Biol 431 Chapter 22: The Respiratory System

Vocabulary flashcards based on Professor Moore's Chapter 22 lecture notes covering the anatomy, mechanics, gas exchange, and control of the respiratory system.

Primary Functions of the Respiratory System

The transport of gases ($O_2$ and $CO_2$) between the external environment and the blood to support aerobic metabolism and maintain extracellular fluid pH balance.

Respiratory Mucosa

The mucosal lining of the respiratory tract consisting primarily of pseudostratified ciliated columnar epithelium (PSCC) with goblet cells and an underlying lamina propria.

Mucociliary Escalator

The process by which cilia sweep mucus containing trapped debris toward the oropharynx for disposal.

Nasal Conchae

Bony structures in the nasal cavity that produce turbulent airflow and increase mucosal surface area for warming, humidifying, and filtering air.

Glottis

The opening between the vocal folds through which air passes to produce sound.

Trachealis Muscle

Smooth muscle on the posterior wall of the trachea that contracts during the cough reflex to increase the velocity of exhaled air.

Carina

The last tracheal cartilage situated at the point where the trachea branches into the left and right primary bronchi.

Terminal Bronchioles

The last segment of the conducting airways, with a diameter less than $0.5\,mm$, each serving a single pulmonary lobule.

Alveolar Pores

Openings that interconnect alveoli to equalize air pressure throughout the lung and provide alternate routes for airflow.

Type II Alveolar Cells

Scattered cuboidal cells that produce surfactant to reduce surface tension and antimicrobial proteins to protect the lungs.

Respiratory Membrane

The $\approx 0.5\,\mu m$ air-blood interface consisting of Type I alveolar cells, capillary endothelial cells, and their fused basement membranes.

Parietal Pleura

The outer layer of the serous membrane that lines the inner surface of the thoracic wall and the superior surface of the diaphragm.

Boyle’s Law

A physical law stating that the pressure of a gas is inversely proportional to its volume ($P_1V_1 = P_2V_2$).

Intrapleural Pressure ($P_{ip}$)

The negative pressure within the pleural cavity produced by the opposing recoil forces of the lungs and the thoracic wall.

Transpulmonary Pressure ($P_{tp}$)

The difference between intra-alveolar and intrapleural pressure ($P_{alv} - P_{ip}$) that prevents the lungs from collapsing.

Atelectasis

A state of lung collapse, which can be caused by a plugged airway or a pneumothorax.

Lung Compliance

A measure of how easily the lungs can be expanded, which decreases with fibrosis or reduced surfactant production.

Minute Ventilation ($V_m$)

The total amount of air moving through the respiratory tract per minute, calculated as respiratory rate ($RR$) times tidal volume ($TV$).

Alveolar Ventilation ($V_A$)

The volume of fresh air that reaches the respiratory zone each minute, calculated as $RR \times (TV - DSV)$, where $DSV$ is dead space volume.

Dalton’s Law

A law stating that the total pressure of a gas mixture is the sum of the partial pressures exerted by each individual gas.

Henry’s Law

A law stating that gases dissolve into or out of a liquid in proportion to their partial pressure gradient.

Ventilation–Perfusion Coupling

An autoregulatory mechanism that matches airflow to blood flow in the alveoli by adjusting bronchiole and arteriole diameters.

Oxyhemoglobin ($HbO_2$)

The molecule formed when oxygen binds to hemoglobin; its formation is enhanced by high partial pressures of oxygen in the lungs.

Bohr Effect

The reduction in hemoglobin's affinity for oxygen caused by a decrease in blood pH or an increase in $\text{PCO}_2$.

Chloride Shift

The exchange of bicarbonate ions ($HCO_3^-$) out of red blood cells for chloride ions ($Cl^-$) into the cells to maintain electrical neutrality.

Haldane Effect

The phenomenon where the unloading of oxygen from hemoglobin increases the protein's ability to bind with carbon dioxide.

Hyperpnea

An increase in ventilation that specifically matches an increase in the metabolic rate of cells, such as during exercise.

Hypercapnia

An increase in arterial $\text{PCO}_2$ typically caused by hypoventilation, which leads to respiratory acidosis.

Ventral Respiratory Group (VRG)

The medullary rhythm-generating and integrative center that controls the basic rate of quiet breathing through phrenic and intercostal nerve signaling.

Central Chemoreceptors

Sensory neurons in the medulla that monitor arterial $\text{PCO}_2$ by detecting hydrogen ion concentration ($[H^+]$) changes in the cerebrospinal fluid.