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Phase 1
Louise Caldwell & Jess Gray
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Aims
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Anatomy of airways
Physiology of breathing
Spirometry
Immunology
Embryology
Histology
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Anatomy of airways
Nose
Turbinates (conchea) on lateral wall create meatuses:
superior – sphenoid sinus opens into it
middle – frontal sinus opens into it
inferior – largest and widest, nasolacrimal duct opens into it
through valve of Hasner
Lined by olfactory epithelium: psuedostratified columnar with
immotile stereocilia w/ pigment granules, serous glands and large
nerve bundles
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Anatomy of airways
Frontal – ophthalmic
division of 5th CN
Maxillary - maxillary
division of 5th CN
Sphenoid - ophthalmic
division of 5th CN, medial
to cavernous sinus
(internal carotid artery)
Ethmoidal – opthalmic
and maxillary divisions of
5th CN, labyrinth of air
cells
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Anatomy of airways
Pharynx = skull base – oesophagus
• Nasopharyx; pharyngeal tonsils in roof, Eustachian tube opens on
lateral walls, opens to oropharynx at the uvula)
• Oropharynx; posterior 1/3 tongue makes floor, palatoglossal &
palatopharyngeal folds on lateral walls with palatine tonsils between
• Laryngopharynx; thyroid cartilage and thyrohyoid membrane on
lateral walls
Larynx = 9 cartilages with valvular function preventing food & drink
entering the lungs
10th CN – recurrent laryngeal: all internal muscles except… (left is long!)
– superior laryngeal: cricothyroid muscle
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Anatomy of airways
Trachea = larynx (C6)– carina(T5)
Semicircular hyaline cartilages
connected by trachealis muscle
Main Bronchi
R more vertically disposed and
shorter (1-2.5cm long)
Lobar Bronchi
R–3 L–2
Segmental Bronchi
R – 10 L – 8
Cartilage becomes irregular until
bronchioles
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Anatomy of airways
Respiratory Bronchi
Terminal Bronchi
Alveoli
-type 1 pneumocytes
-type 2 pneumocytes; secrete surfacant
-alveolar macrophages
No cartilage and columnar ciliated
epithelium
Visceral pleura on lung surface
Parietal pleura on chest wall, pain
sensation
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Physiology
Inspiration: contraction of diaphragm and external
intercostal muscles
Expiration: passive at rest, or contraction of internal
intercostal muscles
C345 innervate diaphragm …
…‘C345 KEEPS THE DIAPHRAGM ALIVE!’
Δ pressure = flow x resistance
Laminar flow; Δpressure∝ flow, majority of flow, low
resistance
Turbulent flow; Δpressure∝ flow^2, higher resistance
Resistance greatest at 5th – 7th generation = intermediate
bronchi – why?
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Physiology
Compliance = capacity of lung to stretch
C=1/E
= ΔV/ΔP
A lung of high compliance expands more with the same
trans-pulmonary pressure
Elasticity = resistance to stretch
FEV1; maximal expiration after maximum
inspiration in 1 sec, normally >80%
FVC; volume of air that can be maximally exhaled
after maximum inspiration, 6 seconds
PEF; peak expiratory flow, measured over time but
effort-dependent, L/min
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FEV1/FVC
Physiology
Control of respiration from
medulla oblongata, which allows
smooth controlled breathing
Dorsal respiratory group fires for
inspiration
Ventral respiratory group fires for
inspiration and expiration and is rhythm
generator
Pneumotaxic area smooths transition &
stops inspiration stimulation
Apneustic area stimulates inspiration,
but overriden by pneumotaxic
Central chemoreceptors in
medulla respond to H+ by
stimulating inspiratory neurons
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Host Defences
• Innate secretory molecules: lysozyme,
complement, mucins
• Neutrophils, monocytes and macrophages,
eosinophils (parasites)
• Mucosal secretions from goblet cells and
submucosal glands; mucociliary escalator
Particles >5um cleared
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Hypersensitivity
1 Immediate antigens interact with IgE bound to mast cells –
histamine release; hayfever, anaphylaxis
2 Antigen Dependent IgM/IgG bind to foreign antigens;
transfusion reaction, haemolytic anaemia (RBCs mistaken for antigens)
3 Immune Complexes form from antibodies and target
and get deposited in skin, lungs, kidneys, etc. Complement damages
tissue; SLE, extrinsic allergic alveolitis (Farmer’s, pigeon fancier’s…)
4 Delayed Type Hypersensitivity T-lymphocytes
interact with antigens, granuloma formation; TB, contact dermatitis
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‘The First Breath’
The lungs have no purpose in the fetus!
- Foregut = anterior outpouching
Week 5 : Lung buds enlarge => R + L bronchi (pseudoglandualur
phase begins inc. angiogenesis)
Week 16: Terminal bronchioles give way to terminal sacs
(canalicular phase)
Week 24+ : Alveolar Sacs, Type 1 + 2 pneumocytes etc
(alveolarisation, constantly maturing even through childhood)
- 24-28+ : surfactant production
• Physiology is OPPOSITE! (Hypoxia= systemic vasodilator but a
vasoconstrictor in the lungs)
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Birth
1.
2.
3.
4.
5.
6.
Fluid squeezed out of lungs by the process
Adrenaline stress = Increase in surfactant release
Air inhaled
Oxygen vasoDILATES pulmonary arteries
Umbilical arteries and ductus arterious constrict
So much crying (and so does the baby)
Histology
Respiratory epithelium
Pseudostratified
ciliated columnar
epithelium with
goblet cells
-nasal cavity + sinuses
-nasopharynx
-false vocal cords
-trachea
-bronchi
-terminal bronchiole
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Histology
Terminal
Bronchiole
Ciliated columnar
epithelium w/ smooth
muscle cells & Clara cells
(function unknown)
Respiratory Bronchiole
Cuboidal ciliated epithelium w/smooth
muscle cells
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Good Luck!
Fact of the Day:
- Breathing in REM sleep relies solely on the
diaphragm!
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[email protected]
The Peer Teaching Society is not liable for false or misleading information…