Chapter 23

Question 1

What are the primary functions of the respiratory system?

Answer 1

Breathing (primary)

Air passageway

Site for exchange of O2 and CO2

Detection of odors

Sound production

Question 2

What is the general structure of mucosa in the respiratory tract?

Answer 2

Epithelium

Basement Membrane

Lamina Propria

Question 3

How does the mucosa change in the respiratory tract?

Answer 3

It becomes progressively thinner along the length of the tract

Exceptions to the general thinning pattern occur in regions subject to abrasion

Question 4

What are the paranasal sinuses from superior to inferior?

Answer 4

frontal

ethmoidal (with sphenoidal located posteriorly)

maxillary

Question 5

What connects all paranasal sinuses to the nasal cavity?

Answer 5

ducts

Question 6

What are the sinus and ducts lined by?

Answer 6

a pseudostratified ciliated columnar epithelium that is continuous with the epithelium of the nasal cavity

Question 7

What happens to mucus?

Answer 7

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

Question 8

What is the main function(s) of the paranasal sinuses?

Answer 8

warm and humidify inhaled air

provide resonance (deep, tonal quality) to the voice

lighten the skull

Question 9

What are the three regions of the pharynx?

Answer 9

nasopharynx (uppermost)

oropharynx (medial)

laryngopharynx (lowest)

Question 10

What are some nasopharynx factoids?

Answer 10

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)

Question 11

What are some oropharynx factoids?

Answer 11

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

Question 12

What are some laryngopharynx factoids?

Answer 12

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

Question 13

what are both the oropharynx and laryngopharynx lined by?

Answer 13

a nonkeratinized stratified squamous epithelium to protect these regions of the pharynx from abrasion associated with swallowing food

Question 14

what is also called the “voice box”?

Answer 14

the larynx

Question 15

What are the functions of the larynx?

Answer 15

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)

Question 16

What is bronchodilation?

Answer 16

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

Question 17

What is bronchoconstriction?

Answer 17

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

Question 18

What is the respiratory zone and its function?

Answer 18

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

Question 19

What are the three types of cells found in the alveoli?

Answer 19

Alveolar Type I cells

Alveolar Type II cells

Alveolar Macrophage

Question 20

Describe alveolar type I cells

Answer 20

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

Question 21

Describe Alveolar Type II cells

Answer 21

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

Question 22

Describe alveolar macrophages

Answer 22

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

Question 23

What is the pleura?

Answer 23

a serous membrane that lines the outer lung surfaces and the adjacent internal thoracic wall

Question 24

What is the visceral pleura?

Answer 24

tightly adheres to the lung surface

Question 25

What is the parietal pleura?

Answer 25

lines the internal thoracic walls, the lateral surfaces of the mediastinum, and the superior surface of the diaphragm

Question 26

Where do the parietal and visceral pleura meet at?

Answer 26

the hilum of each lung

Question 27

what is pulmonary ventilation?

Answer 27

breathing

Question 28

How are pressure gradients established and result in pulmonary ventilaition?

Answer 28

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)

Question 29

what happens during inspiration?

Answer 29

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)

Question 30

what happens during exhalation?

Answer 30

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)

Question 31

What are the different reflexes that can alter breathing rate and depth?

Answer 31

chemoreceptors proprioceptors baroceptors irritant receptors

Question 32

What are chemoreceptors?

Answer 32

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

Question 33

what are proprioceptors?

Answer 33

within muscles, tendons and joints stimulated by body movement increase nerve signals to the respiratory center with a subsequent increase in breathing depth

Question 34

what are baroceptors

Answer 34

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

Question 35

what are irritant receptors?

Answer 35

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)

Question 36

what is the difference between pulmonary and alveolar ventilation?

Answer 36

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

Question 37

what are the four different respiratory volume measurements?

Answer 37

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

Question 38

what are the four respiratory capacities?

Answer 38

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

Question 39

When does partial pressure exist?

Answer 39

when the partial pressure for a specific gas is higher in one region than in another

Question 40

what happens when a partial gradient exists between two regions for a given gas?

Answer 40

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

Question 41

what is alveolar gas exchange?

Answer 41

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

Question 42

what are three ways CO2 is transported?

Answer 42

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