BIOA02H3 Chapter Notes - Chapter 49: Circulatory System, Extracellular Fluid, Heart

• School: UTSC
• Department: Biological Sciences
• Course: BIOA02H3
• Professor: Kamini Persaud

Document Summary

A circulatory system consists of a muscular pump (the heart), a fluid (blood), and a series of conduits (blood vessels) through which the fluid can be pumped around the body. Heart, blood, and vessels are also known collectively as a cardiovascular system. The function of circulatory systems is to transport things around the body. Circulatory systems transport: heat, hormones, respiratory gases, blood cells, platelets, elements of the immune system, nutrients, and waste products. Single-celled organisms serve all of their needs through direct exchanges with the environment. Such organisms are mostly found in aquatic environments or very moist terrestrial environments. Similarly, for multicellular organisms a circulatory system is unnecessary if all of their cells are close enough to the external environment that nutrients, respiratory gases, and wastes can diffuse between the cells and the environment. Small aquatic invertebrates have structures and body shapes that permit direct exchanges between cells and environment.