Anatomy of Lungs Flashcards
Epithelium of the trachea is continuous with what?
Larynx
Where does the trachea begin?
Anterior to C6 vertebrae
In a ligamentous attachment to cricoid cartilage
Ends in mediastinum, Level with T5 vertebrae
What does the trachea branch into?
Right and left primary bronchi
Layers of trachea from deep to superficial?
Mucosa Sub-mucosa Tracheal cartilages Trachealis Muscle Adventitia
Describe the mucosa of the trachea?
Resembles nasal cavity and nasopharynx
Pseudostratified ciliated columnar epithelium- ciliated columnar cells and goblet cells
Underlying layer of elastic and reticular fibers
Describe the sub-mucosa of the trachea?
Thick layer of connective tissue
Surrounds mucosa
Contains mucous glands - secretory ducts in epithelial tissue
Describe the tracheal cartilages?
C-shaped
Open portion faces oesophagus - allows for distortion when swallowing
How many tracheal cartilages?
15-20
Role of tracheal cartilages?
Stiffen tracheal wall and protect airways
Prevent collapse or over expansion
Describe trachealis muscle?
Band of smooth muscle
Contraction reduces diameter of trachea- increases resistance to airflow
What connects the end of each tracheal cartilage?
Trachealis muscle and elastic ligament
What type of stimulation increases the diameter of the trachea?
Sympathetic
What is the carina?
Internal ridge separating 2 bronchi
Which primary bronchi is larger?
Right as it descends at a steeper angle
What is the groove which primary bronchi travel along called?
Hilum
What does the hilum allow to enter?
Pulmonary vessels
Nerves
Lymphatics
How many secondary bronchi?
One for each lobe of the lung
therefore 5
What do secondary bronchi branch into?
bronchioles
which branch into terminal bronchioles
Differences between bronchi and larger bronchioles?
Pseudostratified ciliated columnar epithelium
changes to
Simple columnar epithelium with some goblet cells
Histology of smaller bronchioles?
Ciliated simple cuboidal epithelium with NO goblet cells
Histology of terminal bronchioles?
Nonciliated simple cuboidal epithelium
What replaces incomplete tracheal rings in primary bronchi?
Plates of cartilage - these eventually disappear in distal bronchioles
What increases as cartilage decreases in trachea?
Smooth muscle increases
Which 2 neurotransmitters/hormones relax the smooth muscle which will dilate the airways?
Epinephrine
Norepinephrine
What hormone causes airways to constrict?
Histamine
What membrane separates the two lungs in their chambers?
Mediastinum
What membranes protect the lungs?
Pleural membranes
What lines the inside of the thoracic wall?
Parietal pleura
What membrane surround the actual lungs?
Visceral pleura
What does the fluid between the pleura do?
Reduces friction between the 2 membranes
Causes surface tension causing them to stick together - ensuring the lungs will fill with air on inhalation
What does each lung have structurally? (3)
Apex (superior end of lung) 3 surfaces (costal, mediastinal, diaphragmatic) 3 borders (anterior, inferior &posterior)
How many lobes are in the right lung?
3 lobes - Right upper, right middle and right lower
How many lobes in left lung?
2 lobes- Left upper and left lower
Why does the right lung have more lobes?
Heart sits in the left of the centre of the thoracic cavity
-Upper left lobe is shaped to accomodate the heart with the presence of the cardiac notch
Where does the apex of the lung lie?
Superior to the medial thirds of the clavicles
Where is the base of the lung?
Extends from 6th costal cartilage to the 10th thoracic vertebrae
Blood supply of each lung?
Pulmonary artery supplying
2 Pulmonary Veins draining oxygenated blood from it
What does the bronchial artery do?
Supply blood for nutrition to the root of the lung, supporting tissues of the lung and the visceral pleura
What do terminal bronchioles branch into?
Alveolar ducts
Describe an alveolus?
Cup shaped outpouching
Lined by simple squamous epithelium
Supported by thin elastic basement membrane
Describe an alveolar sac?
Consists of 2 or more alveoli which share the same opening
Describe a Type 1 alveolar cell?
Simple squamous epithelial cells
Forms a nearly continuous lining of alveolar walls
What is the main site of gas exchange?
Type 1 alveolar cells
Which are more common type 1 or type 2 alveolar cells?
Type 1 more common
Describe type 2 alveolar cells?
Round or cuboidal epithelial cells
Free surfaces contain microvilli
What do type 2 alveolar cells do?
Keeps surface between cells and air moist
Contain surfactant - lowers surface tension of alveolar fluid
Describe the respiratory membrane?
Alveolar walls=Type 1 or type 2 alveolar cells and alveolar macrophages
Epithelial basement membrane=Underlies the alveolar wall
Capillary basement membrane= often fused with EBM
Capillary endothelium
What is the pleura?
Serous membrane
2 types
Parietal = covers inner surface of thoracic wall and extends over diaphragm and mediastinum
Visceral= covers outer surface of lungs
Function of pleura?
Secrete pleural fluid
- moist slippery coat that provides lubrication
- Reduces friction between pleura
Where do bronchial arteries arise from?
Aortic arch, thoracic aorta or their branches (mianly IC arteries)
What do bronchial arteries supply?
Oxygenated blood to the smooth muscle of the principal artery, intrapulmonary nerve, nerve ganglia, and interstitial lung tissue
Where does the blood from the upper airway drain?
Into the right atrium
Where does blood from the lower airway drain into?
Pulmonary veins
How are the individual lobes of the lung supplied?
Output of the RV passes into the pulmonary arteries with subsequent branches
What do the pulmonary veins drain into?
Emerge from each lung to empty into left atrium
Pulmonary circulation has low resistance and high pressure. True or false?
False
Both are low - low resistance and low pressure
How is pulmonary blood flow regulated?
Arterioles
What are pulmonary arterioles regulated by?
Alveolar PO2 and PCO2
NOT autonomic nervous regulation
What do arterioles constrict in response to?
Hypoxia
Hypercapnia
-The blood is diverted to better oxygenated areas
How is the lungs response to hypoxia unique?
However in the lungs vasocontstriction occurs to divert pulmonary blood from poorly ventilated areas of the lungs to well ventilated
What is vasoconstriction in the lungs caused by hypoxia called?
Ventilation perfusion coupling
- because the perfusion to each area of the lung matches the extent of ventilation to alveoli in that area
