VOCABULARY ABOUT UNIT 4

Cheer up: When you feel happy about something. When you make someone happy you cheer up someone.
Slow down: To stop doing something.
Chill out: The action of realxing for example listening to music or going to the cinema with friends.
Open up: When you open up to someone you tell him your problems, what's wrong...
Face up to: The action of deal aganist your problems...

AEROBIC AND ANAEROBIC METABOLISM

Explain in detail the differences between the aerobic and anaerobic metabolism and explain the differences between them.

Definition of metabolism and when it occurs.

Metabolism refers to the processes your body uses to break down nutrients, form compounds the cells can use for energy and use those compounds to fuel cellular functions. Your body secretes enzymes to break down food into sugars, proteins, and fats. Then each cell of your body can take these in and use them in aerobic or anaerobic metabolic processes to form adenosine triphosphate (ATP) which is the fuel used in the cell. The calories from food are burned in this way to produce energy in each cell. Your body's overall metabolism includes muscle contraction, breathing, blood circulation, maintaining body temperature, digesting food, eliminating wastes, and the functions of the brain and nervous system. The rate at which you burn calories is called your metabolic rate.

During exercise, you not only increase metabolism in your muscles but also in your respiratory and circulatory systems. You need a faster rate of breathing and heart rate to deliver oxygen and nutrients to your muscles. Your body also must work harder to prevent overheating, such as through sweating.

Your body uses two types of metabolism during exercise to provide the fuel needed for your muscles.

Anaerobic metabolism:

Anaerobic metabolism is the creation of energy through the combustion of carbohydrates in the absence of oxygen. This occurs when your lungs can't put enough oxygen into the bloodstream to keep up with the demands of your muscles for energy. It generally is used only for short bursts of activity, such as when you go for a sprint when running or cycling or when you are lifting heavy weight.

When there isn't enough oxygen in the bloodstream, glucose and glycogen can't be fully broken down to carbon dioxide and water. Instead, lactic acid is produced, which can build up in the muscles and degrade muscle function.

Aerobic metabolism:

Aerobic metabolism is the way your body creates energy through the combustion of carbohydrates, amino acids, and fats in the presence of oxygen. Combustion means burning, which is why this is calling burning sugars, fats and proteins for energy. Aerobic metabolism is used for the sustained production of energy for exercise and other body functions.

Examples of exercises that use aerobic metabolism include walking, running, or cycling with sustained effort.

Your body will often switch aerobic and anaerobic metabolism during sports and exercise activities that require short bursts of sprints as well as sustained jogging, such as in soccer, tennis and basketball.

Aerobic metabolism vs anaerobic metabolism.

Anaerobic metabolism is not as efficient as aerobic metabolism. A molecule of glucose can only produce three ATP molecules under anaerobic metabolism, while it produces 39 with aerobic metabolism. ATP is what fuels the muscles.

Anaerobic metabolism can only use glucose and glycogen, while aerobic metabolism can also break down fats and protein. Intense bouts of exercise in the anaerobic zone and in the red-line zone with a heart rate over 85 percent of your maximum heart rate will result in using anaerobic metabolism to fuel the muscles.

While your body will naturally use the energy pathways that will best get the job done, you have a choice in how strenuously you exercise. Training programs for different sports and activities are designed to make the best use of aerobic and anaerobic metabolism.

• Aerobic metabolism requires oxygen, whereas anaerobic metabolism does not.

• Anaerobic metabolism cannot continue indefinitely. In contrast, aerobic metabolism can continue forever, only under theoretical conditions.

• Carbohydrate, fat, and proteins are used as sources of aerobic metabolism while only carbohydrate is involved for anaerobic metabolism.

• Aerobic metabolism involves low to moderate intensity activities, whereas anaerobic metabolism involves only high intensity activities.

• Anaerobic metabolism takes place in the cytoplasm of cells while aerobic metabolism occurs in mitochondria.

• Aerobic metabolism produces more energy than anaerobic metabolism if the same amount of the same substrate.

• Glycolysis is an anaerobic metabolic pathway, whereas citric acid cycle and electron transport chain are aerobic metabolic pathways.

• Aerobic metabolisms contribute more (around 90%) for the supply of energy while anaerobic metabolism contributes less.

• End product of anaerobic metabolism is lactic acid while that of aerobic metabolism is carbon dioxide and water.