When a group of different tissues work together they form an organ. Your arm, lor example, is composed of muscle, bone, nerve, connective, skin, and blood tissues. Your brain is also an organ, as are the liver, heart, and many other parts of the body.
A group of organs functioning together form a system. One example is the digestive system, made up of many organs, including the mouth, stomach, and intestines, all acting as parts of a unit to handle food.
In summary, cells form tissues, tissues form organs, and organs form systems that work together to create you as a unique individual. And it is the brain, the most important organ of all, that directs this entire life forcc within the body.
BODY SYSTEMS: HOW YOUR ORGANS WORK
We have now moved from looking at a cell, the smallest unit of life, to the body systems. These parts can be considered similar to the many parts of a car needed to make it run, such as the tires, fuel system, and engine. Even the best Pirelli tires will not move your car from a dead stop to traveling at 55 mph on a highway if the fuel injection system is clogged. The same holds true of your body. Each system depends on the other to keep you healthy and building a strong and muscular body.
Eight different systems work within the body. The first three mentioned below do not deal directly with food, the source of energy. The remaining five work at breaking down food so it can be transported to the cells.
Central nervous system Controlled by the brain, the central nervous system directs every body movement. It works something like a television station receiving messages from camera or audio operators about anything seen or heard on their electronic equipment. The eyes, for example, seeing a beautiful woman, send messages to the brain describing her figure, her smile, and the color of her hair and eyes.
Muscular or locomotor system Every body movement is accomplished by the muscular system. We can see it at work when it is being used for activities like lifting a cup, running, or lifting weights at the gym. What we can't see is that the muscles also make blood circulate and push food through the body.
Reproductive system I have already explained the process of mitosis, which produces new body cells, but more familiar to most people is the reproductive system that gives us the birth of a child. This process is similar to mitosis once the ovum and sperm cells come together and form a zygote, which divides in two, beginning the formation of a new life.
VEGETATIVE SYSTEMS: HOW YOUR BODY PROCESSES FOOD
The following five systems are concerned directly with food, the source of energy that builds your body and keeps it in good repair. Most activities of the vegetative systems are not voluntary, but go
MAJOR ARTERIES OF THE BODY
MAJOR VEINS OF THE BODY
on below the level of consciousness. It is the brain, directing their activities, that makes these systems operate together so food can be chemically changed and made available to the cells.
Digestive system Organs like the stomach and intestine are part of the digestive system, which breaks up food for absorption by the body. Since a detailed study of the digestive process is necessary for an understanding of nutrition, it will be fully discussed later.
Respiratory system For the body to use energy from food it must combine with oxygen from the respiratory system. When we inhale, oxygen is absorbed into the bloodstream, where the red blood cells transport it to every part of the body. An exchange of nutrients and waste materials takes place where capillaries link small arteries and veins. By exhaling, we expel air not used by the body, together with carbon dioxide and water, the waste products of this conversion process. Strenuous exercise increases the conversion rate of food into energy.
Cardiovascular or circulatory system Pumped by the heart and muscles lining blood vessels, the cardiovascular system sends blood to all parts of the body via arteries, veins, and capillaries. When food, respiratory gases, and waste materials have been chemically changed they are transported through the body using this system.
Regulating system The endocrine glands form a regulating system that releases hormones needed for work and growth into the bloodstream. The endocrine glands also supply us with the burst of energy we need when we get excited and want to put up a good fight for something.
Excretory system After all the useful nutrients from food have been absorbed, waste material leaves the body through the excretory system. The kidneys, for example, filter the blood and reabsorb essential substances. Other waste passing through this system includes dead blood cells, worn-out tissue, and excess vitamins and minerals.
This overall view of human physiology and biochemistry should give you an idea of how the body works as a whole, with each unit, from a cell to a system, dependent on the others. Keeping this complex, miniature universe in peak condition depends on understanding the role nutrition plays in building your body from within. In addition to discipline and a good training program, a diet designed for optimal nutrition provides the energy, bodybuilding materials, and mental alertness that give you a true competitive edge as a bodybuilder
The following sections explore in depth the relationship between all food and drink and the body systems. The knowledge gained will eventually enable you to design a nutritional program geared specifically to your own body, temperament, and lifestyle.
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