Respiratory System I. Function (job) of the Respiratory System A.Respiration is to provide gas exchange between the blood and the environment. a. Requirements for Gas exchange at the respiratory surface: 1.Thin-walled (so gases can freely diffuse across) 2.Moist- (O2 and CO2 must be in solution or dissolved) 3.In contact with O2 source-(outside environment) 4.In contact with transport system carrying dissolved gases (Circulatory system/Blood) b. Examples of gas respiratory surfaces used for exchange Protists (Amoeba/Paramecium) Surface: Cell membrane Method: Simple direct diffusion through cell membrane to water Earthworm Surface: Moist skin Method: Diffusion through moist mucus coated skin into blood vessels (has hemoglobin to help) Examples of gas respiratory surfaces used for exchange Fish Surface: Gills Method: Diffusion from water to blood vessels in the gills Grasshopper Surface: Air tubes & Sacs Method: Air comes in through spiracles, through the air tubes, moved by muscle contraction (no hemoglobin/blood used) c. Human Respiratory System Surface: Moist air sacs (alveoli) Method: Diffusion across air sacs into blood stream (use hemoglobin to increase amount of O2 that blood can carry) 1. Oxygen is absorbed from the atmosphere into the body. 2. Carbon dioxide is expelled from the body. 3. Inhaling (breahing) brings oxygen into the body that cells need for cell respiration. 4. Cellular Respiration- using oxygen carried by the red blood to the mitochondria to break down food to create ATP (energy) and CO 2 gas as waste. Question 1.What is the main job of the respiratory system? 2.Why does the body need oxygen? Be specific 3.Explain the difference between breathing and cell respiration. Question 1.What is the main job of the respiratory system? provide gas exchange between the blood and the environment. 2.Why does the body need oxygen? Be specific. cell respiration [breaking down food for energy] II. Respiratory System: Subsystems- Components that work together to support the system: A.The Upper Respiratory Tract: 1. Nose (nostrils) - It is the entrance of the respiratory tract. 2. Pharynx - It is situated behind the mouth and is the passage to the stomach and the lungs. 3. Larynx - It is present at the top of trachea and contains vocal cords. It is also known as the voice box. 4. Trachea (windpipe) - It is a tube like structure that helps in passage of air from larynx to the bronchi. B. The Lower Respiratory Tract: 1. Bronchi (bronchioles) - These are the branches (tubes) of the bronchi that conduct air into the lungs. one bronchi goes to each lung and branches into bronchioles 2. Alveoli (air sacs) - The sacs in the lungs where gas exchange occurs. 3. Lungs - The two inverted-cone shaped organs present in the chest of human beings. C. Breathing Process Four Stages of Gas Exchange : 1.Breathing- movement of air in and out of the lungs a.Inhalation - chest cavity increases Diaphragm contracts (flattens) and lowers Ribs raise up and out Lungs inflate because during breathing negative pressure creates a vacuum which sucks air into the lungs Four Stages of Gas Exchange : b. Exhalation - chest cavity is decreased Diaphragm relaxes and moves upward Ribs drop down and in Lungs deflate because positive pressure pushes the air out of the lungs Four Stages of Gas Exchange : 2. External respiration- exchange of gases between outside air and bloodstream in the air sacs Mucus coats air sacs (alveoli) to moisten them O2 diffuses across air sacs into capillaries of air sacs and CO2 diffuses in the opposite direction O2 attaches itself to hemoglobin on the red blood cells Four Stages of Gas Exchange : 3. Transport- movement of gases in the blood between the cells to the lungs (circulatory system) 4. Internal respiration- exchange of gases between the blood stream and the cells of the body At the capillaries, O2 diffuses into the intracellular fluid and then into the body cells & CO2 diffuses in the opposite direction Question 1.Explain what would happen if one of the subsystems in the respiratory system stopped working. ___________________________________ ___________________________________ ___________________________________