The Respiratory System. Respiration Cellular respiration-occurs in the mitochondria, and releases energy from the breakdown of food molecules (ch. 9)

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  • The Respiratory System

  • RespirationCellular respiration-occurs in the mitochondria, and releases energy from the breakdown of food molecules (ch. 9)Respiration-process of gas exchange; blood carries oxygen from lungs to tissues and carries carbon dioxide in the opposite direction

  • Human respiratory systemIncludesNosepharynxLarynxTracheaBronchiLungs

  • To return to the chapter summary click escape or close this document.Air Into Lungs

  • Path of airAir enters nose and moves to the pharynx (passageway for food and air)From pharynx, air moves to the trachea or windpipe (epiglottis covers trachea when you swallow)At these early places, air is warmed, moistened, and filtered by hairs in nasal cavity and mucus produced in cells in the nasal cavity and trachea to keep air clean

  • Path of air cont.From trachea, air moves to larynx (vocal cords) and then into 2 passageways in the chest called bronchi (each leads to a lung)Each large bronchus subdivides into smaller bronchi and those into bronchiolesBronchioles subdivide into millions of alveoli or air sacs (150 million in each lung)Each alveoli is surrounded by capillaries

  • To return to the chapter summary click escape or close this document.Aveoli

  • Gas exchangeAlveoli provide huge surface area for gas exchangeOxygen dissolves in moisture on inner surface of alveoli and diffuses across capillaries into bloodCarbon dioxide in blood diffuses in the opposite direction

  • Air Inhaled air is 21% oxygen and .04% carbon dioxideExhaled air is
  • Oxygen in bloodOxygen dissolves easily and moves into blood without difficultyHemoglobin (oxygen-carrying protein in blood) increase efficiency by increasing oxygen-carrying capacity of blood more than 60 times

  • Breathing structuresLungs sealed in two pleural membranes or sacs in the chest cavityBelow the chest cavity is the diaphragm, a large flat muscle

  • Inhaling Diaphragm contractsRib cage rises up to expand volume of chest cavityCreates a partial vacuum in the chest cavityAtmospheric pressure pushes air into lungs

  • Exhaling Rib cage lowersDiaphragm relaxesPressure in chest becomes greater than atmospheric pressureAir is pushed back out

  • To return to the chapter summary click escape or close this document.How A Diaphragm Works

  • Control of breathingControlled by medulla oblongata of brainCells monitor amount of carbon dioxide in bloodAs CO2 levels rise, nerve impulses from breathing center cause diaphragm to contract and fill lungs with air

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