chapter 24 - the respiratory system

Respiratory System Function

To obtain oxygen and eliminate carbon dioxide. Provides an area for gas exchange

Upper Respiratory System

Includes the nose, nasal cavity, sinuses, and pharynx. Functions to cleanse, warm, and humidify the air

Lower Respiratory System

Includes the larynx, trachea, bronchi, bronchioles, and alveoli.

Conducting Zone

Passages that serve only for airflow; no gas exchange occurs here. Also known as anatomical dead space

Respiratory Zone

Passageways and structures (respiratory bronchioles, alveoli) that participate in gas exchange

External Respiration

Exchange of O2 and CO2 between the atmosphere and body tissues

Internal Respiration

The use of oxygen within mitochondria to generate ATP (cellular respiration)

Nasal Conchae (Turbinates)

Bony scrolls in the nasal cavity that help cleanse, warm, and humidify the air

Respiratory Epithelium

Pseudostratified ciliated columnar epithelium with mucus-secreting goblet cells

Pharynx (Overall)

Common passageway shared by the digestive and respiratory systems

Pharynx Regions

Nasopharynx (air only), Oropharynx (air, food, drink), and Laryngopharynx (air, food, drink)

Larynx (Voice Box)

Primary functions are sound production and keeping food and drink out of the airway

Thyroid Cartilage

The largest laryngeal cartilage; shield-shaped structure that forms the Adam’s Apple

Glottis

The slit-like opening in the larynx that inhaled air leaves through

Epiglottis

Flap of tissue that covers the glottis during swallowing to deflect food into the esophagus

Trachea (Windpipe)

Straight tube whose walls contain C-shaped cartilage rings to keep the lumen open. Bifurcates at the carina

Primary Bronchi

One per lung. The Right primary bronchus has a larger diameter and a steeper angle

Right Lung Lobes

Has 3 lobes: superior, middle, and inferior

Left Lung Lobes

Has 2 lobes: superior and inferior. Contains the cardiac notch (indentation for the heart)

Bronchioles

Small air passages that lack supportive cartilage. They contain smooth muscle to control air flow

Bronchodilation

Increase in the luminal diameter, caused by sympathetic activation (e.g., epinephrine release)

Respiratory Bronchioles

The thinnest, most delicate passages and the beginning of the respiratory zone (gas exchange starts here)

Alveoli

Air sacs in the lung; the site of gas exchange with blood capillaries. Lined by simple squamous epithelium

Type I Alveolar Cells

Simple squamous cells that form the sites of gas diffusion.

Type II Alveolar Cells

Cells responsible for producing surfactant

Surfactant

A fluid that decreases surface tension of the lung, which helps prevent the alveoli from collapsing

Parietal Pleura

The outer membrane that lines the pleural cavity wall

Visceral Pleura

The membrane that covers the lungs directly

Pleural Fluid

Contained in the pleural cavity; reduces friction as the membranes slide on one another

Primary Inspiratory Muscles

Diaphragm and external intercostal muscles

Aging Respiratory System

Elastic tissue deteriorates (reducing inflation/deflation ability) and movement of the rib cage is restricted

Emphysema

Disorder characterized by damaged and permanently enlarged alveoli, leading to inadequate surface area for gas exchange

Asthma

Inflammatory disease characterized by bronchial inflammation, spasms, and excessive mucus production that make breathing difficult