Human Anatomy And Physiology Of Endocrine System Pdf

File Name: human anatomy and physiology of endocrine system .zip
Size: 2397Kb
Published: 05.04.2021

It provides a slower, but longer lasting coordination than the nervous system.

Human Physiology pp Cite as. The biological role of the endocrine system is closely linked to that of the nervous system; the two together coordinate the functions of the other in some cases widely separated organs and organ systems.

Pituitary Gland Overview

Human endocrine system , group of ductless glands that regulate body processes by secreting chemical substances called hormones. Hormones act on nearby tissues or are carried in the bloodstream to act on specific target organs and distant tissues. Diseases of the endocrine system can result from the oversecretion or undersecretion of hormones or from the inability of target organs or tissues to respond to hormones effectively. It is important to distinguish between an endocrine gland, which discharges hormones into the bloodstream, and an exocrine gland , which secretes substances through a duct opening in a gland onto an external or internal body surface.

Salivary glands and sweat glands are examples of exocrine glands. Both saliva, secreted by the salivary glands, and sweat, secreted by the sweat glands, act on local tissues near the duct openings. In contrast, the hormones secreted by endocrine glands are carried by the circulation to exert their actions on tissues remote from the site of their secretion.

As far back as bce , the ancient Chinese were able to diagnose and provide effective treatments for some endocrinologic disorders. For example, seaweed, which is rich in iodine , was prescribed for the treatment of goitre enlargement of the thyroid gland.

Perhaps the earliest demonstration of direct endocrinologic intervention in humans was the castration of men who could then be relied upon, more or less, to safeguard the chastity of women living in harems. During the Middle Ages and later, the practice persisting well into the 19th century, prepubertal boys were sometimes castrated to preserve the purity of their treble voices. This knowledge led to an abiding interest in restoring or enhancing male sexual powers. In the 18th century, London-based Scottish surgeon, anatomist, and physiologist John Hunter successfully transplanted the testis of a rooster into the abdomen of a hen.

The transplanted organ developed a blood supply in the hen, though whether masculinization occurred was unclear. In German physiologist Arnold Adolph Berthold performed a similar experiment, except, instead of hens, he transplanted rooster testes into capons castrated roosters.

The capons subsequently regained secondary sex characteristics, demonstrating that the testes were the source of a masculinizing substance. His conclusions were based in part on observations obtained after he had injected himself with an extract of the testicle of a dog or of a guinea pig. These experiments resulted in the widespread use of organ extracts to treat endocrine conditions organotherapy.

Modern endocrinology largely originated in the 20th century, however. Later, American physiologist Walter Bradford Cannon — used the term homeostasis to describe this inner constancy. This control system permits the prime functions of living organisms—growth, development, and reproduction—to proceed in an orderly, stable fashion; it is exquisitely self-regulating, so that any disruption of the normal internal environment by internal or external events is resisted by powerful countermeasures.

When this resistance is overcome, illness ensues. Human endocrine system Article Media Additional Info. Article Contents. Print print Print. Table Of Contents. While every effort has been made to follow citation style rules, there may be some discrepancies. Please refer to the appropriate style manual or other sources if you have any questions. Facebook Twitter. Give Feedback External Websites. Let us know if you have suggestions to improve this article requires login. External Websites. Robert D.

See Article History. The principal glands of the female and male human endocrine systems. The endocrine system is a complex system of glands that secrete hormones throughout the body.

Get a Britannica Premium subscription and gain access to exclusive content. Subscribe Now. Load Next Page.

The Endocrine System

Numerous glands throughout the body produce hormones. The hypothalamus produces several releasing and inhibiting hormones that act on the pituitary gland, stimulating the release of pituitary hormones. Of the pituitary hormones, several act on other glands located in various regions of the body, whereas other pituitary hormones directly affect their target organs. Other hormone-producing glands throughout the body include the adrenal glands, which primarily produce cortisol; the gonads i. Many of these hormones are part of regulatory hormonal cascades involving a hypothalamic hormone, one or more pituitary hormones, and one or more target gland hormones.

Communication within the human body involves the transmission of signals to control and coordinate actions in an effort to maintain homeostasis. There are two major organ systems responsible for providing these communication pathways: the nervous system and the endocrine system. The nervous system is primarily responsible for rapid communication throughout the body. In this way, neural communication enables body functions that involve quick, brief actions, such as movement, sensation, and cognition. In contrast, the endocrine system relies on only a single method of communication: chemical signaling Table 1. Hormones are transported primarily via the bloodstream throughout the body, where they bind to receptors on target cells, triggering a response.

The endocrine system consists of glands widely separated from each other with no physical connections Fig. Homeostasis of the internal environment is maintained partly by the autonomic nervous system and partly by the endocrine system. The autonomic nervous system is concerned with rapid changes, while endocrine control is mainly involved in slower and more precise adjustments. Although the hypothalamus is classified as a part of the brain rather than an endocrine gland, it controls the pituitary gland and has an indirect effect on many others. The ovaries and the testes secrete hormones associated with the reproductive system after puberty. The endocrine glands are explored in the early sections of the chapter. Problems that arise when abnormalities occur are usually caused by the over- or under-activity of endocrine glands and are explained in the final sections of the chapter.


1. Describe the role and function of the anterior and posterior pituitary, hypothalamus, adrenal glands, endocrine pancreas, and thyroid gland within the endocrine.


An Overview of the Endocrine System

Human endocrine system , group of ductless glands that regulate body processes by secreting chemical substances called hormones. Hormones act on nearby tissues or are carried in the bloodstream to act on specific target organs and distant tissues. Diseases of the endocrine system can result from the oversecretion or undersecretion of hormones or from the inability of target organs or tissues to respond to hormones effectively. It is important to distinguish between an endocrine gland, which discharges hormones into the bloodstream, and an exocrine gland , which secretes substances through a duct opening in a gland onto an external or internal body surface.

17.1 An Overview of the Endocrine System