ANATOMICAL BASIS OF DIFFERENT AIRWAY DISEASES

CHAIRPERSON

PROF. DR. SIBES DASSPEAKER

KOUSHIK MUKHERJEE

CONTENT• ANATOMY OF UPPER AIRWAY• DISEASES OF UPPER AIRWAY• ANATOMY OF LOWER AIRWAY• DISEASES OF LOWER AIRWAY• HISTOLOGY AND DISEASE• EMBRYOLOGY AND RELATED

DISEASES• CILIA AND DISEASE

UPPER AIRWAY• Continuation of the Respiratory

System• Consists of nose, pharynx and

larynx• A multipurpose passage• Airflow requires a patent upper

airway.• State of consciousness is a major

determinant of pharyngeal patency

UPPER AIRWAY• Nose

• Nasopharynx

• Oropharynx

• Laryngopharynx

• Laynx

NOSE• 10,000 L of ambient air passes through

nasal airway per day and 1 L of moisture is added to this air

• Moisture is partly from transudation of fluid through mucosal epithelium and from secretions produced by glands and goblet cells

• Secretions have bactericidal activity, foreign body invasion is further reduced by stiff hairs ( vibrissae ) , ciliated epithelium and extensive lymphatic drainage

NOSE• External nose• Internal nasal cavity

• Nasal cavity- three regions 1. vestibular 2. olfactory 3. respiratory• Frontal, maxillary, sphenoidal, and

ethmoidal sinuses drain into nose.

Pharynx • Funnel-shaped tube of skeletal muscle

that connects to the:– Nasal cavity and mouth superiorly– Larynx and esophagus inferiorly

• Extends from the base of the skull to the level of the sixth cervical vertebra

• divided into three regions– Nasopharynx– Oropharynx– Laryngopharynx

Larynx • Located just below pharynx; also referred

to as the voice box• Several pieces of cartilage form framework• Thyroid cartilage (Adam’s apple) is largest• Epiglottis partially covers opening into

larynx• Vocal cords stretch across interior of

larynx; space between cords is the glottis

Functions of laryngeal muscles• Posterior cricoarytenoid – abductor of vocal cords • Lateral cricoarytenoid – adducts arytenoids closing

glottis• Transverse arytenoid – adducts arytenoid• Oblique arytenoid – closes glottis • Aryepiglottic – closes glottis• Vocalis – relaxes cords • Thyroarytenoid – relaxes tension cords • Cricothyroid – tensor of cords All the muscles of larynx supplied by recurrent laryngeal nerve except cricothyroid which is supplied by external laryngeal nerve

DISEASES OF THE UPPER AIRWAY• Rhinitis—nasal inflammation, as in a cold,

influenza, or allergy1. Infectious rhinitis—common cold2. Allergic rhinitis—hay fever• Sinusitis• Pharyngitis (sore throat)—inflammation or

infection of the pharynx– • Laryngitis—inflammation of the larynx

resulting from infection or irritation• Epiglottis—life threatening

Allergic rhinitis

Sinusitis

Laryngitis

Thumb sign in epiglottitis

Obstructive sleep apnea

Trachea • A tube made up of cartilage and enclosed

posteriorly by tracheal muscle and lined interiorly by ciliated columnar epithelium . It is about 18mm in diameter and 10-11 cm in length in adult

• Extent-lower part of larynx ( C6 ) to T5 , where it divides into left and right bronchi

• Trachea moves with respiration• On deep inspiration carina can descend as

much as 2.5 cm • Right main bronchus is wider and shorter

than left , being only 2.5 cm long

Bronchopulmonary segments

Bronchioles

• Primary Bronchi• One to each lung – continuation of

trachea– Right bronchus is wider and shorter 2.5

cm as opposed to 5 cm and branches from the trachea at a greater angle

• Secondary bronchi – one to each lobe, three in right, two in left

• Tertiary – one to each bronchopulmonary segment – approximately 10 per lung

• All of the above contains hyaline cartilage with no ability to change diameter

• Tertiary ( segmental ) bronchi divides repeatedly to form very small branches called terminal bronchioles and still smaller branches called respiratory bronchioles

• From proximal part of terminal bronchioles gas exchange begins and extends throughout succeeding generations of airways to alveoli.

• Respiarotry bronchiole ends in microscopic passages : alveolar ducts containing 2 or more pulmonary alveoli , atria and air saccules

Clara cells• Club cells, also known as bronchiolar exocrine

cells, and originally known as Clara cells are dome-shaped cells with short microvilli, found in bronchioles of the lungs.

• found in the ciliated simple epithelium• may secrete glycosaminoglycans, uteroglobin and

a solution similar to the component of the lung surfactant to protect the bronchiole lining.

• responsible for detoxifying harmful substances inhaled into the lungs.

• also act as a stem cell, multiplying and differentiating into ciliated cells to regenerate the bronchiolar epithelium.

• Club cells contain tryptase, which is believed to be responsible for cleaving the hemagglutinin surface protein of influenza A virus, thereby activating it and causing the symptoms of flu.

• Clara cells may be important in human disease, both by giving rise to tumours and by taking part in metaplastic changes in bronchiolar disease.

• In humans, many forms of lung cancer may originate from Clara cells, including adenocarcinoma. 

Alveoli• Alveoli – site of gas exchange• Blind ended (‘cup shaped outpouching) • Membrane: simple squamous + elastic basement

membrane• Cells:• – Type I form continuous lining• – Type II Produce alveolar fluid contains surfactant • – Alveolar macrophages (dust cells)

Muscles of respiration Inspiration: (thorax increases in volume and air enters lungs)• Diaphragm flattens• External intercostalsExpiration• Diaphragm relaxes• Internal intercostals depress ribs, reduce width of

thoracic cavityShallow Breathing: only intercostals involved• At rest• During pregnancy (abdominal volume decreases)Deep Breathing: (Diaphragmatic) –• contraction of diaphragm

Accessory muscles of respirationAssist in elevating ribs during inspiration– Sternocleidomastoid– Serratus anterior– Pectoralis minor– ScalenesAssist in decreasing thoracic volume during expiration by compressing abdomen:– Transversus thoracis– Obliques and Rectus abdominis

Few lines about surfectants• Reduces surface tension and therefore

elastic recoil, making breathing easier• Reduces the tendency to pulmonary

oedema• Equalises pressure in large and small

alveoli

Disorders of lower airways• Asthma• COPD• Bronchiectasis• Cystic fibrosis

COPD

Bronchiectasis

Cystic fibrosis

Few lines about histology

Goblet cell

Pseudostratified ciliated cells and mucous (goblet) cells are the two major components of the epithelium. Cilia beat at 1,000 to 1,500 cycles per minute resulting in movement of the mucus blanket at 0.5-1 mm/min in small airways and 5-20 mm/min in the trachea and main bronchi.

Trachea

Pseudostratified epitheliunm

Trachea Bronchi Bronchiole

Few lines on embryology and related diseases• Lung development starts from the gut 24

days after conception; diaphragm forms in cervical region at 3-4 weeks and moves progressively downwards carrying the phrenic nerves with; lung lobes are identifiable at 12 weeks; bronchial tree is completed at 16 weeks and alveoli and capillaries appear at 24 – 28 weeks; surfactant appears at 35 weeks.

diseases

Hyaline membrane disease•  caused by developmental insufficiency

of surfactant production and structural immaturity in the lungs.

• Microscopically, a pulmonary surfactant deficient lung is characterized by collapsed air-spaces alternating with hyper-expanded areas, vascular congestion and, in time, hyaline membranes

• Hyaline membranes are composed of fibrin, cellular debris, red blood cells, rare neutrophils and macrophages

Few lines about cilia

Kartagener syndrome

• Triad of- 1. sinusitis 2. bronchiectasis 3. situs inversus

Normal cilia (A) compared with cilia in Kartagener syndrome with missing dynein arms (B)

A BRIEF ACCOUNT OF ARDS• ARDS is associated with diffuse alveolar

damage (DAD) and lung capillary endothelial injury.

• The early phase is described as being exudative, whereas the later phase is fibroproliferative in character.

• The main site of injury may be focused on either the vascular endothelium (eg,sepsis) or the alveolar epithelium (eg, aspiration of gastric contents).

• Causes OF ARDS are ARDS

Thank you