Presentation on theme: "GAS EXCHANGE. Gas Exchange Gas exchange is a physical method that organisms have for obtaining oxygen from their surroundings and removing excess carbondioxide."— Presentation transcript:
Gas Exchange Gas exchange is a physical method that organisms have for obtaining oxygen from their surroundings and removing excess carbondioxide. Respiratory surface is the surface through which gas exchange takes place.
Characteristics of Respiratory Surface It must be thin walled for diffusion It must be moist (CO 2 and O 2 must be in solution) It must be in contact with a source of oxygen that exist in the surrounding medium In multicellular organisms, it must be in contact with the transport system.(to carry dissolved materials to and from the cells of the organism)
Characteristics of Respiratory Surface Gas exchange through respiratory surfaces takes place by diffusion. The larger the surface area of respiratory surface, the greater the amount of gas exchange can occur in a given time.
In protists and small In large organisms multicellular organisms (animals) exchange of gases takes place directly between cells and environment Most of the body cells are farther from the outside environment, also they have protective outer layer, therefore they need specialized organs or systems that include respiratory surface
Gas Exchange in Protists They have no specialized respiratory systems. Respiratory surface is cell membrane. Gas exchange occurs through body surface by diffusion.
O2O2 CO 2
Gas Exchange in Hydra Respiratory surface is cell membrane. By diffusion both cell layers can exchange dissolved oxygen and carbon dioxide with their surroundings.
Gas Exchange in Hydra CO 2 O2O2 O2O2
Gas Exchange in Planaria Planarian has no respiratory system. O 2 and CO 2 diffuse into and out of individual cells Respiratory surface is cell membrane.
Gas Exchange in Large, Multicellular Organisms Animals in Water *dissolved O 2 is less than 1% in water. *the O 2 that is part of H 2 O is not available for gas exchange. *O 2 diffusion is slow in water. * to obtain enough O2 they must constantly move large amount of water over their respiratory surface. Animals on Land *O 2 makes up 21% of the air. *O 2 diffusion is faster. *They must keep their respiratory surface moist *Most air – breathing animals have respiratory system that extend inside the organism to lower the amount of water lost by evoporation.
Respiratory Pigments Respiratory pigments are colored substances in blood that carry O 2 and CO 2 between the respiratory surface and the body cells. Hemoglobin Red Hemocyanin Blue Chlorocruorins Green Hemoerythrins Red
Gas Exchange in Earthworm O2O2 CO 2
The skin is the respiratory surface. Skin is thin and secretes mucus that keeps it moist. The O 2 passes through the moist skin into the capillaries and the blood carries O 2 to the cells by hemoglobin and picks up CO 2 from the cells to the capillaries. CO 2 then diffuse through the skin into the air. Gas Exchange in Earthworm
Gas Exchange in Grasshopper
In grasshopper gas exchange doesnt depend on circulatory system. Blood does not carry O 2 and CO 2. The respiratory gases are transported through a series of branching air tubes that are called tracheal tubes. Gas Exchange in Grasshopper
Air enters and leaves the body of grasshopper by small openings called spiracles. From each spirical tracheal tubes branch into the body. The fluid filled ends of these tubes acts as respiratory surface. O 2 diffuses from tubes to cells and CO 2 diffuses from cells into the tubes. Gas Exchange in Grasshopper
Gas Exchange in Spiders Spiders have book lungs which consist of a series of thin parallel plates of tissue. The plates of tissue recieve O 2 from the outside environment through a spiracle.
Gas Exchange in Fish
Many animals living in water like fish, oysters, clam and lobsters use gills for respiration. Gills are thin layers of tissue that are richly supplied with blood vessels. As water passes over them, dissolved O2 diffuses from the water across the gill tissue and into the blood. CO2 from the blood diffuses out of the gills into the water.