Lower Respiratory Tract Flashcards
What is the name of the membrane that connects the hyoid bone to thyroid cartilage?
- Thyrohyoid membrane
What ligament connects thyroid cartilage to cricoid cartilage?
- Cricothyroid ligament
Where is the arytenoid cartilage found and what is its purpose?
- Posterior
- Speech production
Classify the epithelium of the true and false vocal folds
- Stratified squamous non-keratinised epithelium
- Due to mechanical abrasion
What is a cricothyroidotomy?
- Through cricoithyroid membrane + insert small round airway
- Under thyroid bone (Adam’s apple)
What is laryngitis?
- Inflammation of the true or false vocal cords
- Difficulty speaking
Describe the trachea
- 10-16cm, diameter=25mm
- Terminates at T4/5 sternal angle- Carina
- Trachealis muscle- smooth involuntary muscle controls diameter of tracheal lumen
- Hyaline cartilage surrounded by perichondrium
- Mucosal folds around lumen- easy contraction/ expansion
What important landmarks are found at the sternal angle?
- T4/5
- Manubrio-sternal joint
- Thymus
- 2nd rib joins manubriosternal joint
- Ascending arch of aorta
- End of arch of aorta
- Bifurcation of trachea
- Bifurcation of pulmonary trunk
- Ligamentum arteriosum
- L recurrent laryngeal nerve from vagus
- Azygos vein over right bronchus into sup vena cave
Describe the bronchi
- Divide into primary, secondary and tertiary
- Right more vertical and wider, therefore more likely for foreign objects to get lodged gere
Describe the primary bronchi
- pulmonary
- Right and left lung
Describe secondary bronchi
- Lobar
- Right- superior, middle, inferior lobe
- Left- superior, inferior lobes
Describe tertiary bronchi
- Segmental
- 10 segments in each lung
What is a bronchopulmonary segment?
- Smallest functional unit of lung
When would a bronchoscopy be done?
- As a result of aspiration of a foreign body
Briefly describe asthma
- Allergic reaction
- Hyperactivity of smooth muscle
- Bronchiole contraction
- Overproduction of mucous (goblet cell metaplasia)
Describe how excessive inflammation can lead to bronchoconstriction
- Hypertrophied smooth muscle in airway walls
- Thickened basement membrane
- Inflammatory cells infiltrate submucosal layer- folds inwards
- Bronchoconstriction
What is Hagen-Poiseulle’s law?
- R = 8nL/ π(r⁴)
Describe how epithelium and cartilage from bronchi and bronchioles changes
- Bronchi: cartilage and respiratory epithelium
- Ciliated simple columnar + goblet cells
- Ciliated low columnar or cuboidal no goblet cells
- Bronchioles: flattened squamous cells and no cartilage
What is a pulmonary lobule?
- Functional unit of lung (1-2.5cm)
- Contains acinars (bundles of alveolar sacs)
- Each lobule is defined by an interlobular septum
- Starts at terminal end of terminal bronchiole to respiratory bronchioles
What cells are found at alveoli?
- Macrophages- dust cells that phagocytose bacteria in lung
- Type 2 pneumocytes- secrete surfactant which reduces tension across alveoli
- Type I pneumocystis- from alveolar wall, very thin allow for effective diffusion, fused to basal lamina to decrease diffusion distance
Describe the hilum of the lung
- Root- pulmonary bronchi, pulmonary artery + vein
- On the right- bronchus superior to everything else, then artery and vein
- On the left- pulmonary artery superior to primary bronchi, then vein (surrounded by pulmonary ligament)
Describe the bronchial circulation
- Supply of oxy. blood to walls of respiratory tree and visceral pleura
- Bronchial artery (small vessels from thoracic aorta)
- Bronchial veins ( drain into azygos system)
Describe bronchial arteries
- Branch off descending arch of aorta
- 2 on left, 1 on right
- Superior left bronchial artery
- Inferior left bronchial artery
- Right bronchial artery
Describe bronchial veins
- Asymmetrical
- Left bronchial vein drains into accessory hemi-azygos vein (in the superior left thoracic cavity)
- Right bronchial vein drains into azygos vein
Describe the bronchial nerve supply
- Sympathetic input (T1-4 vertebrae)- airways dilate
- Parasympathetic input (Cranial Neve X- vagus nerve)- airways constrict
- Forms plexus at bifurcation of bronchi at anterior and posterior pulmonary plexus
