. Biology of the vertebrates : a comparative study of man and his animal allies. Vertebrates; Vertebrates -- Anatomy; Anatomy, Comparative. Chordate Characters 11 4. Ventral Heart The heart, which is the headquarters of the circulatory system, is ventrally located in chordates. In other animals, when a heart is present, it is on the dorsal side of the body. 5. Closed Blood System In chordates the blood courses through a continuous system of tubes from heart, to arteries, to capillaries in the various tissues, to veins, and back to the heart again. Most non-chordates, on the other hand, have an
. Biology of the vertebrates : a comparative study of man and his animal allies. Vertebrates; Vertebrates -- Anatomy; Anatomy, Comparative. Chordate Characters 11 4. Ventral Heart The heart, which is the headquarters of the circulatory system, is ventrally located in chordates. In other animals, when a heart is present, it is on the dorsal side of the body. 5. Closed Blood System In chordates the blood courses through a continuous system of tubes from heart, to arteries, to capillaries in the various tissues, to veins, and back to the heart again. Most non-chordates, on the other hand, have an open blood system, that is, one in which the blood may pass freely back and forth between the blood vessels and surrounding spaces or sinuses. The con- trast is remotely like that between the waterworks of a modern city with water and sewage confined to pipes and mains, and the open ponds and streams of the countryside. 6. Hepatic Portal System Although venous systems, beginning in capillaries in the tissues of the body, ordinarily terminate at the heart, there are places where veins not only begin but also end in capillaries. Such a group of veins is known as a portal system. In most chordates, the food-laden blood from the digestive tract passes through a strainer-like capillary network, the liver, before it arrives at the heart to be sent over the hungry body. The group of veins beginning in capillaries in the digestive tract and ending in hepatic (hepat-, liver) capillaries is known as the hepatic portal system. Although other animals have organs that are called "livers" by courtesy, only chordates have a true liver, or clearing house, where the strained blood is reorganized by addi- tion and subtraction of various substances before being distributed to different parts of the body. 7. A Post-Anal Tail. A true tail may be defined as a continuation \r\ ^.y Umbilical of the body axis posterior to the anal exit of the food tube. That part of a lobster, for example, w
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Keywords: ., bookcentury1900, booksubjectanatomycomparative, booksubjectverte
