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Animal Systems

Endocrine System - On a Molecular Level

The endocrine system is one of the more difficult systems that you will learn about in class. Most of the activities of the system are not seen and you probably don't know that anything is happening. You definitely won't see any obvious problems, only the results of problems. Most of the early information about the endocrine system came from studying things that went wrong with the system.

Even today, there are still many mysteries related to this system and it's activities. The best description we can offer is to describe the endocrine system as the chemical brother of the nervous system. While the nervous system transmits information and instructions using electricity, the endocrine system transmits information with chemicals and biological compounds.

What Does This System Do?

This system controls many of the biochemical pathways that occur in your body. The core tool used by the endocrine system is a compound called a hormone. Your body uses dozens of hormones to regulate your growth, digestion, body temperature, and glucose metabolism (to name a few). A hormone released by an endocrine gland can travel throughout the body and change the activity of cells from many other systems. The endocrine system is also unique in that it uses glands and cells within organs that are all closely related to other systems.

Interacting with Other Systems

We don't know where to begin the discussion of endocrine interaction with other systems. The endocrine system is everywhere and the chemicals produced by the system act in a variety of ways on every cell of your body. The circulatory system is the transport system for endocrine information. While the nervous system uses neurons, the endocrine chemicals and hormones must circulate through the body via blood vessels.

Many glands in your body secrete hormones into the blood. You have a pituitary gland in the base of your skull that releases hormones that control blood pressure and your excretory system. You have a thyroid gland in your neck that controls your bone growth rate and metabolism. You even have a tiny little adrenal gland above your kidneys that releases adrenalin if you get excited. Endocrine glands are everywhere.

Diseases of the System

Because our endocrine system is very delicate, many things can go wrong. An extreme example is if a gland stops working, but they are more likely to work more or less than they should. If you don't get enough iodine in your food, your thyroid gland can have big problems and grow to the size of a baseball called a goiter. Other common problems with your thyroid can increase your body's metabolism and make you jumpy and sweaty (hyperthyroidism) or decrease the levels and make you sluggish (hypothyroidism). Some individuals have a problem making insulin in their pancreas. Those individuals have a disease called diabetes and they are not able to metabolize carbohydrates correctly. They must often take injections of insulin to counteract the problem.

Next Page on Animal Systems
- Overview
- Regulation
- Skeletal
- Muscular
- Circulatory
- Respiratory
- Digestive
- Excretory
- Nervous
> Endocrine
- Integumentary
- Immune
- Lymphatic


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Useful Reference Materials (Endocrinology):
Encyclopædia Britannica:
Books on
- Modern Biology (Rinehart and Holt)
- Campbell Biology: Concepts and Connections (Reese, Taylor, Simon, and Dickey)
- Prentice Hall: Biology (Miller and Levine)
- Principles of Human Physiology (Silverthorn)
- Principles of Human Physiology (Stanfield)

- Chem4Kids: Metabolism
- Chem4Kids: Enzymes
- Geography4Kids: Populations
- Geography4Kids: Carbon Cycle
- Geography4Kids: Oxygen Cycle
- Geography4Kids: Nitrogen Cycle

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