The respiratory system Flashcards
How does the respiratory system develop?
- As a diverticulum from the pharynx
What are the functions of the nasal cavity?
- Induce turbulent flow (nasal conchae)
- Warm and moisten inspired air (allows gases to dissolve)
- Recover water from expired air
- Phonation
- Olfaction
What do nasal conchae do?
- 3 outgrowths on medial surface of nasal cavity
- Increase surface area for inspired air to be moistened and warmed on way in and cooled down on way out
Outline the structure of the nasal cavity
- Enters through nostrils and passes into nasal vestibule (lined by keratinised stratified squamous epithelium)
- Nostrils are lined with nasal hair, which filter dust and other foreign materials
- Epithelium then changes to ciliated pseudostratified columnar epithelium
What are ostia?
- Small orifices that connect paranasal sinuses to the nasal cavity
- Can become blocked if inflamed
How many paranasal sinuses do we have?
- 4 (frontal, sphenoid, ethmoid, maxillary)
What are the 3 sections of the pharynx?
- Nasopharynx
- Oropharynx
- Laryngopharynx
What are the conducting airways of the respiratory system?
- Trachea
- Primary bronchi
- Secondary bronchi
- Tertiary bronchi
- Bronchioles
- Terminal bronchioles
What make up the walls and floor of the thoracic cavity?
- Ribs and costal cartilages make up walls
- Diaphragm makes up floor
Which surfaces articulate with the ribs?
- Vertebrae (articular facets articulate with thoracic vertebrae)
- Sternum
Which bones make up the sternum?
- Manubrium
- Body
- Xiphoid process
What is the mediastinum?
- Septum between lungs
What allows ventilation?
- Movement of joints between ribs and vertebrae
What is meant by the bucket handle movement?
- Need to increase volume in thorax for ventilation to occur
- Need to increase lateral aspect of chest
- Bucket handle movement allows this
- Rib = bucket handle
What is meant by the pump handle movement?
- Sternum moves upwards and anteriorly
- Increases anteroposterior dimension of chest
What happens to the diaphragm on inhalation?
- Diaphragm moves down at least 2 intercostal levels
How do movements of the ribs cause movement of air into the lungs?
- Alveolar pressure must be lower than atmospheric pressure of air to enter alveoli
Where must drains be inserted into the thoracic cavity?
- Must insert above each rib
- Otherwise nerve damage occurs
- Neurovasculature arranged in major bundle below each rib and minor bundle above each rib
What is the innervation of the diaphragm?
- Phrenic nerves
- C3, C4, C5
What are the muscles of ventilation?
- External intercostal muscles (fibres run in antero-inferior direction)
- Internal intercostal muscles (fibres run perpendicular to external intercostal muscles)
- Innermost intercostal muscles (bigger role in forced expiration)
At what level does the vena cava pass through the diaphragm?
- T8
At what level does the oesophagus pass through the diaphragm?
- T10
At what level does the aortic hiatus pass through the diaphragm?
- T12
What are the accessory muscles of respiration?
- Sternocleidomastoid
- Scalenus anterior, medius, and posterior,
- Pectoralis major and minor
- Inferior fibres of serratus anterior and latissimus dorsi
What is the dual blood supply to the thoracic cage?
- Intercostal arteries come from aorta and internal thoracic artery
What is the venous drainage of the thoracic cage?
- Venous system drains into azygous system
What separates the lobes of the lungs?
- Fissures
- Most of back of lung = lower lobe
- Oblique fissure separates lower lobe from rest of lung
- Transverse fissure separates upper lobe
Outline the position of the main bronchi of the lungs
- Right main bronchus sits straight
- Left bronchus sits at an angle
- Foreign objects usually enter right lung
Why is the right side of the diaphragm higher than the left?
- Liver
What is the mediastinum?
- Central compartment of thoracic cavity
- Located between pleural sacs
- Contains most thoracic organs
- Acts as a conduit for structures traversing thorax on their way into abdomen
- Divided into 2 parts by angle of Louie at T4/T5 intervertebral disc
- Superior mediastinum and inferior mediastinum
What are the subdivisions of the inferior mediastinum?
- Anterior - mostly fat
- Middle - heart and pericardium
- Posterior - aorta, oesophagus, azygos vein, thoracic duct
What is the pleura?
- Serous membrane enveloping lungs
- Parietal and visceral
- Parietal pleura has rich somatic innervation from thoracic nerves and is sensitive to pain
Outline the location of the pleura
- Top of parietal pleura goes into superior clavicular fossa
- Extends into superior thoracic aperture
- Pleura almost go down into costophrenic recess (angle between ribs and diaphragm)
- Extend very close to midline
What is the blood supply to the lungs?
- Pulmonary artery
- Pulmonary veins
Why do the lungs not completely die in pulmonary embolism?
- Bronchial arteries supply lung with blood
- Branches of aorta
