The Respiratory System

Blood transports oxygen from the lungs to cells and carries carbon dioxide from the cells to the lungs. It is the function of the respiratory system to transport gases to and from the circulatory system. The respiratory system involves both external respiration and internal respiration. External Respiration is the exchange of gases between the atmosphere and the blood. Internal respiration is the exchange of gases between the blood and the cells of the body.

The Lungs a. Site of gas exchange between the atmosphere and the blood. b. Located inside the thoracic cavity, bounded by the rib cage and the diaphragm.

Passage of Air 1. External respiration begins at the mouth and nose and moves into the pharynx. 2. The pharynx allows passage of both food and air. 3. The epiglottis covers the opening to the air passage when food is swallowed. 4. Air passes from the pharynx to the trachea. 5. The upper end of the trachea is the larynx where sounds are produced. 6. The trachea branches off into two bronchi which lead to the lungs. 7. The bronchi branch into smaller tubes called bronchioles which cluster into tiny air sacs called alveoli. 8. All gas exchange in the lungs occurs in the alveoli.

Nasal Passage Pharynx (throat) Larynx (voice box) Trachea (windpipe) Bronchial Tube Pleura Bronchiole Alveoli Diaphragm

Mechanism of Breathing a. Breathing is the process of moving air into and out of the lungs. b. Inspiration is taking air into the lungs. 1. Ribs move outward. 2. The diaphragm pushes down on the abdomen. c. Expiration is expelling air from the lungs. 1. Rib muscles relax. 2. Elastic tissues of the lungs recoil, deflating the lungs. d. The rate of breathing is controlled by the brain, which monitors the amount of CO2 in the blood.

Expiration Inspiration

Supports the skeletal system Absorbs nutrients from food Which of the following describes the primary function of this body system? Supports the skeletal system Absorbs nutrients from food Responds to stimuli in the environment Exchanges gases with the environment

Supports the skeletal system Absorbs nutrients from food Which of the following describes the primary function of this body system? Supports the skeletal system Absorbs nutrients from food Responds to stimuli in the environment Exchanges gases with the environment