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BILL Why does the body need oxygen? How does the body get required oxygen into the body? Needs oxygen to produce ATP through cell respiration Inhales gases through the lungs, which enters the bloodstream and diffuse into the body cells (Respiratory system) Ventilation, Gas Exchange and Respiration Ventilation is defined as the inhalation and exhalation of air. Gas Exchange is the diffusion of gases results in gas exchange. 2 main sites of gas exchange: Lungs – Oxygen moves from lungs to blood, and CO2 moves opposite Capillary beds – Oxygen diffuses out of blood stream into body cells and CO2 moves from tissues to blood. What is Respiration Respiration – the release of carbon dioxide and the uptake of oxygen within the cells to produce energy The human circulatory system brings about the exchange of oxygen and carbon dioxide between the blood, the air, and the tissues Reasons for need of ventilation system Our bodies simply are too large to allow for simple diffusion of gases across a membrane (similar to amoeba). Ventilation system must also work to ensure that the concentration of gases to be beneficial to body. Major concentration gradient allows for diffusion of gases within our bodies. Major Structures Nose Trachea Pharynx Bronchi Bronchioles Larynx Lungs Alveoli Capillary Movement of Air With each breath, air enters the body through the air passages and fills the lungs, where gas exchange takes place Air enters the body through passages that include the nose and the mouth Movement of Air Movement of Air Pharynx Serves as a passageway for both air and food Air travels down the pharynx into the Larynx Located at the top of the trachea Contains the vocal cords Trachea rings of cartilage maintain shape of “windpipe” Movement of Air Trachea branches into Bronchi Air passes into two large passageways in the chest cavity Each bronchus leads into one of the lungs and subdivides into smaller bronchi called bronchioles Movement of Air The bronchioles subdivide until they reach millions of tiny air sacs called alveoli Alveoli Grouped in clusters Surrounded by capillaries for gas exchange Features of Alveoli Adaptation Advantage Spherical shape Provides a large surface area for efficient gas exchange. Flattened, single cell thickness Allows for easy exchange (doesn’t have to travel through thick cell layers) Moist inner lining of alveolus Assists in diffusion Associated capillary bed Gases can enter blood stream quickly and efficiently. Movement of Air Alveoli Sacs Gas Exchange Within Alveoli Oxygen dissolves in the alveoli and then diffuses across the thin-walled capillaries into the blood Carbon dioxide in the bloodstream diffuses in the opposite direction, across the membrane of an alveolus and into the air within it Gas Exchange Air that is inhaled contains: 21% oxygen And .04% carbon dioxide There are 150 million alveoli in each lung, providing an enormous surface area for gas exchange BILL Draw and label the parts of respiratory system (pg. 170). Include the following: nose, pharynx, larynx, trachea, bronchi, bronchioles, lungs, alveoli. Breathing Movement of air into and out of lungs Ordinary air pressure drives air into lungs How does the body use this force to inflate the lungs? Mechanism of Breathing Key Points: Lungs do not contain muscle, therefore they are unable to perform any purposeful movement. Lungs rely totally on the surrounding muscle to force air in and out (diaphragm, abdomen and intercostal muscles). The lungs are sealed in two sacs, called the pleural membranes, inside the thoracic (chest) cavity, creating a closed environment Mechanism of Breathing Based on inverse relationship of pressure and volume As volume increases, pressure decreases and vice versa Mechanism of Breathing 1. 2. 3. 4. 5. Inhalation causes the diaphragm to contract and the abdominal and intercostal muscles help raise the rib cage, increasing the volume of the thoracic cavity As volume increases, the pressure of the cavity decreases, leading to less pressure pushing on the lungs The volume of lung tissue increases, because of the decreased pressure The pressure inside the lungs now decreases, creating a partial vacuum Air comes in through the oral/nasal cavity because of the vacuum and fills the alveoli of lungs with air Breathing Breathing Exhaling is a passive event and the steps of inhalation are reversed. The diaphragm muscle relaxes, causing the rib cage to lower and decreasing volume of cavity, air rushes out of the lungs due to increased pressure Breathing Breathing Breathing Animation How is Breathing Controlled? Medulla oblongata controls breathing in the brain Medulla Oblongata Monitors the amount of carbon dioxide in the blood As carbon dioxide rises, impulses from brain cause diaphragm to contract, bringing air into lungs Respiratory Disorders Pneumonia is a common lung infection caused by bacteria, a virus, or fungi. Inflammation of the alveoli, the results in an excess lining inside of lungs Can result in a buildup of fluids inside the lungs Treated with rest, fluids, and aspirin/antiinflammatory drugs to treat fever Respiratory Disorders Bronchitis is an inflammation of the lining of the bronchial tubes. May develop from a cold or other respiratory infections Treated with rest, fluids, and possibly prescription for bronchodilator or oral steroids Heart Lung Machine http://il.youtube.com/watch?v=DUGXO-6MOn0 http://il.youtube.com/watch?v=RlRi3R9LXng&featur e=related