LS - Asthma Flashcards
What is the definition of asthma?
Chronic respiratory condition associated with airway inflammation and bronchial hyperresponsiveness. It is characterised by cough, wheeze, chest tightness and breathlessness as well as variable expiratory airflow limitation and decreased exercise tolerance
What is the prevalence of asthma in the UK?
10-15%. Most common respitratory disease in the UK. 1 in 11 chidlren and 1 in 12 adults have it.
What consists of the upper and lower respiraotry tract?
What is their collective purpose?
Upper respiratory tract - nose, paranasal sinuses and nasopharynx. Filters, humidifies and adjusts the temperature of the inspired air
Lower respiratory tract - larynx (vocal chords are present here. Prevent large foreign bodies from lodging within smaller-calibre tubes), trachea, bronchi/bronchioles and alveoli. Conducts air to sites of gaseous exchange
What is the features of the nose and nasal cavity?
Contains large air-filled cavities - paranasal cavities –> a group of four paired air-filled spaces that surround thenasal cavity lined by respiratory epithelium
What is the pharynx?
Joins the skull to the alimentary and respiratory tracts. Divides into the nasopharynx, oropharynx and laryngopharynx .
Allows the crossing over of the digestive and respiratory passageways, prevents food from entering the trachea, contributes to voice production and allows coughing by ‘fixing’ the thorax
What is the hyoid bone?
Holds up the tongue above it and holds up the larynx below it, is located at the C3 to C4 level
What is the cricoid cartilage?
The only complete hyaline cartilage ring that encircles the trachea, marks the inferior border of the larynx at the C5 to C6 level
Where is the trachea?
Arises at the lower border of the cricoid cartilage, travels inferiorly into the superior mediastinum and bifurcates at the level T4/5 at the carina (a ridge of cartilage). The trachea is located anteriorly to the oesophagus and inclines slightly to the right
How do the left and right bronchi differ?
the left bronchus branches off at an angle due to the position of the heart. It passes inferiorly to the arch of the aorta and anteriorly to the thoracic aorta and oesophagus in order to reach the hilum of the left lung
This means that inhaled foreign bodies tend to go down the right bronchus which is wider, shorter and descends more vertically
How do the bronchi continue?
Main bronchi. Cartilage rings completely encircle the lumen. –> lobar (secondary) bronchi. Crescent shaped cartilage. Each supplies a lobe of the lungs –> segmental (tertiary) bronchi. Crescent shaped cartilage. Each supplies a bronchopulmonary segment (functional unit)
What are both the trachea and bronchi lined with?
Ciliated pseudostratified columnar epithelium interspersed by mucus-producing goblet cells.
On a scanning electro micrograph, cilia appear as grass-like structures interspersed with goblet cells. The orange goblet cells also have their own short microvilli
Where is the smooth muscle of the trachea located?
Posteriorly
What are the features of the bronchioles?
They do not contain cartilage or goblet cells. Instead have club cells which produce surfactant lipoprotein which prevents the walls of the small airways from sticking together during expiration
Conducting bronchioles (transport air but not involved in gas exchange) –> terminal bronchioles —> respiratory bronchioles (contain alveoli)
What is the difference between type I and type II alveolar cells?
Type I - form alveolar wall
Type II - secrete pulmonary surfactant
What is Ohm’s law?
Airflow (V) ∝ 1 / Resistance (R). Shows that more resistance will cause less airflow.
