physiology of the respiratory system Flashcards
What is Physiology?
A science that deals with the ways that living things function.
What is pressure?
Force exerted over an area
Elements of pressure
Air is springy. It has inherent elasticity, very suitable for compression and expansion. In a container, air molecules tend to bounce around at random, colliding into the walls of the container The force of these collisions is a function of the number of molecules inside the container. This force is Pressure. Pressure is Force exerted on an Area → P=F/A Example: the air pressure in your car’s tires is about 32 pounds/in2 (PSI)
Different Types of Pressure
Atmospheric air pressure Negative air pressure Positive air pressure Intrapleural pressure Intrapulmonary pressure -
Atmospheric air pressure
760 mm Hg (at sea level)
Negative air pressure
LESS than 760 mm Hg
Positive air pressure
MORE than 760 mm Hg
Intrapleural pressure
pressure within the pleural “balloon” which surrounds the lung
Intrapulmonary pressure
pressure within the alveoli (tiny sacs) of the lung itself
Boyle’s Law equation
An equation to explain the relationship between pressure and volume P * V = K, where: P = pressure V = volume K is a constant (a fixed value), at a given temperature. Pressure and volume are inversely related
Boyle’s Law Breathing Out
If the volume of the lung is decreased…. The pressure increases…. The pressure in the lung is higher than atmosphere….
Boyle’s Law Breathing In
If the volume of the lung is increased…. The pressure decreases… The pressure in the lung is lower than atmosphere….
Lung-Thorax Interface
Lungs have natural tendency to collapse and shrink What would this do to lung volume? At resting state, thorax has natural tendency to expand At resting state, the lung and thorax tissue exert a recoil force So, what keeps them together?
What keeps the thorax tissue and lungs together?
Pleural Linkage
Three essential components of Pleural Linkage
Pleural Linings Intra-Pleural Space Intra-Pleural Fluid
Pleural membrane “sandwich” consists of…
composed of the visceral pleura and parietal pleura. Intrapleural fluid helps establish linkage between these two membranes. Pressure within the intra-pleural space is negative
Why is the pressure within the intra-pleural space negative?
Remember, in the separate state: Lung tissue shrinks Rib cage will expand So…. when lungs and ribs are joined… one tissue is trying to pull away from the other, producing suction within the intra-pleural space.
What is the importance of pleural linkage?
Ribs are acted upon by muscles of respiration Due to pleural linkage, wherever the ribs (and diaphragm) go, the lungs will go too With “bucket and pump” handle maneuvers and movement of the diaphragm, lung volume is altered
sequence of events (expiration)
changes in anterior-posteroir and superior-inferior dimensions (expiration)
changes in lateral dimensions (expiration)
sequence of events (inspiration)
changes in anterior and superior dimensions (inspiration)
changes in lateral dimensios (inspiration)
