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7/28/2014 I. Overview Respiratory System Anatomy & Physiology Chapter 14 A. Function: Brings about the exchange of oxygen and carbon dioxide between the blood, the air, and tissues C. Respiratory tract Pathway of air from nose to lungs Air in the respiratory tract are: B. Organs Nose Pharynx Larynx Trachea Bronchi Lungs – alveoli – Cleansed – by hairs, cilia, and mucus – Warmed – by heat from the blood vessels – Moistened – by the wet surfaces in the passageway Review Necessary to keep lung tissue healthy II. Structure A. Upper Respiratory Tract What happens to air as it travels through the respiratory tract to ensure that the lung tissues remain healthy? – Nasal cavities, pharynx, larynx 1 7/28/2014 1. Nasal Cavity Description: Hollow canals separated by a septum of bone and cartilage Function: Filter, warm, and moisten the air Paranasal Sinuses – Cavities within bones surrounding the nasal cavity – Increases surface area – Increases air turbulence within the nasal cavity – Function of the sinuses Lighten the skull as resonance chambers for speech Produce mucus that drains into the nasal cavity Act Contains lateral projections called conchae The nasal cavity is separated from the oral cavity by the palate – Anterior hard palate (bone) – Posterior soft palate (muscle) Mucous membrane lines nasal cavity – Cilia moves mucous and trapped particles to the pharynx Hard Palate Soft Palate 2. Pharynx – Throat – Nasopharynx – superior region, passageway for air – Oropharynx – where oral cavity joins pharynx, passageway for food and air – Laryngopharynx – inferior region that opens to larynx Description: funnel-shaped passageway between the nasal cavity and larynx Function: Connects nasal and oral cavities to the larynx Three regions of the pharynx Tonsils – located in oropharynx – A lymphatic tissue that protects against inhaled pathogens 2 7/28/2014 3. Larynx Description: Also called the voice box, contains the vocal cords Function: Produces sound Vocal cords are elastic tissues that vibrate producing sound as air travels through Epiglottis - flap of tissue that sits at the base of the tongue – prevents food from entering the trachea, or windpipe, during swallowing – The opening or slit in the vocal cords is called the glottis Review B. Lower Respiratory Tract – Trachea, bronchi, bronchioles, lungs, alveoli List the organs (pathway) air travels through in the upper respiratory tract. 4. Trachea Description: known as the windpipe, flexible tube that connects larynx to bronchi Function: directs air to bronchi Held open by C-shaped hyaline cartilage Trachea is lined with pseudostratified ciliated columnar epithelial cells – Cilia sweeps mucus loaded with dust and other debris away from lungs Cilia Goblet cells Pseudostratified epithelial Basement membrane 3 7/28/2014 Vocabulary Review Breakdown the words “pseudostratified ciliated columnar epithelial” to understand the meaning. “pseudo” – fake “stratified” – layers “ciliated” – with hair like projections “columnar” – cells that are taller than wider 5. Bronchi Description: Left and right branched tubes of the trachea Function: passageway of air to lungs 6. Bronchioles Bronchi enters the right and left lungs – Bronchi subdivide into smaller and smaller branches called bronchioles Right bronchus is wider, shorter, and straighter than left 7. Lungs Description: paired, coneshaped organ that occupy the thoracic cavity Function: contains alveolus where gas exchange occurs Description: Smallest branches of the bronchi Function: Bronchioles lead to the alveoli Apex (superior portion) is near the clavicle Base (inferior portion) rests on the diaphragm Each lung is divided into lobes by fissures – Left lung – two lobes – Right lung – three lobes 4 7/28/2014 8. Alveoli Coverings of the lungs – Visceral pleura covers the lung – Parietal pleura lines the walls of the thoracic cavity – Pleural fluid fills the area between layers of pleura to allow gliding membrane – extremely thin membrane that aids in the rapid exchange of gases Description: Structure made up of simple squamous epithelium surrounded by blood capillaries Function: Exchange of gas Respiratory Gas crosses the respiratory membrane by diffusion – Oxygen enters the blood – Carbon dioxide enters the alveoli Macrophages add protection in alveoli prevents the lung from closing or collapsing Surfactant Review List the organs (pathway) air travels in the lower respiratory tract. Review What gases are exchanged in the respiratory membrane? How are gases moved or transported across the membrane? 5 7/28/2014 A. External Respiration III. Gas Exchange and Transport Exchange of gases between air and blood in the lungs Blood entering the lungs is oxygen-poor and carbon dioxide-rich Oxygen movement into the blood Respiration – process of exchanging gases between the atmosphere and body cells Carbon dioxide movement out of the blood – Blood returning from tissues has higher concentrations of carbon dioxide than air in the alveoli – Pulmonary capillary blood gives up carbon dioxide Blood leaving the lungs is oxygen-rich and carbon dioxidepoor – The alveoli always has more oxygen than the blood – Oxygen moves by diffusion from an area of high concentration to an area of low concentration B. Internal Respiration Exchange of gases between blood and body cells An opposite reaction to what occurs in the lungs – Carbon dioxide diffuses out of tissue to blood – Oxygen diffuses from blood into tissue C. Gas Transport Oxygen transport in the blood – Inside red blood cells attached to hemoglobin (oxyhemoglobin [HbO2]) – A small amount is dissolved in the plasma Carbon dioxide transport in the blood – Most is transported in the plasma as bicarbonate ion (HCO3–) – A small amount is carried inside red blood cells on hemoglobin, but at different binding sites than those of oxygen 6 7/28/2014 Summary Draw a flow map showing the pathway air travels through the respiratory system. Underneath each structure, write down the function. Ex. IV. Mechanism of Breathing Ventilation – manner in which air enters and exits the lungs Two phases – Inspiration – flow of air into lung – Expiration – air leaving lung A. Inspiration Active phase of ventilation Diaphragm and intercostal muscles contract The size of the thoracic cavity increases External air is pulled into the lungs due to an increase in intrapulmonary volume B. Expiration Largely a passive process which depends on natural lung elasticity Diaphragm and intercostal muscles relax As muscles relax, air is pushed out of the lungs Forced expiration can occur mostly by contracting internal intercostal muscles to depress the rib cage 7 7/28/2014 C. Nonrespiratory Air Movements What Happens When you Breath? Can be caused by reflexes or voluntary actions Examples – Cough and sneeze – clears lungs of debris – Laughing – Crying – Yawn – Hiccup D. Ventilation Control Normal breathing rate is 12-20 ventilation per minute Controlled by the respiratory center in the medulla oblongata (brain) Factors that influence ventilation – Nervous input – Chemical input 1. Nervous input – Intercostal and phrenic nerve stimulate muscles to contract for inspiration – Lack of stimulation results in expiration E. Respiratory Volumes 2. Chemical input – Level of carbon dioxide in the blood is the main regulatory chemical for respiration – Increased carbon dioxide increases respiration Normal breathing moves about 500 ml of air with each breath (Tidal Volume [TV]) Many factors that affect respiratory capacity – A person’s size – Sex – Age – Physical condition 8 7/28/2014 Inspiratory reserve volume (IRV) – Amount of air that can be taken in forcibly over the tidal volume – Usually between 2100 and 3200 ml Expiratory Residual volume – Air remaining in lung after expiration – About 1200 ml Vital capacity – The total amount of exchangeable air – Vital capacity = TV + IRV + ERV reserve volume (ERV) – Amount of air that can be forcibly exhaled – Approximately 1200 ml Functional Dead space volume – Air that remains in conducting zone and never reaches alveoli – About 150 ml volume – Air that actually reaches the respiratory zone – Usually about 350 ml Respiratory capacities are measured with a spirometer V. Respiratory Disorders B. Laryngitis – infection of larynx C. Chronic Obstructive Pulmonary Disease (COPD) – Term used to describe several progressive lung diseases – Major causes of death and disability in the United States – Example: chronic bronchitis, emphysema, asthma A. Tonsillitis – occurs when tonsils become inflamed and enlarged – Can make breathing difficult – Tonsils are the first line of defense against pathogens that enter the pharynx 1. Chronic Bronchitis – Airway becomes inflamed and fills with mucus – Loss of cilia and normal cleansing action – Caused by smoking cigars, cigarettes, and some pollutants – Lead to inability to talk audibly – Disappears with treatment 9 7/28/2014 2. Emphysema – Chronic and incurable disorder where the alveoli bursts and fuse into larger air spaces – Reduces surface area for gas exchange – Caused by prolong cigarette smoking 3. Asthma – Disease of the bronchi and bronchioles marked by wheezing and breathlessness – Airways are sensitive to irritants (pollen, animal dander, dust, etc) – Causes muscle in the bronchioles to spasm and may even cause them to become inflamed – Treated with inhalers that stop the spasms or reduce the inflammation D. Lung Cancer Caused by smoking cigarettes & second hand smoke Lung cancer begins with the thickening and callusing of the bronchi Atypical cells appear in tissue, tumor forms Cells break loose and spread to other organs (metastasis) Tumor can grow until it blocks bronchi, cutting off air supply, lung collapses Treatments: – Pneumonectomy – remove a lobe or a whole lung – Chemotherapy – Radiation 10