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Respiratory System Gas Exchange Introduction • What is our atmosphere made of? • Nitrogen 78%, Oxygen 21%, Other 1% • Why is breathing important? – Exchange of O2 and CO2 b/t environment and our bodies • What is the O2 used for? – All cells require O2 for cellular respiration • energy • Other gasses? – CO2 + H2O – Expelled as waste General Functions – Intake of oxygen • For Cellular Respiration – Exhale carbon dioxide – Preservation of life Terminology • Breathing: to take air into the lungs and let it out again (inhale and exhale). • Gas Exchange: the process of diffusion that allows for carbon dioxide to leave the capillaries surrounding the alveoli while facilitating the entrance of oxygen into the capillary. (Carbon dioxide-out: oxygen in) • Cellular Respiration: when cells oxidize organic carbon to obtain energy. This is different from just respiration or the respiratory system. Note: the start product (oxygen) and end product (carbon dioxide) necessitate the need for the respiratory system. Breathing vs. Respiration • Breathing (Terminology) – Intake of O2 – Exhale CO2 – Gasses exchanged in alveoli in lungs • Respiration – C6H12O6 + 6O2 = 6CO2 + 6H2O – Breakdown of sugar into energy – Takes place in all cells • Gas Exchange: – Diffusion allowing for carbon dioxide to leave the capillaries and oxygen to come in. (Carbon dioxide-out: oxygen in) Respiratory Structures and their Functions • Mouth and nostrils – Air enters respiratory system – Allows a larger volume of air to be transferred • Nasal cavities – Provide moisture – Filter and trap particles • Hair and mucous Respiratory Structures and their Functions • Pharynx – In mouth – connect to the back of the oral and nasal cavities. The pharynx is also connected to the trachea and esophagus – Passage for food and air (digestion and gas exchange – Lined with ciliate epithelial cells to trap fine particles – Contains tonsils and adenoids Respiratory Structures and their Functions • Epiglottis – A leaf-like flap of tissue – prevents food from entering the trachea. Respiratory Structures and their Functions • Larynx – Voice box – Ligaments – Air passes, vibrate ligaments, sound produced • Vocal chords Respiratory Structures and their Functions • Vocal chords: two elastic ligaments that produce sounds depending on various tensions. Respiratory Structures and their Functions • Adam’s apple – cartilage that protects the larynx. Respiratory Structures and their Functions • Trachea – Windpipe – Takes air into the lungs. – Lined with cilia • Mucus • Filter extra particles – Cartilage rings • Provide support • Keep trachea open Respiratory Structures and Their Function • Cilia: small hairs that trap particles. Cilia move upwards to move particles back upwards so that they can be spit out. Trachea Pharynx Respiratory Structures and their Functions • Bronchi – Two branches of the trachea – Contain cartilage – Go to R & L lungs • Bronchioles – Smaller branches inside each lung that are less than 1mm in diameter – No cartilage – Rings of muscle – change diameter • Respiratory Structures and their Functions Alveoli – The point of gas exchange – The overall purpose of alveoli is to increase surface area for gas exchange. – Very thin air sacs – Surrounded by capillaries – Site of gas diffusion • Concentration gradient – One cell thick – Each lung - ~ 150 million – Film of lipoprotein – prevents alveoli from sticking together Respiratory Structures and their Functions • Lungs – Two cone shaped organs – right has 3 lobes – left has 2 lobes • shares space with heart – Located in thoracic cavity -base contacts diaphragm and top above the clavicles Respiratory Structures and their Functions • Pleural Membrane – Outer surface of lungs – Inner wall of chest cavity – Reduced friction Respiratory Structures and their Functions • Diaphragm – Band of muscle shaped like a dome – Separates thoracic cavity from abdominal cavity – Helps in breathing Respiratory Structures and their Functions • Ribs: bones that protect the thoracic cavity. Respiratory Structures and their Functions • Intercostal muscles – muscles between the ribs that aid in breathing. Human Gas Exchange System Diagram Answers Section of head and thorax to show respiratory system. left lung (surface) view Right lung (section) 1 Nasal cavity 2 Pharnyx 3 Epiglottis 4 esophagus 5 Cartilage rings 6 Bronchi 7 Lung 8 9 10 11 12 13 14 15 16 17 Heart Pleural membranes Diaphragm Alveoli Pleural membranes Bronchioles Intercostal muscles Ribs Trachea Larynx Mechanism of Breathing BREATHING MOVEMENTS • Oxygen continuously moves from alveoli into blood • Carbon dioxide from blood to alveoli • Air in alveoli must, therefore, be continuously replaced with fresh air INHALATION 1. diaphragm contracts 2. intercostal muscles contract 3. increase in lung volume 4. environmental air pressure is greater than the lung pressure 5. air rushes in to equalize pressure EXHALATION 1. diaphragm relaxes up 2. intercostal muscles relax 3. decrease in lung volume 4. lung pressure is greater than environmental air pressure 5. air rushes out to equalize pressure Inhalation and Exhalation Inhalation and Exhalation Role of Diaphragm • During inhalation – regulates pressure in chest cavity • Contract – flattens, moves down • Volume increases, pressure decreases • Air moves into lungs • During exhalation • Relaxes – dome shaped, moves up • Chest volume decreases, pressure increases • Air moves out Role of the Intercostal Muscles – Intercostal muscles are located between the ribs – Inspiration: Muscles contract, pulls ribs up and out – Expiration: Muscles relax, ribs move down Diffusion Across Alveoli • In LUNGS – – Higher concentration of oxygen than in blood. – Lower concentration of carbon dioxide than in blood. Diffusion Across Alveoli RESULTS • Oxygen moves from the air in the lungs across the alveoli and into the capillary where it becomes attached to hemoglobin. • Carbon dioxide moves from the blood across the alveoli and into the air of the lungs. Alveoli • Characteristics that facilitate diffusion: – have thin walls – kept moist – richly supplied with blood vessels – large surface area REGULATION & CONTROL – Medulla Oblongata -- breathing center • controls rate and depth of breathing • the medulla is sensitive to CO2 levels in the blood • If CO2 (carbonic acid) level too high... – medulla tells diaphragm and intercostals to increase activity • once CO2 levels drop into normal range... – medulla stops sending “increase activity” message REGULATION & CONTROL • Chemoreceptors – – If stimulated – • Diaphragm begins breathing movements • More breathing, lower CO2 levels • Can be controlled – Medulla will take over if CO2 builds up QUANTITIES OF AIR • TIDAL VOLUME – amount air exchanged with each normal breath • INSPIRATORY RESERVE – additional air that can be inhaled over and above the tidal volume • EXPIRATORY RESERVE – extra air that can be forcibly exhaled in excess of the tidal volume QUANTITIES OF AIR • VITAL CAPACITY – the maximum amount of air that can be forcibly exchanged • RESIDUAL VOLUME – amount of air that remains in lungs after forceful expiration. QUANTITIES OF AIR INSPIRATORY RESERVE VOLUME (3 L) VITAL CAPACITY TIDAL VOLUME (1/2 L) EXPIRATORY RESERVE VOLUME (1 L) RESIDUAL VOLUME (1.2L) Transport of Gases • OXYGEN TRANSPORT – hemoglobin transports about 97% of the oxygen – 3% will diffuse into the plasma – the hemoglobin molecule is composed of 4 peptide chains with an iron center – oxygen attaches to hemoglobin to form oxyhemoglobin – oxygen is released in the tissues Carbon Dioxide in the Blood • Approximately – 64% of CO2 – bicarbonate ion in plasma – 27% of CO2 – combines with hemoglobin – 9% of CO2 – is dissolved in plasma Transport of Gases • CARBON DIOXIDE TRANSPORT • CO2 moves away from muscle – CO2 continually diffuses into the blood plasma. – an enzyme (carbonic anhydrase) in red blood cells converts some CO2 and water (from plasma) into carbonic acid – carbonic acid breaks into H+ and bicarbonate ions (hydrogen carbonate) – the H+ combines with hemoglobin • helps avoid significant pH change in blood – the bicarbonate ion stays in the plasma Transport of Gases • When this blood reaches lungs: – new O2 will combine with hemoglobin displacing H+ into plasma. – H+ recombines with bicarbonate ion producing H2O and CO2 which diffuses into alveoli to be exhaled Factors Affecting Breathing Rate 1. Exercise • When exercise occurs carbon dioxide levels accumulate faster than normal. • As a result, your breathing rate and depth increase. 2. Hormones • Hormones such adrenaline increases breathing rate 3. High Altitude • At higher altitudes there is less oxygen present in the atmosphere. • This does not have a great effect on carbon dioxide receptors. • Receptors in the arteries will increase the breathing rate. 4. Carbon Monoxide • CO acts as a competitive inhibitor in the red blood cell • CO attaches to the hemoglobin molecule 200 times stronger (and faster) than O2 or CO2 • This makes the hemoglobin unavailable for O2 or CO2 Holding Your Breath • When you hold your breath carbon dioxide levels begin to build. • As a result, when breathing is resumed it occurs at a faster rate and with greater depth than normal. Hyperventilation • When you hyperventilate your carbon dioxide levels temporarily decrease. • This temporary carbon dioxide decrease would allow you to hold your breath for longer periods of time. DISORDERS Disorders • Bronchitis – – – – – Inflammation of bronchioles Air passages get smaller Excess mucus Harder to exhale than inhale Can lead to asthma and emphysema • Emphysema – Increased resistance to airflow – Over-inflation of the lungs – Alveoli cannot handle pressure • Rupture • Less SA for gas exchange • Lowers O2 levels • Lung Cancer – Uncontrolled growth of cells – Less surface area for diffusion – Blockages may occur Tobacco • People have smoked tobacco for centuries • How is related to this class? • Lung cancer – Most common type of death from cancer – 50% OF SMOKERS WILL DIE FROM SMOKING RELATED CAUSES Healthy vs. Unhealthy The effects of chewing tobacco on a Man. Other Effects of Smoking 1. hair loss 2. cataracts 3. wrinkling 4. hearing loss : 6. tooth decay : 7. lung ailments : 9. heart disease : 16. cancer : a)of the lungs b)of the tongue c) of the mouth, salivary glands and pharynx.