Respiratory System Overview PDF

RESPIRATORY SYSTEM BERNARD MBITHI Organs of the Respiratory System Figure 21.1  INTRODUCTION The major function : –O2 supply the body –Removal of CO2 from the body To accomplish this function, at least four processes ( respiration) must take...

RESPIRATORY SYSTEM BERNARD MBITHI Organs of the Respiratory System Figure 21.1  INTRODUCTION The major function : –O2 supply the body –Removal of CO2 from the body To accomplish this function, at least four processes ( respiration) must take place  INTRODUCTION 1. Pulmonary ventilation: Movement of air into and out of the lungs(breathing).  INTRODUCTION 2. External respiration Movement of oxygen from the lungs to the blood and of carbon dioxide from the blood to the lungs.  INTRODUCTION 3. Transport of respiratory gases Transport of oxygen from the lungs to the tissue cells of the body Transport of CO2 from the tissue cells to the lungs.  INTRODUCTION 4. Internal respiration Movement of O2 from blood to the tissue cells and of CO2 from tissue cells to blood. N/B: Only the first two processes are the special responsibility of the respiratory system  Respiratory System Overview Major Functions enables aerobic respiration in cells: e.g. Glucose + O2  ATP + H2O + CO2 supplies body with oxygen (O2) disposes of carbon dioxide (CO2) waste (7th edition)  Respiratory System Overview homeostatic regulation of body pH (by selectively retaining or excreting CO2) protection from inhaled pathogens and irritating substances (via the respiratory epithelium)  Respiratory System Overview sound production (via vocal cords) sense of smell (via olfactory receptors in nose) Functional Anatomy of the Respiratory System The respiratory system – nose and nasal cavity – Pharynx – larynx – Trachea – bronchi and their smaller branches – lungs and alveoli  Nose and Paranasal Sinuses Produces mucus Provides an airway for respiration Moistens and warms air Filters inhaled air Resonating chamber for speech Houses olfactory receptors Skin is thin – contains many sebaceous glands  NOSE Two types of mucous membrane –Olfactory mucosa - Near roof of nasal cavity, houses olfactory (smell) receptors –Respiratory mucosa - Lines nasal cavity Epithelium is pseudostratified ciliated columnar Goblet cells within epithelium  NOSE Underlying layer of lamina propria has glands that contribute to the mucus layer and blood vessels that warm the air. Cilia move contaminated mucus posteriorly Nasal Cavity  Nasal Conchae 3 paired bony projections along the lateral walls of the nasal cavity Superior and middle nasal conchae - part of the ethmoid bone Inferior nasal conchae - separate bone Function - Particulate matter deflected to mucus-coated surfaces  Nose and Paranasal Sinuses Paranasal sinuses –Frontal –Sphenoid –Ethmoid –Axillary The Paranasal Sinuses Figure 7.11a, b The Paranasal Sinuses Figure 7.11a, b  The Pharynx Funnel-shaped passageway Connects nasal cavity and mouth Shared by the digestive and respiratory systems  The Pharynx Divided into three sections by location –Nasopharynx – superior portion, –Oropharynx – continuous with the oral cavity –Laryngopharynx – between the hyoid bone and the esophagus Type of mucosal lining changes along its length  Nasopharynx Arch-like entranceway – fauces –Extends from soft palate to the epiglottis Epithelium - stratified squamous epithelium  Nasopharynx Two types of tonsils in the oropharynx –Palatine tonsils – in the lateral walls of the fauces –Lingual tonsils – covers the posterior surface of the tongue  Laryngopharynx Passageway for both food and air Epithelium - stratified squamous epithelium Continuous with the esophagus and larynx  The Larynx Prevent food and drink from entering the trachea Passageway for air Produces Sound It connects the pharynx to the trachea  The Larynx Epithelium of the larynx –Stratified squamous – superior portion –Pseudostratified ciliated columnar – inferior portion The Larynx  The Trachea C-shaped cartilage rings keep airway open Carina - marks where trachea divides into two primary bronchi Epithelium - pseudostratified ciliated columnar  Trachea Vocal ligaments of the larynx –Vocal folds (true vocal cords) - act in sound production –Vestibular folds (false vocal cords) - no role in sound production  Trachea Voice production –Length of the vocal folds changes with pitch –Loudness depends on the force of air across the vocal folds  Bronchial Tree Consists of –The respiratory zone –Conducting zone  Bronchial Tree Respiratory zone –Actual site of gas exchange –Composed of the respiratory bronchioles, alveolar ducts, and alveoli, all microscopic structures  Bronchial Tree Conducting zone – Includes all other respiratory passageways, which provide fairly rigid conduits for air to reach the gas exchange sites. – The conducting zone organs also cleanse, humidify, and warm incoming air.  Bronchial Tree Conducting zone Structural changes occur as bronchi diameter diminish Cartilage rings replaced by irregular cartilaginous plates Pseudostratified>columnar>cuboidal Smooth muscle increases.  Bronchi in the Conducting Zone Bronchial tree - extensively branching respiratory passageways –Primary bronchi (main bronchi) Largest bronchi Right main bronchi - wider and shorter than the left MECHANICS OF VENTILATION BERNARD MBITHI  Mechanics of Breathing Pulmonary ventilation consists of two phases 1. Inspiration: gases flow into the lungs 2. Expiration: gases exit the lungs  Pressure Relationships in the Thoracic Cavity Atmospheric pressure (Patm) – Pressure exerted by the air surrounding the body – 760 mm Hg at sea level Respiratory pressures are described relative to Patm – Negative respiratory pressure is less than Patm – Positive respiratory pressure is greater than Patm – Zero respiratory pressure = Patm  Intrapulmonary Pressure Intrapulmonary (intra-alveolar) pressure (Ppul) – Pressure in the alveoli – Fluctuates with breathing – Always eventually equalizes with Patm  Intrapleural Pressure Intrapleural pressure (Pip): – Pressure in the pleural cavity – Fluctuates with breathing – Always a negative pressure (