KSU BSCI 10001 - Chapter 9: Respiratory System

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Chapter 9: Respiratory SystemPathway which air follows:• Nose• Pharynx• Larynx • Trachea• Bronchus• Bronchioles• Alveoli1. 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.• The nasal cavity has a lot of capillaries that warm and moisten the air.• Specialized cells act as odor receptors. (nerve cell endings that recognize different cells)2. Pharynx• 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.3. Larynx • 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 calledthe glottis.(Nose)Epiglottis: shuts off the opening of the trachea.(Mouth)Lower Respiratory tract:1. Trachea2. Bronchial tree3. LungsUpper Respiratory tract:4. Nose5. Pharynx6. Larynx(Larynx)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 tokeep 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 andthen 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.• The alveoli and capillaries are one layer of epithelium to allow exchange of gases.• Alveoli are lined with surfactant that acts as a film to keep alveoli open.The secondary bronchi, bronchioles, andalveoli make up the… Lungs:- Right lung is bigger and has 3 lobes; left lung is smaller and has2 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)- The air pressure within the lungs decreases.- Air flows into the lungs. 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.- The air pressure within the lungs increases.- Air flows out of the lungs.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 bemoved out during one breath Inspiratory and expiratory reserve volume – the increased volume of air moving in or out of the body forcibly. Residual volume – the air remaining in the lungs after maximal, forceful exhalation.How is breathing controlled by the nervous system? Nervous control- Respiratory control center in the brain (medulla oblongata) sends out nerve impulses to contractmuscle for inspiration.- Sudden infant death syndrome (SIDS) is thought to occur when this center stops sending out nerve signals.How is breathing chemically controlled?• Chemical control– 2 sets of chemoreceptors (specific protein molecules) sense the drop in pH: one setis 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- Oxygen and carbon dioxide are exchanged.- The exchange of gases is dependent on diffusion. (high to low)- 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.External respiration:- 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.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 voiceLower 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, usually because of inhaled particles- Emphysema – chronic, incurable disorder in which alveoli are damaged, and thus the surface area for 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


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KSU BSCI 10001 - Chapter 9: Respiratory System

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