COMPARING VERTEBRATE BODY SYSTEMS Skeletal Systems Digestive Systems Circulatory Systems Respiratory Systems Nervous Systems

COMPARING BODY SYSTEMS The job any machine can do depends upon its parts and their arrangement. A saw is able to cut wood because it has teeth. A sewing machine can pierce cloth because it has a needle. Every kind of animal and every kind of plant also has its own peculiar structure. How and where it can live depends upon its structure.

In comparative anatomy the structures of various animals are studied and compared. The drawings (next slide) show the digestive systems of the earthworm, the fish, and the frog. The colored lines trace the animals' digestive tracts. As can be seen, the systems are alike in many ways. Each animal has a mouth, a pharynx, an esophagus, an intestine, and an anus. There are also differences. For example, the frog and the fish have livers whereas the earthworm has a gizzard. The differences enable each animal to digest the food found where it lives.

The drawings show other organs that equip each animal for its way of life. The fish, which lives in water, has gills through which it breathes. It has no lungs. The frog, which lives on land as well as in water, is equipped with lungs for air breathing. The earthworm has neither lungs nor gills. It breathes through its skin.

YOUR TASK: Understand the basic function of each body system. Sketch the system in each vertebrate class if possible. Find the common elements of the system that are in all classes. Find the elements that are unique to a particular class. How do the body features help this creature survive in his ecological niche?

Skeletal Systems Vertebrates have a more or less rigid group of structures composed of cartilage or bone or of a combination of these two connective tissues. In vertebrates, the skeleton formed in the embryo is initially cartilaginous; bone and calcium are deposited as the organism matures. In humans, the process of bone hardening, or ossification, is completed at about the age of 25. The last bone to ossify is the breastbone. The total number of bones in any animal varies with its age; many bones fuse together during the ossification process. The average number of bones in a young human is 200, exclusive of the 6 ossicles found in the ears.

SKELETAL SYSTEMS: FISH Why does a fish have more vertebrae than other vertebrate animals? Why is the skull shaped this way?

SKELETAL SYSTEM:FROG Why does a frog have no ribs? Why are the toes and fingers (phalanges) so long? Why is the trunk so short and the legs so long?

SKELETAL SYSTEMS: TURTLE What is different about a turtle’s vertebrae? Why is it like that? Why are the legs so short? Why are there fewer vertebrae in his neck than in a bird or human?

BIRD SKELETON A bird's skeleton must be light so it doesn't weigh the bird down, yet strong enough to stand the strain of flying. - The bones are thin and hollow, making them very lightweight. The hollow wing bones of large birds have inner braces called struts that keep the bone strong, yet light. The breast bone has a long ridge, or keel, that forms a large place for the powerful wing muscles to attach. The skull bones are thin, paper-like sheets of bone that are very light. The overlapping ribs, together with the breastbone and backbone, form a strong, flexible frame for the attachment of wing muscles. Finger bones are connected together for greater wing strength.

SKELETAL SYSTEMS: BIRD Why are a bird’s bones hollow? What is the function of the “keel”? (Think about white meat on a turkey or chicken!) Why are there so many vertebrae in a bird’s neck? What ability does that give a bird? Why is that vital?

SKELETAL SYSTEMS: HUMAN Humans have an opposable thumb. Why does that matter? Why is there a curve to a human spine? What does the pelvis do in a human?

COMPARING VERTEBRATE BODY SYSTEMS Skeletal Systems Digestive Systems Circulatory Systems Respiratory Systems Nervous Systems

VERTEBRATE DIGESTIVE SYSTEMS What happens to food after it is eaten? The all creatures use various kinds of food for energy and growth. To be used, however, food must be changed into a form that can be carried through the bloodstream. The body's process of extracting useful nutrients from food is called digestion.

STOMACH The saclike expansion of the alimentary canal between the esophagus and the small intestine is called the stomach. It is a hollow, muscular organ that stores food and passes it along in small amounts to the intestines for digestion. In some animals the stomach also partially digests the food.

LIVER From the blood, the liver cells take up excess sugar, which is in the form of glucose, and convert it to glycogen for storage. Whenever blood sugar levels drop, glycogen is reconverted to glucose and added to the blood. If the liver uses up its full capacity to store glycogen, it converts glucose to fat for storage in fatty tissue. This fat is reconverted to glucose when glycogen stores are consumed. Amino acids, the products of digested proteins, are also taken up; some are stored and some processed into new blood proteins. Vitamins and minerals--especially A, D, B12, and iron--are also stored in the liver and added to the blood as needed.

INTESTINES The lining of the small intestine contains many folds. These folds increase the surface area that can be in contact with the food products. The lining surface of the intestinal folds is further increased by many microscopic fingerlike projections called villi. The digested food is passed through the cell membranes of the villi into the blood and lymph, which carry it to the cells. The body can then use the food for energy and growth. Peristalsis moves material through the intestine.

VERTEBRATE DIGESTIVE SYSTEMS: FISH What is the function of the liver, stomach and intestine?

VERTEBRATE DIGESTIVE SYSTEMS: FROG Why does a frog have a urinary bladder but a fish doesn’t? What is the difference between the large intestine and the small intestine? Why would a frog have both large and small intestines but not a fish?

VERTEBRATE DIGESTIVE SYSTEM: TURTLE In general, carnivores have shorter intestines than herbivores or omnivores. Why would that be?

VERTEBRATE DIGESTIVE SYSTEMS: BIRD Why is it helpful to a bird to not have a heavy jaw and teeth? Why does a bird have a gizzard? What does the crop do?

BIRD DIGESTION Instead of a jaw, with heavy bones, teeth, and muscles, a bird has a slender beak. The work of chewing is done by the crop, in which preliminary food breakdown occurs, and by the gizzard, a part of the stomach where food is ground up.

VERTEBRATE DIGESTIVE SYSTEMS: HUMAN

COMPARING VERTEBRATE BODY SYSTEMS Skeletal Systems Digestive Systems Circulatory Systems Respiratory Systems Nervous Systems

VERTEBRATE CIRCULATORY SYSTEMS The cardiovascular, or circulatory, system is composed of the heart and the blood vessels--arteries, veins, and capillaries. Its purpose is to provide nutrients and oxygen to the tissues and to remove wastes from them. It is also where the body fights infections. Circulation of blood consists of two main circuits. Pulmonary circulation carries blood from the heart to the lungs where waste gases, mostly carbon dioxide, are removed from the blood, and oxygen is taken on by hemoglobin in the erythrocytes, or red blood cells.

WATCH THE HEARTS!! Quickly sketch each kind of heart. Pay attention to circulation patterns. Observe how warm-blooded and cold-blooded hearts are different.

HUMAN HEART Human heart and circulatory system.

VERTEBRATE CIRCULATORY SYSTEMS: FISH What does the red and blue coloration represent? Why does the circulatory system include the gills?

VERTEBRATE CIRCULATORY SYSTEMS: FROG How is a frog heart different from a fish or human heart? Why? What parts are found in all hearts?

REPTILE CIRCULATION The internal organs of reptiles are similar to those of birds and mammals. No reptile has gills; all rely on well-developed lungs for respiration. The reptile heart has a divided atrium, which receives blood from the lungs and body; the heart's ventricle, which pumps blood out of the heart, is partially divided in most reptiles. Crocodiles and alligators, however, have two separate, complete ventricles and thus have four-chambered hearts as do birds and mammals.

VERTEBRATE CIRCULATORY SYSTEMS: TURTLE Why would a turtle’s heart be different from another reptile like a crocodile? Compare a turtle heart to fish and frog hearts.

BIRD RESPIRATION Birds are warm-blooded animals, like human beings. They live at a much faster pace, however. Flying takes a great deal of energy, and all their life processes are speeded up. The body temperature of a bird is higher than that of most other animals. A human being's normal temperature is 98.6o F (37o C). The swift has a temperature of 111.2o F (44o C); a duck, 109.1oF (42.8o C); a heron, 105.8oF (41o C); some thrushes, 113oF (45o C); and sparrows, 107oF (41.6o C). A bird's heart beats faster than a human heart, and birds breathe more rapidly than humans. The human heart beats, on average, 72 times a minute. The hummingbird's heart beats, on average, 615 times a minute. Because of their high rates of metabolism, birds burn up calories very quickly. Small birds must eat almost constantly during the daylight hours.

VERTEBRATE CIRCULATORY SYSTEMS: BIRD Why would a bird heart be a four-chambered heart like mammalian hearts?

VERTEBRATE CIRCULATORY SYSTEMS: HUMAN What is the difference between the left side of the heart and the right side? Why are the right side chambers thinner walled then the left side?

COMPARING VERTEBRATE BODY SYSTEMS Skeletal Systems Digestive Systems Circulatory Systems Respiratory Systems Nervous Systems

RESPIRATORY SYSTEMS All living things need oxygen. Oxygen enables them to metabolize, or burn, nutrients, releasing the energy required to grow, reproduce, and maintain life. In the metabolic process, oxygen combines with the carbon in food and forms carbon dioxide as a waste product. The respiratory system is an organism's apparatus for taking in oxygen and expelling carbon dioxide and water vapor.

GILLS Most fish breathe by means of gills. They consist of many tiny filaments supplied with blood vessels. Water enters the open mouth. Then the fish closes its mouth and the water is forced over the filaments and out through the opercula. Oxygen dissolved in the water is absorbed into the bloodstream through the delicate membrane of the filaments. Inside the mouth are straining devices called gill rakers. They prevent food and debris from passing over and injuring the gills.

LUNGS Lung Details Lung View

VERTEBRATE RESPIRATORY SYSTEMS: FISH Why are gills different from lungs? In what ways are gills like lungs?

VERTEBRATE RESPIRATORY SYSTEMS : FROG A frog can breathe through his skin as well as his lungs. What would you predict that a cross-section of skin would be like? What happens to a frog when you handle it?

VERTEBRATE RESPIRATORY SYSTEMS: TURTLE A turtle does not breathe through his skin. How would you predict that the relative size of frog and turtle lungs would compare?

VERTEBRATE RESPIRATORY SYSTEMS: BIRD A bird’s lungs are enormous compared to his body size.Why would a bird have bigger lungs?

BIRD RESPIRATION Birds never get out of breath, because they have very strong hearts and a breathing system that works very well. The movement of a bird's wings pushes in on the lungs and air sacs, causing old, stale air to move out of them. Then fresh air can move in. The faster a bird flies, the more the wings push on the lungs, and the more the oxygen moves into the lungs and air sacs. This gives the bird all of the oxygen it needs for the hard work of flying.

VERTEBRATE RESPIRATORY SYSTEMS: HUMAN Why are there blue and red lines drawn through these lungs? Lungs and gills have a high “surface to volume ratio.” What does that mean? Why do they all have it? Why must lung and gill surfaces remain moist?

COMPARING VERTEBRATE BODY SYSTEMS Skeletal Systems Digestive Systems Circulatory Systems Respiratory Systems Nervous Systems

VERTEBRATE NERVOUS SYSTEMS Information about the outside world as well as the inner workings of the body speeds to and from the brain through nerves. Nerves are bundles of the long, tubelike extensions of nerve cells. Impulses fired through them uniquely convey information throughout the body. Nerve impulses travel only in one direction. If information from the stomach, for example, is transmitted to the brain through one nerve, action orders from the brain cannot travel back to the stomach over the same nerve. Another must carry the return message.

NERVOUS SYSTEM: THE BRAIN The brain stem,(medulla oblongata), is involved with the most basic processes, such as relaying information between parts of the brain or between the brain and the body and regulating basic body functions. The cerebellum, behind it, controls balance and coordination. The cerebrum, the topmost part of the brain, is the "thinking" part of the brain. Pay close attention to the relative size of brain parts. They give important clues about behavior.

VERTEBRATE NERVOUS SYSTEMS:FISH Which is larger, the olfactory bulb (controlling smell signals) and the optic lobe (controlling sight)? What does that tell you? The cerebrum is much smaller than the medulla oblongata. What does that tell you?

FISH NERVOUS SYSTEM The brain of a fish is very simple. The cerebrum, which in humans is the center of thought and reasoning, is missing entirely, though a fish has a sensitive nervous system. The eye is similar to that of other backboned animals. Fish are usually nearsighted but can distinguish colors. Eyesight may be very sharp. The archerfish feeds by knocking insects off of twigs several feet above the surface of the water with a drop of water spit from its mouth. The sense of smell is located in deep pits in the head. In some fish it is very keen. Sharks are attracted from a great distance by the odor of blood. Fish do not have ears, but a hearing apparatus is buried deep in the head.

VERTEBRATE NERVOUS SYSTEMS:FROG Which is larger, the olfactory bulb (controlling smell signals) and the optic lobe (controlling sight)? What does that tell you? Compared with a fish, the cerebrum is much larger in a frog and the medulla oblongata is smaller. What does that tell you? Why does a frog need such a large optic lobe?

VERTEBRATE NERVOUS SYSTEMS:TURTLE Which is larger, the olfactory bulb (controlling smell signals) and the optic lobe (controlling sight)? What does that tell you? Compare the cerebrums of fish, frog and turtle. Is there a pattern? Compare the cerebellums of fish, frog and turtle. Is there a pattern? Compare the medulla oblongatas of fish, frog and turtle. Is there a pattern?

REPTILIAN NERVOUS SYSTEM The reptile's senses of sight, smell, and hearing are similar to those of other vertebrates, though the levels of development of these senses vary among reptile groups. Snakes lack ears and can detect only ground vibrations or airborne vibrations of low frequency. Snakes and lizards have a specialized, chemically sensitive organ, called Jacobson's organ, located in the roof of their mouths. These animals can detect the presence of chemicals in their surroundings by flicking their tongues out and in rapidly, pressing the tongue against the organ with each retraction. Heat-sensitive organs line the lips of some boas and pythons and are also located on the sides of the heads of pit vipers. Thus, because the pit vipers can sense infrared radiation, they can detect and strike their prey even in total darkness.

VERTEBRATE NERVOUS SYSTEMS:BIRD Which is larger, the olfactory bulb (controlling smell signals) and the optic lobe (controlling sight)? What does that tell you? Compare the cerebrums of each successive creature. Is there a pattern? Compare the cerebellums of each successive creature. Is there a pattern? Compare the medulla oblongatas of each successive creature. Is there a pattern?

VERTEBRATE NERVOUS SYSTEMS:HUMAN Can you find the olfactory and optic centers? What does that tell you about relative sensory capacity? Humans have the largest relative cerebrums. Why would that be?