Respiratory System Chapter 17 PDF

Structural Plan   Basic plan of respiratory system would be similar to an inverted tree if it were hollow; leaves of the tree would be comparable to alveoli, with the microscopic sacs enclosed by networks of capillaries Diffusion is the mode for gas exchange that occurs in the respiratory mechan...

Structural Plan   Basic plan of respiratory system would be similar to an inverted tree if it were hollow; leaves of the tree would be comparable to alveoli, with the microscopic sacs enclosed by networks of capillaries Diffusion is the mode for gas exchange that occurs in the respiratory mechanism Copyright © 2017, Elsevier Inc. All Rights Reserved. 3 Respiratory Tracts  Upper respiratory tract ➢ ➢ ➢  Nose Pharynx Larynx Lower respiratory tract ➢ ➢ ➢ Trachea Bronchial tree Lungs Copyright © 2017, Elsevier Inc. All Rights Reserved. 5 Respiratory Mucosa     Mucous membrane that lines the air distribution tubes in the respiratory tree More than 125 mL of mucus produced each day forms a “mucus blanket” over much of the respiratory mucosa Mucus serves as an air purification mechanism by trapping inspired irritants such as dust and pollen Cilia on mucosal cells beat in only one direction, moving mucus upward to pharynx for removal Copyright © 2017, Elsevier Inc. All Rights Reserved. 6 Nose  Structure ➢ ➢ ➢ ➢ Nasal septum separates interior of nose into two cavities Mucous membrane lines nose Nasal polyps: Noncancerous growths that project from nasal mucosa (associated with chronic hay fever) Frontal, maxillary, sphenoidal, and ethmoidal sinuses drain into nose Copyright © 2017, Elsevier Inc. All Rights Reserved. 8 Functions of the Nose   Warms and moistens inhaled air Contains sense organs of smell Copyright © 2017, Elsevier Inc. All Rights Reserved. 10 Structure of the Pharynx    Pharynx (throat) is about 12.5 cm (5 inches) long Divided into nasopharynx, oropharynx, and laryngopharynx Two nasal cavities, mouth, esophagus, larynx, and auditory tubes all have openings into pharynx Copyright © 2017, Elsevier Inc. All Rights Reserved. 11 Structure of the Pharynx (Cont.)   Pharyngeal tonsils and openings of auditory tubes open into nasopharynx; other tonsils found in oropharynx Mucous membrane lines pharynx Copyright © 2017, Elsevier Inc. All Rights Reserved. 12 Functions of the Pharynx    Passageway for food and liquids Air distribution; passageway for air Tonsils: Masses of lymphoid tissue embedded in pharynx provide immune protection Copyright © 2017, Elsevier Inc. All Rights Reserved. 14 Structure of the Larynx   Located just below pharynx; also referred to as the voice box Several pieces of cartilage form framework ➢ ➢   Thyroid cartilage (Adam’s apple) is largest Epiglottis partially covers opening into larynx Mucous lining Vocal cords stretch across interior of larynx; space between cords is the glottis Copyright © 2017, Elsevier Inc. All Rights Reserved. 16 Functions of the Larynx   Air distribution; passageway for air to move to and from lungs Voice production Copyright © 2017, Elsevier Inc. All Rights Reserved. 18 Laryngeal Cancer    Incidence increases with age and alcohol abuse Occurs most often in men over age 50 If larynx removed, “esophageal speech” or electric artificial larynx needed for speech Copyright © 2017, Elsevier Inc. All Rights Reserved. 19 Upper Respiratory Infections (URIs)  Rhinitis: Nasal inflammation, as in a cold, influenza, or allergy ➢ ➢  Infectious rhinitis—common cold Allergic rhinitis—hay fever Pharyngitis (sore throat): Inflammation or infection of the pharynx Copyright © 2017, Elsevier Inc. All Rights Reserved. 20 Laryngitis  Inflammation of the larynx resulting from infection or irritation ➢ ➢ Epiglottitis: Life-threatening condition caused by Haemophilus influenzae type B (Hib) infection Croup: Non–life-threatening type of laryngitis caused by parainfluenza viruses producing a barking cough Copyright © 2017, Elsevier Inc. All Rights Reserved. 21 Anatomical Disorders   Deviated septum: Septum that is abnormally far from the midsagittal plane (congenital or acquired) Epistaxis (bloody nose) can result from mechanical injuries to the nose, hypertension, or other factors Copyright © 2017, Elsevier Inc. All Rights Reserved. 22 Trachea  Structure ➢ ➢ ➢  Tube (windpipe) about 11 cm (4.5 inches) long that extends from larynx into the thoracic cavity Mucous lining C-shaped rings of cartilage hold trachea open Function: Passageway for air to move to and from lungs Copyright © 2017, Elsevier Inc. All Rights Reserved. 23 Obstruction of the Trachea     Blockage of trachea occludes the airway, and if complete, causes death in minutes Tracheal obstruction causes more than 4000 deaths annually in the United States Abdominal thrust maneuver is a lifesaving technique used to free the trachea of obstructions; also called abdominal thrusts Tracheostomy—surgical procedure in which a tube is inserted into an incision in the trachea so that a person with a blocked airway can breathe Copyright © 2017, Elsevier Inc. All Rights Reserved. 25 Structure of the Bronchi, Bronchioles, and Alveoli  Trachea branches into right and left bronchi ➢ ➢   Right primary bronchus more vertical than left Aspirated objects most often lodge in right primary bronchus or right lung Each bronchus branches into smaller and smaller tubes (secondary bronchi), eventually leading to bronchioles Bronchioles end in clusters of microscopic alveolar sacs, the walls of which are made up of alveoli Copyright © 2017, Elsevier Inc. All Rights Reserved. 26 Functions of Bronchi, Bronchioles, and Alveoli   Bronchi and bronchioles: Air distribution; passageway for air to move to and from alveoli Alveoli: Exchange of gases between air and blood ➢ Type II cells produce surfactant to help reduce surface tension or "stickiness" Copyright © 2017, Elsevier Inc. All Rights Reserved. 28 Respiratory Distress  Relative inability to inflate the alveoli ➢ ➢ Infant respiratory distress syndrome (IRDS): Leading cause of death in premature infants, resulting from lack of surfactant production in alveoli Adult respiratory distress syndrome (ARDS): Impairment of surfactant by inhalation of foreign substances or other conditions Copyright © 2017, Elsevier Inc. All Rights Reserved. 30 Structure of the Lungs    Size: Large enough to fill the chest cavity, except for middle space occupied by heart and large blood vessels Apex: Narrow upper part of each lung, under collarbone Base: Broad lower part of each lung; rests on diaphragm Copyright © 2017, Elsevier Inc. All Rights Reserved. 31 Structure of the Pleura  Moist, smooth, slippery membrane that lines chest cavity and covers outer surface of lungs; reduces friction between the lungs and chest wall during breathing Copyright © 2017, Elsevier Inc. All Rights Reserved. 33 Lungs and Pleura (Cont.)    Function: Breathing (pulmonary ventilation) Pleurisy: Inflammation of the pleura Atelectasis: Incomplete expansion or collapse of the lung (alveoli); can be caused by: ➢ ➢ Pneumothorax: Presence of air in the pleural space Hemothorax: Presence of blood in the pleural space Copyright © 2017, Elsevier Inc. All Rights Reserved. 35 Disorders of the Lower Respiratory Tract      Acute bronchitis Pneumonia Tuberculosis Restrictive pulmonary disorders Obstructive pulmonary disorders ➢ ➢ ➢ ➢  COPD Chronic bronchitis Emphysema Asthma Lung cancer Copyright © 2017, Elsevier Inc. All Rights Reserved. 37 Respiration  Mechanics of breathing ➢ ➢ ➢ Pulmonary ventilation includes two phases called inspiration (movement of air into lungs) and expiration (movement of air out of lungs) Changes in size and shape of thorax cause changes in air pressure within that cavity and in the lungs because as volume changes, pressure changes in the opposite direction Air moves into or out of lungs because of pressure differences (pressure gradient); air moves from high air pressure toward low air pressure Copyright © 2017, Elsevier Inc. All Rights Reserved. 38 Learning Objectives Lesson 17.2: Respiration, Gas Exchange, and Lower Respiratory Tract Disorders 4. 5. 6. 7. Discuss respiration and pulmonary ventilation, including the mechanics of breathing and pulmonary volumes. Describe the regulation of ventilation, and identify breathing patterns. Compare, contrast, and explain the mechanism responsible for the exchange of gases that occurs during external and internal respiration. Describe the transport of gases by blood. Copyright © 2017, Elsevier Inc. All Rights Reserved. 39 Inspiration   Active process: Muscles increase volume of thorax, decreasing lung pressure, which causes air to move from atmosphere into lungs (down the pressure gradient) Inspiratory muscles include diaphragm and external intercostals ➢ ➢ Diaphragm flattens during inspiration: Increases top-to-bottom length of thorax External intercostals: Contraction elevates the ribs and increases the size of the thorax from front to back and from side to side Copyright © 2017, Elsevier Inc. All Rights Reserved. 42 Expiration     Reduction in the size of the thoracic cavity decreases its volume and thus increases its pressure, so air moves down the pressure gradient and leaves the lungs Quiet expiration ordinarily a passive process During expiration, thorax returns to its resting size and shape Elastic recoil of lung tissues aids in expiration Copyright © 2017, Elsevier Inc. All Rights Reserved. 43 Expiration (Cont.)  Expiratory muscles used in forceful expiration are internal intercostals and abdominal muscles ➢ ➢ Internal intercostals: Contraction depresses the rib cage and decreases the size of the thorax from front to back Abdominal muscles: Contraction elevates the diaphragm, thus decreasing size of the thoracic cavity from top to bottom Copyright © 2017, Elsevier Inc. All Rights Reserved. 44 Volumes of Air Exchanged in Pulmonary Ventilation     Volumes of air exchanged in breathing can be measured with a spirometer Tidal volume (TV): Amount normally breathed in or out with each breath Vital capacity (VC): Largest amount of air that one can breathe out in one expiration Expiratory reserve volume (ERV): Amount of air that can be forcibly exhaled after expiring the tidal volume Copyright © 2017, Elsevier Inc. All Rights Reserved. 45 Volumes of Air Exchanged in Pulmonary Ventilation (Cont.)   Inspiratory reserve volume (IRV): Amount of air that can be forcibly inhaled after a normal inspiration Residual volume (RV): Air that remains in the lungs after the most forceful expiration Copyright © 2017, Elsevier Inc. All Rights Reserved. 47 Regulation of Ventilation   Regulation of ventilation permits the body to adjust to varying demands for oxygen supply and carbon dioxide removal Brainstem: Central regulatory centers are called respiratory control centers (inspiratory and expiratory centers) ➢ Medullary centers: Under resting conditions the medullary rhythmicity area produces a normal rate and depth of respirations (12 to 18 per minute) Copyright © 2017, Elsevier Inc. All Rights Reserved. 48 Central Regulatory Centers   Pontine centers: As conditions in the body vary, these centers in the pons can alter the activity of the medullary rhythmicity area, thus adjusting breathing rhythm Brainstem centers are influenced by information from other parts of the brain and from sensory receptors located in other body areas Copyright © 2017, Elsevier Inc. All Rights Reserved. 49 Regulation of Respiration   Cerebral cortex: Voluntary (but limited) control of respiratory activity Receptors influencing respiration ➢ ➢ Chemoreceptors: Respond to changes in carbon dioxide, oxygen, and blood acid levels; located in carotid and aortic bodies Pulmonary stretch receptors: Respond to the stretch in lungs, thus protecting respiratory organs from overinflation Copyright © 2017, Elsevier Inc. All Rights Reserved. 50 Breathing Patterns      Eupnea: Normal breathing Hyperventilation: Rapid and deep respirations Hypoventilation: Slow and shallow respirations Dyspnea: Labored or difficult respirations Orthopnea: Dyspnea relieved by moving into an upright or sitting position Copyright © 2017, Elsevier Inc. All Rights Reserved. 52 Breathing Patterns (Cont.)    Apnea: Stopped respiration Cheyne-Stokes respiration (CSR): Cycles of alternating apnea and hyperventilation associated with critical conditions Respiratory arrest: Failure to resume breathing after a period of apnea Copyright © 2017, Elsevier Inc. All Rights Reserved. 53 Pulmonary Gas Exchange     Carbaminohemoglobin breaks down into carbon dioxide and hemoglobin Carbon dioxide moves out of lung capillary blood into alveolar air and out of body in expired air Oxygen moves from alveoli into lung capillaries Hemoglobin combines with oxygen, producing oxyhemoglobin Copyright © 2017, Elsevier Inc. All Rights Reserved. 54 Blood Transportation of Gases     Oxyhemoglobin breaks down into oxygen and hemoglobin Oxygen moves out of tissue capillary blood into tissue cells Carbon dioxide moves from tissue cells into tissue capillary blood Hemoglobin combines with carbon dioxide, forming carbaminohemoglobin Copyright © 2017, Elsevier Inc. All Rights Reserved. 56 Blood Transportation of Gases (Cont.)  Transport of oxygen ➢ ➢  Only small amounts of oxygen (O2) can be dissolved in blood Most oxygen combines with hemoglobin to form oxyhemoglobin (HbO2) to be carried in blood Transport of carbon dioxide ➢ ➢ ➢ Dissolved carbon dioxide (CO2): 10% Carbaminohemoglobin (HbCO2): 20% Bicarbonate ions (HCO3−): 70% Copyright © 2017, Elsevier Inc. All Rights Reserved. 57