Respiratory System – Chapter 23

109 question-and-answer flashcards covering key concepts, structures, functions, and clinical perspectives of the respiratory system as presented in Chapter 23.

What is respiration in the context of the respiratory system?

The exchange of O2 and CO2 between the atmosphere and body cells.

Why do body cells require oxygen?

For aerobic ATP production; they must also dispose of the CO2 produced.

Name the main components of the respiratory system.

Respiratory passageways in the head, neck, trunk, and the lungs.

List the four general functions of the respiratory system.

Air passageway, gas-exchange site, detection of odors, sound production.

Which structures form the upper respiratory tract?

Nose, nasal cavity, pharynx, and larynx.

Which structures form the lower respiratory tract?

Trachea, bronchi, bronchioles, alveolar ducts, and alveoli.

Which zone transports air but does not engage in gas exchange?

The conducting zone (nose to terminal bronchioles).

Which zone of the respiratory tract participates directly in gas exchange?

The respiratory zone (respiratory bronchioles, alveolar ducts, alveoli).

What tissues compose the respiratory mucosa?

Epithelium on a basement membrane and an areolar lamina propria.

How does the respiratory epithelium change from the nasal cavity to the alveoli?

It becomes progressively thinner.

Name three sources of mucus in the airway.

Goblet cells, mucous glands, and serous glands.

Which protein increases the viscosity of mucus?

Mucin.

Approximately how much mucus does the respiratory tract produce daily?

About 1–7 tablespoons.

List three antimicrobial substances found in respiratory mucus.

Lysozyme, defensins, and IgA antibodies.

Define sputum.

Mucus mixed with saliva and trapped debris that is coughed up.

What is the first conducting structure for inhaled air?

The nose.

The nasal cavity extends from the to the .

Nostrils (nares) to the choanae.

What structure divides the nasal cavity into left and right portions?

The nasal septum.

What are nasal conchae also called?

Turbinate bones.

What is the primary function of the nasal conchae?

Create turbulence to warm, cleanse, and humidify incoming air.

Why are nosebleeds (epistaxis) common in the nasal respiratory region?

Because of its extensive vascular network.

Which epithelium lines the paranasal sinuses?

Pseudostratified ciliated columnar epithelium.

Why can inflamed sinus ducts lead to infections?

Blocked drainage causes mucus accumulation where microbes can grow.

Name the three regions of the pharynx.

Nasopharynx, oropharynx, and laryngopharynx.

Which part of the pharynx serves only as an air passageway?

The nasopharynx.

What type of epithelium lines the nasopharynx?

Pseudostratified ciliated columnar epithelium.

What epithelium lines the oropharynx and laryngopharynx?

Nonkeratinized stratified squamous epithelium.

Give five functions of the larynx.

Sound production, air passage, prevention of food entry, pressure generation in abdomen, and sneeze/cough reflexes.

Between which cartilages do the vocal ligaments extend?

Thyroid cartilage and arytenoid cartilages.

What tissue covers the vocal ligaments to form vocal folds?

Mucosa (avascular elastic connective tissue beneath).

What is the opening between the vocal folds called?

The rima glottidis.

What structures together constitute the glottis?

The rima glottidis plus the vocal folds.

What are vestibular folds commonly called?

False vocal cords.

What is the main function of vestibular folds?

To protect the vocal cords; they do not produce sound.

How does adduction of the vocal folds affect the rima glottidis?

It narrows (closes) the rima glottidis.

What determines the range of an individual’s voice?

The length and thickness of the vocal cords.

What primarily controls the pitch of the voice?

Tension on the vocal cords.

On what factor does loudness of the voice depend?

The force of air passing across the vocal cords.

Why can laryngitis be life-threatening in children?

Severe inflammation may swell the epiglottis and obstruct the airway.

Which lower-tract structures are directly involved in gas exchange?

Respiratory bronchioles, alveolar ducts, and alveoli.

What epithelium lines the trachea?

Pseudostratified ciliated columnar epithelium.

What supports the walls of the main bronchi?

Incomplete rings of hyaline cartilage.

Do bronchioles contain cartilage?

No; their walls have thicker smooth muscle instead.

Which tissue changes bronchiole diameter?

Smooth muscle in the bronchiole wall.

Name two primary treatments for asthma.

Inhaled steroids and bronchodilators.

What does exercise-induced asthma cause during exertion?

Excessive constriction of airways (bronchoconstriction).

What epithelium lines respiratory bronchioles?

Simple cuboidal epithelium.

What epithelium lines alveoli?

Simple squamous epithelium.

Roughly how many alveoli are found in each lung?

About 300–400 million.

What is the role of alveolar pores?

Provide collateral ventilation between adjacent alveoli.

What is the primary function of alveolar type I cells?

Form the thin alveolar epithelium of the respiratory membrane for gas exchange.

What is the main function of alveolar type II (septal) cells?

Secrete pulmonary surfactant to reduce surface tension and prevent alveolar collapse.

What do alveolar macrophages do?

Engulf microorganisms and debris in the alveoli.

Approximately how thick is the respiratory membrane?

About 0.5 micrometers.

How many bronchopulmonary segments are in the right lung?

Ten segments.

How many bronchopulmonary segments are typically in the left lung?

Eight to ten segments.

Why is each lung enclosed in a separate pleural cavity?

To limit the spread of infections from one lung to the other.

Name the two layers of the pleura.

Visceral pleura and parietal pleura.

What is the purpose of serous fluid in the pleural cavity?

To lubricate and allow the pleural surfaces to slide easily during breathing.

Why do lungs remain inflated under normal conditions?

Intrapulmonary pressure is greater than intrapleural pressure.

List the four sequential processes of respiration.

Pulmonary ventilation, pulmonary gas exchange, gas transport, and tissue gas exchange.

Define inspiration and expiration.

Inspiration is inhalation (air into lungs); expiration is exhalation (air out of lungs).

What is the medical term for quiet, restful breathing?

Eupnea.

Where are the autonomic nuclei that regulate breathing located?

In the brainstem.

State Boyle’s law in relation to breathing.

At constant temperature, gas pressure is inversely proportional to volume (P1V1 = P2V2).

What is the atmospheric pressure at sea level?

About 760 mm Hg (1 atm or 14.7 psi).

How does intrapleural pressure compare to intrapulmonary pressure between breaths?

It is about 4 mm Hg lower (keeps lungs inflated).

During quiet inspiration, which muscles contract?

The diaphragm and external intercostal muscles.

What characterizes forced breathing compared with quiet breathing?

It recruits additional muscles and causes larger volume and pressure changes.

Where is the ventral respiratory group (VRG) located?

In the anterior medulla oblongata.

Where is the dorsal respiratory group (DRG) found?

In the posterior medulla oblongata.

What is another name for the pontine respiratory center?

The pneumotaxic center.

Which nerves carry motor signals to the diaphragm?

The phrenic nerves.

Which nerves carry motor signals to the intercostal muscles?

The intercostal nerves.

What do central chemoreceptors monitor to regulate breathing?

The pH of cerebrospinal fluid (reflecting CO2 levels).

Where are peripheral chemoreceptors located?

In the carotid bodies and aortic bodies.

What is the most potent chemical stimulus for breathing rate?

Blood PCO2 (partial pressure of carbon dioxide).

When does hypoxic drive occur?

When low arterial PO2 becomes the primary stimulus for breathing, as in advanced emphysema.

Which reflex prevents over-inflation of the lungs?

The Hering-Breuer (inflation) reflex triggered by stretch receptors.

Which receptors trigger the sneeze and cough reflexes?

Irritant receptors in air passageways.

Which brain area enables voluntary control of breathing?

The frontal lobe of the cerebral cortex.

Provide the basic formula that relates airflow to pressure and resistance.

F = ΔP / R (flow equals pressure gradient divided by resistance).

Name three factors that increase airway resistance.

Reduced elasticity of lung/chest wall, narrowed bronchioles, or collapsed alveoli.

Define compliance in pulmonary physiology.

The ease with which the lungs and chest wall expand.

What is a partial pressure?

The individual pressure exerted by a specific gas within a mixture of gases.

State Dalton’s law briefly.

The total pressure of a gas mixture equals the sum of its individual partial pressures.

According to Henry’s law, what two factors determine how much gas dissolves in a liquid?

The gas’s partial pressure and its solubility coefficient.

Which of the respiratory gases is most soluble in water?

Carbon dioxide (about 24 times more soluble than O2).

What causes decompression sickness (the bends)?

Rapid ascent causes dissolved nitrogen to form bubbles in blood and tissues.

Name two anatomical features that maximize efficiency of the respiratory membrane.

Its large surface area (~70 m²) and minimal thickness (~0.5 µm).

Define ventilation-perfusion coupling.

Physiologic matching of airflow (ventilation) and blood flow (perfusion) in the lungs.

How do bronchioles respond to decreased airflow?

They constrict (bronchoconstriction).

How do pulmonary arterioles respond to high alveolar PO2?

They dilate to increase perfusion.

What is the principal cause of emphysema?

Cigarette smoking.

What percentage of CO2 is transported as bicarbonate ions in plasma?

About 70 percent.

Roughly what percent of oxygen is dissolved directly in plasma?

About 2 percent.

What is carbaminohemoglobin?

Hemoglobin with CO2 bound to its globin portion.

What does the cooperative binding effect of hemoglobin mean?

Each bound O2 increases hemoglobin’s affinity for the next O2 molecule.

After blood passes resting systemic tissues, what is the typical hemoglobin saturation?

About 75 percent.

Why is an oxygen reserve important?

It allows additional O2 delivery during heightened metabolic demand, such as exercise.