Respiration Physiology PDF

Respiratory System © 2012 Pearson Education, Inc. Learning Objectives Describe the primary functions of the respiratory system. Describe the respiratory defense system. © 2012 Pearson Education, Inc. Six Functions of the Respiratory System 1. Provides extensive gas exchange surface are...

Respiratory System © 2012 Pearson Education, Inc. Learning Objectives Describe the primary functions of the respiratory system. Describe the respiratory defense system. © 2012 Pearson Education, Inc. Six Functions of the Respiratory System 1. Provides extensive gas exchange surface area between air and circulating blood 2. Moves air to and from exchange surfaces of lungs 3. Protects respiratory surfaces from outside environment – dehydration temperature changes and pathogens 4. Produces sounds – for speaking, singing & communiction 5. Participates in olfactory sense – detection of odours 6. Assists in the regulation of blood volume and pressure - converting angiotensin I to angiotensin II © 2012 Pearson Education, Inc. Learning Objectives Describe the respiratory defense system. © 2012 Pearson Education, Inc. The Respiratory Defense System Foreign particles and pathogens in inhaled air – damage to gas exchange surface Defense system - consists of a series of filtration mechanisms Removes particles and pathogens = prevents contamination © 2012 Pearson Education, Inc. Components of the Respiratory Defense System Mucous cells and mucous glands (lamina propria) – produce mucus that bathes exposed surfaces Nasal cavity a) cilia sweep mucus & trapped debris/microorganisms to the pharynx for swallowing – gastric enzymes & acids b) Filtration hairs in the nasal cavity removes large particles (>10 µm) Lower respiratory tract cilia also beat to sweep debris trapped in mucus mucus towards pharynx for swallowing - mucus escalator: Rate of mucus production depends on presence of unpleasant stimuli – dust, allergens or pathogens Alveolar macrophages engulf small particles that reach lungs © 2012 Pearson Education, Inc. The Respiratory Epithelium of the Nasal Cavity and Conducting System Movement of mucus to pharynx Ciliated columnar epithelial cell Mucous cell Stem cell Mucus layer Lamina propria A diagrammatic view of the respiratory epithelium of the trachea, indicating the direction of mucus transport inferior to © 2012 Pearson Education, Inc. the pharynx. The Respiratory Defense System © 2012 Pearson Education, Inc. Learning Objectives Describe the functions of the organs of the respiratory system © 2012 Pearson Education, Inc. The Nose, nasal cavity and paranasal sinuses The Nose A primary passageway for the entrance of air into the respiratory system Air enters the respiratory system - through a pair nostrils or external nares Nasal hairs - in the nasal vestibule and trap large airborne particles The Nasal Cavity The nasal septum - divides nasal cavity into left and right Superior portion of nasal cavity is the olfactory region Provides sense of smell (olfactory epithelium) Paranasal sinuses – produce mucous secretions © 2012 Pearson Education, Inc. Structures of the Upper Respiratory System Frontal sinus Nasal conchae Nasal cavity Superior Middle Internal nares Inferior Entrance to auditory tube Pharyngeal tonsil Nasal vestibule Pharynx External nares Hard palate Nasopharynx Oral cavity Oropharynx Laryngopharynx Tongue Soft palate Palatine tonsil Mandible Epiglottis Lingual tonsil Hyoid bone Glottis Vocal fold Thyroid cartilage Cricoid cartilage Trachea Esophagus Thyroid gland The nasal cavity and pharynx, as seen in sagittal section with the nasal septum removed © 2012 Pearson Education, Inc. The Pharynx or throat A chamber shared by digestive and respiratory systems Extends from internal nares to entrances to larynx and esophagus Divided into three parts: The Nasopharynx The Oropharynx The Laryngopharynx © 2012 Pearson Education, Inc. Respiration - Introduction to Gas Exchange Refers to two integrated processes 1. External respiration Includes all processes involved in exchanging O2 and CO2 with the environment 2. Internal respiration Result of cellular respiration Involves the uptake of O2 and production of CO2 within individual cells © 2012 Pearson Education, Inc.  Pulmonary ventilation (breathing) 1. Gas diffusion Across membranes and capillaries 2. Transport of O2 and CO2 Between alveolar capillaries Between capillary beds in other tissues © 2012 Pearson Education, Inc. An Overview of the Key Steps in Respiration Respiration External Respiration Internal Respiration Pulmonary ventilation O2 transport Tissues Gas Gas diffusion diffusion Lungs Gas Gas diffusion diffusion CO2 transport © 2012 Pearson Education, Inc. Pulmonary Ventilation Is the physical movement of air in and out of respiratory tract Provides alveolar ventilation The respiratory membrane is the air-blood barrier, where gases are exchanged. The larynx routes air and food into their proper channel and plays an important role in speech production. © 2012 Pearson Education, Inc. Learning Objectives Define the terms eupnea and hyperpnea and differentiate between the two. Describe the exact mechanisms by which ventilation occurs during eupnea. © 2012 Pearson Education, Inc. Eupnea and Hyperpnea Eupnea – also known as quiet breathing or resting respiratory rate. Hyperpnea - increased depth of breathing when required to meet metabolic demand of body tissues, such as during or following exercise. © 2012 Pearson Education, Inc. Pressure and Airflow to the Lungs Air flows from area of higher pressure to area of lower pressure A Respiratory Cycle Consists of: An inspiration (inhalation) An expiration (exhalation) © 2012 Pearson Education, Inc. Compliance An indicator of expandability Low compliance requires greater force High compliance requires less force Factors That Affect Compliance Connective tissue structure of the lungs Level of surfactant production Mobility of the thoracic cage © 2012 Pearson Education, Inc. Injury to chest wall Injury to the chest wall causes: Pneumothorax allows air into pleural cavity Atelectasis (also called a collapsed lung) is a result of pneumothorax © 2012 Pearson Education, Inc. Learning Objectives List the muscles responsible for respiratory movements and describe the role of each © 2012 Pearson Education, Inc. The Respiratory Muscles Most important are: The diaphragm External intercostal muscles of the ribs Accessory respiratory muscles - activated when respiration increases significantly The Mechanics of Breathing Inhalation - always active Exhalation - active or passive © 2012 Pearson Education, Inc. Muscles Used in Inhalation Diaphragm Contraction draws air into lungs 75% of normal air movement External intercostal muscles Assist inhalation 25% of normal air movement Accessory muscles assist in elevating ribs Sternocleidomastoid Serratus anterior Pectoralis minor Scalene muscles © 2012 Pearson Education, Inc. Muscles Used in Exhalation Internal intercostal and transversus thoracis muscles Depress the ribs Abdominal muscles Compress the abdomen Force diaphragm upward © 2012 Pearson Education, Inc.  Five Reasons for Efficiency of Gas Exchange 1. Substantial differences in partial pressure across the respiratory membrane 2. Distances involved in gas exchange are short 3. O2 and CO2 are lipid soluble 4. Total surface area is large 5. Blood flow and airflow are coordinated © 2012 Pearson Education, Inc.  Partial Pressures in Alveolar Air and Alveolar Capillaries Blood arriving in pulmonary arteries has: Low PO 2 High PCO 2 The concentration gradient causes: O2 to enter blood CO2 to leave blood Rapid exchange allows blood and alveolar air to reach equilibrium © 2012 Pearson Education, Inc. An Overview of Respiratory Processes and Partial Pressures in Respiration External Respiration Systemic Pulmonary PO2 = 40 Alveolus circuit circuit PCO2 = 45 Respiratory membrane PO2 = 100 PCO2 = 40 Pulmonary PO2 = 100 capillary PCO2 = 40 Systemic circuit © 2012 Pearson Education, Inc.  Respiratory centres Medulla oblongata respiratory rhythmicity centres set the pace of respiration Pons: apneustic centre and pneumotaxic centre adjust output of medullary centres They regulate the rate & depth of respiration in response to sensory stimuli or input from other brain centres © 2012 Pearson Education, Inc.  References Fundamentals of Human Anatomy and Physiology, by F.H. Martini. 9th Ed. Benjamin Cummings Publishing. Human Physiology, An Integrated Approach by D. Silverthorn. 3rd Ed. Benjamin Cummings. Human Physiology and Mechanisms of Disease, by A.C. Guyton and J.E. Hall. 6th Edition. W.B. Saunders. © 2012 Pearson Education, Inc.