Trachea, bronchial tree and lungs Flashcards
What are the conducting portions of the respiratory system?
- Nose, nasal cavity, paranasal sinuses
- Pharynx (nasopharynx, oropharynx, laryngopharynx)
- Larynx
- Trachea
- Bronchi, bronchial tree
- Terminal bronchioles
What are the respiratory portions of the respiratory system?
- Respiratory bronchioles
- Alveoli (ducts and sacs)
Describe the Trachea
- Fibrous and cartilaginous tubeconducting air from larynx to bronchi
- 10-11 cm long, ~2.5cm diameter, from C6 to T4/5 vertebral levels
- Has “c shaped” cartilage rings to maintain patency
- Posteriorly, smooth muscle called trachealis which joins each end of the rings, controls diameter
Describe the Carina
Point where the trachea divides into two main bronchi T4/5 level
What structures are posterior to the Trachea?
- Oesophagus
What structures are anterior to the Trachea?
- Thyroid gland isthmus
- Brachiocephalic trunk, Left brachiocephalic vein
- Cardiac plexus nerves (sympathetic and parasympathetic)
- Tracheobronchial lymph nodes
- Manubrium
What surface landmark marks the bifurcation of the Trachea?
Sternal Notch
What structures pass laterally to the Trachea?
- Thyroid gland lobes
- Parathyroid glands
- Left and Right Common carotid arteries
- Aortic arch and left subclavian artery
- Azygous arch and right Vagus nerve
What structures lie posterolaterally to the Trachea?
- Left and right recurrent laryngeal nerves
Describe the arterial supply of the Trachea
- Inferior thyroid artery
- Bronchial artery
Describe the venous drainage of the Trachea
- Inferior thyroid vein
- Bronchial veins
Describe the lymphatic drainage of the Trachea
- Pre and Paratracheal nodes
Describe the nerve supply of the Trachea
Pulmonary plexus
- Parasympathetic from Vagus nerve
- Sympathetic from Sympathetic trunk
What is the sympathetic system’s effect on the Trachea?
Dilation
What is the parasympathetic system’s effect on the Trachea?
Constriction
Describe the structure of the Bronchi
Continuation of the Trachea
- Complete cartilage rings
- Smooth muscle
How many secondary bronchi are there?
3 Right
2 Left
How many Bronchial Arteries are there?
1 Right
2 Left
Describe Bronchioles
- Serial divisions of conducting bronchioles, down to 20-25 generations
- As number increases size individually decreases but total surface area increases
- Becomes respiratory bronchioles –> alveolar ducts –> alveolar sacs
Describe Alveoli
- Single cell thick sac
- Surrounded by vasculature
- Large surface area - efficient for gas exchange
Describe the histology of the Trachea
- Cartilage - ossifies with age
- Respiratory epithelium - ciliated pseudostratified columnar
- Trachealis muscle
Describe the histology of the bronchioles
- No cartilage
- Smooth muscle
- Respiratory epithelium - ciliated pseudostratified columnar
What are club cells?
- Non-ciliated cuboidal epithelial cells found in terminal bronchioles
- Produce protective secretions
Describe the walls of the Alveoli
Pneumocytes
* Type I - thin to allow for gas exchange
* Type II - produce surfactant
What are the functions of the Lungs?
- Gas exchange
- pH balance
- Prostaglandin synthesis
- Metabolic functions - angiotensin I to angiotensin II
Describe the lobes and fissures of the left lung
Superior Lobe
Oblique Fissure
Inferior Lobe
Describe the lobes and fissures of the right lung
Superior Lobe
Horizontal Fissure
Middle Lobe
Oblique Fissure
Inferior Lobe
Where do the vasculature and airways enter the lung?
Root of the Lung in the Hilum
Describe Lung Segments
Right and Left:
* Superior lobe
Apical
Posterior
Anterior
- Inferior lobe
Superior (apical)
Anterior basal
Posterior Basal
Medial basal
Lateral basal
Right only:
* Lateral and medial segments of middle lobe
Left only:
* Superior lingular and inferior lingular of superior lobe
Describe the clinical significance of Lung Segments
Separated by Septa
* Infection typically confined to one segment
* Can be resected as one unit
* Each have own arterial supply from pulmonary artery
What is the Root of the Lung
Connection of the Lung to the Mediastinum
Contains:
* Main bronchus
* Pulmonary Arteries and Veins
* Bronchial Arteries and Veins
* Lymph Nodes and Vessels
Describe the Arterial Supply of the Lung
Bronchial Arteries
* 2 Left - supplied by Aorta
* 1 Right - supplied by 3rd Intercostal Artery
Pulmonary Arteries
* From pulmonary trunk
* Most superior structure in Hilum
Describe the Venous Drainage of the Lungs
Bronchial Veins
* Drain to Azygos on the Right, Hemiazygos on the Left
* Can re-enter pulmonary circulation
Pulmonary Veins
* Two per side (Superior and Inferior)
Describe the Pulmonary Plexus
Divided into Anterior and Posterior parts
* Relative to the trachea and bronchi
Supplied from
* Vagus parasympathetically
* Sympathetic Trunk
Supplies lungs and visceral pleura
Describe the parasypathetic system’s effect on the lungs
Bronchoconstriction, vasodilation and secretomotor
Describe the sympathetic system’s effect on the lungs
Bronchodilation and vasoconstriction
Describe the Lymphatic drainage of the Lungs
- Subpleural plexus
- Intrapulmonary Nodes
- Hilar Nodes
- Tracheobronchial Nodes
- Paratracheal Nodes
- Bronchomediastinal trunks
Describe the clinical considerations of Asthma
Commonest lung condition - >8 million people UK
Airway diameter reduced by inflamation
Different types
* Allergic
* Non-allergic
* Occupational
Salbutamol treatment
* β2 receptor agonist - relaxes bronchial muscle
Descrobe the clinical considerations of COPD
Common - biggest risk factor is smoking
Causes
* Mucus hypersecretion
* Alveolar desctruction
* Emphysema
* Chronic bronchitis
Describe the clinical considerations of Lung Cancer
Smoking is the biggest risk factor
* Bronchial carcinoma (95% of primary tumours)
* Common site for metastatic tumours - via lymphatic system
Asbestos
* Mesothelioma
Pancoast Tumour
* Tumour in the Apical lobe
* Can cause nerve compression
Poor prognosis
Describe the clinical considerations of pneumothorax
Air in pleural cavity - “Collapsed Lung”
Causes
* Spontaneous in tall, thin males
* Penetrating chest injury
* Lung damage
* Higher risk in certain syndromes
Describe the clinical considerations of Pneumonia
Infective
* Bacterial
* Viral
* Fungal
Can affect one or multiple lobes
* Lobar pneumonia
More likely with underlying health conditions or frailty
Lying supine is a risk factor
Describe the clinical considerations of Cystic Fibrosis
Commonest genetically transmitted disease
* Autosomal recessive
* 1 in 2000
Mucous too thick due to abnormal ionic composition
* Malfunctioning chloride transporter
Describe the clinical considerations of Foreign Body Aspiration
Items have tendency to the right bronchus
* Not always detectable by X-ray
Bronchoscopy to visualise/retrieve
Describe the clinical considerations of Pulmonary Embolism
Blockage occurs in pulmonary artery
* Thrombus from lower limb
* Fat
* Air
* Tumour
Risk factors
* Immobilisation
* Recent surgery
* Malignancy
* Paralysis
* Smoking
* Obesity
Describe a Tracheostomy
Incision into trachea via 2nd and 3rd tracheal rings
* Non-emergency procedure
* Likely to be long term
* Consider position of the inferior thyroid veins
Describe a Bronchoscopy
Camera inserted to visualise the lungs
* Performed under sedation
* Can occur alongside device to remove foreign body or take biopsy
