Lung Structure

Question 1

What is the structure of the nose like?

Answer 1

Anterior nares open into the enlarged
Vestibule
Skin lined
Stiff hairs

Surface area of nose
Doubled by turbinates

Question 2

What do turbinates create?

Answer 2

Turbinates create
Superior meatus
Olfactory epithelium
Cribriform plate
Sphenoid sinus
Middle meatus

Question 3

What are the sinus openings?

Answer 3

Sinus openings
Inferior meatus
Nasolacrimal duct

Question 4

What do sinus openings do?

Answer 4

All these openings:Increases S.A and therefore permits you to humidify and control your air for gas exchange

Question 5

Where is the paranasal sinus?

Answer 5

Paranasal sinuses also control/effect vocal cords

Pneumatized (air-filled) of the frontal,maxillary,ethmoid,sphenoid bones
Arranged in pairs
Evagination (become turned/externally exiting) of mucus membrane from nasal cavity

Question 6

Where is the frontal sinus?

Answer 6

Frontal sinuses

Within frontal lobe
Midline septum
Over orbit and across superciliary arch
Nerve supply - ophthalmic division of V(fifth cranial nerve) - trigeminal nerve (sensory)

Question 7

Where is the maxillary sinus?

Answer 7

Maxillary sinuses

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 via the Hiatus semilunaris - where it (mucus/secretion) drains back into the nasal cavity

Question 8

Where is the ethmoid sinus?

Answer 8

Ethmoid sinuses

Between the eyes
Labyrinth of air cells (honeycomb/labyrinth structure)
Also drain via Semilunar hiatus of the middle meatus (areas created in nasal cavity by the turbinates)
Nerve supply - ophthalmic and maxillary fifth (trigeminal) nerve
Anterior to pituitary fossa

Where intraocular pain comes from

Question 9

Where is the sphenoid sinus?

Answer 9

Sphenoid sinuses (v.examinable)

Medial to the cavernous sinus
Carotid artery linked to 3,4,5 and 6 cranial nerves
Inferior to optical canal, dura and pituitary gland
Empties into sphenoethmoidal recess, lateral to the attachment of nasal septum
Nerve supply - ophthalmic fifth (role in sensory innervation of paranasall sinuses)
Clinical relevance: infections

Question 10

What is the pharynx like?

Answer 10

Fibromuscular tube lined with epithelium
Squamous and columnar ciliated, mucous glands

Question 11

What is the nasopharynx like?

Answer 11

Nasopharynx

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 12

What is the oropharynx lie?

Answer 12

Oropharynx

Soft palate anteriorly
•Palatine tonsils on the lateral walls
–Palatoglossal folds
–Palatopharyngeal folds
•Inferiorly to the hyoid bone

Question 13

What is the larynx like?

Answer 13

Larynx

Valvular (valve) 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 14

What are the laryngeal cartilages?

Answer 14

What are the laryngeal cartilages?

Single
Epiglottis
Thyroid
Cricoid

Double
Cuneiform
Corniculate
Arytenoid

Question 15

What is the laryngeal innervation (larynx?)?

Answer 15

Laryngeal innervation:

superior laryngeal nerve
Inferior ganglion
Lateral pharyngeal nerve

Divides into:
Internal - sensation
External - cricothyroid muscle
Recurrent laryngeal nerve
All muscles except cricothyroid
R and l different courses

Question 16

What is the course of the Right and left RLNs?

Answer 16

Left:
Lateral to arch of aorta
Loops under aorta
ascends between oesophagus and trachea

Right:
Right subclavian artery
Plane between trachea and oesophagus

Question 17

What is gas exchange like?

Answer 17

20m2 gas exchange area per lung - large surface area
Minute ventilation approx 5 litres of air in and out
Cardiac output approx 5 litres per minute
Regional differences in ventilation and perfusion (blood supply)

Question 18

What is the trachea like?

Answer 18

Trachea:

Larynx to carina (5th thoracic vertebra, T5)

Commences at cricoid cartilage
Oval in cross section
Lined with Pseudo stratified, ciliated, columnar epithelium
Goblet cells - produce mucus
Semicircular cartilages - incomplete
Trachealis muscle joins incomplete circuit
Mobile (3 cm and 1cm, superior and inferior)

Question 19

What is the supply of the trachea?

Answer 19

Sensory innervation: recurrent laryngeal nerve
Arterial supply: inferior thyroid artery
Venous drainage: brachiocephalic, accessory hemiazygos veins and the azygos veins

Question 20

What are the main bronchi like?

Answer 20

Left and Right main bronchi

Sharp division between these (The carina) - tumours must be a certain distance away to operate on to remove
R main bronchus more vertically disposed
1-2.5cm long (shorter), related to the R pulmonary artery
L main bronchus
5cm long (longer), related to the aortic arch

Question 21

What is the structure of the lungs?

Answer 21

Lungs (Lobar bronchi)

Right lung - 3 lobes - upper, middle and lower
Horizontal(upper and middle) and oblique fissa

Left Lung - 2 lobes - upper (+lingula) and lower and oblique fissa

Question 22

What is the Acinus?

Question 23

What is the alveoli’s made up of?

Answer 23

Alveoli:

Type I pneumocytes Pavement
Type II pneumocytes Surfactant producers

•Alveolar macrophage
•Basement membrane
•Interstitial tissue
•Capillary endothelial cells

Width of erythrocyte can be the limiting factor for humans to oxygenate blood

Question 24

What are the pleura?

Answer 24

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

Question 25

What is the bronchial and pulmonary blood supply like?

Answer 25

Pulmonary circulation
•L and R pulmonary arteries run from R ventricle

Bronchial?

Question 26

What layers must oxygen pass?

Answer 26

Oxygenation:

Alveolar epithelium
Tissue interstitium
Capillary endothelium
Plasma layer
Red cell membrane
Red cell cytoplasm
Hb binding forces