Anatomy and Physiology
Anatomy and Physiology BIOH 113 - 01
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BIOH 112 - 01
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This 7 page Class Notes was uploaded by Meaghan Raw on Monday March 28, 2016. The Class Notes belongs to BIOH 113 - 01 at University of Montana taught by Heather Dawn Labbe (P) in Spring 2016. Since its upload, it has received 9 views. For similar materials see Human Form and Function II in Biological Sciences at University of Montana.
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Date Created: 03/28/16
BIOH 113 Chapter 22: The Respiratory System - The respiratory system acts with the cardiovascular system to bring oxygen to the body and removes carbon dioxide from the body Major Functions: - To supply the body with oxygen and dispose of carbon dioxide - Respiration: o Pulmonary ventilation- air moving into and out of the lungs o External respiration- gas exchange between the lungs and blood o Transport- transport of oxygen and carbon dioxide between the lungs and tissues o Internal respiration- gas exchange between systemic blood vessels and tissues Classification: - Structural o Upper respiratory o Lower respiratory - Functional o Conducting zone o Respiratory zone Structures: - Upper respiratory o All structures above the vocal chords o Mouth, nose, nasal cavity, pharynx, and larynx - Lower respiratory o Trachea, bronchi, bronchioles, lungs Functions: - Respiratory zone o Site of gas exchange o Consists of bronchioles, alveolar ducts, and alveoli - Conducting zone o Provides rigid conduits for air to reach the sites of gas exchange o Includes the nose, nasal cavity, pharynx, and the trachea Important transitions within the airways as they get smaller: - Cartilage support structures change - Epithelium types change - Amount f smooth muscle increases Nose and Nasal Cavity: Nose: - The only externally visible part of the respiratory system - Functions: o Provides an airway for respiration o Moistens and warms entering air o Filters air clearing it of debris o Houses olfactory receptors Nasal Cavity: - Lies in and posterior to the externa nose - Divided by a midline septum - Opens posteriorly into the nasopharynx via internal nares - Cranial bones form the roof - The floor is composed of hard and soft palates - Superior, medial, and inferior conchae o Protrude medially from lateral walls o Increase mucosal area o Enhance air turbulence and help to filter air - Respiratory mucosa: o Lines balance of the nasal cavity o Glands secrete mucus containing lysozyme and defensins to help destroy bacteria - Inspired air: o Humidified by the high water content in the nasal cavity o Warmed by rich plexuses of capillaries Paranasal Sinuses: - Sinuses in bones that surround the nasal cavity - Sinuses lighten the skull and help to warm and moisten the air Pharynx: - Funnel shaped tube of skeletal muscle that connects to the: o Nasal cavity and mouth superiorly o Larynx and esophagus inferiorly - Divided into three regions: o Nasopharynx o Oropharynx o Laryngopharynx Nasopharynx: - Lies posterior to the nasal cavity, inferior to the sphenoid, and superior to the level of the soft palate - Strictly an air passageway - Pseudostratified columnar epithelium - Closes during swallowing - Pharyngeal tonsils lie high on the posterior wall - Pharyngotympanic (auditory) tubes open into the lateral walls Oropharynx: - Extends inferiorly from the level of the soft palate to the epiglottis - Serves as a common passageway for food and air - Stratified squamous epithelium - Palatine tonsils lie in the lateral walls - Lingual tonsil covers the base of the tongue Laryngopharynx: - Serves as a common passageway for food and air - Lies posterior to the upright epiglottis - Extends to the larynx, where respiratory and digestive pathways diverge - Stratified squamous epithelium Larynx: - Voice box - Attaches to the hyoid bone and pens into the laryngopharynx superiorly - Continuous with the trachea posteriorly - Three functions: o Provide a patent airway o Act as a switching mechanism to route air and food into the proper channels o Functions in voice production Structure and Function: - 9 cartilage types - Vestibular folds- play no part in the voice; help to close the glottis - Vocal folds- vibrate as air goes by Vocal Production: - Speech: intermittent release of expired air while opening and closing the glottis - Pitch: determined by the length and tension of the vocal chords - Loudness: depends on the force at which the air rushes across the vocal chords - The pharynx resonates, amplifies, and enhances sound quality - Sound is shaped into language by the action of the pharynx, tongue, soft palate, and lips Trachea: - Flexible and mobile tube extending from the larynx into the mediastinum - Composed of three layers o Mucosa- made up of goblet cells and ciliated epithelium o Submucosa- connective tissue deep to the mucosa o Adventitia- outermost layer made of C-shaped rings of hyaline cartilage Bronchi: - The carina of the last tracheal cartilage marks the end f the trachea and the beginning of the right and left bronchi - Air reaching the bronchi is saturated with water vapor and warm and cleansed - Bronchi sub divide into secondary bronchi with each supplying a lobe of the lung - There are 23 orders of branching in the lungs Bronchial Tree: - Tissue walls mimic that of the trachea - Bronchioles: o Consist of simple cuboidal and simple columnar epithelium o Complete layer of circular smooth muscle o Lack cartilage support and mucus producing cells o Last structure of the conducting zone is the terminal bronchiole Respiratory Zone: - Defined by the presence of alveoli - Begins as terminal bronchioles - Respiratory bronchioles lead to alveolar ducts then to terminal clusters of alveolar sacs composed of alveoli o Alveoli: Provide surface area for gas exchange Make up most of the lungs volume Approximately 300 million of them Respiratory Membrane: - Air blood barrier o Alveolar and capillary walls - Alveolar Walls o Single layer of type one epithelial cells o Permit gas exchange by simple diffusion o Secrete angiotensin converting enzyme o Type 2 secretes surfactant - Alveoli o Type one squamous pneumonocytes Make up the walls of alveoli Together with the capillaries make up the blood air barrier o Type two granular pneumonocytes Secrete surfactant Reduce surface tension o Surrounded by fine elastic fibers o Contain open pores that: Connect adjacent alveoli Allow air pressure throughout the lung to be equalized o House macrophages that keep alveolar surfaces sterile Lungs: Anatomy: - Lungs occupy all of the thoracic cavity except the mediastinum - Root- site of vascular and bronchial attachments - Costal surface- anterior, lateral, and posterior surfaces in contact with the ribs - Apex- narrow superior tip - Base- inferior surface that rests on the diaphragm - Hilus- indentation that contains pulmonary and systemic blood vessels - Cardiac notch- cavity that accommodates that heart - Left lung- separated into upper and lower lobes by the oblique fissure - Right lung- separated into three lobes by the oblique and horizontal fissures Blood Supply: - Lungs are perfused by two circulations o Pulmonary o Bronchial - Pulmonary arteries o Supply the blood to by oxygenated o Branch profusely o Feed into capillary network surrounding alveoli - Pulmonary veins o Carry oxygenated blood from the respiratory zones to the heart Pleurae: - Thin double layered serosa - Parietal pleura: o Cover the thoracic wall and the superior face of the diaphragm o Continues around the heart and between the lungs - Visceral pleura: o Covers externa lung surface o Divides the thoracic cavity into three chambers A central mediastinum Two lateral compartments each containing a lung - Functions: o Produces a serous fluid which has two major roles Reducing friction between the cavity wall and the organ Creates surface which keeps the lungs inflated Pulmonary Ventilation: - A 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 Breathing: - Consists of two phases: o Inspiration- air flows into the lungs o Expiration- gases exit the lungs Inspiration: - The diaphragm and external intercostal muscles contract and rib cage rises - Intrapulmonary volume increases - Intrapulmonary pressure drops below atmospheric pressure - Air flows into the lungs and down its pressure gradient until intrapulmonary pressure = atmospheric pressure Expiration: - Inspiratory muscles relax and the rib cage descends passively - Thoracic cavity volume decreases - Elastic lungs recoil passively and intrapulmonary volume drops - Gases flow out of the lungs down the pressure gradient until intrapulmonary pressure is equal to atmospheric pressure Factors Affecting Ventilation: - Airway resistance - Alveolar surface tension - Lung compliance Respiratory Volumes: - Tidal volume o Air that moves into and out of the lungs with each breath - Inspiratory reserve volume o Air that can be inspired forcibly beyond tidal volume - Expiratory volume o Air that can be evacuated from the lungs after a tidal expiration - Residual volume o Air left in the lungs after strenuous expiration Respiratory Capacity: - Inspiratory o Total amount of air that can be inspired after a tidal expiration - Functional Residual o Amount of air that remains in the lungs after a tidal expiration - Vital o The total amount of exchangeable air - Total lung o Sum of all the lung volumes Dead Space: Anatomical: - Volume of conducting respiratory passageways Alveolar: - Alveoli that cease to act in gas exchange due to collapse or obstruction Total: - Sum of anatomical and alveolar dead spaces Respiration: External: - Factors influencing the movement of oxygen and carbon dioxide across the respiratory membrane o Partial pressure gradients and gas solubility o Matching of alveolar ventilation and pulmonary blood perfusion o Structural characteristics of the respiratory membrane Internal: - The factors promoting gas exchange between the systemic capillaries and tissue cells are the same as those acting in the lungs o Partial pressure and diffusion gradients are reversed