Part 1 Single and Double Circulatory systems Levels

Part 1: Single and Double Circulatory systems

Levels of Organisation (from Year 9) CELLS are the smallest structural and functional unit of every organism. Groups of cells with similar structures, performing a shared function form a TISSUE. An ORGAN is a structure made up of a group of tissues, working together to perform a specific function. Several organs with related functions working together to perform a body function form an ORGAN SYSTEM. Groups of organs systems together make up an ORGANISM.

Why is it called the ‘circulatory system’? Organs: Heart + Vessels (these CELLS are the smallest structural and are functional unittoofbe every organism. considered tubular-like organs) Groups of cells with similar structures, Related – a pump performingfunctions a shared function form athat TISSUE. pushes blood around the body, An ORGAN isoxygen a structure made up ofcells, a group delivering to respiring of tissues, provide working together to perform a vessels a transport system specific function. for blood ensuring one-way flow! Several organs with related functions working together to perform a body function form an ORGAN SYSTEM. Groups of organs systems together make up an ORGANISM.

Amoeba: unicellular protozoan Tapeworm: flatworm 1 mm thick. Earthworm: round and segmented worm.

Functions of the Circulatory System To carry O……………. . to all the cells in the body To carry F…………. to all the cells in the body To remove W…………… from the cells of the body To distribute H……………. around the body To form part of the D………………. . the body has against microbes (harmful organisms) To H………………. itself and prevent blood loss by clotting

Study the diagram: Why do you think this is called a single circulatory system? Blood has to pass through two capillary systems, those of the gills and the body, before returning to the Heart. This results in a marked drop in blood pressure before the blood completes a circuit - exchange of materials is not so good; adequate for fish but not mammals. *Single links to heart with 2 chambers

Study the diagram: Why do you think this is called a double circulatory system? Bonus Q 1) Describe the pathway that the blood takes during one circulation. Bonus Q 2) What are the advantages of this system?

• A suitable medium in which to carry materials. This is normally a liquid based on water i. e. ……………. . • A closed system of tubular vessels that contains the transport medium i. e. ……………. . • A mechanism for moving the transport medium within the vessels i. e. ……………. . • A mechanism to maintain the flow of the medium in one direction i. e. ……………. . • A means of controlling the flow to meet the changing needs of the organism i. e. ……………. .

By meticulous dissection and ingenious experiments Harvey showed that the blood flows away from the heart in arteries and returned in veins. On tying a ligature around the upper arm, the valves in the veins show up as small swellings. If blood is pushed up to a point above one of these swellings, it fails to flow back even if pushed, indicating that the normal direction of blood flow is towards the base of the arm. However, he was unable to demonstrate the existence of vessels connecting the arteries and veins.

Conduct some research into the historical discoveries of circulation including contributions from the following six people: Galen, Harvey, Malphigi, de Vinci, Vesalius and Fabricius. A mini timeline would be useful