Chapter 17 Respiratory System

Objectives Describe the functions of the respiratory system Describe the structures and functions of the organs of respiration Explain the breathing and respiratory process Discuss how breathing is controlled by neural and chemical factors Discuss respiratory disorders Define the key words that relate to this chapter

Respiratory System Functions Exchange of oxygen and carbon dioxide Production of sound Respiration External respiration Internal respiration Cellular respiration or oxidation

Respiratory Organs and Structures Nasal cavity Pharynx Larynx Trachea Bronchi Bronchioles Alveoli Lungs Pleura Mediastinum

The Nasal Cavity Anterior nares or nostrils Nasal septum Turbinates or nasal conchae bones Cilia Olfactory nerve Sinuses

The Pharynx Also called the throat Common passageway for food and air Subdivided Nasopharynx Oropharynx Laryngopharynx Epiglottis

The Larynx Also called voice box Nine fibrocartilaginous plates Mucous membrane Glottis

The Trachea Also called windpipe Hyaline cartilage Mucous membrane and ciliated epithelium

The Bronchi and the Bronchioles Right and left bronchus Bronchi subdivide into bronchioles Alveolar sacs (alveoli)

The Alveoli Sacs of single layer epithelial tissue Surrounded by bed of capillaries Surfactant Exchange of oxygen and carbon dioxide

The Lungs Separated by the mediastinum and the heart Apex is top of each lung; broad lower part is base Base rests over the diaphragm Right lung has three lobes; left lung has two lobes

The Pleura A thin, moist, slippery membrane of tough endothelial cells that covers lungs Each lung encased in double-walled sac Two pleura membranes Visceral or pulmonary pleura lines the lungs Parietal pleura lines the wall of the thorax Pleural fluid

The Mediastinum Also called the interpleural space Located between the lungs Contains the thoracic viscera

Mechanics of Breathing Pulmonary ventilation is called breathing Due to changes in pressure which occur within the chest cavity Variation in pressure caused by cellular respiration and mechanical breathing movements

The Breathing Process Inhalation/inspiration Exhalation/expiration Respiratory movements and frequency of respiration

Control of Breathing Neural factors Respiratory center is located in the medulla oblongata in the brain During inflation, the nerve endings in the walls are stimulated sending a message to the medulla by way of the vagus nerve, inhibiting inspiration and stimulating expiration

Controls of breathing Chemical factors Dependent upon the level of carbon dioxide in the blood Respiratory center senses the increased carbon dioxide in the blood and increases the respiratory rate

Lung Capacity and Volume Tidal volume Amount of air that moves in and out of the lungs with each breath (normal amount is about 500ml) Residual volume Amount of air that cannot be voluntarily expelled from the lungs Allows for continuous exchange of gases between breaths Normal residual volume is 1,500 ml