Respiratory System Part 1 PDF

RESPIRATORY RESPIRATORY SYSTEM Marie A. Román Martínez, PhD Department of Biology Office hours: by appointment Email: [email protected] Copyright-This presentation is intended for educational purpose only. No part of this presentation may be reproduced or transmitted in any form without written pe...

RESPIRATORY RESPIRATORY SYSTEM Marie A. Román Martínez, PhD Department of Biology Office hours: by appointment Email: [email protected] Copyright-This presentation is intended for educational purpose only. No part of this presentation may be reproduced or transmitted in any form without written permission. Objectives 1. Describe the five processes involved in respiration. 2. List the functions of the respiratory system. 3. Describe the structures and functions of the respiratory system. 4. Describe the mechanism of breathing. 5. Describe the various respiratory volumes and capacities and the significance of each. 6. Describe the mechanisms of gas exchange in the lungs and the body tissues. 7. Describe how oxygen and carbon dioxide are transported by the blood. 8. Describe the major disorders of the respiratory system. 2 Introduction The primary role is to supply the blood with oxygen and to remove carbon dioxide from the blood. 1. Breathing Movement of air into and out of the lungs. 2. Alveolar gas exchange Exchange of O2 and CO2 between air in pulmonary alveoli and blood in alveolar capillaries. 3. Gas transport 4. Systemic gas exchange Transport of O2 and Exchange of O2 and CO2 between lungs CO2 between blood in systemic capillaries and tissues. and tissues cells. 5. Aerobic respiration The use of O2 and production of CO2 during ATP production. 3 Introduction In addition to gas exchange, respiratory system is responsible for: Detecting odors. Producing sound. Regulating blood pH. Trapping and defending the body from airborne pathogens. Assisting in movement of venous blood and lymph. 4 Subdivisions of Respiratory System Upper respiratory tract: Nose and pharynx Lower respiratory tract: Larynx, trachea, bronchi and lungs. 5 Nose Nasal bones support the nose bridge, remaining portion is supported by septal nasal cartilage. Nostrils are the external openings that allow air to enter and leave nasal cavity. Has hairs to filter large airborne particles and insects. Nasal cavity is the inner nose chamber. Three nasal conchae project from lateral walls. Increases surface area of and create air turbulence in nasal cavity. Nasal septum divides nasal cavity into right and left portions. Palate separates the nasal cavity from the oral cavity: Hard palate Soft palate 6 Nose Olfactory mucosa Mucous membrane containing the olfactory epithelium. Lines the superior nasal conchae and superior nasal septum. Respiratory mucosa Mucous membrane containing pseudostratified ciliated columnar epithelium. Lines rest of nasal cavity, larynx, trachea, bronchi. Globet cells in epithelium produce mucus. Moistens incoming air and traps particles including microorganisms. Pseudostratified ciliated columnar epithelium Air is warmed by blood vessels in mucosae. Cilia move trapped particles to pharynx where they can be swallowed. Destroyed by gastric juice in stomach. Image obtained from Table 5.2 from Saladin Anatomy & Physiology 9th edition 7 Nose Paranasal sinuses are air filled cavities in the bones around the nasal cavity. In the ethmoid, frontal bone, maxillae, and sphenoid. Functions: Lighten the skull. Sound resonating chambers during speech. Open into nasal cavity, which increase nasal cavity surface area. Lined with respiratory mucosae and the secreted mucus drains into the nasal cavity. 8 Pharynx Also called the throat. Passageway behind the nasal and oral cavities, extending downward to larynx and esophagus. Muscular wall lined with mucous membrane containing stratified squamous epithelium. Consists of three parts: Nasopharynx Oropharynx Laryngopharynx Auditory tubes: Image obtained from Figure 22.3 from Saladin Anatomy & Physiology 9th edition Equalize air pressure on each side of the tympanic membrane. 9 Pharynx Tonsils, clumps of lymphoid tissue that occur at openings to pharynx. Sites of immune responses. And may become sore and swollen when infected. Three sets of tonsils: Palatine tonsils Pharyngeal tonsil—(adenoid) Lingual tonsil. 10 Larynx Cartilaginous, boxlike structure. Passageway for air between pharynx and trachea. Supported by ligaments that extend from hyoid bone. The three largest cartilages are: 1. Thyroid cartilage Projects forward (Adams apple). 2. Cricoid cartilage Connects to trachea 3. Epiglottis Cartilaginous flap that keeps solids (food) and liquids from entering larynx. 11 Larynx Vocal folds (cords) Two bands of elastic connective tissue covered by respiratory mucosa. Relaxed during resting breathing. Vibrate when contracted to produce vocal sounds. Pitch (high or low tone) determined by vibration frequency of the vocal cords. High-frequency vibrations lead to high-pitched sound and vice versa. Loudness determined by vibration amplitude. The larger the amplitude, the louder the volume, and vice versa. Glottis Vocal folds and the space between them. Vestibular folds (false vocal cords) Lie above vocal folds. Keep solids and liquids from entering glottis. No role in sound production. 12 Larynx Changes occur during swallowing. Goal is to prevent solids and liquids from entering larynx and direct them into esophagus. Muscles lift larynx upward. Epiglottis fold over to cover glottis. Food is directed into esophagus, whose opening is located just behind the larynx. If solids or liquids enter larynx, coughing occurs. 13 Image obtained from Figure 22.3 from Saladin Anatomy & Physiology 9th edition 14 Trachea Airway that extends from larynx into thoracic cavity. Branches to form right and left main bronchi. C-shaped tracheal cartilages support the trachea. Hold airway open during breathing. Open portion of the tracheal cartilages allows esophagus to expand slightly during swallowing. Inner wall lined by respiratory mucosa. Beating cilia move the mucus and entrapped particles upward into pharynx where they are coughed up or swallowed. 15 Bronchi, Bronchioles, and Pulmonary Alveoli Bronchi: Main bronchi enters its respective lung, branch into lobar bronchi, one for each lobe. Lobar bronchi branch into segmental bronchi, one for each segments within each lung. The bronchi continue to branch into smaller and smaller bronchi. Bronchial walls possess cartilaginous rings. As branches get progressively smaller, the amount of cartilage tissue gradually decreases. All of the bronchi form the bronchial tree. 16 Bronchi, Bronchioles, and Pulmonary Alveoli Bronchioles: Very small tubes lacking cartilage that branch from bronchi. Possess smooth muscle that aids in regulating air flow. Bronchoconstriction- contraction of the smooth muscle tissue, which decreases airflow. Bronchodilation- relaxation of the smooth muscle tissue, which increases airflow. Lined with mucous membrane containing simple cuboidal epithelium. Cannot remove foreign particles effectively. Bronchioles branch to form smaller and smaller bronchioles that lead to microscopic alveolar ducts. 17 Bronchi, Bronchioles, and Pulmonary Alveoli Alveolar ducts, which branch from smallest bronchioles terminate in pulmonary alveoli (tiny air sacs). The primary function of the bronchial tree and bronchioles is to carry air into and out of the pulmonary alveoli during breathing. 18 Bronchi, Bronchioles, and Pulmonary Alveoli Type I Type II Site of alveolar gas exchange: O2 and CO2 diffuse readily through the thin respiratory membrane. Bronchial tree and bronchioles have no role in alveolar gas exchange. Filled with watery fluid to aid diffusion. Surfactant prevents pulmonary alveolar collapse during exhalation. Reduce attraction between water molecules (surface tension). The surfactant is a mixture of lipoproteins secreted by great (type II) alveolar cells. Approx. 300 million pulmonary alveoli per lung. Surface area approx. 75 m2, holding approx. 5,800 ml of air. 19 Lungs Cone-shaped and are separated by the mediastinum. Consists of pulmonary alveoli, air passageways, blood and lymphatic vessels, nerves, and connective tissues. Lungs are divided into lobes: Left lung has two lobes (superior and inferior). Right lung has three lobes (superior, middle, and inferior). 20 Lungs Two layers of serous membranes called pleurae surround each lung. Visceral pleura- firmly attached to the surface of each lung. Parietal pleura- lines the inner wall of the thoracic cage. Pleural cavity –space between the visceral and parietal pleurae. Filled with pleural fluid to: Reduce friction between pleurae as the lungs inflate and deflate. Help hold the pleurae together. 21 Breathing Breathing is the process that exchanges air between atmosphere and pulmonary alveoli. Air moves along an air pressure gradient. Air moves from high pressure region to low pressure region. There are three pressures important to breathing: atmospheric pressure, intraalveolar pressure, intrapleural pressure. Atmospheric pressure: Pressure of air surrounding earth →760 mmHg at sea level. Decreases at higher elevations. 22 Breathing Intra-alveolar (intrapulmonary) pressure: Air pressure within the lungs that fluctuates during breathing. Changes measured in cm H2O. If pressure reaches -1 cm H2O, pressure has decrease 1 cm H2O below atmospheric pressure. If pressure reaches +1 cm H2O, pressure has increased 1 cm H2O above atmospheric pressure. Intrapleural pressure: Pressure within the pleural cavity. Normally -5 to -8 cm H2O during breathing. It keeps lungs stuck to the inner walls of the thoracic cage. Keeps lungs expanded even during exhale. If it equaled atmosphere pressure, lungs would collapse. 23 Inspiration Lungs are at rest→ air pressure in the lungs is the same as the atmospheric pressure. Process of moving air into lungs: Intra-alveolar pressure < atmospheric pressure. Allows for air to flow from the higher air pressure in the atmosphere toward the lower air pressure within the lungs. Contraction of diaphragm and external intercostal muscles Causes an increase in lung volume, which results in a decrease in intra-alveolar pressure. 24 Inspiration Process of resting inspiration: The diaphragm contracts, moves downward and flattens, which increases the volume of the thoracic cavity. Thoracic cavity size increases. Lungs are pulled along when thoracic cage expands. Increase lung volume and decrease intraalveolar pressure to -1 cm H2O. Higher atmospheric pressure pushes air towards the lower intra-alveolar pressure in lungs. Air inflow continues until both pressures are equal. 25 Inspiration Forceful inspiration requires additional muscles: Sternocleidomastoid, scalenes, serratus anterior, pectoralis minor. Contraction further elevates and protracts ribs. Causes greater increase in thoracic cavity volume. Intra-alveolar pressure decrease to a greater extent, which results in greater airflow into the lungs. 26 27