Hormones Diverse Structures for Diverse Functions

Virtually every process in a complex organism is regulated by one or more hormones: maintenance of blood pressure, blood volume, and electrolyte balance; embryogenesis; sexual differentiation, development, and reproduction; hunger, eating behavior, digestion, and fuel allocation—to name but a few. We examine here the methods for detecting and measuring hormones and their interaction with receptors, and consider a representative selection of hormone types.

The coordination of metabolism in mammals is achieved by the neuroendocrine system. Individual cells in one tissue sense a change in the organism's circumstances and respond by secreting a chemical messenger that passes to another cell in the same or different tissue, where it binds to a receptor molecule and triggers a change in this second cell. In neuronal signaling (Fig. 23-1a), the chemical messenger (neurotransmitter; acetylcholine, for example) may travel only a fraction of a micrometer, across the synaptic cleft to the next neuron in a network. In hormonal signaling, the messengers—hormones—are carried in the bloodstream to neighboring cells or to distant organs and tissues; they may travel a meter or more before encountering

(a) Neuronal signaling

Nerve impulse

Target cells

Nerve Contraction Secretion impulse

100 Weight Loss Tips

100 Weight Loss Tips

Make a plan If you want to lose weight, you need to make a plan for it. Planning involves setting your goals both short term and long term ones. With proper planning, you would be able to have an effective guide on the steps that you want to take, towards losing pounds of weight. Aside from that, it would also keep you motivated.

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