![]() The frog is covered by a soft, thin, moist skin composed of two layers, an outer epidermis and an inner dermis (see Skin). The liquid plasma carries solid elements such as red blood cells and white blood cells. These carry the oxygen-laden blood to the tissues.įrog blood has both a solid and a liquid portion. The lung vessels, however, are filled with oxygen-poor blood, blocking the oxygen-laden blood and forcing oxygen-laden blood to detour into the arteries. When the oxygen-poor blood flows from the ventricle into vessels leading to the lungs, the oxygen-laden blood tries to "follow" it. The pool of oxygen-poor blood at the bottom of the ventricle holds up the oxygen-laden blood and prevents it from sinking to the bottom. Meanwhile, oxygen-laden blood is received by the left atrium and enters the same single ventricle. This causes oxygen-poor blood entering the right atrium to pass all the way down to the bottom of the ventricle. Instead of "perching" on top of the ventricle, the right atrium dips downward into the ventricle. Such mixing is prevented by a unique arrangement of the frog's heart. The oxygen-laden and oxygen-poor bloods, however, do not mix. Oxygen-laden blood and oxygen-poor blood containing waste gases are present together in the frog ventricle at all times. In man, the lower heart chamber is divided into two compartments, the right ventricle and the left ventricle. The frog heart, however, has only one lower chamber, a single ventricle. There are two upper chambers of the heart, the right atrium and the left atrium. The frog heart is the only organ contained within the coelom which has its own protective covering. Internal organs contain smooth muscle tissue. Skeleton-moving muscles are made of skeletal, or "striated," muscle. The calcaneus in the human skeleton is the heel bone.Īs in other vertebrates, the frog skeleton is moved by muscles (see Muscles). The astragalus corresponds to the human talus. These are the astragalus and the calcaneus. A third division of the frog's leg consists of two elongated anklebones, or tarsals. ![]() In man and in the frog, the femur is the single upper leg (thigh) bone. ![]() Man has two lower leg bones, the tibia and the fibula. The single "shinbone" is the tibiofibula. The hind legs of the frog are highly specialized for leaping. Both frog and man have one "upper arm" bone, the humerus. Man has two forearm bones, the radius and the ulna. The frog has one "forearm" bone, the radio-ulna. The shoulders and front legs of the frog are somewhat similar to man's shoulders and arms. The urostyle, or "tail pillar," is a downward extension of the vertebral column. Only a spikelike bone, the urostyle, remains as evidence that primitive frogs probably had tails. Only nine vertebrae make up the frog's backbone, or vertebral column. The skull is flat, except for an expanded area that encases the small brain. The frog's body is supported and protected by a bony framework called the skeleton (see Skeleton). All the frog's internal organs-including the heart, the lungs, and all organs of digestion-are held in this single hollow space. There is no such partition in the frog's coelom. The human chest is separated from the abdomen by a powerful muscular partition, the diaphragm (see Diaphragm). Man's internal organs are housed in one of three distinct hollow cavities-the chest, the abdomen, and the pelvis. The stubby trunk forms walls for a single body cavity, the coelom. A short, almost rigid neck permits only limited head movement. The flat head contains the brain, mouth, eyes, ears, and nose. The frog's anatomy, however, is much simpler.Īs in other higher vertebrates, the frog body may be divided into a head, a short neck, and a trunk (see Vertebrates). ![]() Both man and the frog have the same kinds of organs and systems of organs. The body structure, or anatomy, of the frog is very similar to the anatomy of man. Here's some information that you may find useful
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