THE RESPIRATORY SYSTEM

FUNCTIONS OF THE RESPIRATORY SYSTEM Transports air into the lungs and facilitates the diffusion of oxygen into the blood stream Receives carbon dioxide from the blood and exhales it

Organs of the Respiratory system S LIDE 13.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Nose  Pharynx  Larynx  Trachea  Bronchi  Lungs - alveoli Figure 13.1

O RGANIZATION OF THE RESPIRATORY SYSTEM Upper Respiratory System – Nose, nasal cavity, paranasal sinuses, and pharynx Lower Respiratory System – Larynx, Trachea, Bronchi, Bronchioles, Alveoli

S LIDE 13.3 B Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 13.2 Upper Respiratory Tract

N OSE, NASAL CAVITY, PARANASAL SINUSES Primary passageway for air entering the respiratory system The only externally visible part of the respiratory system The maxillary, nasal, frontal, ethmoid, and sphenoid bones form the lateral and superior walls of the nasal cavity The mucous secretions produced in the paranasal sinuses keep the nasal cavity moist and clean

P HARYNX ( THROAT ) Chamber shared by the digestive and respiratory systems The pharnyx is divided into the nasopharynx, oropharynx, and laryngopharynx 1. Nasopharynx – superior portion of pharynx 2. Oropharynx – oris/mouth; extends between the soft palate and the base of the tongue at the level of the hyoid bone 3. Laryngopharynx – inferior part of pharynx; entrance to larynx and esophagus

L ARYNX ( VOICEBOX ) Cartilaginous structure that surrounds and protects the glottis (narrow opening where inhaled air leaves the pharynx and enters larynx) Epiglottis – superior to the glottis; composed of elastic cartilage; during swallowing the larynx is elevated and the epiglottis folds back over the glottis, preventing the entry of both liquids and food into the respiratory tract Sound production - air passing through the glottis vibrates the vocal folds and produces sound waves (phonation)

T RACHEA ( WINDPIPE ) Tough, flexible tube Transports air between the larynx and primary bronchi Cilia and mucus protect the respiratory tree by trapping inhaled debris and sweeping it toward the pharynx, where it is removed through coughing or swallowing Branches within the mediastinum, giving rise to the right and left primary bronchi Right bronchus supplies the right lung, left bronchus supplies the left lung

LUNGS Air moves into the lungs through the trachea (windpipe) The trachea branches out into two bronchi (main airways that reach into each lung) Bronchioles (network of tubes) brings air closer to the site of external respiration At the end of each bronchiole are groups of microscopic structures called alveoli (thin-walled air sacs covered with capillaries) Gas exchange takes place as oxygen and carbon dioxide spread across the walls of the capillaries and alveoli

Lungs S LIDE B Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 13.4b

R ESPIRATION External respiration – oxygen moves from the blood into the lungs Internal respiration – oxygen moves from the blood into the cells, and carbon dioxide moves from the cells into the blood Continual exchange of gases in both external and internal respiration is essential for survival