Hands Off Glands: The Endocrine System
The Endocrine System
Many diverse parts of the body work together in an amazingly complicated system of actions and reactions. Connecting these parts together and coordinating their actions is the job of the endocrine system.
Parts of the endocrine system
1. Glands (nine total in a person).
2. Hormones—chemical messages.
3. Bloodstream—message delivery system.
Get the Message
Hormones are produced by specific endocrine glands but often function in cells all over the body. What makes the hormones message work only in the correct cells at the right time?
Receptors for specific hormones are located in target cells. The cell can turn the receptors on or off, plus the glands can change the amount of hormone released at a given time.
Feedback Mechanisms
Endocrine glands are controlled by feedback mechanisms that are similar to heating systems in homes. When the temperature goes below the thermometer setting, the thermostat sends a signal to the furnace and the heat starts. When the room reaches a comfortable temperature, the heat turns back off. In the body endocrine glands and their hormones are controlled the same way.
Example: The kidneys control water concentration in the blood. What signal tells the kidneys when to work? A hormone called ADH is secreted when blood water is low. ADH slows down the kidneys so less water is removed. When water in the blood is high, ADH is not secreted and the kidneys start to work again.
Major Glands and their Hormones
|Gland |Location |Hormone |Action |
|Pituitary |base of brain |ADH |water balance; thirst |
| | |Oxytocin & Prolactin |milk production |
| | |FSH |egg release |
| | |LH |egg implantation |
| | |TSH |thyroid stimulation |
| | |ACTH |adrenal stimulation |
| | |GH |growth in cells |
| | |MSH |melanin production |
|Thyroid |neck |thyroxine |metabolism |
| | |calcitonin |decrease calcium in blood |
|Parathyroid |on thyroid |PTH |increase calcium in blood |
|Adrenal |on kidney |corticosteroids |ion balance, nutrient absorption |
| | |(dozens of different types) | |
| | |epinephrine/norepinephrine (adrenaline) |“fight or flight” |
|Pancreas |near stomach |insulin |decrease blood glucose |
| | |glucagon |increase blood glucose |
|Testes |groin |testosterone |sex characteristics, sperm production |
|Ovaries |lower abdomen |estrogen |sex characteristics |
| | |progesterone |maintain uterus for pregnancy |
................
................
In order to avoid copyright disputes, this page is only a partial summary.
To fulfill the demand for quickly locating and searching documents.
It is intelligent file search solution for home and business.