Obstetrics & gynaecology

Research shows OB-GYNs hesitate to talk about fertility

A new study shows that many OB-GYNs are uncomfortable counseling their patients on fertility at a time when more women are delaying pregnancy and needing their doctors to be more vigilant about this education.

Obstetrics & gynaecology

What couples considering IVF need to know

(HealthDay)—In vitro fertilization (IVF) is widely used in the United States to help infertile couples have children. But there are a number of things people should know when considering it, an infertility specialist says.

Oncology & Cancer

TGF-beta pathway protects against uterine cancer

Two new mouse models of uterine cancer shed light on how this disease—the most common gynecological cancer in the U.S. - happens. Led by researchers at Baylor College of Medicine, the team of scientists found that the Transforming ...

Oncology & Cancer

Cryopreservation giving kids with cancer a brighter future

In recent years, significant strides in pediatric cancer research have drastically decreased the odds of children dying after they are diagnosed. As the chances of children dying from cancer are decreasing, health care providers ...

Obstetrics & gynaecology

For women undergoing IVF, is fresh or frozen embryo transfer best?

The world's first baby born via in-vitro fertilization turned 40 years old this summer. Still, after four decades, IVF is a relatively new field with ongoing debate on how to get the best results for families who have placed ...

Health

Shift work unwinds body clocks, leading to more severe strokes

Statistics show that some 15 million Americans don't work the typical nine-to-five. These employees (or shift workers), who punch in for graveyard or rotating shifts, are more prone to numerous health hazards, from heart ...

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Endocrinology

Endocrinology (from Greek ἔνδον, endo, "within"; κρῑνω, krīnō, "to separate"; and -λογία, -logia) is a branch of biology and medicine dealing with the endocrine system, its diseases, and its specific secretions called hormones, the integration of developmental events such as proliferation, growth, and differentiation (including histogenesis and organogenesis) and the coordination of metabolism, respiration, excretion, movement, reproduction, and sensory perception depend on chemical cues, substances synthesized and secreted by specialized cells.

Endocrinology is concerned with the study of the biosynthesis, storage, chemistry, and physiological function of hormones and with the cells of the endocrine glands and tissues that secrete them.

The endocrine system consists of several glands, all and in different parts of the body, that secrete hormones directly into the blood rather than into a duct system. Hormones have many different functions and modes of action; one hormone may have several effects on different target organs, and, conversely, one target organ may be affected by more than one hormone.

In the original 1902 definition by Bayliss and Starling (see below), they specified that, to be classified as a hormone, a chemical must be produced by an organ, be released (in small amounts) into the blood, and be transported by the blood to a distant organ to exert its specific function. This definition holds for most "classical" hormones, but there are also paracrine mechanisms (chemical communication between cells within a tissue or organ), autocrine signals (a chemical that acts on the same cell), and intracrine signals (a chemical that acts within the same cell). A neuroendocrine signal is a "classical" hormone that is released into the blood by a neurosecretory neuron (see article on neuroendocrinology).

Hormones act by binding to specific receptors in the target organ. As Baulieu notes, a receptor has at least two basic constituents:

Between these is a "transduction mechanism" in which hormone binding induces allosteric modification that, in turn, produces the appropriate response.

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