2 The bronchial tree The bronchial tree starts with 2 main _________ that lead from the trachea into the lungs. The bronchi continue to branch until they are small _____________ about 1 mm in diameter with thinner walls. Bronchioles eventually lead to elongated sacs called ________. 9.3 The Lower Respiratory Tract
3 The lungs The secondary bronchi, bronchioles, and alveoli make up the lungs. The right lung has 3 lobes while the left lung has 2 lobes. Each lobe is divided into lobules. Each lung is enclosed by membranes called pleura. 9.3 The Lower Respiratory Tract
4 The alveoli There are 300 million alveoli in the lungs that greatly increase _____________. Alveoli are enveloped by blood capillaries. The alveoli and capillaries are __________ of epithelium to allow exchange of gases. Alveoli are lined with ____________ that act as a film to keep alveoli open. 9.3 The Lower Respiratory Tract
6 2 phases of breathing/ventilation 1. Inspiration – an _______ process of inhalation that brings air into the lungs 2. Expiration – a typically _________ process of exhalation that expels air from the lungs 9.4 Mechanism of Breathing
7 Inspiration The __________ and ___________ muscles contract. The diaphragm ________ and the rib cage moves upward and outward. Volume of the thoracic cavity and lungs increase. The air pressure within the lungs ___________. Air flows into the lungs. 9.4 Mechanism of Breathing
9 Expiration The diaphragm and intercostal muscles ______. The diaphragm moves ________ and becomes ______-shaped. The rib cage moves downward and inward. Volume of the thoracic cavity and lungs ________. The air pressure within the lungs _________. Air flows out of the lungs. 9.4 Mechanism of Breathing
11 Different volumes of air during breathing ___________ – the small amount of air that usually moves in and out with each breath ___________ – the maximum volume of air that can be moved in plus the maximum amount that can be moved out during one breath Inspiratory and expiratory ______________ – the increased volume of air moving in or out of the body _________ volume – the air remaining in the lungs after exhalation 9.4 Mechanism of Breathing
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