Week 9: Flashcards
Primary function of the pulmonary system:
Primary function of the pulmonary system is the exchange of gases between the environmental air and the blood.
Three step process for exchange of gases between environmental air and blood:
(1) ventilation
(2) diffusion
(3) perfusion,
Ventilation
The movement of air into and out of the lungs
Diffusion
The movement of gases between air spaces in the lungs and the bloodstream
Perfusion
The movement of blood into and out of the capillary beds of the lungs to the body organs and tissues.
Ventilation and Diffusion are carried out by what systems?
Pulmonary System
What parts are included in the pulmonary system?
- Two lungs
- The upper and lower airways
- The diaphragm
- The chest wall (thoracic cage)
The lungs are divided into what?
Lobes
What are the lobes of the lungs?
Three in the right lung (upper, middle, lower)
Two in the left lung (upper, lower)
Each lobe of the lungs is further divided into what?
Segments and lobules
Mediastinum
Space between the lungs
What does the mediastinum contain?
It is the space between the lungs and contains the heart, great vessels, and esophagus.
What delivers air to each section of the lung?
A set of conducting airways or bronchi
What does the lung tissue around the bronchi do?
The lung tissue that surrounds the airways supports the bronchi, preventing distortion or collapse of the airways as gas moves in and out during ventilation
Diaphragm
dome-shaped muscle that separates the thoracic and abdominal cavities and is involved in ventilation.
How are lungs protected by contaminants in inspired air?
By a series of mechanical barriers.
What is included in the upper respiratory tract (upper airways)?
- The nasopharynx
- Oropharynx
- Laryngopharynx
- Nasal Cavity
The upper airway is lined with what?
Lines with ciliated mucosa.
What does the ciliated mucosa do in the upper airways?
Warms and humidifies inspired air and removes foreign particles from it.
Larynx
Connects the upper and lower airways.
What is important about the internal larnyx?
The internal larynx muscles control vocal cord length and tension.
These muscles also contribute to voice pitch
What is important about the external larynx?
External laryngeal muscles move the larynx as a whole.
What is the trachea supported by?
U-shaped cartilage
What does the trachea connect?
The trachea connects the larynx to the bronchi
The trachea branch off into what?
The trachea branches into two bronchi
Where does the trachea branch off at?
The trachea branches into two bronchi at the carina
Where does the left and right bronchi enter the lungs?
At the hila or “roots” of the lungs
The bronchial walls have three layers:
- Epithelial lining
- Smooth muscle layer
- Connective tissue layer
The epithelial lining of the bronchi contains what?
Goblet cells and ciliated cells
Goblet cells
Produce a mucous blanket that protects the airway epithelium
Ciliated epithelial cells in the lungs- What does it do?
Ciliated epithelial cells rhythmically beat the mucous blanket (made by goblet cells) toward the trachea and pharynx, where is can be swallowed or expectorated by coughing.
Where do the conducting airways terminate?
In the:
Respiratory bronchioles
Alveolar ducts
Alveoli
The respiratory bronchioles, alveolar ducts and alveoli make up what? What do they all participate in?
These thin walled structures together are called the acinus.
All of them participate in gas exchange
What are the primary gas exchange units of the lungs?
The alveoli
What happens in the alveoli?
The alveoli are the primary gas exchange units of the lung, where oxygen enters the blood and carbon dioxide is removed.
Bronchioles subdivide to form tiny tubes called?
Alveolar ducts
Alveolar ducts end in what?
Alveolar ducts end in clusters of alveoli called alveoli sacs
What do alveolar cells do?
- Alveolar cells provide a protective interface with the environment
- Are essential for adequate gas exchange,
- Preventing entry of foreign agents, and
- maintaining mechanical stability of the alveoli.
Two major types of epithelial cells that appear in the alveolus
- Type 1
- Type 2
Type 1 Alveolar cells
Provide structure
Type 2 alveolar cells
Alveolar cells secrete surfactant
Surfactant
A lipoprotein that coats the inner surface of the alveolus and lowers alveolar surface tension at the end expiration, thereby preventing lung collapse
Where does the pulmonary artery divide and enter the lungs?
The pulmonary artery divides and enters the lung at the hila.
What occurs during pulmonary circulation?
The pulmonary circulation facilitates gas exchange, delivers nutrients to lung tissues, acts as a reservoir for the left ventricle, and serves as a filtering system that removes clots, air, and other debris from the circulation
How does pressure and resistance of pulmonary circulation compare to systemic circulation?
The pulmonary circulation has a lower pressure and resistance than the systemic circulation.
Alveolocapillary membrane
The shared alveolar and capillary walls composed the alveolocapillary membrane.
What occurs across the alveolocapillary membrane?
Gas exchange occurs across this membrane.
What does the pulmonary veins do?
Each pulmonary vein drains several pulmonary capillaries.
How are the pulmonary veins arranged in the lungs?
Pulmonary veins are dispersed randomly throughout the lung and then leave the lung at the hila and enter the left atrium.
What does bronchial circulation do?
It both moistens inspired air and supplies nutrients to the conducting airways, large pulmonary vessels, lymph nodes, and membranes (pleurae) that surround the lungs.
What does the bronchial circulation NOT do?
The bronchial circulation does not participate in gas exchange.
What happens to the pulmonary artery lumina as the smooth muscle in the arterial walls contract?
The caliber of pulmonary artery lumina decreases as smooth muscle in the arterial walls contracts.
What happens to pulmonary artery pressure when contraction of occurs?
Contraction increases pulmonary artery pressure.
What happens to caliber of pulmonary artery as muscles relax?
Caliber increases as these muscles relax, decreasing blood pressure.
Contraction (vasoconstriction) and relaxation (vasodilation) occurs in response to what?
Contraction (vasoconstriction) and relaxation (vasodilation) occurs in response to both local humoral conditions and by the autonomic nervous system (ANS)
What is the most important cause of pulmonary artery constriction?
Low alveolar partial pressure of oxygen (PAO2)
Hypoxic Pulmonary Vasoconstriction
Pulmonary artery constriction caused by low alveolar partial pressure of oxygen
What is the function of the pulmonary system? (Three things)
The pulmonary system
(1) ventilates the alveoli,
(2) diffuses gases into and out of the blood, and
(3) perfuses the lungs so that the organs and tissues of the body receive blood that is rich in O2 and deficient in CO2
Respiration
The exchange of O2 and CO2 during cellular metabolism
The “Respiratory rate” is actually what?
Ventilatory rate
Ventilatory Rate
Number of times gas is inspired and expired per minute
How is the volume of ventilation calculated?
Ventilatory rate (breaths per minute) x amount of air per breath (liters per breath or tidal volume)
Volume of ventilation is also known as?
Minute Volume or Minute ventilation
How is minute volume expressed?
Expressed in liters per minute
How to calculate effective ventilation
Ventilatory rate x tidal volume minus the dead space
Dead space ventilation (VD)
Dead-space ventilation (VD) is the volume of air per breath that does not participate in gas exchange.
Dead space ventilation is __1___without ____2___
- Ventilation
without
- Perfusion
Anatomic dead space
Volume of air in the conducting airways
Alveolar dead space
Volume of air in unperfused alveoli
What is the gaseous form of carbonic acid?
Carbon dioxide (CO2)
How is carbon dioxide produced
Carbon dioxide (CO2), the gaseous form of carbonic acid (H2CO3), is produced by cellular metabolism.
Why does CO2 need to be eliminated?
CO2 is eliminated to maintain a normal arterial CO2 pressure (PaCO 2) of 40 mm Hg and normal acid-base balance
What is needed to maintain normal PaCO2 levels?
- Adequate ventilation
- Elimination of CO2
Diseases that limit the ventilatory rate or tidal volume or both lead to?
decrease ventilation and result in CO2 retention.
How would a healthcare professional determine the adequacy of ventilation?
If a healthcare professional needs to determine the adequacy of ventilation, an arterial blood gas analysis or capnography must be performed to determine if there is CO2 retention.