Lungs, Pleura, and the Mechanics of Ventilation Flashcards
The lungs are divided into bronchopulmonary segments (BP), how many BP are there for each lung?
10
Each BP segment is served by a
Segmental (tertiary) bronchus and a pulmonary artery and vein
Bronchopulmonary segments can also be projected to the
Chest wall
The trachea bifurcates at the level of the
Sternal angle (T4-T5)
More vertical and slightly larger in diameter
Right bronchus
The fetus is surrounded by excessive amniotic fluid. This is referred to as
Polyhydramnios
Does not allow the fetus to swallow amniotic fluid, causing polyhydramnios
Tracheoesophageal fistula
The developing lungs evaginate into the pleural cavities and become covered with
Pleura
The arrangement of the lung in the pleural cavities, the heart in the pericardial cavity, and the organs in the abdominal cavity is the
Same
The apex of the lungs is superior to the
Medial 1/3 of the clavicle
Parietal pleura turns back on itself and forms
Reflections
Some of these reflections are at very acute angles so that during quiet breathing the lungs do not enter these areas. This is called a
Recess
Since their is no lung tissue in these recesses, during quiet breathing, which two things touch?
Parietal pleura touch eachother
Boyle’s law requires a constant
Teperature
Boyles law says that at a constant temperature
P1V1 = P2V2
This pressure-volume relationship governs
Normal and pathologic respiratory function
Allows all three dimensions of the thoracic cavity to be increased
Muscular action
The most important muscle for ventilation
Diaphragm
Contraction of the diaphragm increases the superior-inferior dimensions of the
Thoracic cavity
Pivot during respiration to increase the anterior-posterior dimensions of the thoracic cavity
Ribs 2-6
During this process, the anterior ends of ribs 2-6 move
Up and down
During this process, the sternum moves
Anteriorly
This is referred to as the “pump handle” movement caused by the
External intercostal muscles
Ribs 7-10 pivt on an axis through the head of the rib and sternocostal joint to increase the
Transverse Dimension of the thoracic cavity
This is the “bucket handle” movement and is caused by contraction of the
Diaphragm
Promotes the “bucket handle” movement of the ribs by acting as a platform for the diaphragm to push against
Lives
As the liver resists further inferior displacement, ribs 7-10 are pulled
Laterally by the diaphragm
At rest, the elastic recoil of the chest wall balances the elastic recoil of the
Lungs
At rest, the intrapleural pressure is ALWAYS
Negative
At rest, the intrapleural pressure is always negative because the lungs and chest wall are pulling in
Opposite directions
At rest, Alveolar pressure is equal to
Atmospheric pressure
During inspiration, force of muscular contraction exceeds elastic recoil, thus
The thoracic cavity enlarges
During inspiration, the intrapleural pressure is increasingly
Negative
What is the relationship between alveolar pressure and atmospheric pressure during inspiration?
Alveolar pressure is less than atmospheric pressure
During inspiration, the force of diaphragm contraction exceeds the elastic recoil and resistance from
Abdominal organs
During expiration, inspiratory muscles
Relax
During expiration, what happens to the elastic recoil of the lungs?
It is increased
During expiration, the intrapleural pressure becomes
Less negative
During expiration, what is the relationship between alveolar and atmospheric pressure?
Alveolar pressure is greater than atmospheric pressure
During expiration what happens to intraabdominal pressure
It increases
Causes unilateral paralysis of the diaphragm
Unilateral phrenic nerve loss
Changes in intrathoracic pressure during ventilation affect venous return to the heart by the
Great veins
Lowers intraorthotic pressure which dilates the great veins and increases venous return to the heart
Deep breath
Provides more blood to carry more oxygen
Deep breath
Laughing and coughing are essentially
Forced exhalations
We know that expiration increases the
-impedes venous return
Intraorthotic pressure
Thus, the face flushes and the veins in the neck flush when we
Laugh or cough (due to increased intraorthotic pressure)
People with comprised ventilatory function may have trouble breathing when
Lying down
Overweight people have trouble breathing when lying down because
It is harder for the diaphragm to push down against the abdominal wall without gravity
An important protective mechanism for the lungs and bronchi
Cough reflex
Both follow bronchial tree into the lungs
Sympathetic and parasympathetic nerves
POSTGANGLIONIC thoracic splanchnics that innervate smooth muscle and blood vessels of the bronchial tree
Lung sympathetics
PREGANGLIONIC fibers that synapse on small ganglia along the bronchial tree
Parasympathetic lung fibers
The POSTGANGLIONIC PARASYMPATHETIC fibers then innervate
Smooth muscles of the bronchial tree
POSTGANGLIONIC SYMPATHETIC fibers of the lungs innervate
Smooth muscle and blood vessels of bronchial tree
Afferent fibers follow the bronchial tree back to the CNS via the
Vagus nerve
The afferents from the lung that travel in the vagus nerve provide feedback about
Stretch, pain, and pressure in the pulmonary veins
Contributes to ANY function requiring an increase in either intraorthotic or intraabdominal pressure
Diaphragm
Participates in phonation, laughing, singing, coughing, sneezing, urination, defecation, and parturition
Diaphragm
When air enters the pleural cavity and the lung collapses due to loss of negative intrapleural pressure
Pneumothorax
In open pneumothorax, upon inspiration, atmospheric pressure on the injured side shifts the mediastinum to the intact side which
Compresses the lung on that side
When a flap of tissue acts as a valve, opening on inspiration and closing on expiration
Tension Pneumothorax
In a tension pneumothorax in the left side, the left lung will be collapse and the right lung will be compressed during
Inspiration AND expiration
Blood in the lung
Hemothorax
The head of the ribs articulates with
2 Vertebral Bodies
The tubercle of the rib articulates with the
Transverse processes
