Hormones:the first step

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The information of hormones are transmitted to target cells through receptors.

Target Cells
How a hormone works is just like the way a radio (a receptor) catches radio wave (hormone) that a radio station (secreting organ) broadcasts. In order to listen to the program, you need to have a radio (a receptor) and also the radio needs to be set to the station you want to listen to.

Target Cells
The cell that has the receptor for a certain hormone is the 'target cell' of the hormone.
Hormone itself reach all cells, but the command of the hormone are transmitted only to the target cells, which has the receptors for that hormone.
The organ that has a lot of target cells is a target organ.

In hormonal system, the route of orders from sender to recipient is blood vessels. The hormone effects only the cells that have the receptor to a certain hormone, and tells the orders. You can call the cell, the target cell.Though hormone can be conveyed to the cell which has no receptor, it doesnft make sense as an order. For example, though estrogen secreted from ovary can be conveyed to all cells of our body, it effects only the target cells like muliebria or fatty tissue.

Target Cells
When you focus only on the target cell, please refer to the figure on the left. Secretion of a hormone from hormone-secreting organ increases, and the hormonal concentration in the plasma increases. As a result, orders to target cells increase. The target organ obeys the order and increases or decreases its activity. As a result to that, a certain effect appears. We will stick to the left figure in this text for a while.

Achievement Quiz
1. Secreted hormones are conveyed to only target cells. [a right / b wrong ]

2. The cell that has the receptor to a certain hormone [a receives / does not receive]the information that the hormonal secretion increased.

3. The cell that doesn't have the receptor to a certain hormone [a receives / does not receive]the information that the hormonal secretion increased.

4. A target cell of a certain hormone [a has/ doesn't have]the receptor of the hormone.
Answer
1. The correct answer is b. Can a substance which is secreted internally be conveyed only to particular cells?

2. The correct answer is a. The cell has the receptor,so it receives the hormone as well as the order of the hormone .

3. The correct answer is b. If a cell doesn't have a receptor, it receives the hormone but not the order of the hormone.

4. The correct answer is a. No receptor means no order from the hormone, which means no effects.
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