Flashcards in Constanzo Chapter 5- Respiratory Physiology Deck (233)
Brings air into and out of the lungs.
Lined with alveoli, where gas exchange occurs.
Components of the Conducting Zone
Nose, Nasopharynx, trachea (main), bronchi, bronchioles, terminal bronchioles.
Conducting airways smooth muscle Sympathetic innervation
Adrenergic neurons activate B2 receptors.
Leads to increases in airway diameter, resulting in relaxation and dilation.
Epinephrine from the adrenal medulla and B2-adrenergic agonists (Isoproterenol).
Conducting airways smooth muscle Parasympathetic innervation
Cholinergic neurons activate muscarinic receptors.
Leads to decrease in airway diameter contraction and constriction of the airways.
Ex. Muscadine and carbachol.
Can be blocked by muscarinic antagonists (like atropine).
Treatment for asthma
They dilate the airways.
Respiratory Zone structures
Transitional structures. They have cilia and smooth muscle, but alveoli occasionally bud off their walls.
Completely lined with alveoli, but they contain no cilia and little smooth muscle.
Pouchlike evaginations of the walls of the respiratory zone.
300 million alveoli per lung.
200 micrometers in diameter.
Large surface area to facilitate gas exchange.
RImmed with elastic fibers, epithelial cells, type I and type II pneumocytes.
Type II Pneumocytes
Have regenerative capacity for type I and II.
Keep the alveoli free of dust and debris.
Pulmonary blood flow
Cardiac output of right heart.
Delivered by the pulmonary artery from the left ventricle.
Gravitational Effects on pulmonary blood flow.
1. Lowest at the apex of the lungs
2. Highest at the base.
When lying down:
Blood supply to the conducting airways, very small fraction of the pulmonary blood flow.
Measures static volumes of the lung.
Measured by displacing a bell.
500mL (Including air that fills the alveoli AND the airways)
Volume of air inspired of expired during normal, quiet breathing.
Inspiratory Reserve Volume
Additional volume that can be inspired above the tidal volume.
Expiratory Reserve Volume
Additional volume that can be expired below the tidal volume.
Volume of gas remaining after a maximal forced expiration.
IC. 3500 mL (500 +3000)
Tidal volume plus the inspiratory reserve volume.
Functional Residual Capacity
FRC. 2400 mL (1200 + 1200)
Expiratory Reserve Volume + Residual Volume.
Volume remaining in the lungs after a normal tidal volume is expired.
Equilibrium Volume of the lungs
Functional Residual Capacity.
VC. 4700 mL (3500 +1200)
Inspiratory capacity + Expiratory reserve volume.
Volume that can be expired after maximal inspiration.
Value increases with:
Total Lung Capacity
TLC. 5900 mL (4700+1200)
Vital capacity plus the residual volume.
Cannot measure Residual Volume, therefore cannot measure quantities that depend on it either (FRC, TLC).
Other methods must be taken into account to measure FRC, the equilibrium volume.
Methods for measuring FRC
The subject breathes a known amount of helium, added to the spirometer.
Because it is insoluble, it goes into the lungs. The amount in the lungs, measured by the spirometer is used to "back-calculate" the lung volume.
If it is done after a normal tidal volume is expired, the volume is the FRC.
Variant of Boyle's Law:
At constant T, PXV= constant.
If one increases, the other must decrease.
The subject is placed in a box and after expiring a normal tidal volume. The mouthpiece is closed and then he attempts to breathe, so the volume in his lungs increases while the pressure drops. This leads to a increase in box pressure which is measurable.