Chapter 9 Respiratory System Pathway which air follows Nose Pharynx Larynx Trachea Bronchus Bronchioles Alveoli 1 Nose The nose opens at the nostrils nares and leads into the nasal cavities lago oropharynx Hair and mucus contains hidroactive enzymes breakdown bacteria in the nose filter the air Specialized cells act as odor receptors nerve cell endings that recognize different cells The nasal cavity has a lot of capillaries that warm and moisten the air 2 Pharynx 3 Larynx The pharynx is a funnel shaped cavity commonly called the throat It has 3 portions based on location nasopharynx oropharynx and laryngopharynx Tonsils provide a lymphatic defense during breathing at the junction of the oral cavity and pharynx The larynx is a triangular cartilaginous structure passing air b w pharynx trachea It is called the voice box and houses vocal cords There are 2 mucosal folds that make up the vocal cords with an opening in the middle called the glottis Nose Mouth Larynx Epiglottis shuts off the opening of the trachea Upper Respiratory tract Lower Respiratory tract 4 Nose 5 Pharynx 6 Larynx 1 Trachea 2 Bronchial tree 3 Lungs 4 Trachea The trachea is a tube often called the windpipe that connects the larynx with the primary bronchi It is made of connective tissue smooth muscle and cartilaginous rings The trachea is lined with cilia and mucus that help to keep the lungs clean Bronchial Tree The bronchial tree starts with 2 main 5 Bronchus that lead from the trachea into the lungs The bronchus continue to branch until they are smaller airway passages named bronchi and then as the airway passages make their way out to the lung tissue the passages become smaller and are referred to as 6 Bronchioles They are about 1 mm in diameter with thinner walls Bronchioles eventually lead to elongated sacs called 7 Alveoli There are 300 million alveoli in the lungs that greatly increase surface area of gas exchange Single layer of epithelial cell for rapid and ready diffusion of gasses Alveoli are enveloped by blood capillaries Alveoli are lined with surfactant that acts as a film to keep alveoli open The alveoli and capillaries are one layer of epithelium to allow exchange of gases The secondary bronchi bronchioles and alveoli make up the Lungs Right lung is bigger and has 3 lobes left lung is smaller and has 2 lobes Each lobe is divided into lobules through which they pass Each lung is enclosed by double layer membranes called pleura Smoking reduces lung capacity due to position of tobacco in their alveoli Athletes have higher lung capacities have maximum ability of oxygen supply 2 phases of breathing ventilation Inspiration an active process of inhalation that brings air into the lungs because of contraction The diaphragm and intercostal muscles contract The diaphragm flattens and the rib cage moves upward and outward Volume of the thoracic cavity and lungs increase volume is inversely proportional to pressure Air flows into the lungs The air pressure within the lungs decreases Expiration a typically passive process of exhalation that expels air from the lungs The diaphragm and intercostal muscles relax The diaphragm moves upward and becomes dome shaped The rib cage moves downward and inward Volume of the thoracic cavity and lungs decreases Air flows out of the lungs The air pressure within the lungs increases Different volumes of air during breathing Tidal volume the small amount of air that usually moves in and out with each breath Vital capacity the maximum volume of air that can be moved in plus the maximum amount that can be Inspiratory and expiratory reserve volume the increased volume of air moving in or out of the body moved out during one breath forcibly Residual volume the air remaining in the lungs after maximal forceful exhalation Respiratory control center in the brain medulla oblongata sends out nerve impulses to contract Sudden infant death syndrome SIDS is thought to occur when this center stops sending out How is breathing controlled by the nervous system Nervous control muscle for inspiration nerve signals How is breathing chemically controlled Chemical control 2 sets of chemoreceptors specific protein molecules sense the drop in pH one set is in the brain and the other in the circulatory system we feel touch in skin thanks to these and active nerve fibers which carry that message to the brain Both are sensitive to carbon dioxide levels that change blood pH due to metabolism Exchange of gases in the body The exchange of gases is dependent on diffusion high to low Oxygen and carbon dioxide are exchanged Partial pressure is the amount of pressure each gas exerts PCO2 or PO2 Oxygen and carbon dioxide will diffuse from the area of higher to the area of lower partial pressure Blood knows what action to do because of particular gas will flow depending on the partial pressure Exchange of gases between the lung alveoli and the blood capillaries PCO2 is higher in the lung capillaries than the air thus CO2 diffuses out of the plasma into the lungs The partial pressure pattern for O2 is just the opposite so O2 diffuses the red blood cells in the lungs External respiration Internal respiration The exchange of gases between the blood in the capillaries outside lungs and the tissue fluid PO2 is higher in the capillaries than the tissue fluid thus O2 diffuses out of the blood into the tissues Upper respiratory tract infections Sinusitis blockage of sinuses Tonsillitis inflammation of the tonsils Laryngitis infection of the larynx that leads to loss of voice Lower respiratory tract disorders Pneumonia infection of the lungs with thick fluid build up Tuberculosis bacterial infection that leads to tubercles collections of encapsulated bacteria Pulmonary fibrosis lungs lose elasticity because fibrous connective tissue builds up in the lungs Emphysema chronic incurable disorder in which alveoli are damaged and thus the surface area for usually because of inhaled particles gas exchange is reduced Asthma bronchial tree becomes irritated causing breathlessness wheezing and coughing Lung cancer uncontrolled cell division in the lungs that is often caused by smoking and can lead to death Things you should know about tobacco and health All forms of tobacco can cause damage It deposits in lungs and alveoli walls Smoking increases a person s chance of lung mouth larynx esophagus bladder kidney pancreatic stomach and cervix cancers harm to an unborn child Smoking also increases the chance of chronic bronchitis
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