Respiratory Anatomy

Nasal cavity

Senses odors; warms, moistens, and filters air as it enters respiratory system

Pharynx

Passageway for air to travel from the nasal cavity to the larynx and for food from the oral cavity to the esophagus

Epiglottis

Small, moveable flap that prevents food and liquid from entering the trachea; in an upward position at rest and closes during swallowing

Glottis

Comprised of vestibular folds, vocal folds, and the space between them, which is used for breathing, sound production, and protecting the trachea from food aspiration

Valsalva maneuver

Performed when the glottis is closed while performing forced expiration, causing increased intra-abdominal pressure to stabilize the body’s core

Trachea

Tube connecting the larynx and bronchi that is constantly open due to C-shaped cartilage; cilia is present to move mucus and trapped particles up to the pharynx

Larynx

Consists of the epiglottis and glottis; “voice box”

Bronchoconstriction

Narrowing of the bronchioles via parasympathetic stimulation

Bronchodilation

Widening of the lumen of bronchioles via sympathetic stimulation

Lungs

Main breathing organs that facilitate gas exchange with the environment

Respiratory bronchioles

Final and smallest division of bronchioles within the lungs

Alveolus

Tiny air sac at the end of bronchioles that is the primary site for gas exchange

Alveolar duct

Tube of smooth muscle and connective tissue that opens to a cluster of alveoli

Alveolar sac

Cluster of many alveoli

Alveolar pores

Holes that connect adjacent alveoli to maintain an equal air pressure throughout the alveoli and lungs

Pleurae

Membranes that enclosure the lungs and line the chest cavity to reduce friction between these surfaces during breathing

Parietal pleura

Membrane that is attached to chest wall in thoracic cavity

Visceral pleura

Membrane that is tightly adhered to the lungs

Conducting zone

Respiratory organs and structures that are not directly involved in gas exchange; includes nasal cavity, pharynx, larynx, trachea, bronchi, and terminal bronchioles

Respiratory epithelium

Tissue comprised of ciliated columnar epithelial cells that protect tissues from external irritants and pathogens

Goblet cell

Specialized columnar epithelial cell that produces mucus to trap debris

Cilia

Hair-like structures on the respiratory epithelium that move mucus and debris towards the throat to be swallowed via their constant upward beating motion

Alveolar macrophage

Phagocytic cell that moves around alveoli to remove debris and pathogens

Type I alveolar cell

Very thin squamous epithelial cell that makes up 97% of the surface area of alveoli; highly permeable to gases

Type II alveolar cell

Cuboidal cells in alveoli that secrete pulmonary surfactant

Pulmonary surfactant

Phospholipid secretion that reduces the surface tension of water to keep alveoli open when exhaling

Respiratory membrane

Combination of alveoli and capillary membranes (with fused basement membrane) that allows gases to cross by simple diffusion

External respiration

The exchange of gases with the external environment; occurs at alveoli

Internal respiration

The exchange of gases with the internal environment; occurs at body tissues

Anoxia

A state of no oxygen, which quickly causes cell death

Tidal volume

Amount of air moving into and out of the lungs during one respiratory cycle