Anatomy and Physiology of Respiratory System Flashcards
What is the function of the nasal cavity?
- Mucus and hairs trap pollutants and pathogens
- Epithelial cells warm, moisten and filter the air
Describe the role and divisions of the pharynx
Muscular tube connecting the oral + nasal cavities to the larynx + oesophagus
NASOPHARYNX
- contains adenoid tonsils
- lined with respiratory epithelium
OROPHARYNX
- contains: posterior third of tongue, lingual + palatine tonsils + superior constrictor muscle
- involved in swallowing
LARYNGOPHARYNX
- between superior border of the glottis and inferior border of cricoid cartilage
- contains the middle and inferior phrayngeal constrictor muscles
Describe the structure of the trachea
10-12cm long tube
composed of C-shaped hyaline cartilage
The free ends of these rings are supported by the trachealis muscle
lined with ciliated pseudostratified columnar epithelium, interspersed by goblet cells, which produce mucus
Where does the trachea bifurcate into the 2 main bronchi?
At the carina
Lies under junction of the manubrium sterni and the 2nd costal cartilage
Differentiate between + describe the 2 main bronchi
Right main bronchus –
- wider
- shorter
- descends more vertically
Left main bronchus –
- passes inferiorly to the arch of the aorta
- passes anteriorly to the thoracic aorta and oesophagus in order to reach the hilum of the left lung.
Briefly describe the bifurcation of the bronchi
-
Primary (main) bronchi divide into secondary (lobar) bronchi
- primary bronchi are completely encircled by cartilage
- lobar bronchi supply each lobe (2 left, 3 right)
- smaller bronchi have crescent shaped cartilage
- lobar bronchi split into segmental bronchi- each supplying a functional unit of lung (bronchopulmonary segment)
- these split into bronchioles
How do bronchioles mantain patency?
They do not have cartilage or mucus-seceting goblet cells
club cells produce surfactant lipoprotein which act as lubricant
What 3 types of cell make up the lining of the alveoli?
Type 1 pneumocytes
- majority of lining
- very thin layer of cytoplasm for gas exchange
- connected by tight junctions to limit movement of fluid across the alveoli
Type 2 pneumocytes
- MORE numerous BUT cover less of lining
- Have microvilli and produce surfactant to maintain alveolar patency
Alveolar macrophages
Briefly describe the divisions of the lungs
- Divided into lobes by invaginations of the pleura
- Right lung: superior, middle, inferior
- Left lung: superior and inferior lobe
- The upper lobe lies mainly in front of the lower lobe
- Each lobe is further subdivided into bronchopulmonary segments by fibrous septa
- Each bronchopulmonary segment is further subdivided into individual lobules.
- Within each lobule a terminal bronchus supplies an acinus
Describe the 2 pleurae of the lungs
Serous membrane of connective tissue lined with simple squamous epithelium:
- Visceral pleura – covers the lungs.
- Parietal pleura – covers the internal surface of the thoracic cavity. Thicker than visceral.
These two parts are continuous with each other at the hilum of each lung.
Explain the importance of the pleural cavity
Potential space between the parietal and visceral pleura.
It contains a small volume of serous fluid with two major functions:
- Lubrication- surfaces can slide
-
Surface tension- pulls visceral + parietal pleura together
- in pneumothorax, air gets in space and tension is lost
How do the lungs generate negative pressure?
Compliance
The lungs have an inherent elastic property giving them a tendency to collapse away from the thoracic wall generating a negative pressure within the pleural space.
The strength of the retractive force is related to the volume of the lung with higher lung volumes stretching more and causing greater negative intrapleural pressure
