Resp Anatomy Flashcards
What are the three surfaces of the lungs?
Diaphragmic, costal, mediastinal
What is the carina?
Sensitive area between primary L/R bronchus for coughing reflex and bronchus obstruction
Which bronchus is longer and steeper?
Left longer and steeper angle so more likely to get things stuck in it, right shorter and smaller angle
How many bronchopulmonary segments does each lung have and where are they concentrated and why?
Left - 8-9
Right - 10
More in the inferior lobe as larger shape and forced lower for better perfusion
How does infection affect the functional bronchopulmonary units?
Infection doesn’t spread between units because each is separated by CT so still function even if one affected
Outline the innervation of the lung?
GVA - sensory to stretch/pressure in mucosa, chemosensitive in respiratory tree
Para - Vagus which bronchoconstricts and vasodilates and mucosal control
Symp - T1-5 ganglion - vasoconstricts (endocrine controls bronchodilation)
Outline pleural innervation?
Visceral - GVA only detect stretch
Parietal - symp only detecting pressure, pain, temp with phrenic innervating mediastinal parietal nerves with referred pain to shoulder
What part of the respiratory tree is the acinus? (4)
Terminal branch, resp bronchioles, alveolar ducts, sacs
Histology of trachea and bronchi?
Conductive tubes so pseudostratified columnar epithelium with goblet cells and cilia
Histology of bronchioles and alveoli
starts to transition from resp to cuboidal to simple squamous with thicker sm to adjust lumen size
Cells of the alveolar ducts and sacs? (3)
- Type 1 pneumocyte - squamous with large SA for gas exchange covering 95% areolar surface and fused to basement membrane
- Type 2 pneumocyte - cubodial covering 5% of alveolar lining. Synthesis and secretion of surfactant to reduce alveolar fluid accumulation
- Alveolar macrophages - dust cells which patrol alveoli and are easily observed once they ingest something
What is the first stage of development of the lungs?
Embryonic week 4-7
-tertiary bronchi develop from secondary bronchi which develop from primary. Pulm arteries follow bronchi to remove O2 and visceral pleura adheres to lung
What is the second stage of development of the lungs?
Pseudoglandular week 6-17
- final number of bronchopulmonary segments formed, tertiary bronchioles develop, still have thick wall and dense mesenchyme
What is the third stage of development of the lungs?
Canalicular week 16-28
- terminal to resp bronchioles, alveolar ducts and primitive alveoli. Walls start to thin and epithelium starts to differentiate into type 1 and 2 pneumocytes. Formation of capillary beds and increased diameter of bronchi
What is the fourth stage of development of the lungs?
Saccular week 28-36
- further differentiation and increase in primitive alveoli. Type 1 and 2 develop still and surfactant lowers surface tension so easier to breathe. Diffusion distances reduces so increased gas exchange and at 36 weeks, have ability to breathe and transpire (early term before 37 weeks so lung development compromised)
What is the fifth stage of development of the lungs?
Alveolar week 36 - 22 years old
- Alveolarization and septation and multiplication of alveoli including the thinning of airspace walls and formation and differentiation on craniocaudal fashion. Subphases - 1st from 36w to 2/3 yo is fast, from 2/3yo until adult is slow, set at 18/22 years old, terminal bronchiole enlargement is final
What is the sixth stage of development of the lungs?
Microvascular maturation birth until 3-21 years old
- fusion of capillary networks of interalveolar septa from double to single layer to reduce distance to optimize cap to airspace
Developmental errors of lungs? (3)
- Tracheoesophageal fistula with or without atresia (narrowing) of trachea/oesophagus
- Congenital diaphragmatic hernia with incomplete fusion of septum transversum and pleuroperitoneal folds
- Asymmetric branching abnormalities - unilateral agenesis, aplasia (bronchi but no lung tissue) or hypoplasia (lung tissue but no alveoli)