BIOD 151 Anatomy Module 2 Study Guide_2020 | BIOD151 Anatomy Module 2 Study Guide - Respiratory System - Portage Learning

BIOD 151 Anatomy Module 2 Study Guide - Respiratory System - Portage Learning Module 2: Respiratory System General Anatomy of Respiratory System: Gross anatomy is the study of the organs and structures of the human body visible to the naked eye. When looking at the lungs from a gross anatomical perspective, the lungs are paired and found in the chest cavity (Figure 2.1). Notice that the lungs are not symmetrical. The right lung has three lobes: superior, middle, and inferior. The left has two lobes: superior and inferior. This asymmetry is due the position of the heart which is situated slightly to the left of the median plane. The hilum is known as the “root” of the lung. This is where the pulmonary vessels and bronchi enter each lung (Figure 2.2). Healthy lung tissue has a very light texture and is peachy/pink in color. Figure 2.1 Anterior view: Gross anatomy of lungs. The right lung has three lobes (superior, middle, inferior) while the left lung has two lobes (superior, inferior). The right and left lung both have oblique fissures separating the lobes. The right lung also has a horizontal fissure separating the superior and middle lobes. Figure 2.2 View of Hilum (root) of right lung. The hilum (highlighted in blue) is where the pulmonary vessels and bronchi enter through each lung. The pleurae are membranes that cover the surface of the lung and the cavity surrounding the lungs. The visceral pleura directly covers the lungs and the parietal pleura covers the surfaces surrounding the lungs: the rib cage, diaphragm, and mediastinum. The space that is formed between the pleurae is called the pleural space or cavity. Normally, this space is empty except for a scant amount of fluid. However, in the diseased state, this cavity can fill with air or fluids. The pleurae reduce friction and provide a negative pressure environment needed for lung inflation. The pleurae also help to pull the lungs open with the chest wall during inhalation. The anatomical organization of the respiratory system allows the respiratory system to perform three main functions: 1) Air conduction, 2) Air filtration, and 3) Exchange of Gases. This third step is also called respiration. The respiratory system also has roles in vocalizations, the sense of smell, and the body’s pH regulation. The body’s pH regulation is discussed further in Anatomy and Physiology II. Carbon dioxide forms carbonic acid which must be buffered with bicarbonate ions. The following outlines the major portions of the respiratory system: a. Conducting portion i. Nostril -Nasal Cavities ii. Pharynx: Nasopharynx, Oropharynx, Laryngopharynx iii. Larynx iv. Trachea v. Paired (primary, secondary, tertiary) bronchi (bronchi is the plural form of bronchus) b. Filtration portion i. Nostrils: hairs, cilia, and mucus producing goblet cells ii. Trachea and bronchi: cilia and mucus producing goblet cells c. Respiratory portion i. Bronchioles (respiratory and terminal) ii. Alveolar ducts iii. Alveolar sacs iv. Alveoli The human respiratory system includes all structures that conduct air to and from the lungs. Air moves through the nasal cavity (Figure 2.3, Figure 2.4), the pharynx (Figure 2.5), the larynx (Figure 2.6) the trachea, and the bronchi to the lungs (Figure 2.7). Along the way, air is filtered so that it is free of debris, warmed, and humidified. By the time the air reaches the lungs, it is at body temperature and is saturated with water. The nasal cavities or fossae, composed of bone and cartilage, are made up of several parts. The left and right fossae are separated by the nasal septum. The vestibule is the most external portion of the nasal cavity just inside the nostrils. The vestibule is lined with stratified squamous epithelium which is a continuation of the skin from the face. Short thick hairs called vibrissae are also found here and act as a screening device for the respiratory tract. Past the vestibule, multiple nasal conchae or folds are present in the nasal cavity increasing the surface area so that the incoming air can be warmed and humidified. To accomplish warming the air, the nasal cavity is highly vascularized (has a large amount of blood vessels). This is one reason why nosebleeds can commonly occur. Figure 2.3 Midsagittal view of upper respiratory structures Figure 2.4 The nasal cavities (left nasal cavity is highlighted in blue) are part of the conducting portion of the respiratory system - - - -