Frogs

The two organisms discussed I this report are humans and Frogs. The Taxonomy of an organism includes kingdom, phylum, class, order, family, genus, and species. Humans are classified by the kingdom animalia, phylum chordate, class mammalia, order primates, family hominidae, genus homo, and species homo sapiens. Frogs are classified as kingdom animalia, phylum chordate, and genus and species Rana pipens. A frogs habitat is usually spent on land for most of its adult life. However frogs reproduction and development must take place in water or in a moist place. Some adaptations frogs have that aid in their survival are having thin skin that contains mucus-secreting glands. Also they have two pairs of limbs, which can be used for swimming, jumping or walking.

The anatomy of a frog is very similar to the anatomy of humans. Both humans and frogs have the same kinds of organs and systems of organs. Digestion in a frog begins in the mouth. Although the frog has teeth, they are basically useless. The frogs tongue however is very important. Most of the time the tongue is folded back toward the throat. From here the frog is able to flick out the tongue very fast to catch its prey. The tongue is also very sticky. From the frogs mouth food passes into the stomach by the esophagus. From there the food moves into the small intestine. This is where most of the digestion takes place. There are large digestive glands, the liver and the pancreas, which are attached by ducts. Liquid wastes from the kidneys go through the ureters to the urinary bladder. Solid wastes from the large intestine go into the cloaca. Both the liquid and solid wastes leave the body through the cloaca. The digestive system in humans is much more complicated. In humans digestion beings in the mouth. Once food enters the mouth chewing and saliva starts to break it up and make it easier to swallow. Then the food goes down through the esophagus to the stomach. While in the stomach, contractions of the muscular wall continue to break down food mechanically. Chemical digestion continues when acid and enzymes are secreted into the stomach cavity. Then the food passes through the small intestine. Here enzymes from the pancreas complete the chemical part of digestion. Fat is digested with bile. Bile is made in the liver and stored in the gall bladder. Whatever is left of the food, mostly liquid, enters the large intestine. Here most of the fluid is absorbed. Whatever is not absorbed is passed out of the body through the anus.

The frog, unlike a human, has only a three chambered heart. The frog only has one lower chamber while a human has two, the right and left ventricle. The frog has one muscular ventricle and two thin-walled atria. Blood that leaved the ventricle enters a large blood vessel that branches into two atria's. These then divide into many smaller arteries, which then are divided into capillaries. Veins are used to return blood from the capillaries to the heart. The right and left pulmonary veins carry blood from the lungs to the left atrium. As the frog breaths using air with its lungs the blood is oxygenated. Blood from all the other parts of the body is brought back through three large veins into a thin-walled sac. Blood form the sac enters the right atrium. The right and left atria then empty blood into the ventricle. So therefore blood that is pumped out by the ventricle is a mixture of oxygenated blood that is from the left atrium and deoxygenated blood that is from the right atrium. Circulation in humans is a bit different. Humans have a four chambered heart. The two upper, think-walled chambers are the atria. The two lower, thick-walled chambers are the ventricles. The circulatory system consists of two major pathways. Pulmonary circulation, which is the first pathway, carries blood between the heart and the lungs. Systemic circulation, which is the second pathway, carries blood between the heart and the rest of the body. Pulmonary circulation removes carbon dioxide from the blood and adds oxygen. The only arteries that are able to carry oxygen-poor blood are the pulmonary arteries. Systemic circulation supplies blood to the liver. Capillaries and veins carrying nutrient-rich blood from the digestive organs come together to form the portal vein, leading to the liver. Blood from the liver reenters the systemic circulation through the inferior vena cava. Coronary circulation is a branch of systemic circulation. Coronary circulation supplies blood to the muscle of the heart. The coronary arteries come down both sides of the heart, which branches of going into the heart muscle. Capillaries are then formed when the arteries divide. Most blood is then drained in to the right atrium. Hepatic-Portal Circulation is also a branch of systemic circulation. Hepatic-Portal Circulation carries blood from the digestive track to the liver. This circulation helps to maintain the balance of glucose in the blood. Another type of circulation is Renal Circulation. Renal circulation is a branch of systemic circulation that carries blood to and from the kidneys. As you can see circulation in the human is much more complex than the circulation in the frog.

The Excretory system of the frog is rather simple. Carbon dioxide that is produced by the frog is excreted through its skin. The kidneys excrete other metabolic wastes that are produced by the frog. Urine is formed from wastes that are filtered from the blood. The urine from each kidney is carried by the ureters to the bladder, which is stored there temporarily. From the bladder, the urine passes into the cloaca and out of the body. In the human, excretion takes place in the large intestine. One of the main functions of the large intestine is the reabsorption of water from food. The reabsorption into the capillaries of the large intestine helps the body conserve water. The large intestine also absorbs vitamins that are produced by bacteria that normally live in the large intestine. The large intestine is also in charge of the elimination or excretion of undigested and indigestible materials from the digestive track. As this material, which consists of cellulose, bacteria, bile, and mucus, travels through the intestine it becomes feces. The rectum is where the fecal matter is stored. It is periodically eliminated through the anus.

The frogs' nervous system consists of a brain, a spinal cord, and nerves. Some parts of the frogs' nervous system are the same as those in the human's nervous system. Like humans, frogs have a central nervous system and a peripheral nervous system. The Frog has 10 cranial nerves that originate in the frog's brain. Humans have 12. Also, the frog has only 10 pairs of spinal nerves. Humans have 30 pairs. In the frog the medulla regulates automatic functions such as digestion and respiration. The cerebellum controls body

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