Week 5 Lungs and Trachea Flashcards
What are the lungs?
Vital organs of respiration
main function is to oxygenate blood
What seperates the two lungs?
the heart, great vessels and other viscera in the mediastinum
What is the Pleura?
Connective tissue that forms a closed sac called the pleural sac
What are the layers of the pleura?
Outer parietal layer (lines the thoracic cage, diaphragm and media stinum
Inner visceral layer:
Lines the lungs
Thin layer exists between the two
Where do the two layers of pleura become continuous with each other?
at the root of the lung
What defines the right lung from the left?
heavier Larger shorter (right dome of diapragm sits higher) wider (heart bulging on left) Horizontal fissure
What defines the left lung from the right?
Has a deep cardiac notch on the superior lobe of the left lung
What are lung fissures
lungs are divided into lobes by fissures
They are grooves on the surface of an organmarking it into divisions
They extend from the surface of the lungs to the hilum, sometimes not complete
How many lobes does the left lung have?
two
How many lobes does the right lung have?
three
How are the lobes of the lungs divided further into segments?
by the divisions of the bronchi that supply them
What are the lungs covered in?
Cervical pleura
How many surfaces of the lungs are there and what are they?
Costal surface (adjacent to sternum,costal cartilages and ribs) Mediastinal surface (relates to the mediastinum and vertebrae and includes the hilum) Diaphragmatic surface (rests on the convex dome of the diaphragm)
where does the costal surface lie? What else constitutes the costal surface?
adjacent to the sternum, costal cartilages and ribs
it is large, smooth and convex
separates the ribs from the costal cartilages and intercostal muscles by pleura
posteriorly it relates to the thoracic vertebrae
Where does the mediastinal surface lie? What else constitutes to this surface?
Relates to the mediastinum containing the the heart and the pericardium
has a pericardial cavity which is deeper in the left lung
is the location of the hilum and the root of the lung as well as pleural sleeve covering
it is the point at which the following structures leave and enter the lung:
main bronchus
pulmonary vessels
bronchial vessels
lymphatic vessels
nerves
How is the root of the lung formed?
by the following structures that pass through the hilum; main bronchus pulmonary vessels bronchial vessels lymphatic vessels nerves
the root of the lung is also enclosed in a pleural sleeve
What structures are found on the mediastinal surface?
groove for the oesophagus Cardiac impression (for heart)
difference in mediastinal surface in right and left lung?
Left has a reater cardiac impression
left has a prominant continuous groove for the aortic arch and descending thoracic aorta
also has a smaller groove for the oesophagus
details about the diaphragmatic surface?
Is concave
forms the base of the lung
rests on the dome of the diaphragm
has a deeper concavity due to the liver
How many lung borders are there and what are they called?
3;
Anterior
inferior
posterior
What forms the anterior border? What does it overlap?
The costal and mediastinal surfaces anteriorly
Overlaps the heart
What forms the inferior border?
Circumscribes the diaphragmatic surface of the lung, separates this durface from the mediastinal and costal surfaces
What forms the posterior border? Where does it lie?
where the costal and mediastinal surfaces meet posteriorlrly
lies either side of the thoracic vertebral column
What is the arterial supply to the lung?
Left and right pulmonary arteries (oxygenate deoxygenated blood and contribute to the root of the lung)
These give off their first branch to the superior lobe before entering the hilum
Within the lung they divide further into lobar and segmental branches
arteries and bronchi are paired in the lungs
What is the venous supply to the lungs?
Pulmonary veins
Carry oxygenated blood to the left atrium of the heart from the lungs
run independently from the arteries
Bronchial arteries:
Supply the structures that comprise the root of the lung, the supporting tissues and pleura
Where do the left bronchial arteries arise?
From the thoracic aorta (usually 2)
Where does the right bronchial artery arise?
from either;
the thoracic aorta
the superior posterior intercostal artery
the common trunk with left superior bronchial artery
What is the function of the bronchial veins?
Drain part of the blood supplied to the lungs by the bronchial arteries
Right by azygos veins
Left by accessory azygos vein
Nerve supply to the lungs?
Parasympathetic:
Vagus
Sympathetic:
T1-T6 by cardiopulmonary splanchnic nerves
Where are the lower borders of the lungs found anteriorly, laterally (within the mid axillary line) and posteriorly?
Anteriorly (midclavicular line): 6th rib Laterally (midaxillary line): 8th rib Posteriorly: 10th rib (the pleural sits 2 spaces lower)
Where does the hilum sit?
behind 3rd and 4th costal cartilages at the sternal margins
level of T5-T7 vertebrae
Where are the oblique fissures?
Fissures formed by the line from the Spinous process of T3 to T6 rib in the mid clavicular line
Where are the Horizontal fissures?
found on the right 4th costal cartilage, meets the oblique fissure in the mid axillary line
Where is the trachea?
Extends from the larynx into the thoraxwhere it divides into left and right main bronchi
Inferior end of the larynx (C6 just below the cricoid cartilage) to the angle of Louis (T4-T5) IV disc
What is the function of the trachea? How long is it?
Is a passage for air to the lungs 10cm long, may lengthen to 15cm during inspiration
What is the trachea?
A large section of hyaline cartilaginous tube which is supported by incomplete cartilagenous rings (tracheal rings)
Where does the trachea divide into left and right bronchi?
At the transverse thoracic plane
What sits in relation to the trachea?
Laterally: Common carotid arteries Brachiocephallic trunk (on the right) Anteriorly: isthmus of the thyroid gland inferior thyroid veins Posteriorly: oesophagus
What epithelium does the trachea have?
Pseudostratified columnar ciliated epithelium
What is the blood supply to the trachea?
Inferior thyroid arteries
bronchial arteries
(these anastomose at the tracheal wall)
Veins drain into the inferior thyroid plexus (left at the braciocephallic vein)
Where do the main bronchi run?
Pass inferomlaterally from the bifurcation of the trachea to the hila of each lung
What to the bronchi contain?
c shaped hyaline cartilaginous rings
Right main bronchus
is wider, shorter and runs more vertically than the left and passes directly to the lung
Left main bronchus
passes inferolaterally
passes inferior to the arch of the aorta
anterior to the oesophagus and thoracic aorta
then passes into the hilum of the lung
What happens to the bronchi when they enter the hilum
They branch to form the bronchial tree
What do the main bronchi branch into?
Lobar (or secondary) bronchi
How many lobar bronchi are there?
5:
2 on the left
3 on the right
(each supplies the corresponding lobe)
What do lobar bronchi divide into?
segmental bronchi (pyramidal in shape, separated by ajoining segments by connective tissue) Each segment is supplied independently by a tertiary bronchus and artery
What do segmental bronchi divide into?
Terminal bronchioles
What do terminal bronchioles divide into?
Respiratory bronchioles
What do respiratory bronchioles give off?
2-5 alveolar ducts which give rise to 5-6 alveolar sacs
What are all the segments of the bronchi?
Main bronchus (or primary) Lobar bronchus Segmental bronchus Terminal bronchioles Respiratory bronchioles Alveolar ducts Alveolar sac Alveoli
What is the arterial supply to the trachea
Bronchial arteries
(usually 3, 2 on left and 1 on right)
Left bronchial arteries arise from the left aspect of the thoracic aorta
Right bronchial arteries arise off either;
Thoracic aorta
superior posterior intercostal artery
common trunk with the left superior lobal bronchial artery
Bronchial veins
Are a superficial system
Drain the hila region and visceral pleura
drain into the azygos vein on the right
Drain into the accessory azygos on the left
deep veins drain into a main pulmonary vein or directly into the left atrium
