ILA respiratory failure Flashcards
Describe the anatomical structure air will pass through as it travels from the nose to the alveoli
External nares, nasal cavity, internal nares, nasopharynx, oropharynx, laryngopharynx, trachea, main bronchi, lobar bronchus, segmental bronchus, subsegmental bronchus, conducting bronchiole, terminal bronchiole, respiratory bronchioles, alveolar ducts, alveolar sacs and alveoli.
Upper airway structures
nose, nasal passages, paranasal sinuses (frontal and sphenoid), pharynx (naso, oro and laryngo), larynx above vocal cords
Paranasal sinuses
Sphenoid and frontal
Nasal chonchae
superior, middle and inferior
Lower airway structures (sequence)
larynx below vocal cords, trachea, main bronchus, lobar bronchi, segmental bronchi, subsegmental bronchi, conducting bronchiole, terminal bronchiole, respiratory bronchioles, alveolar ducts, alveolar sacs and alveoli
Where are lower airway structures derived from?
developing foregut
Number of generations in respiratory tree
23 on average
Proximal divisions
closest to top of tree - bronchi. Transmit air to lower airways
Distal divisions
respiratory bronchiole, alveolar ducts and alveoli. Specialised for gas exchange
Structure of trachea and its divisions
C shaped tracheal rings of hyaline cartilage. Branches into left and right main bronchus. Bronchi branch into smaller sections (bronchioles). Bronchioles lead to air sacs and alveoli.
Tracheal rings
C-shaped hyaline cartilage, Prevents trachea from collapsing.
Suspension of lungs
suspended within pleural cavity of thorax
Pleurae
2 thin membranes, one cell layer thick, surrounding the lungs.
Inner and outer pleurae
Inner is visceral pleura covering the lungs. Outer is parietal pleura lining inner surface of chest wall.
Function of pleura
Secretes fluid, which allows the lungs to move freely within the pleural cavity while expanding and contracting
Lung lobes
Right lung has three - superior, middle and inferior. Left lung has two - superior and inferior, and portion of superior lobe (lingula). Divided into bronchopulmonary segments.
Carina
Point where two mainstem bronchi branch off from base of trachea.
Lung surfaces
costal surface - adjacent to ribcage, diaphragmatic surface - downward toward diaphragm, mediastinal surface - toward centre of chest, againts heart, vessels and carina
Costal surface
Adjacent to ribcage
Diaphragmatic surface
Faces downwards toward diaphragm
Mediastinal surface
Faces toward centre of chest, lies against heart, great vessels and carina
Airway resistance formula
R(AW) = deltaP/volumetric airflow
deltaP formula
atmospheric pressure - alveolar pressure
Determinants of airway resistance
diameter of airways
airflow being laminar or turbulent
Laminar airflow
Less resistance. Fluid flows in parallel layers w/out disruption between them.
Turbulent airflow
Large changes in pressure difference. Increased resistance.
Airways prone to turbulent airflow
Larger airways more prone to turbulent airflow
Where is the greatest resistance to airflow? (+explanation)
Bronchi of intermediate size, between 4th and 8th bifurcations. Individual small airways have greater resistance than large airways - more small airways than large ones.
Medullary respiratory centre function
Sets basic rhythm for breathing
Ventral respiratory group function
Generates breathing rhythm and integrates data coming into the medulla
Dorsal respiratory group
Integrates input from stretch receptors and peripheral chemoreceptors
Pontine respiratory group
influences and modifies medulla oblongata functions. Controls involuntary respiration
aortic and carotid bodies
monitor blood pCO2, pO2, pH
hypothalamus
monitors emotional state and body temp
cortical areas of the brain
control voluntary breathing
proprioceptors
send impulses regarding joint and muscle movements
pulmonary irritant reflexes
protect respiratory zones from foreign material
inflation reflex
protects lungs from over-inflating
where is involuntary respiration controlled?
not under concious control. respiratory centre in upper brainstem: medulla oblongata and pons
where are chemoreceptors located?
central: ventrolateral surface of medulla oblongata. peripheral: aortic and carotid bodies
medulla oblongata function and components
sends signals to muscles controlling respiration and controls reflexes for non-respiratory air movements.
contains ventral respiratory group (VRG) and dorsal respiratory group (DRG)
VRG function
stimulates expiratory movements. neurons stimulate accessory muscles to contract –> forced inspiration or expiration. exhalation
VRG neurons
rostral retrofacial nucleus
caudal nucleus retroambiguus
nucleus paraambiguus
pre-boetzinger complex
where do VRG neurons send their impulses to?
inspiratory - down the phrenic nerve: laryngeal and pharyngeal (from nucleus ambiguus)
diaphragm and external intercostals (from rostral area of nucleus retroambigualis)
expiratory - output stops: abdominals and internal intercostals (caudal area)
where is the DRG located?
dorsomedial region of medulla. composed of cells in solitary nucleus.
what is the solitary nucleus?
series of purely sensory nuclei in the medulla oblongata. solitary tract runs through it, w/ nerves innervating it from facial, glossopharyngeal and vagus. forms circuits contributing to autonomic function
DRG function
generation of respiratory rhythm and inhalation
DRG stimulation and inhibition
stimulated by apneustic centre in lower pons. inhibited by pneumotaxic centre. SN appropriates responses from chemoreceptors and mechanoreceptors
DRG inspiration and expiration mechanisms
increase in firing of cells in solitary tract and VRG –> contraction of respiratory muscles. DRG neurons send impulses down the phrenic and intercostal nerves to stimulate diaphragm and external intercostals to contract. exhalation - cells stop firing.
pneumotaxic centre location
upper part of the pons
pneumotaxic nuclei
subparabrachial nucleus and medial parabrachial nucleus
pneumotaxic centre function
controls rate and pattern of breathing. limits inspiration - inspiratory off-switch. limits bursts of action potentials in phrenic nerve.
pneumotaxic centre and increasing rate and length of breathing
signals drg to speed up
bursts of drg activity are elongated
pneumotaxic centre and tidal volume
decreases tidal volume
apneustic centre location
lower pons
apneustic centre function
promotes inspiration by stimulation of DRG in medulla - delays switch off signal of inspiratory ramp provided by pneumotaxic centre. Controls intensity of breathing. inhibits expiratory neurons
Apneustic centre inhibition
inhibited by pulmonary stretch receptors
