Ch 1 Structure and Function Flashcards
What is the prime function of the lung?
To allow oxygen to move from the air into the venous blood and carbon dioxide to move out.
What is Fick’s law of diffusion?
The amount of gas that moves across a sheet of tissue is proportional to the area of the sheet but inversely proportional to its thickness.
What is the area of the blood-gas barrier in the lung?
Between 50 and 100 square meters.
How many alveoli are there in the human lung?
About 500 million.
What is the diameter of an alveolus?
About 1/3 mm.
What are the conducting airways?
A series of branching tubes that lead inspired air to the gas-exchanging regions of the lung.
What is the volume of the anatomic dead space?
About 150 ml.
What is the volume of the alveolar region?
About 2.5 to 3.0 liters.
What type of flow occurs in the conducting airways during inspiration?
Bulk flow.
What happens to gas movement in the respiratory zone?
Gas movement is chiefly by diffusion.
What makes the pulmonary blood vessels unique?
They form a series of branching tubes from the pulmonary artery to the capillaries and back to the pulmonary veins.
What is the diameter of a capillary segment?
About 7 to 10 μm.
How long does a red blood cell spend in the capillary network?
About 0.75 seconds.
What role does surfactant play in the lung?
It dramatically lowers the surface tension of the alveolar lining layer, increasing alveolar stability.
How are large particles filtered in the respiratory system?
They are filtered out in the nose.
What mechanism removes smaller particles from the conducting airways?
A moving staircase of mucus propelled by tiny cilia.
What type of cells engulf particles in the alveoli?
Macrophages.
True or False: The alveoli have cilia.
False.
Fill in the blank: The lung can be regarded as a collection of _______.
[500 million bubbles]
What is the primary role of blood vessels in the lung?
To transport blood to and from the alveoli for gas exchange.
What happens to the lung during resting breathing?
It returns passively to its preinspiratory volume.
What is the thickness of the thinnest part of the blood-gas barrier?
About 3 μm
What is the total area of the blood-gas barrier?
About 1 square meter
What percentage of the area of the alveolar wall is occupied by capillaries?
About 10%
What can happen if the pressure in the capillaries rises to abnormally high levels?
The blood-gas barrier can be damaged
Does oxygen cross the blood-gas barrier by active transport?
False
In what order does oxygen traverse the layers of the blood-gas barrier?
Surfactant, epithelial cell, interstitium, endothelial cell, plasma, red cell membrane
What is the Po2 (in mm Hg) of moist inspired gas of a climber on the summit of Mt. Everest with a barometric pressure of 247 mm Hg?
42
What is the volume of the conducting zone of the human lung?
About 150 ml
What is the volume of the respiratory zone?
About 2.5 to 3 liters
How does gas movement occur beyond the terminal bronchioles?
By diffusion in the alveolar region
What is the average time a red cell spends in the pulmonary capillaries?
About 0.75 s
What is the expected outcome if the thickness of the blood-gas barrier exceeds 0.8 μm?
Decreased rate of diffusion of oxygen into the pulmonary capillaries
What is the impact of left pneumonectomy on lung volume?
Reduced by one-third
What is the reduction in the ability of the blood-gas barrier to transfer gases after left pneumonectomy?
30%
What causes the pulmonary artery pressure to increase more during exercise than preoperatively?
Increased demand for blood flow
What is the reduction in exercise capacity after the left lung removal?
20%
Fill in the blank: The conducting airways extend to the _______.
Terminal bronchioles
True or False: The bronchial circulation has significantly higher blood flow than the pulmonary circulation.
False
What happens to gas flow in the alveolar ducts?
Predominant mode is diffusion rather than convection
What is the mean pressure in the pulmonary artery?
About 100 mm Hg
What distinguishes a respiratory bronchiole from a terminal bronchiole?
The presence of alveoli in the walls of the respiratory bronchiole
