Structure of Lungs Flashcards
What are the 2 parts of the respiratory portion ?
Upper respiratory tract
Lower respiratory tract
What structures are found in the upper tract ?
Nasal Cavity
Nasopharynx
Epiglottis
Larynx
Trachea
What structures are found in the lower tract ?
Main bronchi
Branch bronchi
Small bronchi
Bronchioles
Distal respiratory tree
What structure surrounds the trachea posteriorly ?
Oesophagus
What are bronchi ?
Continuation of trachea, have smooth muscle and complete cartilage rings.
Where do the bronchi receive blood from ?
The bronchial arteries, one right and 2 left
Features of bronchi
As number increases, the size individually decreases but the total surface area increases.
State the generation from trachea to alveolar sacs.
Trachea
Bronchi
Bronchioles
Terminal bronchioles
Respiratory bronchioles
Alveolar ducts
Alveolar sacs
What forms around alveoli ?
Capillary beds
What is an advantage of alveoli being one cell thick ?
This provides a large surface area for efficient gas exchange.
Briefly describe how the trachea and bronchi divide and extend into the lung.
In the mediastinum, at the level of the fifth thoracic vertebra, the trachea divides into the right and left primary bronchi.
The bronchi branch into smaller and smaller passageways until they terminate in tiny air sacs called alveoli.
What type of epithelium is respiratory epithelium ?
Ciliated pseudostratified columnar epithelium
What is the trachea ?
The trachea, or windpipe, is a 10-11 cm long fibrocartilaginous tube of the lower respiratory tract.
What is the function of the trachea ?
Air transport in and out of the lungs;
Protection of the respiratory tract by warming and moistening the air and propelling foreign particles upwards towards the pharynx for expulsion.
What is the position of the trachea ?
The trachea extends between the larynx and thorax, consisting of two parts; cervical and thoracic.
It ends at the level of the sternal angle (T5) where it divides into two main bronchi, one for each lung.
What are the 4 layers of the trachea ?
Mucosa
Submucosa
Musculocartilagenous layer
Fibroelastic adventitia
Mucosa
Innermost layer lined with pseudostratified ciliated columnar epithelium
Submucosa
Consists of connective tissue, which contains mucus glands, smooth muscle, vessels, nerves and lymphatics
Musculocartiagenous layer
Represented by cartilaginous rings and intervening smooth muscle
What substances make up the bronchi ?
Respiratory epithelia
Smooth muscle
Hyloid cartilage
What substances make up the bronchioles ?
Respiratory epithelium
Smooth muscle
What substances make up the terminal bronchiole ?
Sparse smooth muscle
Club cells
Alveoli
What are pneumocytes ?
The cells that line the alveoli and comprise of the majority of the inner surface of the lungs.
Club cells - epithelium type
Non-ciliated cuboidal epithelium
Club cell function
Produces protective secretions
Goblet cells that line the trachea function
Secrete mucus which traps any unwanted substances
What is the pleural cavity ?
A fluid filled space that surrounds the lungs.
Where is the pleural cavity found ?
In the thorax, separating the lungs from its surrounding structures.
What is the pleural cavity bounded by ?
A double layered serous membrane called pleura
How is pleura formed ?
By an inner visceral pleura and outer parietal layer.
What is found between the 2 layers of pleura ?
A small amount of serous fluid is held within the cavity.
Function of the serous fluid in the pleural cavity
The lubricated cavity allows the lungs to move more freely during breathing.
Parietal pleura
Lines the boundaries of the cavity
Costal pleura
Lines the thoracic wall
Diaphragmatic pleura
Lines the diaphragm
Mediastinal pleura
Lines the mediastinum
Visceral pleura
Lines the surface of the lung itself
Parietal vs Visceral pleura
Parietal pleura is thicker and more durable outer layer, whereas visceral pleura is more delicate, thinner layer.
Mediastinum
Contains the heart
Name the surfaces of the lungs
Costal pleura
Medial (mediastinal & vertebral) pleura
Diaphragmatic pleura
What are the lobes of the left lung ?
Superior
Inferior
What are the fissures of the left lung ?
Oblique
What are the lobes of the right lung ?
Superior
Middle
Inferior
What are the fissures of the right lung ?
Oblique
Horizontal
Blood supply in the lungs
Pulmonary Trunk
Pulmonary arteries
Superior and inferior pulmonary arteries
Intercostobronchial trunk & Thoracic aorta
Bronchial arteries
List the structures passing through the root of each lung
Main bronchus
Pulmonary Artery (deoxygenated blood to lung)
Pulmonary Veins (2, oxygenated blood to the heart)
Bronchial arteries
Lymph nodes and vessels
What is inspiration ?
The process of transporting air into the lungs
What happens during inspiration ?
The diaphragm contracts
The external intercostal muscles contract
The thoracic cavity expands
Air enters the lungs
What is expiration ?
The process of transporting air out of the lungs
What happens during expiration ?
The diaphragm relaxes
The external intercostal muscles relax
The thoracic cavity reduces
Air exits the lungs
Name some common pathologies that may affect the lungs and pleural cavities
Asthma
COPD
Cancer
Foreign body aspiration
Pneumothorax
Pneumonia
Cystic fibrosis
What causes asthma ?
Inflammation of the airways, therefore a reduced diameter.
What drug is used to treat asthma ?
Salbutamol
COPD
Chronic Obstructive Pulmonary Disease
Risk factor for COPD
Smoking
Results of COPD
Mucus hyper secretion
Destruction of alveoli
Where is cancer primarily found in the lungs ?
Bronchial carcinoma
Foreign body aspiration
Items have a tendency to the right main bronchus, as it is wider, shorter and more vertical
Pneumothorax
Air in pleural cavity, collapsed lung
Pneumonia
Affects the lobe/segment
Cystic fibrosis
Mucus is too thick due to abnormal ionic compression
