Control of the Endocrine System
- A hormone is a chemical messenger produced by an endocrine gland and carried by the blood
- They are chemicals which transmit information from one part of the organism to another and bring about a change
- They alter the activity of one or more specific target organs
- Hormones are used to control functions that do not need instant responses
- The endocrine glands that produce hormones in animals are known collectively as the endocrine system
- A gland is a group of cells that produces and releases one or more substances (a process known as secretion)
- Control of the endocrine system is primarily by the hypothalamus and the pituitary gland
The hypothalamus
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- The hypothalamus monitors the blood as it flows through the brain and, in response, releases hormones or stimulates the neighbouring pituitary gland to release hormones
- The hypothalamus plays an important role in some homeostatic mechanisms
- Hypothalamus functions include
- Regulating body temperature
- The hypothalamus monitors blood temperature and initiates a homeostatic response if this temperature gets too high or too low
- Osmoregulation
- Cells in the hypothalamus monitor the water balance of the blood and releases the hormone ADH if the blood becomes too concentrated
- ADH increases absorption of water in the kidneys
- Cells in the hypothalamus monitor the water balance of the blood and releases the hormone ADH if the blood becomes too concentrated
- Regulating digestive activity
- The hypothalamus regulates the hormones that control appetite as well as the secretion of digestive enzymes
- Controlling endocrine functions
- The hypothalamus causes the pituitary gland to release hormones that control a variety of processes e.g. metabolism, growth and development, puberty, sexual functions, sleep, and mood
- Regulating body temperature
- The hypothalamus monitors the blood as it flows through the brain and, in response, releases hormones or stimulates the neighbouring pituitary gland to release hormones
The pituitary gland
- The pituitary gland is located below the hypothalamus
- Its role is to produce a range of hormones
- Some of these directly influence and regulate processes in the body while some stimulate the release of further hormones from other endocrine glands
- The pituitary gland is divided into two sections; the anterior pituitary and posterior pituitary
- The anterior pituitary produces and releases hormones
- The posterior pituitary stores and releases hormones produced by the hypothalamus e.g. ADH and oxytocin