Study Guide for Chapter 49

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University of Toronto Scarborough
Biological Sciences
Mary Olaveson

Chapter 49 Circulatory System -Circulatory systems 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 -Multi cellular organisms do not need to have a circulatory system if all of its cells are in close contact with the external environment if able to get all the bodys needs from the environment -Circulatory systems carry material to and from all regions of the body to maintain the optimum composition of the interstitial fluids, which in turn serve the needs of the cells. Speed up the delivery of nutrients and deliver them preferentially to the most active tissues. Open circulatory system- extra cellular fluid squeezes through intercellular spaces as the animal moves. - Muscular pumps are usually involved to help pump the fluid in these systems - The contractions of this simple heart propel the extra cellular fluid through vessels leafing to different regions of the body, but the fluid leaves those vessels to trickle through the tissues and eventually return to the heart. - Ex arthropods and mollusks and other invertebrates Closed circulatory system- a system of vessels keeps circulating blood separate form the interstitial fluid. -Blood is pumped through this vascular system by one or more muscular hearts, and some components of the blood never leave the vessels. -Ex vertebrates, annelids, and some other invertebrate groups(earth worms) one large ventral blood vessel carries blood from the anterior end to its posterior end. Smaller vessels branch off and transport the blood to even smaller vessels. In the smallest vessels, respiratory gases, nutrients and metabolic wastes diffuse between the blood and the interstitial fluid. Closed circulator systems have several advantages over open systems: Fluid can flow more rapidly through vessels than through inter cellular spaces, and can therefore transport nutrients and waste to and from tissue more rapidly. By changing resistance in the vessels, closed systems can be selective in directing blood to specific tissues Specialized cells and large molecules that aid in the transport of hormones and nutrients can be kept within the vessels, but can drop their cargo in the tissues where it is needed. Support higher levels of metabolic activity -As circulatory systems become more complex, the blood that flows to the gas exchange organs becomes more completely separated from the blood that flows to the rest of the body. -Complex systems have two separate circuits:
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