Essentials of Human Anatomy & Physiology PDF

Essentials of Human Anatomy & Physiology Thirteenth Edition Global Edition Chapter 13 The Respiratory System Edited by ISD- Anatomy...

Essentials of Human Anatomy & Physiology Thirteenth Edition Global Edition Chapter 13 The Respiratory System Edited by ISD- Anatomy & Physiology Faculty in May 2023 Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Learning Outcomes 1.Describe the structural characteristics and functions of each of the following respiratory organs: nose, pharynx, larynx, trachea, the main bronchi and the bronchial tree and the lungs. 2. Define pulmonary ventilation, external respiration, respiratory gas transport and internal respiration. 3. Discuss the mechanics of pulmonary ventilation or breathing. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Learning outcomes 4.Discuss respiratory volumes and capacities. 5.Discuss the process of gas exchanges in the lungs and tissues. 6. Describe how oxygen and carbon dioxide are transported in the blood. 7. Explain the neural control of breathing. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Functional Anatomy of the Respiratory System Organs of the respiratory system include: – Nose – Pharynx – Larynx – Trachea – Bronchi – Lungs—alveoli Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 13.1 The Major Respiratory Organs Shown in Relation to Surrounding Structures Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Functional Anatomy of the Respiratory System Gas exchanges between the blood and external environment occur only in the alveoli of the lungs. Upper respiratory tract includes passageways from the nose to larynx. Lower respiratory tract includes passageways from trachea to alveoli. Passageways to the lungs purify, humidify, and warm the incoming air Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  The Nose The only externally visible part of the respiratory system. – Nostrils (nares) are the route through which air enters the nose – Nasal cavity is the interior of the nose – Nasal septum divides the nasal cavity – Olfactory receptors for sense of smell are located in the mucosa of the superior part of the nasal cavity beneath the ethmoid bone. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Concept Link 1 Recall that any area open to the outside of the body, including respiratory passages, is lined with mucous membrane (mucosa), which is a “wet,” or moist, membrane (Chapter 4, p. 129). Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 13.2b Basic Anatomy of the Upper Respiratory Tract, Sagittal Section Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  The Nose Respiratory mucosa – Lines the nasal cavity – Moistens air – Traps incoming foreign particles – Destroys bacteria chemically through the action of lysozyme enzymes. – Moves contaminated mucus to the posterior of the throat where it is swallowed and digested by stomach juices. (cough or sneeze) Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Superior, middle and inferior conchae are projections from the lateral walls which increase the surface area of the mucous membrane for trapping of inhaled foreign particles (dust and microbes). – Air passageways: superior, middle and inferior nasal meatuses. The palate separates the nasal cavity from the oral cavity: – Hard palate is anterior and supported by bone – Soft palate is posterior and unsupported Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Paranasal sinuses – Cavities within the frontal, sphenoid, ethmoid, and maxillary bones surrounding the nasal cavity. – Functions of Sinuses: ▪ Lighten the skull ▪ Act as resonance chambers for speech ▪ Produce mucus Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  The Pharynx Commonly called the throat. Muscular passageway from nasal cavity to larynx Three regions of the pharynx: 1. Nasopharynx—superior region behind nasal cavity. 2. Oropharynx—middle region behind mouth. 3. Laryngopharynx—inferior region behind the larynx and connected below to the esophagus. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Figure 13.2a Basic Anatomy of the Upper Respiratory Tract, Sagittal Section Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Oropharynx and laryngopharynx serve as common passageway for air and food – Epiglottis routes food into the posterior tube which is the esophagus. Pharyngotympanic tubes or Eustachian tubes open into the nasopharynx. – Drain the middle ear and could be a source of infection from the pharynx to the middle ear. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 13.2b Basic Anatomy of the Upper Respiratory Tract, Sagittal Section Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  The Pharynx Tonsils are clusters of lymphatic tissue that play a role in protecting the body from infection. Types of tonsils: 1. Pharyngeal tonsil (adenoid) is located in the nasopharynx. 2. Palatine tonsils (2) are located in the oropharynx at the end of the soft palate. 3. Lingual tonsil is found at the base of the tongue. 4. Tubal tonsils protect the openings of the pharyngotympanic tubes. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  The Larynx Commonly called the voice box. Located inferior to the pharynx Functions – Routes air and food into proper channels – Plays a role in speech Made of eight rigid hyaline cartilages The four main cartilages of larynx are Epiglottis, Thyroid, Arytenoid and Cricoid – Thyroid cartilage (Adam’s apple) is the largest Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  The Larynx Anterior view Posterior view Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  The Larynx Epiglottis – Spoon-shaped flap of cartilage. – Protects the superior opening of the larynx. – Routes food to the posteriorly situated esophagus and routes air toward the trachea. – During swallowing, the epiglottis rises and forms a lid over the opening of the larynx. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  The Larynx Vocal folds (true vocal cords) These are a pair of folds formed from the mucous membrane of the larynx. Functions: – Vibrate with expelled air – Allow us to speak. Glottis is the opening between the vocal cords Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. The Larynx Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  The Trachea Commonly called the windpipe 4-inch-long tube that connects to the larynx. Walls are reinforced with C-shaped rings of hyaline cartilage. – Patent airway – Trachealis muscle Lined with ciliated mucosa – Cilia beat in a superior direction – Goblet cells produce mucus Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 13.3a Anatomy of the Trachea and Esophagus Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  The Main Bronchi Formed by division of the trachea Each bronchus (primary bronchus ) enters the lung at the hilum (medial depression) Right bronchus is wider, shorter, and straighter than left. Bronchi subdivide into smaller and smaller branches called the secondary and tertiary Bronchi. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 13.1 The Major Respiratory Organs Shown in Relation to Surrounding Structures Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  The Lungs Occupy the entire thoracic cavity except for the central mediastinum Apex of each lung is near the clavicle (superior portion) Base rests on the diaphragm Each lung is divided into lobes by fissures – Left lung—two lobes – Right lung—three lobes Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  The Lungs Serosa covers the outer surface of the lungs – Pulmonary (visceral) pleura covers the lung surface – Parietal pleura lines the walls of the thoracic cavity Pleural fluid fills the area between layers – Allows the lungs to glide over the thorax – Decreases friction during breathing Pleural space (between the layers) is more of a potential space Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 13.4a Anatomical Relationships of Organs in the Thoracic Cavity Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 13.4b Anatomical Relationships of Organs in the Thoracic Cavity Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. The Lungs The bronchial (respiratory) tree – Network of branching passageways – Conduits to and from the respiratory zone – Main bronchi ( primary )subdivide into smaller branches (secondary and Tertiary bronchi ) and eventually into bronchioles – All except the smallest passageways have reinforcing cartilage in the walls Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Respiratory Zone Structures and the Respiratory Membrane Terminal bronchioles lead into respiratory zone structures and terminate in alveoli Respiratory zone, only site of gas exchange, includes: – Respiratory bronchioles – Alveolar ducts – Alveolar sacs – Alveoli (air sacs) are in millions and make up the bulk of the lungs Conducting zone structures include all other passageways Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 13.5a Respiratory Zone Structures Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 13.5b Respiratory Zone Structures Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Respiratory Zone Structures and the Respiratory Membrane Alveoli – Simple squamous epithelial cells largely compose the walls – Alveolar pores connect neighboring air sacs Pulmonary capillaries cover external surfaces of alveoli Stroma of lung is elastic connective tissue that allows the lungs to stretch and recoil Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Respiratory Zone Structures and the Respiratory Membrane Respiratory membrane (air-blood barrier) – On one side of the membrane is air, and on the other side is blood flowing past – Formed by alveolar and capillary walls Gas crosses the respiratory membrane by diffusion – Oxygen enters the blood – Carbon dioxide enters the alveoli Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Respiratory Zone Structures and the Respiratory Membrane Alveolar macrophages (“dust cells”) – Add protection by picking up bacteria, carbon particles, and other debris Surfactant-secreting cells – Surfactant (a lipid molecule) – Coats gas-exposed alveolar surfaces Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 13.6 Functional Anatomy of the Respiratory Membrane (Air-Blood Barrier) Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Respiratory Physiology Four events of respiration 1. Pulmonary ventilation—moving air into and out of the lungs (commonly called breathing) 2. External respiration—gas exchange between pulmonary blood and alveoli ▪ Oxygen is loaded into the blood ▪ Carbon dioxide is unloaded from the blood Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Respiratory Physiology 3. Respiratory gas transport—transport of oxygen and carbon dioxide via the bloodstream 4. Internal respiration—gas exchange between blood and tissue cells in systemic capillaries Movement of the gas is from an area of higher concentration toward an area of lower concentration Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Mechanics of Breathing Pulmonary ventilation – Mechanical process that depends on volume changes in the thoracic cavity – Volume changes lead to pressure changes, which lead to the flow of gases to equalize pressure Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Concept Link 2 Recall that pressure changes also drive other processes in the body, such as filtration (passive transport; Chapter 3, pp. 96–98) and blood flow (Chapter 11). In these processes, substances move from high to low pressure and achieve a specific function, such as membrane transport or circulation. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Mechanics of Breathing Two phases of pulmonary ventilation – Inspiration ▪ Flow of air into lungs – Expiration ▪ Air leaving lungs Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Mechanics of Breathing Inspiration (inhalation) – Diaphragm and external intercostal muscles contract which makes the thoracic cavity bigger, and the lungs expand. – The above causes Intrapulmonary volume to increase and the Gas pressure inside the lungs becomes less than the atmospheric pressure. – Thus Air flows into the lungs until intrapulmonary pressure equals atmospheric pressure Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 13.7a Rib Cage and Diaphragm Positions During Breathing Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Mechanics of Breathing Expiration (exhalation) – Passive process that depends on natural lung elasticity – Intrapulmonary volume decreases – Gas pressure increases – Gases passively flow out to equalize the pressure – Forced expiration can occur mostly by contraction of internal intercostal muscles to depress the rib cage Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Mechanics of Breathing Intrapleural pressure – The pressure within the pleural space is always negative (lower than pressure inside lungs) – Major factor preventing lung collapse – If intrapleural pressure equals atmospheric pressure, the lungs recoil and collapse Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Respiratory Volumes and Capacities Respiratory volumes and capacities are done to assess the respiratory system. Tidal volume (TV) – Normal quiet breathing – 500 ml of air is moved in/out of lungs with each breath. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Inspiratory reserve volume (IRV) =3,100 ml – Amount of air that can be taken in forcibly above the tidal volume. Expiratory reserve volume (ERV) = 1,200 ml – Amount of air that can be forcibly exhaled beyond tidal volume. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Residual volume (RV) =1,200 ml – Air remaining in lung after expiration – Cannot be voluntarily exhaled Vital capacity – The total amount of exchangeable air – Vital capacity = TV + IRV + ERV – 4,800ml in men; 3,100mliin women Total Lung Capacity = TV+IRV+ERV+RV = 6000 ml. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Respiratory Volumes and Capacities te Respiratory capacities are measured with a spirometer. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 13.9 Graph of the Various Respiratory Volumes in a Healthy Young Adult Male Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  External Respiration Oxygen is loaded into the blood – Oxygen diffuses from the oxygen-rich air of the alveoli to the oxygen-poor blood of the pulmonary capillaries. Carbon dioxide is unloaded out of the blood – Carbon dioxide diffuses from the blood of the pulmonary capillaries to the alveoli. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 13.11a The Loading and Unloading of Oxygen (O2 ) and Carbon Dioxide (CO2 ) in the Body O sub 2 C O sub 2 Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Gas Transport in the Blood Oxygen transport in the blood – Most oxygen travels attached to hemoglobin and forms oxyhemoglobin (HbO2 ) – A small dissolved amount is carried in the plasma Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Gas Transport in the Blood Carbon dioxide transport in the blood – Most carbon dioxide is transported in the plasma as bicarbonate ion (HCO3 − ) – A small amount is carried inside red blood cells on hemoglobin, but at different binding sites from those of oxygen Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Concept Link 3 Remember that blood pH should remain between 7.35 and 7.45 (Chapter 10, p. 354). Buffers, such as bicarbonate ion, minimize changes in pH in order to maintain homeostasis. Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Gas Transport in the Blood For carbon dioxide to diffuse out of blood into the alveoli, it must be released from its bicarbonate form: – Bicarbonate ions combine with hydrogen ions and form carbonic acid (H2CO3) – Carbonic acid splits to form water + CO2 – Carbon dioxide diffuses from blood into alveoli Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 13.11a The Loading and Unloading of Oxygen (O2 ) and Carbon Dioxide (CO2 ) in the Body O sub 2 C O sub 2 Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Internal Respiration Exchange of gases between blood and tissue cells An opposite reaction from what occurs in the lungs – Carbon dioxide diffuses out of tissue cells to blood (called loading) – Oxygen diffuses from blood into tissue (called unloading) Copyright © 2022 Pearson Education, Ltd. All Rights Reserved. Figure 13.11b The Loading and Unloading of Oxygen (O2 ) and Carbon Dioxide (CO2 ) in the Body O sub 2 C O sub 2 Copyright © 2022 Pearson Education, Ltd. All Rights Reserved.  Control of Respiration – Neural centers that control rate and depth of breathing are located in the medulla and pons Normal respiratory rate (eupnea) – 12 to 15 respirations per minute Hyperpnea – Increased respiratory rate, often due to extra oxygen needs. Hypopnea: Abnormally slow or shallow breathing. 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