Chapter 45 (3)

In all but the simplest invertebrates, the _ and __ systems are integrated in the control of reproduction and development.

The signals that direct __ and __ in insects origingates in th ebrain.
There, __ cells produce __, a peptide neurohormone. Inr esponse to __, the __ glands, a pair of endocrine glands just behind the brain release __. __ promotes each successive molt, as well as the metamorphosis of the caterpillar into a butterfly during the final molt.

__ causes both molting and metamorphosis. There are a pair of small endocrine glands just behind the brain. Called the __, they secrete a third signaling molecule, __. As itsname suggests, one of the many functions of __ is to maintain larval (juvenile) characteristics.

__ influences development indirectly by modulating hte activity of __. In the presence of high levels of __ , __ stimulates molting that results in a larger larva. At the end of the larval stage, the level of __ wanes. When the __ level is low, __- induced molting produces the cocoon, or pupal form, within which metamorphosis occurs.

In vertebrates, the __ plays a central role in integrating the endocrine and nervous systems. One of several endocrine glands located in the brain, the __ receives info from nerves throughout the body and from other parts of the brain. In response, it itnitiates endocrine signaling appropriate to environmental conditions.

Signals from the __ travel to the __, a gland located at its base. Roughly the size and shape of a lima bean, the __ has discrete posterior and anterior parts (lobes), which are actually two glands, the __ and the __. These glands initially develop in eparate regions of the embryo. Although they fuse together later in development, their functions are distinct.

The __, or __ is an extension of the hypothalamus that grows downward toward the mouth during embryonic development. The __ stores and secretes two hormones made by the hypothalamus.

The __, or __ develops from a fold of tissue at the roof the emryonic mouth; this tissue grows upward toward the rain ande ventually lsoes its connection to the mouth. Hormones released by the hypothalamus regulate secretion of hormones by the __.

Under the control of the hypothalamus, the __ and __ produce a set of hormones central to endorine signaling throughout the body.

The posterior pituitary releases two neurohormones, __ and __. Synthesized in the hypothalamus, these hormones travel along the long axons of neurosecretory cells to the posterior pituitary. There they are stored, to be released as needed.

One funciton of __ in mammals is to regulate milk release during nursing; this function is mediated by a simple neurohormone pathway. In such pathways, a stimulus received by a sensory neron stimulates a neurosecretory cell.

The neurosecretory cell then secretes a neurohormone, which diffuses into the bloodstream and travels to target cells. __ functions in breast-feeding.

the __ pathway regulating the mammary gland provides an example of a __. Unlike negative fgeedback, which dampens a stimulus, __ reinforces a stimulus, leading to an even greater response.

__ has several additional roles realted to reproduction. When mammals give birth, it induces target cells in the uterine muscle sto contract. This pathway, too, is characterized by + feedack regulation, such that it drives the birth process to completion. __ also functions in regulating mood and sexual arousal in both males and females.

The second hormone released b the __, __ or __, helps regulate blood osmolarity.

The __ synthesizes and secretes many different hormones and is itself regulated by hormones secreted by the hypothalamus. each hypothalamic hormone is either a __ or an __, reflecting its role in promoting or inhibiting release of one or more specific hormones by the anterior pituitray.

__ is a product of hte hypothalamus that stimulates the anterior pituitary to secrete __, also known as __. Every anterior pituitary hormone is controlled by at least one __. SOme have both a __ and an __.

The hypothalamic releasing and inhibiting hormones are secreted near capillaries at the base of the hypothalamus. The capillaries drain into short blood vessles. called __ vessles, hcih subdivide into a second capillary bed within the anterior pituitary. n thi way, the __ and __ hormones have direct access to the gland they control.

Sets of hormones from the hypothalamus, the anterior pituitary and a target endocrine gland are often organized into a __. Signals to the brain stimulate the hypothalamus to secrete a hormone that in turn either stimulates or inhibits release of a partiular anterior pituitary hormone. The anterior pituitary hormone acts on a target endocrine tissue, stimulating secretion of yet another hormone that exerts systemic metabolic or developmental effects.

When a young child's body temp drops, the hypothalamus secretes __, which targets the anterior pituitary, which responds by secreting __, which acts on the thyroind gland to stimulate release of __> As it accumulates, __ increases metabolic rate, releasing thermal energy that raises body temp.

Like simple hormone pathways, __ typically involve negative feedback. In the case of the thyroid hormone pathway, __ itself carries out - feedback. Because thyroid hormone blocks __ release from the anterior pituitary and __ release from the hypothalamus, the - feedback loop prevents overproduction of __. Overall, the hormone cascade pathway brings about a self-limiting response to the oringinal stimulus in the target cells.

TSH is an example of a __- a hormone that regulates the functio of endocrine cells or glands. Three other anterior pituitary hormones act primarily or exclusively as __ hormones: __, __ and __.

__ and __ stimulate the activities of the male and female gonads, the testes and ovaries. For this reason, they are also known as __.

__ stimulates the produciition and secretion of steroid hormones by the adrenal cortex.

Two major hormones of the anterior pituitary target nonendocrine tissues and are thus __. They are __ and __.

__ is remarkable for the diversity of its effects among vertebrate species.

__ regulate the activity of pignmet-containg cells in the skin of some amphibians. In mammals, __ appears to act on neurons in the brain, inhibiting hunger.

__, which is secreted by the anterior pituitary, stimultes growth through tropic and nontropic effects. A major target, the liver, responds to __ by releasing __, which circulte in the blood and directly stimulate bone and cartilage growth.
- In the absence of __, teh skeleton of an immature animal stops growing. __ also exerts diverse metabolic effects thta tend ot raise blood glucose levels, thus opposing the effects of insulin.

Abnormal production of __ in humans can result in several disorders, depending on when the problem occurs and whether it involves __ or __.