Respiratory Objectives Flashcards
What are the anatomical structures of the conducting system?
Nose, larynx, nasolarynx, trachea, bronchi, bronchioles, and terminal bronchioles.
Why are these conducting zone structures important?
They are important in humidifying, filtering, and warming air before it reaches the respiratory zone.
What is the function of the conducting zone?
To bring air into and out of the respiratory zone for gas exchange.
What is another name for the conducting zone and why?
It is known as anatomic dead space because gas exchange does not occur here.
What are the conducting airways lined with and what is their function?
Mucus-secreting and ciliated cells that function to remove inhaled particles.
How is the conducting zone innervated?
The walls of the conducting system contain smooth muscle with sympathetic and parasympathetic innervation.
How do the parasympathetic and sympathetic innervations affect the conducting zone?
Parasympathetic muscarinic receptors are activated to constrict the airways. Sympathetic beta 2 receptors are activated by epinephrine to dilate the airways. Changes in diameter of the airways changes the airflow.
What are the anatomical structures of the respiratory zone?
Bronchioles, alveolar ducts, and alveolar sacs
Describe the differences between the structures of the respiratory zone.
Respiratory bronchioles are transitional structures that have cilia and smooth muscle. Alveolar ducts are completely lined with alveoli, contain NO CILIA and LITTLE smooth muscle, and terminate into alveolar sacs which are also lined with alveoli. Alveoli are pouchlike invaginations of the walls of the respiratory bronchioles, alveolar ducts, and alveolar sacs that are thin-walled with large surface for diffusion of gases. Alveoli that are poorly perfused with blood are also called dead space.
What is the function of the respiratory zone?
Site of gas exchange.
What are the alveolar walls lined with?
Elastic fibers and epithelial alveolar cells called type 1 and type 2 pneumocytes.
What is the function of type 1 pneumocytes?
Type 1 pneumocytes cover 95% of the alveolar surface, keep alveoli dry, are extremely thin and designed for efficient gas exchange between alveolus and pulmonary capillaries.
What is the function of type 2 pneumocytes?
Type 2 pneumocytes cover 5% of the alveolar surface and synthesize pulmonary surfactants, secrete cytokines, and have a regenerative capacity for type 1 and 2 pneumocytes.
What is the function of pulmonary surfactants?
To reduce the surface tension of alveoli and prevent alveoli from collapsing at the end of expiration.
What are the two phases of the respiratory cycle?
Expiration and inspiration.
Describe how inspiration occurs.
The thorax and lungs are enlarged by the contraction of the external intercostal muscles and the diaphragm.
Describe how expiration occurs.
Internal intercostal muscles contract to assist expiration and are aided by abdominal muscles. This is a passive process in a resting state.
Which phase requires more effort (with the exception of horses)?
Inspiration
What are the two types of breathing and how are they characterized?
Abdominal and costal breathing. Abdominal breathing is characterized by visible movement of the abdomen. Costal breathing is characterized by pronounced rib movements.
What is the functional residual capacity (FRC) and what is its purpose?
It is the air that remains in the lungs at the end of normal exhalation and serves as a reservoir for air and helps provide constancy to the blood concentrations of the respired gases.
What is pulmonary ventilation?
The process of exchanging the gas in the airways and alveoli with gas from the environment
How are respiratory pressures expressed?
In relation to atmospheric pressure, which is set at zero.
What must be true in relation to barometric pressure for air to flow in the lungs?
The pressure in the lungs must be higher or lower than barometric pressure (PB) which is relatively constant.
What three pressures effect pulmonary ventilation?
Pleural pressure, alveolar pressure, and transpulmonary pressure
What is pleural pressure and how does it influence pulmonary ventilation?
It is the pressure exerted outside the lungs within the thoracic cavity (pleural cavity) and is usually less than atmospheric pressure. If the volume of the lungs are increases, the pressure decreases. The pressure is always negative or the lung with collapse. Also known as intra-pleural pressure.
What is alveolar pressure and how does it influence pulmonary ventilation?
Also known as intra-pulmonary pressure and is the pressure within the alveoli that increases and decreases with each breath. It is always equal to atmospheric pressure at the end of the inspiration and expiration phases.
What is transpulmonary pressure and how does it influence ventilation?
This is the pressure difference between the alveolar pressure and pleural pressure in the lungs. It is equal and opposite to the elastic reoil pressure of the lung. If transpulmonary pressure is equal to zero (alveolar pressure = pleural pressure), the lung collapses. The pressure is positive under normal conditions.
What is recoil pressure?
The mean of the elastic forces in the lungs that tend to collapse the lungs at each instant of respiration
What is Boyle’s Law?
“The pressure exerted by a constant number of gas molecules in a container is inversely proportional to the volume of the container.” Pressure decreases, volume increases = inspiration. Pressure increases, volume decreases = expiration.
List the two major functions of pulmonary surfactants.
Pulmonary surfactants displace water molecules and decrease the surface tension which (1) prevents the collapse of the lungs at the end of expiration and (2) increase pulmonary compliance.
What is pulmonary compliance?
Lung compliance (distensibility) is the extent to which the lungs will expand for each unit increase in transpulmonary pressure
What factors affect compliance?
Those conditions that destroy lung tissue or cause it to be fibrotic or that in any way impedes lung expansion. A lack of surfactant is associated with decreased compliance.
What is elasticity and how does it apply to the lungs?
Elasticity is the tendency to return to its initial size after being distended. Lungs must be able to get smaller when the stretching force is released for expiration to occur. The elastic tension increases during inspiration when lungs are stretched and is reduced by elastic recoil during expiration.
What is minute ventilation (VE)?
Also called minute respiratory volume. It is the total volume of air breathed per minute. It is the sum of alveolar ventilation and dead space ventilation.
What is minute ventilation determined by?
It is determined by the tidal volume and the number of breaths per minute.
What is tidal volume and what does it ventilate?
It is the amount of air breathed in or out during a respiratory cycle. Tidal volume ventilates not only the alveoli, but also the airways leading to the alveoli.
