Planet Earth and Its Environment A 5000-million year Journey

Part of the Patterns in Nature ModuleBiology in Focus, Preliminary CourseGlenda Childrawi and Stephanie HollisPatterns in NatureTopic 13: Movement of Chemicals in Plants and AnimalsDOT Point(s)Explain the relationship between the requirements of cells and the need for transport systems in multicellular organisms.Compare the roles of the respiratory, circulatory and excretory systemsCompare open and closed circulatory systems using one vertebrate and one invertebrate as examples

bridlepath.wordpress.comMovement of ChemicalsFor the normal functioning of plants and animals, chemical substances needed by the organism must be transported into and around the body.

Waste substances also need to be transported from where they are produced to the outside of the body.

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Movement of ChemicalsExamples of the movement of chemicals from the external environment into the organism include:Oxygen from the air into an animal for respirationCarbon dioxide from the air into a plant for photosynthesis

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Movement of ChemicalsExamples of the movement of chemicals from inside an organism to the outside include:Wastes such as carbon dioxide or urea out of an animalOxygen produced by photosynthesis carried out of a plant

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Movement of ChemicalsExamples of the movement of chemicals within the organism from the site where they have been produced to the site where they will be used or expelled:Food carried from leaves in plants to storage organsOxygen carried from the lungs of an animal to the muscle cells where energy is requiredCarbon dioxide carried from the muscle cells where it is a waste to the lungs where it can be expelledChemical messengers such as hormones from glands where they are produced to organs where they act (in animals)

nhptv.orgMovement of ChemicalsIf the chemicals that are being moved into the body, within the body or out of the body are gases, this movement is termed gaseous.

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Movement of ChemicalsWhen gases move into and out of an organism they need to move across the surface of the body. In some organisms this could be a general movement across the entire body surface, but in most, a special surface area has been developed for this to occur. This is called the respiratory surface.

What process do you think this gaseous exchange involved???

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The Respiratory SystemThe terms breathing, respiration and gaseous exchange are all related but do not mean the same thing. Respiration: a biochemical process occurring in all cells (inside mitochondria) in which energy is released from nutrients (food) that had combined with oxygen.Breathing: a mechanical rhythmic process to allow an organism to inhale and exhaleGaseous exchange: a physical process where gases move by diffusion, often across cell membranes.

nhptv.orgThe Respiratory SystemThe respiratory system enables organisms to take in oxygen and remove carbon dioxide from their bodies. It allows gaseous exchange between an organism and its external environment.mariemakings.blogspot.com

The Respiratory SystemGaseous exchange may take place externally (between the external environment and internal environment) or internally (between different parts of an organism's internal environment) For example, In mammals:Externally: oxygen moves into the lungs, across the surface of the air sacs and into the blood stream. Carbon dioxide moves out of the bloodstream into the air sacs and out of the lungsInternally: Oxygen moves from the bloodstream out of a blood vessel, into the surrounding cells. Carbon dioxide moves from the cells into the bloodstream.nhptv.orgThe Respiratory SystemThe respiratory system is made up of tissues and organs that are specialised for gaseous exchange. In animals the respiratory organs are varied, such as lungs in mammals, gills in fish and a tracheal system in insects.

See handout figure 4.2 (Bio in Focus Text pg 158)sci.sdsu.edu

Movement of ChemicalsIn large, multicellular organisms, special systems called transport systems, are needed to ensure the efficient movement of substances within their bodies.

Well now explore these special systems.

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Transport SystemsWe already know, unicellular organisms are so small that their surface area to volume ratio is adequate (large enough) to allow them to rely on simple diffusion to supply their bodies with the requirements needed to survive.

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Transport SystemsMulticellular organisms are bigger in size and so their total surface area to volume ratio is smaller. Cells near the centre of these organisms would be way to far away from the surface for substances from the outside environment to reach them efficiently by diffusion and osmosis.

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Transport SystemsSome large organisms are also very active and need more nutrients and oxygen to provide them with the energy they need. They also produce more wastes which need to be removed. To efficiently do this an effective transport system is required.

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Transport SystemsAn effective transport systems have the following features:A system of vessels in which substances are transportedA way of ensuring the materials flow in the correct directionA medium in which the chemicals can be carriedA mechanism to ensure substances are released where they are needed and picked p from where they are not needed.

In animals this system is called the circulatory system.

nhptv.orgThe Circulatory SystemThe Circulatory system carries substances needed by the body from their point of entry into the body (or from their site of production) to the parts of the body where they will be stored or used.

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The Circulatory SystemIn animals, nutrients are carried in a fluid medium (most often the blood) that circulates the body, picking up and dropping off chemicals.

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The Circulatory SystemThe main functions of the circulatory system are:Transport of gases (oxygen and carbon dioxide), nutrients, waste products, hormones and antibodies.Maintenance of a constant internal environment (pH, ions, blood gases and osmotic pressure)Removal of toxins and pathogensDistribution of heat

nhptv.orgThe Circulatory SystemA circulatory system is classified as closed or open depending on the flow of its transport fluid. Closed Circulatory System: the transport fluid flows in vessels only. (characteristic of all vertebrates such as fish, frogs, reptiles, birds and mammals)Open Circulatory System: at some stage of circulation the transport fluid leaves the vessels and enters spaces or cavities in the body bathing the organs directly. (characteristic of invertebrates such as spiders, insects, crabs and snails)

nhptv.orgThe Circulatory SystemIn both open and closed circulatory systems, the blood vessels are responsible for the transport of blood and its contents, but the capillary networks (closed system) or fluid in the body cavity (open system) carry out the other functions to maintain a stable internal environment.tutorvista.com

The Excretory SystemWeve discussed how chemicals enter and are moved around the body, the last thing we will look at is how waste chemicals are removed from the body which is called excretion.

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The Excretory SystemExcretion involves expelling metabolic wastes (wastes that have been made by cells as a by-product of metabolism) from the body.

This is not the same as passing undigested food or faces sureshnzb.webnode.com

The Excretory SystemNitrogenous wastes are the main excretory wastes in vertebrates and are toxic if they accumulate in the body. As their name suggests, they contain the chemical element nitrogen which cannot be stored in the body.tutorvista.com

The Excretory SystemThe most common examples of nitrogenous wastes that are excreted are the substances urea, uric acid and ammonia. These wastes are transported from where they have been produced to where they will be excreted.

marietta.eduThe Excretory SystemThe main function of the excretory system is to remove metabolic wastes from the transported medium (blood) and to expel them to the outside.Nitrogenous wastes, together with water and substances like salts, they combine to form urine in mammals. The kidneys act as organs of excretion and send this material to the bladder where it is removed from the body.Carbon dioxide is transported to the lungs where it is then exhaled and removed from the bodynhptv.orgActivity-Hand out summary of excretory system found on the teacher resource CD

nhptv.orgHomework-Students to complete Comparing these systems in mammals activity found on teacher resource CD

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