Respiratory Tract Structure

Question 1

Nose function

Answer 1

Most superior portion of the respiratory tract
Multiple functions:
- Temperature of inspired air (0.25 second contact)
- Humidity (75-80% RH)
- Filter function
- Defence function - Cilia take inhaled particulates backwards to be swallowed

Question 2

Nose

Answer 2

• Anterior nares open into the enlarged: Vestibule -
  Skin lined, Stiff hairs. Surface area of nose -
  Doubled by turbinates.
• Turbinates create: Superior meatus - Olfactory epithelium, Cribriform plate, Sphenoid sinus. Middle meatus - Sinus openings. Inferior meatus - Nasolacrimal duct.

Question 3

The paranasal sinuses

Answer 3

Pneumatised areas of the;
- Frontal
- Maxillary
- Ethmoid
- Sphenoid bones
Arranged in pairs
Evagination of mucous membrane from the nasal cavity

Question 4

Frontal sinus

Answer 4

Within frontal bone
Midline septum
Over orbit and across superciliary arch
Nerve supply – ophthalmic division of V nerve

Question 5

Maxillary sinuses (IMPORTANT)

Answer 5

Located within the body of the maxilla.
Pyramidal shape.
Base – lateral wall of the nose.
Apex – zygomatic process of the maxilla.
Roof – floor of the orbit.
Floor – alveolar process.
Open into the middle meatus.
Hiatus semilunaris.

Question 6

Ethmoid sinuses

Answer 6

Between the eyes
Labyrinth of air cells
Semilunar hiatus of the middle meatus
Nerve supply - ophthalmic and maxillary V nerve

Question 7

Sphenoid sinuses (IMPORTANT)

Answer 7

Medial to the cavernous sinus - Carotid artery, III,IV, V, VI
Inferior to optic canal, dura and pituitary gland
Empties into sphenoethmoidal recess, lateral to the attachment of the nasal septum
Nerve supply – ophthalmic V

Question 8

Pharynx

Answer 8

Fibromuscular tube lined with epithelium
Squamous and columnar ciliated, mucous glands
Skull base -> C6 -> Oesophagus
Anterior -> Nasal Cavities, mouth and larynx
- Nasopharynx
- Oropharynx
- Laryngopharynx (hypopharynx)

Question 9

Nasopharynx

Answer 9

Bounded by: base of skull, Sphenoid rostrum, C Spine
Posterior nose (choana), Inferiorly at soft palate opens to oropharynx.
Eustachian tube orifices (lateral wall) - Supply air to middle ear
Pharyngeal tonsils on posterior wall

Question 10

Oropharynx

Answer 10

Soft palate anteriorly
Palatine tonsils on the lateral walls
Palatoglossal folds - 1st fold.
Palatopharyngeal folds - 2nd fold.
Inferiorly to the hyoid bone.

Question 11

Larynx

Answer 11

Valvular function -Prevents liquids and food from entering lung
Rigid structure
9 cartilages
Multiple muscles
Arytenoid cartilages rotate on the cricoid cartilage to change vocal cords

Question 12

Laryngeal cartilages

Answer 12

Single: Epiglottis, Thyroid, Cricoid.
Double: Cuneiform, Corniculate, Arytenoid.

Question 13

Laryngeal innervation

Answer 13

The vagus (X):
- Superior laryngeal nerve - Inferior ganglion - Lateral pharyngeal wall -Divides into Internal (Sensation) and External (cricothyroid muscle).
- Recurrent laryngeal nerve - All muscles except cricothyroid - R and L different
Left - lateral to arch of aorta, loops under aorta, ascends between trachea and oesophagus.
Right - R Subclavian artery, plane between trachea and oesophagus.

Question 14

Lower respiratory tract functions

Answer 14

Gas exchange:
20m2 gas exchange area per lung
Minute ventilation approx 5 litres
Cardiac output approx 5 litres per minute
Regional differences in ventilation and perfusion (blood supply)

Question 15

Lower respiratory structure

Answer 15

Main Airways:
- Trachea
- Main Bronchi
- Lobar Bronchi
- Segmental branches
- Respiratory Bronchiole
- Terminal Bronchiole
- Alveolar Ducts and Alveoli
Pleura

Question 16

Trachea

Answer 16

Larynx to carina (5th thoracic vertebra, T5)
- Commences at cricoid cartilage.
- Oval in cross section
- Pseudo stratified, ciliated, columnar epithelium
- Goblet cells
- Semicircular cartilages
- Trachealis muscle joins incomplete circuit.
- Mobile (3 cm and 1cm, superior and inferior)

Question 17

Main bronchi

Answer 17

Left and Right main bronchi
- Sharp division between these - The carina
- R main bronchus more vertically disposed - 1-2.5cm long, related to the R pulmonary artery
- L main bronchus - 5cm long, related to the aortic arch

Question 18

Lobar bronchi

Answer 18

Right:
- Upper lobe
- Middle lobe
- Lower lobe
Left:
- Upper lobe and lingular
- Lower lobe

Question 19

Segmental bronchi

Answer 19

Right: Upper lobe (Apical, Anterior, Posterior), Middle lobe (Medial and Lateral), Lower lobe (Apical, Ant, Post, Med, Lat).
Left: Upper lobe (Apico-posterior, Anterior), Lingular (Superior and Inferior), Lower lobe (Apical, Ant, Post, Lat).

Question 20

Acinus

Answer 20

Distal to the terminal bronchiole
Alveoli more profuse with increasing generation of subdivision
Ducts are short tubes with multiple alveoli
Interconnection between alveoli exist (pores of Kohn)

Question 21

Alveoli

Answer 21

Type I pneumocytes Pavement
Type II pneumocytes Surfactant producers
Alveolar macrophage
Basement membrane
Interstitial tissue
Capillary endothelial cells

Question 22

Pleura

Answer 22

2 main layers, of mesodermal origin
Visceral Applied to the lung surface
Parietal Applied to the internal chest wall
Each a single cell layer
Small amount of fluid between
Continuous with each other at lung root
Parietal pleura has pain sensation
Visceral pleura has only autonomic innervation