This lesson describes the hypothalamus as it relates to the endocrine system. It will examine the anatomic features of the hypothalamus and how it uses the pituitary gland to communicate with the rest of the body. A short quiz will follow.
What Is a Hypothalamus?
Every organization needs some form of structure in order for messages to be delivered and received. Without methods of communication, order can break down into chaos in a short matter of time. Just try to imagine how much work the employees of an office would be able to get done if they lost access to their phones and email!In the case of the endocrine system, the hypothalamus plays a super-sized role by making decisions about what actions need to be taken by various endocrine glands throughout the body. Its primary purpose is to make sure that the body stays in a continual state of balance, known as homeostasis.
The hypothalamus is only about the size of a pearl, and is located in the middle part of the brain. It monitors the state of the body through the circulatory and nervous systems, and effectively links these two systems to the endocrine system through the pituitary gland.The hypothalamus communicates with the anterior portion of the pituitary gland by way of hormonal messages. Neurosecretory cells in the hypothalamus create hypothalamic-releasing and hypothalamic-inhibiting hormones, which tell the anterior pituitary to start or stop an action. Located in the pituitary stalk, a unique arrangement of capillaries and veins, called a portal system, allows the hypothalamic hormones to pass directly to the anterior pituitary without circulating through the body.The hypothalamus uses the posterior portion of the pituitary gland like a warehouse and distribution center. Neurosecretory cells in the hypothalamus create anti-diuretic hormone (ADH) and oxytocin, which are sent through axons in the pituitary stalk to be stored in the posterior pituitary.
When the hypothalamus detects that either of these hormones are needed, they are released from the posterior pituitary into the circulatory system to do their jobs.
Role of the Hypothalamus
A good way to visualize the relationship between the hypothalamus and the pituitary gland is like the President and his Chief of Staff. While the hypothalamus, or President, makes the decisions, the pituitary gland, or Chief of Staff, executes those decisions by sending out commands to the rest of the body.When the hypothalamus detects that something is out of balance, it sends a message to the pituitary gland that a corrective action is needed. When the pituitary gland gets this message from the hypothalamus, it releases specific hormones into the bloodstream that can stimulate other endocrine glands, organs or tissues depending on what action is needed. It’s kind of a like a game of telephone.
Instead of the hypothalamus communicating directly with the body, it relies on the pituitary gland to send out the messages. The hypothalamus continues to monitor the state of the body, and when it detects that balance has been restored, it tells the pituitary gland to stop sending out stimulating hormones, thereby stopping the corrective action.An example of this process is when we become dehydrated.
The hypothalamus is able to detect the increased blood concentration caused by the loss of water. To correct the situation, it uses the posterior pituitary to release anti-diuretic hormone (ADH) into the circulatory system. When ADH reaches the kidneys, it causes more water to be reabsorbed into the bloodstream, diluting the blood. When the hypothalamus detects the return to a normal blood concentration, it stops the release of ADH from the pituitary gland and the kidneys return to normal functioning.
The hypothalamus is responsible for maintaining homeostasis. It monitors the state of the body through the circulatory and nervous systems, and effectively links these two systems to the endocrine system through the pituitary gland. When the hypothalamus detects that something is out of balance, its sends a message to the pituitary gland that a corrective action is needed.
Depending on the need, either hormones produced in the anterior pituitary, or hypothalamic hormones stored in the posterior pituitary, are released into the body. When balance has been restored, the hypothalamus tells the pituitary gland to stop sending out stimulating hormones, thereby stopping the corrective action.