Chapter 23: The Respiratory System

Vocabulary flashcards covering the anatomy, physiology, and regulatory mechanisms of the respiratory system as presented in the lecture notes.

Upper respiratory system

The portion of the respiratory system located above the larynx.

Lower respiratory system

The portion of the respiratory system extending from the larynx down.

Conducting portion

The segment of the respiratory tract from the nasal cavity to the terminal bronchioles.

Respiratory portion

The segment of the respiratory tract consisting of the respiratory bronchioles and alveoli.

Alveoli

Air-filled pockets within the lungs where all gas exchange takes place.

Respiratory mucosa

A lining consisting of an epithelial layer and an areolar layer that covers the conducting portion of the respiratory system.

Mucus escalator

The process where cilia sweep debris trapped in mucus toward the pharynx.

Alveolar macrophages

Also known as dust cells, these cells engulf small particles that reach the lungs.

External nares

The nostrils through which air enters the respiratory system into the nasal vestibule.

Meatuses

Constricted passageways (superior, middle, and inferior) that produce air turbulence to warm and humidify incoming air.

Pharynx

A chamber shared by the digestive and respiratory systems extending from the internal nares to the entrances of the larynx and esophagus.

Thyroid cartilage

The large, unpaired cartilage of the larynx commonly referred to as the Adam’s apple.

Epiglottis

Elastic cartilage that folds back over the glottis during swallowing to prevent food and liquids from entering the respiratory tract.

Phonation

The process of sound production at the larynx.

Articulation

The modification of sound by other structures to produce speech.

Trachea

The ‘windpipe’ which contains $15-20$ C-shaped tracheal cartilages and extends from the cricoid cartilage into the mediastinum.

Carina

An internal ridge that separates the right and left primary bronchi.

Hilus

A groove along the medial surface of the lung where pulmonary nerves, blood vessels, and lymphatics enter.

Cardiac notch

An indentation in the left lung formed because the lung is displaced leftward by the heart.

Bronchodilation

The enlargement of bronchiole diameter caused by sympathetic activation.

Bronchoconstriction

The reduction in bronchiole diameter caused by parasympathetic activation or histamine release.

Septal cells (Type II cells)

Specialized cells in the alveoli that produce surfactant.

Surfactant

An oily secretion containing phospholipids and proteins that reduces surface tension on alveolar surfaces to prevent collapse.

External respiration

The processes involved in exchanging $O_2$ and $CO_2$ with the environment.

Internal respiration

The uptake of $O_2$ and production of $CO_2$ by individual cells, also known as cellular respiration.

Atmospheric pressure

The weight of air, which is $760\,mm\,Hg$ (1 atmosphere) at sea level.

Tidal volume

The amount of air moved in and out of the lungs in a single respiratory cycle.

Pneumothorax

An injury to the chest wall that allows air into the pleural cavity.

Atelectasis

The medical term for a collapsed lung.

Eupnea

Quiet breathing involving active inhalation and passive exhalation.

Hyperpnea

Forced breathing involving active inhalation and active exhalation assisted by accessory muscles.

Anatomic dead space

The volume of air that remains in the conducting passages and does not reach the alveolar exchange surfaces.

Dalton’s law

The principle stating that each gas contributes to the total pressure in proportion to its number of molecules.

Partial pressure

The pressure contributed by a single gas within a mixture of gases.

Hemoglobin saturation

The percentage of heme units containing bound oxygen.

Chloride shift

An exchange mechanism where bicarbonate ions move into the plasma in exchange for $Cl^-$ ions without using $ATP$.

Carbaminohemoglobin

Hemoglobin that has carbon dioxide bound to the amino groups of its globular proteins.

Hypercapnia

An increase in the $P_{CO_2}$ of arterial blood, commonly caused by hypoventilation.

Hypocapnia

An abnormally low $P_{CO_2}$ in the blood resulting from excessive ventilation (hyperventilation).