The Respiratory System Chapter 17 The Respiratory System

Anatomy of the Respiratory System and Upper Respiratory Disorders Lesson 17.1 Anatomy of the Respiratory System and Upper Respiratory Disorders Discuss the generalized functions of the respiratory system, list the major organs of the respiratory system and describe the function of each, and describe the major disorders of the upper respiratory tract.

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

Structural Plan of the Respiratory Organs

The Gas-Exchange Structures of the Lung

Respiratory Tracts Upper respiratory tract—nose, pharynx, and larynx Lower respiratory tract—trachea, bronchial tree, and lungs

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

Respiratory Mucosa Lining the Trachea

Nose Structure Nasal septum separates interior of nose into two cavities Mucous membrane lines nose Frontal, maxillary, sphenoidal, and ethmoidal sinuses drain into nose Nasal polyps—noncancerous growths that project from nasal mucosa (associated with chronic hay fever)

The Paranasal Sinuses The paranasal sinuses and the lacrimal sacs drain into the nasal cavity

Functions of the Nose Warms and moistens inhaled air Contains sense organs of smell

Structure of the Pharynx Pharynx (throat) 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

Structure of the Pharynx, Cont'd. Pharyngeal tonsils and openings of auditory tubes open into nasopharynx; other tonsils found in oropharynx Mucous membrane lines pharynx

Sagittal Section of the Head and Neck

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

Tonsillitis

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

The Larynx

Functions of the Larynx Air distribution; passageway for air to move to and from lungs Voice production

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

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

Laryngitis Inflammation of the larynx resulting from infection or irritation Epiglottitis—life-threatening condition caused by Haemophilus influenzae type B (Hib) infection Croup—not life-threatening type of laryngitis caused by parainfluenza viruses producing a barking cough

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

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

Cross Section of the Trachea

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 The Heimlich 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

A tracheostomy tube in place What structure is posterior to the trachea? 27

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

Alveoli

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 in the alveoli produce surfactant to help reduce surface tension or "stickiness"

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

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

Lungs

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

Lungs and Pleura

Lungs and Pleura 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

Pneumothorax

Respiration, Gas Exchange & Lower Respiratory Tract Disorders Lesson 17.2 Respiration, Gas Exchange & Lower Respiratory Tract Disorders Compare, contrast, and explain the mechanism responsible for the exchange of gases that occurs during internal and external respiration. Describe the transport of gasses by blood, and list and discuss the volumes of air exchanged during pulmonary ventilation. Identify and discuss the mechanisms that regulate respiration, and identify breathing patterns. Identify and describe the major disorders of the lower respiratory tract.

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

Mechanics of Breathing

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

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

Expiration 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

Exchange of Gases in Lungs Oxygen moves from alveoli into lung capillaries Hemoglobin combines with oxygen, producing oxyhemoglobin 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

Exchange of Gases in Lungs & Tissue Capillaries

Exchange of Gases in Tissues 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

Blood Transportation of Gases 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) in plasma—10% Carbaminohemoglobin (HbCO2)—20% Dissolved in blood fluids and converted to Bicarbonate ions (HCO3−)—70% H2O + CO2 <-> H2CO3 <-> H + HCO3- Water carbon dioxide carbonic acid hydrogen bicarbonate

The Process of Respiration Gas Exchange Requires a pressure gradient External respiration (exchange)—between lung alveoli and capillary blood Oxygen leaves alveoli and enters capillaries. Carbon dioxide leaves capillaries and enters alveoli. Internal respiration (exchange)—between blood and tissues Oxygen leaves capillaries and enters tissue. Carbon dioxide leaves tissue and enters capillaries.

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

Volumes of Air Exchanged in Pulmonary Ventilation, Cont'd. Expiratory reserve volume (ERV)—amount of air that can be forcibly exhaled after expiring the tidal volume 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

Pulmonary Ventilation Volumes

Regulation of Respiration Regulation of respiration 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) The two most important control centers for regulating breathing rhythm in the medulla are ventral respiratory group (VRG) for basic breathing patterns dorsal respiratory group (DRG) adjusting breathing with an increase in RR with increase in PH

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

Regulation of Respiration

Regulation of Respiration, Cont'd. 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 over inflation

Regulation of Respiration (cont.) Breathing Patterns Measured in breaths per minute Adults: 12 to 20 Children: 20 to 40 Infants: more than 40

Breathing Patterns Eupnea—normal breathing Hyperventilation (Tachypnea) —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

Breathing Patterns, Cont'd. Apnea—stopped respiration Cheyne-Stokes respiration (CSR)—cycles of alternating apnea and hyperventilation associated with critical conditions Kussmaul respiration— deep rapid respirations seen with acidosis (DKA) Respiratory arrest—failure to resume breathing after a period of apnea

Regulation of Respiration (cont.) Abnormal Ventilation Hyperventilation High oxygen level and low CO2 level (hypocapnia) Increases blood pH (alkalosis) Hypoventilation Insufficient air in alveoli Decreases blood pH (acidosis) Results of hypoventilation: Cyanosis Hypoxia Hypoxemia

Respiratory Disorders (cont.) Infection Common cold Respiratory syncytial virus (RSV) Croup Influenza Pneumonia Lobar pneumonia Bronchopneumonia Pneumocystis pneumonia Tuberculosis

Pneumonia 61

Respiratory Disorders (cont.) Sudden Infant Death Syndrome (SIDS) Also called crib death Unexplained death Seemingly healthy infant Under 1-year-old Usually occurs in sleep

Respiratory Disorders (cont.) Allergic Rhinitis (Hay Fever) Hypersensitivity to allergens Watery discharge from eyes and nose Seasonal or chronic Asthma Inflammation of airway tissues Spasm in bronchial tubes May be related to hypersensitivity to allergens

Respiratory Disorders (cont.) Chronic Obstructive Pulmonary Disease (COPD) Includes both chronic bronchitis and emphysema Normal air flow obstructed Reduced exchange of oxygen and carbon dioxide Air trapping and overinflation of lungs Dyspnea

Respiratory Disorders (cont.) Cancer Lung cancer Most common cause of cancer-related deaths. Most important cause is cigarette smoking. Cancer of larynx Linked to cigarette smoking and alcohol consumption High cure rate

Bronchogenic carcinoma. 67