Term
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Definition
Any animal system that uses a fluid to transport substances within vessels may be called a circulatory system
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Term
Some Invertebrates Have No Circulatory System
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Definition
Cnidarians and flatworms
§ Circulate water in gastrovascular cavity to move substances to and from cells
§ Diffusion meets the cells needs.
§ Drawback: organisms must remain small and/or flat
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Term
Two ways to circulate fluid internally
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Definition
Open circulatory system
Closed circulatory system
Both systems utilize a transport fluid (blood) within one or more vessels and some sort of pumping device to keep blood flowing
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Term
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Definition
found in arthropods and some molluscs
§ Vessels transport blood (actually a mixture of blood and tissue fluid called hemolymph) to open places (termed sinuses) within the body cavity where it directly bathes the organs
§ Body cavity is called a hemocoel
§ Insects have trachae (numerous little air tubes) that supply oxygen-laden air directly to flight muscles
§ Makes up for open circulatory system
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Term
Closed circulatory system
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Definition
found in annelids (earthworms) and all vertebrates
§ Blood never runs free and is always contained in blood vessels
§ Heart pumps blood, which usually consists of cells and plasma, into a system of blood vessels and valves prevent the backward flow of blood
§ Blood moves into capillaries, for exchanges with tissue fluid
§ Blood then moves from small veins into larger veins § Veins return blood to the heart for repumping
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Term
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Definition
O2-poor blood from all regions of body collects in right atrium and then passes into right ventricle, which pumps it into the pulmonary trunk
§ Pulmonary trunk divides into the right and left pulmonary arteries, which carry blood to the lungs
§ As blood passes through pulmonary capillaries, carbon dioxide is given off and oxygen is picked up
§ O2-rich blood returns to left atrium of through pulmonary veins
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Term
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Definition
Arteries contain O2-rich blood and have a bright red
color, but veins contain O2-poor blood
§ Aorta and the venae cavae are the major blood vessels in systemic circuit
§ Coronary arteries are extremely important because they serve the heart muscle itself
§ Portal systems begin and end in capillaries
§ Hepatic portal system takes blood from the intestines to the liver
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Term
Blood’s numerous functions include the following:
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Definition
`Transports substances to and from the capillaries, where exchanges with tissue fluid take place
`Helps defend the body against invasion by pathogens (e.g., disease-causing viruses and bacteria)
`Helps regulate body temperature
`Forms clots, preventing a potentially life-threatening loss of blood
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Term
Cardiac conduction system
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Definition
The SA (sinoatrial) node initiates the heartbeat every
0.85 seconds and is called the cardiac pacemaker
§ Electrocardiogram (ECG) is a recording of the electrical changes that occur in the heart during a cardiac cycle
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Term
Systole refers to contraction of the heart chambers
Diastole refers to relaxation of these chambers
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Definition
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