Structure of the Lungs Flashcards
Tell me four facts about the trachea
Palpable anteriorly, above suprasternal notch
• C-shaped rings of hyaline cartilage supporting a fibro-elastic and muscular air-transport tube
• Starts at C6, ends at T 4/5 (sternal angle) at carina
• Trachealis muscle (posteriorly positioned) alters tracheal diameter
Trachea
Why are foreign bodies more likely to enter the right lung?
Its size and shape, the right main bronchus is slightly more vertical, shorter and wider than the left.
Tell me about the lobes of the lung
the left lung has two lobes whereas the rich lobe is comprised of three lobes, however they both have one main bronchus.
How are the bronchi supplied with oxygen
they are supplied OXYGENATED blood via the bronchial arteries
Tell me about lobar bronchi
Since the left lung has two lobes its has two secondary bronchi, the superior and inferior. The right lung however has three lobes so three secondary lobar bronchi, the superior, middle and inferior
Bronchioles
Bronchi continue to divide into smaller and smaller branches becoming conducting bronchioles, and then respiratory bronchioles, always decreasing in diameter and eventually becoming alveoli
What is the volume of mucus produced per day?
1.5 litres
In the bronchi the epithelial cells are still, pseudo stratified, ciliated, columnar but they are what?
They are slightly flattened compared to the trachea
As the bronchi move into the lungs the c-shaped cartilage is replaced by what?
cartilage plates
Tell me about the transformation from the bronchial tree to the bronchioles
they have a lumen of less than 1mm in diameter , the epithelium cells become ciliated columnar (thinner and flatter) and are in a surrounding band of smooth muscle. The cartilage and glands disappear and the bronchiole is held open by the surrounding lung tissue
What happens in asthma
the smooth muscle surrounding the bronchioles in the wall may excessively narrow the lumen
Tell me about the terminal and respiratory bronchioles
The epithelium in these bronchioles becomes non-ciliated cuboidal and the goblet cells disappear
Where does gas exchange occur
in the respiratory alveoli that bud from the respiratory bronchioles
Where are alveoli found
the outpocketings of respiratory bronchioles, alveolar ducts and alveolar sacs. They are separated by septa which is a thing layer containing capillaries, these are the air blood barrier for gas exchange
What is pleura
membranes which cover the lungs as well as the cavity walls
What is the pleural cavity
the space between the layers of pleura
What are the four different names for parietal pleura
cervical
costal
Mediastinal
Diaphragmatic
How are the lungs separated
by the mediastinum
Tell me about the left lung
slightly longer and narrower, predominantly to make room for the heart and pericardium, the space for the heart is called the cardiac notch
What keeps the lungs partially inflated
The negative pressure from the pleura cavities
What causes a collapsed lung
Air in the pleural cavity
Whats the general relationship between artier and veins in terms of blood
arteries = oxygenated veins = deoxygenated
How do we drain lymph fro the lung
via a sub-pleural plexus and a plexus alongside the bronchi to hilarious lymph nodes
What is the hilum
The root of the lung where the main structures pass into and out of the lung
Tell me about the right lung
Slightly wider and shorter, mainly due to dome of the diaphragm being higher on the left side
Where is the trachea located
The sternal notch, if deviated could be a tumour or collapsed lung
Tell me about the positioning of the lungs
The apex is above the clavicle
inferiorly the lungs ends two rib spaces higher than the bottom of the cage
Normal respiration does not extend to the lower parts of the pleural cavity
Overview of the mechanisms of respiration
- Respiration varies from quiet during rest through to a range of forced respirations during severe exercise or respiratory distress.
- Inhalation/Inspiration must increase the diameters of the thorax to create a negative pressure, which sucks air into the lungs via the trachea and larynx etc.
- Diaphragmatic contraction causes its descent, increasing its vertical diameter.
- Rib elevation (with assistance from intercostal muscles) pushes the sternum up and forward, and the ribs outward, to increase anteroposterior and lateral diameters.
- Exhalation/Expiration is by muscle relaxation (passive) and elastic recoil (remember the high amount of elastic tissue in the lungs and bronchi).
What expands the capacity of the ribs
the intercostal muscles expand the size of the thoracic cavity during inspiration and raise the ribs pushing the sternum outwards.
Tell me about the diaphragm
muscular at the periphery
tendinous at its centre
left and right domes
motor and sensory supply is the phrenic nerve (C3.C4.C5 Keep the diaphragm alive)
