ESL 91
SPRING, 2002

WanFen 1
WanFen 2

WanFen Li
ESL 91
Spring, 2002

Essay Topic: Explain why it is important to understand the basic principles of diet and nutrition. How does this understanding help us in our everyday lives?

Basic nutrition is the science of food and how the body uses it in health and disease. Nutrition is the basic support for our life. People cannot live without nutrition. In the daily diet, we get energy from food and it maintains our life. Nutrition is very important in our everyday life. It affects our bodies to be healthy or unhealthy.

Our body needs five major groups of nutrients, which are carbohydrates, proteins, fats, vitamins and minerals. Every day we get the food and we have to balance each of the nutrients. Carbohydrates are needed in the diet primarily to supply energy for the body. They have an average value of 4.1 calories per gram. We can get carbohydrate from rice, bread, cereal, and potatoes. Our diet is made up mostly of carbohydrates. We eat cereal for breakfast. For lunch, we eat a sandwich, which is made from bread. We also eat noodles, rice, and chips. These have many carbohydrates. Protein forms important parts of the muscle, blood and bone. It supports growth and maintains healthy body cells. We can find it in meat, fish, eggs, beans, and milk. Fat forms part of the structure of every cell. It is the most concentrated source of energy. It has 9 calories per gram. We can find it in oil, butter, fatty meat, and margarine. Vitamins are organic substances required in small amounts to help promote and regulate the chemical reactions and the process in the body. We can find them in some fruits, milk, and cheese.

In our daily diet, we have a lot of food. What food is healthy? Which is good for your body? Food directly influences your health and body. In the growth period, teenagers and children should eat more than what they need for growth. At that time, they are growing. The protein is good for their bones and muscles. They should get more nutrition from meat, milk, cheese, and fish.

Many girls try to lose weight. They donít let themselves eat much or they just eat a little. This is not good for the people who are in the growth period. That situation may keep them from growing taller. I have experience with this problem. When my body began to grow in every part, the shape of my body became fat. I was worried that I would be very fat, so I forced myself to eat only a little food. I ate the low fat and low calorie food mostly. That caused me not to have enough energy to use in my bodyís growth.

Some food is good for different parts of the body. Fruits and vegetables have a lot of water and many vitamins. When people are in the adolescence, some of them might have acne on the face. Under that situation, eating more fruits and vegetables is good for them. These foods can lessen the acne and they are good for the skin. For example, there is vitamin E in the oranges. It can help the skin to be smoother. Grapes have acidity and it can help the hair to be shinier. Many fruits are good for beauty. In todayís market, many beauty products are made from fruit. For example, lemon is widely used in beauty products. We can make a drink with lemon and honey that is very good for our skin.

In America, many people donít balance their nutrition. They eat too many fatty foods, like butter, ice cream, and fried foods. There are many fat people in America. People donít consider that their diet might cause some diseases, like high blood pressure, diabetes, and heart disease. People should consider their diet. Nutritionists advise people to eat mostly carbohydrates in the daily diet. Second are vegetables and fruits. Third are meats, milk and yogurt. Fourth are the fats, oils and sweets. If people want to lose weight, they need to do exercise and control their diet. Fat people should eat less fatty food. They should eat the low fat and low calorie foods.

Nutrition is important for our health and body. It can influence our life directly. Food and energy are necessary to support life. We canít miss nutrition in our everyday life. We should consider what kind of nutrition is good for our health.

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Mari-Liis Oropev
ESL 91
Spring, 2002

Essay Topic: Explain the meaning of homeostasis. Why is maintaining the body in a state of homeostasis important to our general health and well-being? Some of the problems resulting from a body out of homeostasis were mentioned in the textbook reading. What other negative consequences can you think of?

Homeostasis refers to any process that living things use to actively maintain fairly stable conditions necessary for survival. A thousand automatic reactions take place in our body. These reactions all work to keep our internal environment in the right conditions. The human body maintains steady levels of temperature and other vital conditions, such as body water, oxygen, blood pressure, and blood glucose.

Homeostatic reactions are inevitable and automatic if the system is functioning properly. Sometimes we can feel that our body needs something. When we are running, we start to breathe harder because the body needs more oxygen. When we feel hungry, our body lets us understand that energy is needed. We feel thirsty because we lose water in our urine, breathing, and sweating.

Negative feedback is a situation in which an organism automatically opposes any changes. For example the human body uses different kinds of processes to control its temperature at 98.6 degrees Fahrenheit. One of the physical responses to overheating is sweating, which cools the body by making more moisture on the skin. In cold surroundings our body reduces heat loss by sweating less and reducing blood circulation to the skin. In whatever situation we are, our body knows what to do; it either raises or lowers the normal temperature automatically.

Positive feedback is a response to change from the normal condition that increases temperature even more. If our body temperature is 107, the negative system is shut down. The increased temperature speeds up the body chemistry, which causes temperature to rise even more. This cycle of positive feedback can only end in death if not stopped.

Homeostatic reactions are automatic and may be maintained by many systems operating together. Becoming flushed is one of the body's automatic responses to heating. The skin reddens because its small vessels automatically expand to bring more heated blood to the surface where it can cool.

If the minerals such as calcium or phospharus are imbalanced, the body is out of balance. If we have additional calcium, we can lose it by urine. If excess calcium is not lost, it may stay in the body and became toxic. Non-functioning calcium can cause a number of problems. It can lead to plaque on our teeth that irritates our gums. It can also contribute to kidney stones, bone spurs, gallstones and cataracts.

If our calcium level drops to less than we need, we are faced with a new problem. This could leave an excess of phosphorus, which is secreted or retained. If too much is retained, it can became toxic. When there is an excess of phosphorous in our bloodstream, the message will be sent to our body that calcium is needed. The body will pull the calcium right out of the bones causing osteoporosis and other bone disorders.

Minerals donít work by themselves; they only work in relation to each other. This means the whole system can be immobilized if one of the minerals is missing. Vitamins, enzymes, and hormones are unable to function properly. This opens the door to infectious diseases. We have come to believe that colds, flu and other diseases are part of living, but actually they are caused by our body being out of homeostasis.

When the systems in our body are functioning within normal parameters, we are in homeostasis .Our bodyís immune system is able to maintain glorious health where bacteria, viruses and parasites have a difficult time living. Balanced body chemistry is the most important thing in maintaining health.

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Wanfen Li
ESL 91
Spring, 2002

Essay Topic: Explain the meaning of homeostasis. Why is maintaining the body in a state of homeostasis important to our general health and well-being? Some of the problems resulting from a body out of homeostasis were mentioned in the textbook reading. What other negative consequences can you think of?

Homeostasis is one of the fundamental characteristics of living things. It is the maintenance of equilibrium or constant conditions. When anabolism and catabolism, the two processes of the metabolism, are balanced, then the body is in a state of homeostasis or dynamic equilibrium. Homeostasis is important to our general health and well-being.

Homeostasis maintains the internal environment of the body to stop imbalance. Factors such as temperature, salinity, acidity, and the concentrations of nutrients and wastes affect the fitness of our body fluids to maintain life. These properties affect the chemical reactions and keep us alive. We have to build the physiological mechanism to maintain them at a fit level.

The organs and tissues that maintain homeostasis are control systems. They respond to change. Control systems work primarily through two types of mechanism, which are negative feedback and positive feedback. Negative feedback is the most common type of control system. In negative feedback, a change in the internal environment is monitored by the receptor and transmitted to the control center. The control center activates effectors that cancel the effect of the stimulus and rebuild the homeostatic condition. For example, the concentration of calcium in the blood is maintained at 9-11 mg/dl. This is the homeostatic condition. It is maintained as increased Ca++ response when the concentration in blood rises above 9-11, or decreased Ca++ response when the concentration of blood calcium falls below 9-11.

In contrast to negative feedback, positive feedback is relatively uncommon in the human body. In positive feedback, a change in the homeostatic condition is detected by receptors and the information is transmitted to the control center. The control center activates effectors that increase the stimulus. For example, the normal body temperature is 37C. If the outside environment stimulates the temperature to increase, the homeostasis works normally, and that would become fever.

Metabolism is the bodyí s chemical reaction. According to the process of metabolism, the cells change and food changes into energy. Metabolism also maintains the bodyí s temperature and changes complex chemicals into simple substances. Anabolism and catabolism are the two processes of metabolism. Balancing these two processes is important for our body and health. Otherwise, the body would become unhealthy.

Anabolism, the constructive metabolism, is the process of growing new cells and maintaining all tissues of the body. When people become taller or fatter, they need to grow new cells. Those are part of the process of anabolism. Catabolism, the destructive metabolism, is the process of spending energy for all external and internal physical activity. When people are doing exercise, or the heart is beating, they need to use energy. Those are the catabolism processes. The food that people take and the energy that people use should be in the balanced amount. When anabolism is greater than catabolism, then the body gains weight. When catabolism is greater than anabolism, then the body loses weight or becomes diseased.

For example, when a person eats too much, the food changes into energy; then his body gains a lot of energy. If this energy is not used up, it accumulates fat; then the body gains weight and become fatter. On the other hand, when a person cannot eat enough food and he needs to spend a lot of energy, then he cannot have enough energy. His body would lose weight and cannot maintain the tissues. That might lead to hunger and cause disease. Balancing the diet and exercise could help the body to balance the two processes of metabolism.

Maintaining homeostasis is important to our health and well-being. It can support the growth of new cells, maintain the tissues of the body, and produce energy to spend in the physical activity. It can also maintain the bodyís weight and reduce some diseases. It keeps the body normal.

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