cough reflex if food enters trachea
What are the 4 layers of the bronchus?
Respiratory epithelium -> smooth muscle -> mucous & serous glands -> cartilage
What is between the cartilage rings in the trachea?
Connective tissue - allows for flexibility
What is the shape of cartilage in the bronchus?
Crescent moon-shaped (not as big as C)
What cells do bronchiole have instead of goblet cells?
Club cells
What do club cells do?
Secrete watery substance to prevent walls from sticking together during expiration
Secrete chemicals to break down bacteria
Describe the walls of bronchioles
simple columnar or cuboidal epithelia with club cells on top of smooth muscle
Where is the site of major broncho-constriction?
Bronchioles
What is the difference between terminal and respiratory bronchioles?
Respiratory bronchioles have alveoli buds
What is the final branch of the conducting zone?
Terminal bronchioles
What is the first branch of the respiratory zone?
Respiratory bronchioles
What generation of branching forms bronchioles?
16th
What is the final branch of the respiratory zone?
Alveolar sacs
What is an alveolar sac?
More than 2 alveoli in an area
What are the 2 types of alveolar cells?
Type 1: Pneumocytes
Type 2: Surfactant cells
Describe type 1 alveolar cells
Squamous epithelium
What is the purpose of type 2 alveolar cells?
Reduce surface tension, preventing alveolar collapse
What is the 3rd type of alveolar cell, and what does it do?
Alveolar macrophage - picks up and destroys debris that the conducting system has failed to filter
What is the final line of immune defence in the lungs?
Alveolar macrophage
Describe the order in which oxygen must pass through to get from the lungs to the blood
Lumen of alveolus -> type 1 pneumocyte cytoplasm -> fused basement membrane of Type I alveolar cell and endothelial cell -> cytoplasm of capillary endothelium -> blood plasma -> RBC
How many lobes does the right lung have?
3
How many lobes does the left lung have?
2
What is the name of the region in which arteries, veins and bronchi enter each lung?
Hilum
What is the name of the bronchi supplying each lobe?
Lobar bronchi
What is the name of the bronchi supplying each lung?
Main stem bronchi
What is the name of the bronchi supplying each segment?
Segmental bronchi
How many segments are in the left lung?
8
How many segments are in the right lung?
10
What are the 3 factors affecting pulmonary ventilation?
Surface tension, lung compliance, airway resistance
Is expiration active or passive?
Passive
Is inspiration active or passive?
Active
What percentage of air movement into and out of the lungs is the ribcage responsible for?
25%
What muscles are involved with inspiration and what do they do?
External intercostal muscles - contract during inspiration to lift ribs upwards
What muscles are involved with expiration and what do they do?
Internal intercostal muscles - usually not contracting - only contract during forceful exhalation to drag ribs downwards
What is the relationship between volume and pressure?
Volume is inversely proportional to pressure (e.g. as volume increases pressure decrease)
What does contraction of the diaphragmatic muscle do, and when does this occur?
Flatten the diaphragm, pulling it down - increasing the volume of the thorax during inspiration
What percentage of the bulk flow of air is the diaphragm responsible for during quiet breathing?
75% (this decreases during exercise)
What is VT?
Tidal volume - the volume of air per breath at rest ~0.5L
What is FRC?
Functional residual capacity - the amount of air in the lungs after passive expiration (~1.8L - 2.4L)
What is VR?
Residual volume - the volume of air in the lungs that cannot be expelled ~1/2 FRC
What is ERV?
Expiratory Reserve Volume - the extra air exhaled forcefully on top of VT - (FRC-VR)
What is IRV
Inspiratory reserve volume - additional air inhaled on top of VT
What is the calculation for ventilation (L/min)?
VT x Respiratory Frequency
What is FEV1?
Forced expiratory volume - the volume of gas exhaled in 1 sec during forced exhalation
What is FEC?
Maximum expiration after maximum inhalation
How is the visceral pleura attached to the lungs?
Surface tension
When are the forces on the chest wall and forces on the lungs balanced?
At FRC
What is the equation for residual volume?
TLC - VC
What is the approximate dead space in a healthy person?
150ml
What would you expect the pleural pressure to be after a pneumothorax?
0mmHg
Where is total resistance the largest?
Segmental Bronchi
Where is total resistance the lowest in the respiratory tract?
Bronchioles
What is the equation for calculating lung health?
FEV1/FVC
What is the normal/healthy percentage for FEV1/FVC?
80%
What is used to measure gas volume dynamics (FEV1/FVC)?
Vitalograph
What is VE, and how is it calculated?
Minute ventilation - VT x F or VA + VD
What is the VE for hyperventilation?
> 6L/min
What is the VE for hypoventilation?
<6L/min
What is VA, and how is it calculated?
Alveolar ventilation - VT-VD x f
What is used to measure lung volumes?
Spirometer
What happens to pleural pressure during inspiration?
Becomes more negative
What happens to pleural pressure during expiration?
Becomes less negative
What is the most important respiratory muscle?
Diaphragm
What percentage of VT does VD represent?
30%
What shape is the diaphragm when relaxed?
Dome
What are the 2 equations for compliance?
△V/△P & 1/elasticity
What is La Place’s Law?
P = 2T/R
What two things affect compliance?
Amount of elastic tissue in the lungs & amount of surfactant in the alveoli
What percentage of total lung capacity does anatomical dead space make up?
3%
What is the effect of sympathetic stimulation on the lungs?
Bronchodilation
What are the receptors in the smooth muscle of bronchioles called for sympathetic nerves?
Beta2-adrenoceptors
What is the effect of parasympathetic stimulation on the lungs?
Bronchoconstriction
What are the receptors in the smooth muscle of bronchioles called for parasympathetic nerves?
Muscarinic Receptors
What is the reflex that controls bronchodilation called?
Hering-Breuer Reflex
Describe the Hering-Breuer Reflex
Inhalation -> stretch of mechanoreceptors in bronchioles -> increased vagus nerve stimulation to resp. centre in medulla -> increased sympathetic stimulation of Beta2-adrenoceptors on bronchioles -> bronchodilation
What is HP?
Hydrostatic pressure
What is Pa?
Pulmonary blood pressure
What is PV?
Arterial venous difference
What is PA?
Alveolar pressure
What is Q?
Cardiac output
What is HP the same as?
Pa
What makes the lungs have elasticity?
Collagen and elastin fibres
What is the capacity of the resting position of the lung?
Functional residual capacity
Why is a highly compliant lung bad?
High compliance means low elasticity, so expiration will require a lot of effort (no longer be passive at rest)
What device is used to measure pressures inside different areas of the lungs?
Manometer
How many times do the airways divide?
23
Describe the flow of air in the conducting zone
Fast and turbulent
Describe the flow of air in the respiratory zone
Slow and laminar
How much less resistance is there in the respiratory bronchioles/smaller airways than in the trachea?
500x less
Describe the arteries and veins of pulmonary circulation
Thin-walled, low-pressure, small amount of smooth muscle, lots of branching decreasing resistance, highly compliant
Why is it necessary to have slow and laminar airflow in the alveoli?
Provides time for gas exchange
How is mean blood pressure calculated?
Diastolic p + (1/3 systolic p - diastolic p)
What is the mean pulmonary BP?
14 mmHg
What is the mean systemic BP?
93 mmHg
What is the benefit of sheet blood flow?
Increased surface area for gas exchange due to increased contact between blood and alveoli
What does hypoxia in an alveoli cause?
Vasoconstriction
What could hypoxia in alveoli be due to?
Bronchoconstriction e.g. asthma, pollen
What part of the lung receives the most blood supply and why?
The bottom, due to gravity
Why is VA/Q not 1?
The lungs are not fully perfused and ventilation is higher at the base of the lungs
What does an increase in blood flow and pressure to the lungs result in (in terms of gas in blood)?
Increased O2 in blood as the top of the lungs are recruited
What are the 5 factors affecting gas exchange?
Area, thickness of tissue, partial pressure differences, solubility of gas, molecular weight of gas
What is the diameter of alveoli?
0.3mm
How many times more soluble is CO2 compared with O2?
25 times
What is a small △P with a larger △V indicate?
High compliance
What disease results in low-compliant lungs?
Fibrosis
What is COPD the result of?
Smoking - causes reduced elastic fibres and an overinflated lung at rest
What disease results in highly compliant lungs?
COPD - chronic obstructive pulmonary disorder
What is the drug that asthmatics take?
Salbutamol
Describe fibrosis
Stiff lungs due to build up of pathogens (e.g. coal), deflated lungs, widened mid-sternal space and fluffy areas of fibrotic tissue (typically at base)
What are some of the effects of fibrosis on a patient?
Increased effort required to inflate lungs
Describe COPD
Expanded lungs, barrel chest, flattened diaphragm, reduced mid-sternal space
Where are ventilation and perfusion the lowest?
Apex of the lung
Where are ventilation and perfusion the highest?
Base of the lung
Where is the alveoli volume the largest?
Apex of lung
Explain the differences in negative pressures in the intrapleural space
The apex of the lung has a more -ve intrapleural pressure due to gravity, resulting in a larger pleural space at the apex and hence smaller (more -ve) lressure. Pleural space at base of lung is smaller, resulting in a less negative intrapleural pressure
What is the cause of pulmonary hypertension?
Hypoxia
What is hypoxia?
Low O2 in lungs
What follows hypoxia in an alveoli?
Vasoconstriction
Describe how pulmonary hypertension is caused, and how it can cause right heart failure.
Hypoxia -> vasoconstriction -> increased pulmonary artery resistance and ∴ BP -> increased afterload on RV -> RV becomes stretched, baggy and weak -> RV failure
Describe how pulmonary oedema may be caused and what it results in
Blood clot or atheromas in LV -> LV not pumping properly -> increased congestion and BP in pulmonary veins -> oedema -> reduced lung compliance and reduced gas exchange -> breathlessness (dyspnoea) -> systemic hypoxia
What is breathlessness also known as?
Dyspnoea
What is hypoxemia?
Low O2 in blood
What is the effect of hyperventilation on CO2 levels?
Decrease
What is the effect of hypoventilation on CO2 levels?
Increase
What is the effect of hypoventilation on O2 levels?
Decrease
What may increased CO2 result in?
Acidosis
What may decreased CO2 result in?
Alkalosis
What does a sudden increase in pulmonary arterial pressure result in?
Recruitment of previously closed vessels and distension of the lumens of already patent vessels
When is the ventilation: perfusion ratio less than one?
What there is more perfusion than ventilation
Where is the ventilation: perfusion ratio the highest?
The apex of the lung
Where is the ventilation: perfusion ratio the lowest?
The base of the lung
What are 4 consequences of pulmonary hypertension?
Increased pressure in pulmonary capillaries
Fluid movement into alveoli
Pulmonary oedema
Breathlessness
What are the lung segments called?
Bronchopulmonary segments
How many segments are in the right lung?
10
How many segments are in the left lung?
8
Each lung segment has its own…
Blood and air supply
What is normal breathing also called?
Eupnoea
What is the expected Hb saturation % at pO2 40mmHg?
75%
What is the effect of exercise on pH?
Decrease in pH
How is the majority of CO2 transported in blood?
Conversion to bicarbonate ion
What would excitation of the phrenic nerve lead to?
Contraction of the diaphragm and increased thorax volume
What would a decrease in pH lead to?
Increased ventilation
What is Eupnoea?
Normal breathing
What is no breathing called?
Apnoea
What is apnoea?
No breathing
What is the sensation of breathlessness called?
Dyspnoea
What is dyspnoea?
Sensation of breathlessness
What is asphyxia?
Deprivation of oxygen
What is no oxygen called?
Anoxia
What is anoxia?
No oxygen
What is deprivation of oxygen called?
Asphyxia
What is hypercapnia?
High CO2
Why is low CO2 called?
Hypocapnia
What is high CO2 called?
Hypercapnia
What is hypocapnia?
Low CO2
What is ischaemia?
Inadequate blood supply to an organ
What is inadequate blood supply to an organ known as?
Ischaemia
What has the largest impact on the direction of gas flow?
Pressure differences
What is the effect of hyperventilation on pO2 and PCO2?
Increased pO2 and decreased pCO2
What 2 main things affect compliance?
Elastic tissue and surfactant
How many heme groups are in hemoglobin and myoglobin?
4 & 1
What is the relationship between temperature and gas solubility?
Inverse relationship, solubility increases as temperature decreases.
What has the greatest effect on the ability of blood to transport O2?
Amount of Hb
What is the effect of higher temperatures on Hb-O2 affinity?
Decrease in affinity
What is the concentration of O2 in plasma directly proportional to?
Its partial pressure
What two things does an increase in SV do to pulmonary veins/capillaries?
Increased distension and recruitment
What would occur if lung capillaries did not distend and recruit with increased blood?
Oedema
What is the purpose of the Cl- shift?
Maintains cellular electroneutrality
What are the 2 ways in which oxygen is transported in the blood?
Binds with Hb and dissolves in plasm
What gas is diffusion limited?
CO2
What gases are perfusion limited?
O2 and NO2
How does the affinity of Hb-O2 change with pO2’s?
Decrease in pO2 = decrease in affinity - needed for association in lungs and dissociation at tissues
What is the Bohr effect?
A shift of the O2 dissociation curve to the right due to increased H+, CO2, temp, DPG or low O2 in tissues - represents decreased affinity of Hb to O2
What is the Haldane effect?
A shift of the O2 dissociation curve to the left due to decreased H+, CO2, temp, DPG or high O2 in tissues - represents increased affinity of Hb to O2
What are the four ways CO2 may be transported in the blood?
Dissolved
Converted to HCO3-
Combined with amine groups
As H2CO3 and CO3- ions
What transports Cl- and HCO3- across the RBC membrane?
Antiporter
Why is the conversion of CO2 to HCO3- faster in RBC?
They contain the enzyme carbonic anhydrase
Describe the affinities of Hb and HbO2 for CO2
Hb - higher affinity for CO2
HbO2 - lower affinity for CO2
What syndrome may occur if your chemoreceptors fail?
Congenital hypoventilation syndrome
Where are the PNS chemoreceptors located?
Aortic and carotid bodies
What nerves connect the PNS chemoreceptors and the medulla?
Vagal (aortic) and glossopharyngeal (carotid) (X & IX)
What are the stimulants of PNS chemoreceptors?
Low O2, H+, high CO2 (mainly high CO2), increased SNS activity
What is the response time of PNS chemoreceptors?
Fast - within 1 breath
What is the response time of the CNS chemoreceptors?
Slow ~30 sec
What is the reflex response of the PNS chemoreceptors?
Increased breathing rate and depth of breathing
Where are CNS chemoreceptors located?
Neurons and Astrocytes <0.5mm beneath the surface of the ventral medulla
What is the main stimulant of CNS chemoreceptors?
H+ ions
Do CNS chemoreceptors respond to O2 levels?
No
Why is the response time of CNS chemoreceptors slow?
Because only CO2 can cross the BBB, and CSF contains limited carbonic anhydrase, so the conversion of CO2 to H+ is slow
What is the reflex response of CNS chemoreceptors?
Increased minute ventilation
What type of binding is O2-Hb?
Co-operative
What are the effectors of the respiratory centre in the medulla?
Respiratory muscles
What are the units for peak flow rate?
L/min
What are the units for dry spirometry?
mL
What are the units for dry spirometry?
mL
Would an asthmatic have a higher or lower peak flow rate than a normal person?
Lower due to increased airway resistance
What does wet spirometry measure?
Tidal volume
Inspiratory reserve volume
Expiratory reserve volume
Vital capacity
What does dry spirometry measure?
Forced vital capacity & Forced expiratory volume
How would an asthmatic’s FEV1 differ from that of a healthy individual?
Reduced
What does the downward movement of liquid in the outer arm of a manometer indicate?
Negative pleural pressure
What is the intrapleural pressure in the box lung model when no force is being applied?
0 cm H20
How does the content of the intrapleural space in the lung model differ from real lungs?
Air in lung model is expandible, serous fluid in human is not expandable
What 3 factors affect peak flow rate between individuals?
Age, sex and height
What is Dalton’s law?
In a mixture of gases each gas exerts its own partial pressure
What is Boyles law?
At a constant temp, volume of gas varies inversely with pressure
What is the difference between lung volumes and lung capacities?
Volumes are measured and capacities are calculated
What does La Places law measure?
Surface tension induced pressure in Alveoli
