Chapter 23 Flashcards
What are the primary functions of the respiratory system?
Breathing (primary)
Air passageway
Site for exchange of O2 and CO2
Detection of odors
Sound production
What is the general structure of mucosa in the respiratory tract?
Epithelium
Basement Membrane
Lamina Propria
How does the mucosa change in the respiratory tract?
It becomes progressively thinner along the length of the tract
Exceptions to the general thinning pattern occur in regions subject to abrasion
What are the paranasal sinuses from superior to inferior?
frontal
ethmoidal (with sphenoidal located posteriorly)
maxillary
What connects all paranasal sinuses to the nasal cavity?
ducts
What are the sinus and ducts lined by?
a pseudostratified ciliated columnar epithelium that is continuous with the epithelium of the nasal cavity
What happens to mucus?
the mucus (with its trapped particulate matter) is swept from each paranasal sinus through their ducts into the nasal cavity and then into the pharynx where it is swallowed
What is the main function(s) of the paranasal sinuses?
warm and humidify inhaled air
provide resonance (deep, tonal quality) to the voice
lighten the skull
What are the three regions of the pharynx?
nasopharynx (uppermost)
oropharynx (medial)
laryngopharynx (lowest)
What are some nasopharynx factoids?
the superiormost region of the pharynx is located directly posterior to the nasal cavity and superior to the soft palate
lined by a pseudostratified ciliated columnar epithelium
normally ONLY air passes through
its lateral walls have paired openings into auditory tubes that connect the nasopharynx to the middle ear (they equalize pressure on either side of the tympanic membrane {eardrum})
the posterior wall of it houses a single pharyngeal tonsil (when enlarged it is referred to as an adenoid)
What are some oropharynx factoids?
the middle pharyngeal region immediately posterior to the oral cavity
extends from the level of the soft palate superiorly to the hyoid bone inferiorly
the palatine tonsils are located on lateral walls and linguinal tonsils at the base of the tongue, providing defense against ingested or inhaled foreign materials
What are some laryngopharynx factoids?
the inferior narrowed region of the pharynx located directly posterior to the larynx
Both the oropharynx and the laryngopharynx serve as a common passageway for food and air
what are both the oropharynx and laryngopharynx lined by?
a nonkeratinized stratified squamous epithelium to protect these regions of the pharynx from abrasion associated with swallowing food
what is also called the “voice box”?
the larynx
What are the functions of the larynx?
Produces Sound – mucosa covered ligaments within the larynx, called vocal folds, vibrate as air is passed over them during expiration (the vibration produces sound)
Serves as a Passageway for Air – the vocal folds of the larynx typically are open or abducted to allow for the passage of air
Prevents Ingested Materials from Entering the Respiratory Tract – during swallowing, the laryngeal inlet is covered by the epiglottis to prevent ingested materials from entering the lower respiratory passageway
Assists in Increasing Pressure in the Abdominal Cavity – occurs when the vocal folds are adducted and close off the rima glottidis (opening between the folds) and simultaneously abdominal muscles contract to increase abdominal pressure (referred to as the valsalva maneuver)
Participates in Both a Sneeze and Cough Reflex – both a sneeze and a cough result in an explosive blast of exhaled air (both help remove irritants from the respiratory tract)
What is bronchodilation?
the process of widening the airways/lumen (opening) in the lungs by relaxing the muscles that surround the airways, thus allowing more air to flow through
What is bronchoconstriction?
the narrowing of the airways in the lungs due to the tightening of the smooth muscles surrounding the bronchi and bronchioles, leading to difficulty breathing, wheezing, and coughing
What is the respiratory zone and its function?
it is composed of respiratory bronchioles, alveolar ducts and alveoli which are all microscopic structures
it is where the gas exchange (O2 intake and CO2 release) occurs
What are the three types of cells found in the alveoli?
Alveolar Type I cells
Alveolar Type II cells
Alveolar Macrophage
Describe alveolar type I cells
the most common of the cells (making up 95% of the alveolar surface)
The primary cells that form each alveolus
They collectively form the alveolar epithelium of the respiratory membrane
AKA squamous alveolar cells
Describe Alveolar Type II cells
much less numerous, cuboidal cells that secrete an oily fluid called pulmonary surfactant
The purpose of surfactant is to prevent the collapse alveoli
AKA septal cells
Describe alveolar macrophages
a leukocyte that may be either fixed or free
Fixed alveolar macrophages remain within the connective tissue of the alveolar walls
Free alveolar macrophages are migratory cels that continually move across the alveolar surface within the alveoli
* both types engage in phagocytosis to engulf microorganisms and particulate material that reaches the alveoli
able to leave the lungs either by entering the lymph vessels or by being coughed up in sputum and then expectorated from the mouth
AKA dust cell
What is the pleura?
a serous membrane that lines the outer lung surfaces and the adjacent internal thoracic wall
What is the visceral pleura?
tightly adheres to the lung surface
What is the parietal pleura?
lines the internal thoracic walls, the lateral surfaces of the mediastinum, and the superior surface of the diaphragm
Where do the parietal and visceral pleura meet at?
the hilum of each lung
what is pulmonary ventilation?
breathing
How are pressure gradients established and result in pulmonary ventilaition?
Changes in lung volume driven by muscle contractions and the elastic recoil of the lungs and chest wall, causing air to flow from areas of higher pressure (atmosphere) to areas of lower pressure (lungs)
what happens during inspiration?
the diaphragm contracts and descends and the external intercostal muscles contract thus expanding the cavity (this expansion increases the volume of the lungs
According to Boyle’s Law an increase in volume leads to a decrease in pressure
The intra-alveolar pressure becomes lower than the atmospheric pressure
Air flows from an area of higher pressure (atmosphere) to an area of lower pressure (lungs)
what happens during exhalation?
the diaphragm and external intercostal muscles relax, decreasing the volume of the chest cavity (the lungs recoil thus decreasing their volume)
The intra-alveolar pressure becomes higher than the atmospheric pressure
air flows from an area of higher pressure (lungs) to an area of lower pressure (atmosphere)
What are the different reflexes that can alter breathing rate and depth?
chemoreceptors
proprioceptors
baroceptors
irritant receptors
What are chemoreceptors?
the primary catalyst that alters the breathing rate and depth
Nerve signals from these receptors are sent along sensory neurons to the medullary respiratory center which ultimately results in a change in the rate and depth of breathing
The most important stimulus affecting breathing rate and depth is blood Pco2 where the chemoreceptors are very sensitive to changes in its levels
what are proprioceptors?
within muscles, tendons and joints stimulated by body movement
increase nerve signals to the respiratory center with a subsequent increase in breathing depth
what are baroceptors
within both the visceral pleura and bronchiole smooth muscle are stimulated by stretch that initiate a reflex to prevent overstretching of the lungs by inhibiting inspiration activities (inhalation reflex AKA hering-breuer reflex)
Protects the lungs from damage due to overinflation
When overstretched these baroceptors send nerve signals through the vagus nerves to the respiratory center to shut off inspiration activity thus resulting in expiration
Meant to serve only as a protective reflex after infancy
what are irritant receptors?
when stimulated they initiate a sneezing or coughing reflex
Sneezing initiated by irritants in the nasal cavity
Coughing initiated by irritants in the trachea and bronchi
Nerve signals are relayed by sensory neurons to the medulla oblongata
Sneezing/coughing nuclei initiate nerve signals along motor neurons which cause the vocal cords (initially closed by open abruptly as the pressure increases in the thoracic cavity)
what is the difference between pulmonary and alveolar ventilation?
Pulmonary ventilation is the overall process of breathing (air moving in and out of lungs)
Alveolar ventilation specifically refers to the air reaching the alveoli for gas exchange
It is a subset of pulmonary ventilation
what are the four different respiratory volume measurements?
Tidal Volume (TV): the amount of air inhaled or exhaled per breath during quiet breathing
Typically averages 500 mL
Inspiratory Reserve Volume (IRV): the amount of air that can be forcibly inhaled beyond the tidal volume after a normal inspiration
A measure of lung compliance
Expiratory Reserve Volume (ERV): the amount that can be forcibly exhaled beyond the tidal volume after a normal expiration
A measure of lung and chest wall elasticity
Residual Volume (RV): the amount of air left in the lungs even after the most forceful expiration
what are the four respiratory capacities?
Inspiratory Capacity (IC): the sum of the tidal volume plus the inspiratory reserve volume
Functional Residual Capacity (FRC): the sum of the expiratory reserve volume plus the residual volume
It is the volume of air that is normally left in the lungs after a quiet expiration
Vital Capacity (VC): the sum of the tidal volume plus both the inspiratory reserve volume and expiratory volume (the residual volume is not part of VC)
VC is significant because it is a measure of the maximum amount of air that can be forcefully expired after a forced inspiration
Total Lung Capacity (TLC): the sum of all the volumes, including the residual volume, and is the maximum volume of air that the lungs can hold
When does partial pressure exist?
when the partial pressure for a specific gas is higher in one region than in another
what happens when a partial gradient exists between two regions for a given gas?
the gas moves from the region of its higher partial pressure to the region of its lower partial pressure
It may continue to move until the partial pressures in the two regions become equal
The exchange of respiratory gases in both pulmonary gas exchange and tissue gas exchange is dependent upon partial pressure gradients
what is alveolar gas exchange?
The process by which oxygen (O2) diffuses from the alveoli of the lungs into the pulmonary capillaries while carbon dioxide (CO2) moves in the opposite direction from the blood into the alveoli to be exhaled
what are three ways CO2 is transported?
CO2 binds to hemoglobin at each of the four globular protein regions
Hemoglobin that is bound to CO2 is referred to as carbaminohemoglobin
Approximately 23% of the overall CO2 in the blood is transported in this form
CO2 is dissolved in plasma
About 7% of CO2 transported in the blood remains dissolved in the plasma
The majority of CO2 is converted to bicarbonate for transport
