Structure and function of the airways Flashcards
What is the function of the respiratory system?
Gas exchange facilitated by mechanical stability (cartilage), control of calibre (Smooth muscle) and mucociliary protection and cleansing
What is the role of the nasal conchae and nasal hairs?
They’re highly vascularised and warm and humidify the air and nasal hairs filter out large particles
How is the upper respiratory tract structured?
Stems down to trachea which divides into primary, secondary and tertiary bronchi
Right pulmonary bronchus is more at a vertical angle meaning food or foreign objects move easily down here and can cause choking
After tertiary bronchi are bronchioles, terminal bronchioles and then alveoli
What surrounds the lungs?
Two lungs are surrounded by visceral pleura
The parietal pleura covers the thorax, mediastinum and diaphragm
The space between these two pleura is the pleural cavity and has a small amount of serous, pleural fluid
How are the lungs structured?
Each lung is divided into lobes
Right lung has 3 lobes, left has 2
The lobes are divided by fissures
How is the right lung structured?
Has 3 lobes: superior, middle and inferior
Separated by horizontal fissure and oblique fissure
How is the left lung structured?
2 lobes: superior and inferior
Separated by oblique fissure
How can the pleural cavity be affected?
Pneumothorax= air in the pleural cavity Haemothorax= blood in the pleural cavity
What cells are found in the alveolar region and what occurs here?
Where gas exchange occurs
Type I cells: very thin, delicate barrier- facilitates gas exchange
Type II cells: replicate to replace type I cells, secrete surfican, antiproteases and has xenobiotic metabolism
Most of alveolar surface covered in type I cells due to their high S.A despite there being more type II cells
What are lung cells called?
Pneumocytes
What is the tracheobronchial circulation?
Tracheal circulation return via systemic veins
Bronchial circulation returns via brachial and pulmonary veins to both sides of heart
Apex has low blood flow
Base has high blood flow
What is the role of the tracheobronchial circulation?
Warming and humidifying Good gas exchange Clearing mediators of inflammation Clear drugs Supply tissues with cells Supply tissues with plasma
What cells are found in the airway wall?
Goblet cells- contribute to mucus production to clear foreign particles and maintain clear, healthy airways- found on epithelium
Mucin is secreted by goblet cells that are found on submucosal glands
Airway wall also contains serous cells that secrete anti-bacterial enzymes as well as water, Na+ and Cl- into airway
What is the role of cilia?
Cells which line epithelium are ciliated, brush and basal cells
Cilia contribute to mucociliary clearance through cilia moving mucus
How is the ciliary cell structured?
Structure of ciliary cell is described as 9+2 patters, where outer and inner arms are connected by dynein
Microtubules anchored by intracellular proteins
Apical hooks on cilia interact with mucus
