UNIT 2 The nutrition function Natural Science 2. Secondary Education DIFFERENT CIRCULATORY SYSTEMS

UNIT 2 Different circulatory systems CIRCULATORY SYSTEMS Click on each box to find out more two types can be OPENCLOSEDSINGLEDOUBLE Natural Science 2. Secondary Education

They are present in most animals and consist of: A circulating liquid, like blood, that transports substances throughout the organism. Vessels, which the liquid travels through. A pumping mechanism, the heart, which moves the liquid. Circulatory systems Blood vessels: Arteries Veins Capillaries Heart An example of a closed circulatory system, that of a mammal. UNIT 2 Different circulatory systems Go back to the Start menu Natural Science 2. Secondary Education

Found in arthropods and molluscs. The circulating liquid leaves the vessels to bathe the organism’s tissues with oxygen and nutrients. Once substances have been exchanged with the tissues, the liquid is drawn back to the vessels. Animals with open circulatory systems The open circulatory system of an arthropod The circulating liquid is transported through the vessels to the tissues, where substances are exchanged. A hole-filled heart pumps the circulating liquid. UNIT 2 Different circulatory systems Go back to the Start menu Natural Science 2. Secondary Education

Found in vertebrates and some invertebrates, such as annelids. The circulating liquid is only found inside the vessels. The exchange of substances takes place through the walls of the smallest vessels, called capillaries. There are two types: Single Double The closed circulatory system of a fish A heart with no holes pumps the circulating liquid. The circulating liquid stays inside the vessels. Substances are interchanged in the capillaries. UNIT 2 Different circulatory systems Go back to the Start menu Animals with closed circulatory systems Natural Science 2. Secondary Education

Found in some invertebrates and in fish. The heart pumps the circulating liquid, which travels to the respiratory organs, where it absobs oxygen. From there it travels throughout the rest of the body. After interchanging substances with the body, the blood goes back to the heart. The single closed circulatory system of a fish 1: The heart pumps the blood. 2: The blood goes to the gills, where oxygen is absorbed. 3: The blood travels throughout the body interchanging substances. 4: The blood travels from the different organs back to the heart. UNIT 2 Different circulatory systems Go back to the Start menu Animals with single closed circulatory systems Natural Science 2. Secondary Education

Found in land vertebrates. The heart pumps the blood to the lungs in pulmonary circulation. The blood releases carbon dioxide and absorb oxygen. The blood then returns to the heart, where it is pumped to the organs. Substances are interchanged in the organs. The blood then travels from the different organs back to the heart. The double closed circulatory sytem of a bird 1: The heart pumps the blood. 2: The blood travels to the lungs, where it absorbs oxygen, and returns to the heart. 3: The heart pumps the blood again, which flows to different organs. 4: The blood travels from the different organs back to the heart. UNIT 2 Different circulatory systems Go back to the Start menu Animals with double closed circulatory systems Natural Science 2. Secondary Education