HHP:1100 Human Anatomy - Chapter 25 - B - Lower Respiratory Tract Lecture Notes PDF

HHP:1100 HUMAN ANATOMY The Respiratory System: Pulmonary Ventilation through the Bronchial Tree  HHP:1100 Lecture Overview Human Anatomy 1. Lower Respiratory Tract 2. Gross Anatomy of the Lungs 3. Pulmonary Ventilation 4. Respirat...

HHP:1100 HUMAN ANATOMY The Respiratory System: Pulmonary Ventilation through the Bronchial Tree  HHP:1100 Lecture Overview Human Anatomy 1. Lower Respiratory Tract 2. Gross Anatomy of the Lungs 3. Pulmonary Ventilation 4. Respiratory System Disorders 2  1. Lower Respiratory Tract HHP:1100 Human Anatomy Review Lower respiratory tract contains conducting portions and respiratory portions – Larynx, trachea, bronchi, bronchioles, terminal bronchioles ▪ No gas exchange – Respiratory bronchioles, alveolar ducts, and alveoli ▪ Site of respiration 3  1. Lower Respiratory Tract HHP:1100 Human Anatomy Bronchial Tree Trachea splits into right and left main (primary) bronchi Continued splitting leads to progressively smaller tubes that eventually are less than 1 mm in diameter – bronchioles 4  1. Lower Respiratory Tract HHP:1100 Human Anatomy Bronchial Tree Bronchiole walls do not contain cartilage but have a relatively thick layer of smooth muscle – Controls bronchoconstriction, bronchodilation Final segment of conducting pathway consists of terminal bronchioles 5  1. Lower Respiratory Tract HHP:1100 Human Anatomy Respiratory Portion Terminal bronchioles Respiratory bronchioles Alveolar ducts Alveolar sac Small, saccular outpocketings = alveoli – Site of gas (oxygen and carbon dioxide) diffuse between pulmonary capillary blood, air in the lungs 6  1. Lower Respiratory Tract HHP:1100 Human Anatomy Alveoli Alveolar wall is mainly formed from two types of cells: – Alveolar type I cells: ▪ Simple squamous epithelial → rapid gas diffusion – Alveolar type II cells ▪ Almost cuboidal in shape ▪ Produce pulmonary surfactant: ↓surface tension within alveolus and 7 prevents its collapse  1. Lower Respiratory Tract HHP:1100 Human Anatomy Alveoli ▪ In premature babies, the surfactant- producing cells are underdeveloped, which can cause the alveoli to collapse – This causes IRDS (Infant Respiratory Distress Syndrome), which is the leading cause of death of premature babies in the U.S. 8  1. Lower Respiratory Tract HHP:1100 Human Anatomy Alveoli Respiratory membrane is the thin wall between alveolar lumen and the blood across which gases diffuse 1. Plasma membrane of the type I alveolar cell 2. Plasma membrane of the capillary cell 9  HHP:1100 Summary: Upper, Lower Respiratory Tracts Human Anatomy 10  2. Gross Anatomy of the Lungs HHP:1100 Human Anatomy Pleura and Pleural Cavities Review: outside of lung and inside of thoracic wall are lined by pleura – Visceral pleura – Parietal pleura – Space between = pleural cavity ▪ Pleural fluid 11  HHP:1100 2. Gross Anatomy of the Lungs Human Anatomy Each lung is conical in shape – base – apex Costal surface Mediastinal surface – hilum – Root of lung enters at hilum ▪ Bronchi, pulmonary vessels, lymphatic vessels, nerves 12  2. Gross Anatomy of the Lungs HHP:1100 Human Anatomy Left Lung Unique Structures – Left Lung: – Slightly smaller than right lung to accommodate heart – Cardiac notch – Oblique fissure that divides the lung into superior, inferior lobes 13  2. Gross Anatomy of the Lungs HHP:1100 Human Anatomy Right Lung Unique Structures – Right Lung: – Oblique and horizontal fissures that divide it into superior, middle, and inferior lobes 14  2. Gross Anatomy of the Lungs HHP:1100 Human Anatomy Bronchopulmonary Segments 10 bronchopulmonary segments in right lung, 8–10 in left lung – Each segment supplied by its own tertiary bronchus and a branch of a pulmonary artery and vein Each segment is surrounded by and isolated from other segments by connective tissue 15  HHP:1100 3. Pulmonary Ventilation Human Anatomy Pulmonary ventilation (“breathing,”) is the movement of air into and out of the respiratory system structures Gas exchange involves four simultaneous processes 1. Pulmonary ventilation 2. Alveolar gas exchange ▪ External respiration exchanges gases between atmosphere and blood 3. Gas transport within the blood 4. Systemic gas exchange (between blood and body cells) ▪ Internal respiration exchanges gases between blood and body’s cells 16  3. Pulmonary Ventilation HHP:1100 Human Anatomy Mechanics of Breathing Movement of gases follows Boyle’s law – Volume and pressure inversely related Inhalation – ↑ thoracic cavity volume → ↓ intrapulmonary pressure → air flows into the lungs Exhalation: the opposite occurs ↓ thoracic cavity volume → ↑ intrapulmonary pressure → air flows out of the lungs 17  3. Pulmonary Ventilation HHP:1100 Human Anatomy Mechanics of Breathing During inhalation and exhalation, the thoracic cavity changes in all three dimensions – Vertical changes result from diaphragm movement – Lateral changes result from the rib cage elevation or depression – Anterior-posterior changes occur as the sternum moves anteriorly or posteriorly 18  3. Pulmonary Ventilation HHP:1100 Human Anatomy Skeletal Muscles of Breathing Classified as muscles of quiet breathing, forced inhalation, and forced exhalation 1. Quiet breathing: inhalation and exhalation, respectively ▪ Diaphragm, external intercostals 19  3. Pulmonary Ventilation HHP:1100 Human Anatomy Skeletal Muscles of Breathing 2. Forced inhalation: allows deeper inspirations by increasing thoracic cavity expansion when they contract – Sternocleidomastoid, scalenes, pectoralis minor, serratus posterior superior, and erector spinae 20  3. Pulmonary Ventilation HHP:1100 Human Anatomy Skeletal Muscles of Breathing 3. Forced exhalation: contract during hard exhalations (e.g., coughs) and work to decrease thoracic volume – Internal intercostals, abdominal muscles, transversus thoracis, and serratus posterior inferior 21  3. Pulmonary Ventilation HHP:1100 Human Anatomy Types of breathing Eupnea - – Costal breathing – – Diaphragmatic breathing – Hyperpnea – 22  3. Pulmonary Ventilation HHP:1100 Human Anatomy Lung capacities Used to measure respiratory function 23  3. Pulmonary Ventilation HHP:1100 Human Anatomy Lung capacities Tidal volume (TV) – Vital capacity (VC) – 24  3. Pulmonary Ventilation HHP:1100 Human Anatomy Lung capacities Inspiratory Reserve Volume (IRV) – Expiratory Reserve Volume (ERV) – 25  3. Pulmonary Ventilation HHP:1100 Human Anatomy Lung capacities Residual Volume (RV) – Total Lung Capacity – 26  4. Respiratory System Disorders HHP:1100 Human Anatomy Smoking Mucous covers the epithelium of the respiratory system: eliminates dust and pollen, traps particles, etc. to purify inhaled air Tobacco smoke irritates epithelial cells, destroys macrophages – Toxins reach alveoli – Frequent coughing is attempt to clean itself Of all cases of lung cancer, 90% are caused by smoking – ~500,000 deaths/year Life expectancy of a smoker is 13-14 years less than that of a nonsmoker Nonsmokers exposed to cigarette smoke are at risk, and children exposed to cigarette smoke have an increased rate of asthma, bronchitis, and 27 pneumonia  4. Respiratory System Disorders HHP:1100 Human Anatomy Common Cold Caused by a virus that enters the cells of the upper respiratory tract – >150 cold viruses – Spreads by mucous droplets containing the virus Symptoms – nasal stuffiness, scratchy throat, headache, sneezing, and coughing – “Upper respiratory tract infection” Usually occurs in winter because people are confined and are in 28 close contact with one another  4. Respiratory System Disorders HHP:1100 Human Anatomy Pneumonia Can be bacterial or viral Fluid builds up in the alveoli Can cause death 29  4. Respiratory System Disorders HHP:1100 Human Anatomy Bronchitis Viral or bacterial infection Acute – usually bacterial, responds to antibiotics Symptoms – heavy mucous discharge, persistent cough Chronic – caused by infection or the environment (ex. smoking) 30  4. Respiratory System Disorders HHP:1100 Human Anatomy Asthma Compromised airflow during “attacks” due to inflammation, mucous secretion, and bronchoconstriction. Symptoms – wheezing, shortness of breath Causes – exercise, allergens (hyper-responsiveness) Treatment – inhalers (bronchodilators and/or 31 steroid)  4. Respiratory System Disorders HHP:1100 Human Anatomy Emphysema A disease characterized by the alveoli becoming brittle and eventually rupturing 32  4. Respiratory System Disorders HHP:1100 Human Anatomy Pulmonary Fibrosis Environmental particles (contaminants) are inhaled Causes: asbestos, silica, coal dust Causes cells in the lungs to form fibrous CT, making the lungs less elastic and therefore less efficient 33  HHP:1100 Learning Outcomes Human Anatomy You Should Be Able To … 1. define the following terms associated with general functions of the respiratory system: inhalation (inspiration), exhalation (expiration), external respiration, internal respiration 2. list, in order, the respiratory structures that air passes through during inhalation and exhalation 3. compare and contrast the main anatomical differences between the trachea, bronchi, and bronchioles 4. identify and describe the gross anatomic features of the bronchial tree, including: main (primary) bronchi, bronchioles, terminal bronchioles, respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli 34  HHP:1100 Learning Outcomes Human Anatomy You Should Be Able To … 5. identify the structural components of the respiratory membrane and explain its function 6. identify and describe the gross anatomy of the pleura and lungs including: visceral pleura, parietal pleura, pleural cavity, pleural (serous) fluid, lung fissures, lobes of the right and left lungs 7. describe the changes in thoracic volume and pressure associated with pulmonary ventilation (quiet breathing, forced inhalation, forced exhalation), eupnea, hyperpnea 8. Understand the various physiological measures of lung function 9. explain how the clinical disorders included in this set of lecture slides influence respiratory system structures and functions 35