The foundations of the endocrine system are the hormones andglands. As the body's chemical messengers, hormones transfer information and instructions from one set of cells to another. Although many different hormones circulate throughout the bloodstream, each oneaffects only the cells that are genetically programmed to receive and respond to its message. Hormone levels can be influenced by factors such as stress, infection, and changes in the balance offluid and minerals in blood.
A gland is a group of cells that produces and secretes, or gives off, chemicals. A gland selects and removes materials from the blood, processes them, and secretes thefinished chemical product for use somewhere in the body. Some types of glands release their secretions in specific areas. For instance, exocrine glands, such as the sweat and salivary glands, releasesecretions in the skin or inside of the mouth. Endocrine glands, on the other hand, release more than 20 major hormones directly into the bloodstream where they can be transported to cells in other partsof the body.
Parts of the Endocrine System
The Adrenal Glands
The adrenal glands produces a set of hormones called corticosteroids.
The Pineal Gland and Gonads
The pineal gland islocated in the middle of the brain. It secretes melatonin, a hormone that may help regulate the wake-sleep cycle.
The gonads are the main source of sex hormones. In males, the testes are located inthe scrotum. The female gonads, the ovaries, are located in the pelvis.
The hypothalamus is a collection of specialized cells that is located in the lower central part of the...