Endocrinology - Endocrine Disorders

What is endocrinology ?

Endocrinology is a medical specialty and biological science concerned with the endocrine system, or glands that have secretions in the body, such as thyroid, pituitary, pancreas, and adrenal glands. The exocrine system (salivary glands, sweat glands) are not covered here. Doctors and biologists who specialize in endocrinology, endocrinologist called.

Hormones in humans

A hormone is a substance that is issued by a gland to the blood, and somewhere in the body affects the functioning of a body. The influence can be stimulating or inhibiting. A hormone gland has no duct. The hormone ends up in numerous capillaries, which run through the endocrine glands. Therefore one speaks of an endocrine gland or glands with internal secretion. The gland product enters the internal environment, cq the blood. Via the blood vessels will be a hormone in all parts of the body, but, for organs that are susceptible to the hormone in question respond. Examples of endocrine glands are thyroid, pituitary, adrenal gland.

Called exocrine glands that have a duct, or glands with external secretion. Their gland product comes into the external environment arise. Examples of these glands are the salivary glands (and other digestive glands), sweat glands, sebaceous glands.

The function of hormones
Hormones play an important role in regulating processes in the body organs by "on" or turn "off". Process control is among other things necessary to keep the internal environment constant. That is to say, to ensure that the fluctuations in the internal environment will not be too large.
A striking example is the regulation of heat production and heat loss from the body, causing the body temperature to be kept constant at 0.1 ° C. This hormone system works incidentally with the nervous system. Another famous example is the hormone insulin, which regulates glucose uptake by the muscles. People who produce or insulin sensitivity is not good, have diabetes.

Negative feedback
Process control is unthinkable without the phenomenon of negative feedback. A process leads to a (change of) a certain state. The state is working back at the process, so that changes are opposed to the state; the state is maintained.

However, not all endocrinological processes may be negatively fed back, the maturation of a follicle is an example of positive negative feedback, as well as the determination of the sex by formation of the sex hormones in the indifferent gonad. This has the effect of an exponential growth, which is also desired in the two cases.

Heat production and heat release in humans
The hypothalamus is a part of the front portion of the brainstem; a part of it passes through in the pituitary. In the hypothalamus, are thermo-receptors, which measure the temperature of the blood. And there is also the compensator for the heat, as co compensator for the heat. This left out of consideration. The role of the nervous system, is discussed here only insofar as the endocrine system is involved. At a low temperature of the blood gives the hypothalamus off the hormone TRH, TSH-releasing hormone. This is via blood vessels in the stem of the pituitary gland at the anterior end. Certain cells respond by releasing the hormone TSH, thyroid stimulating hormone.

The pituitary gland, or brain appendage exists in humans mainly of two parts: the anterior lobe and the posterior lobe. The anterior lobe is made up of glandular tissue and works on the command of the hypothalamus; this makes hormones, which inhibit or stimulate the pituitary. The posterior lobe is composed of nerve tissue; this releases hormones into the blood off, made by the hypothalamus, viz., oxytocin and ADH. The pituitary gland plays a central role in the endocrine system.
If the pituitary TSH issues, it comes through the blood in the thyroid, which reacts with the release of thyroxin.

The thyroid gland produces the hormone thyroxine. This stimulates the aerobic dissimilation in the cells and hence the heat production. The release of the hormone thyroxine is controlled by the pituitary gland. This gland is again controlled by the hypothalamus. If the hormone thyroxine into the blood, it stimulates many organs combustion: the degradation metabolism is increased. As a result, the body temperature will rise thereof. The thyroxine also has an influence on the hypothalamus and in the pituitary. Namely it inhibits the release of TRH and the release of TSH.

Diagnosis of endocrine disorders in humans

Hormone Production of man can be measured through blood tests in a clinical laboratory. Not only the hormones themselves, but also the substances which control the endocrine glands from the brains can be measured in the blood. For example, in the case of the adrenal gland (producer of cortisol) the ACTH production are measured by the pituitary gland. Because the hormone production is variable over the day, it is important in order to take off on a standardized time of blood.

Another way to study the hormone production is to carry out a function test. A function test is a test in which the hormone production is suppressed in a healthy person after administration of a particular substance, but not in patients. The test can also be performed in a different way so that the hormone production is properly elicited in those cases in which it is believed that the hormone production is not sufficient (for example, to small children who is suspected of a growth hormone deficiency). Since there is a sample of blood at multiple points in time, these tests are often much more informative than the measurement of a single blood value.

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