Glossary of key terms
anterior pituitary:
lobe of the pituitary gland that produces stimulating hormones, as well as growth hormone, prolactin and
melanocyte-stimulating hormone
diurnal rhythm:
response of the hypothalamus and then the pituitary and adrenals to wakefulness and sleeping
glands:
organised groups of specialised cells that secrete hormones, or chemical messengers, directly into the bloodstream to
communicate within the body
hormones:
chemical messengers working within the endocrine system to communicate within the body
hypothalamic–pituitary axis (HPA):
interconnection of the hypothalamus and pituitary to regulate the levels of certain endocrine
hormones through a complex series of negative feedback systems
hypothalamus:
“master gland” of the neuroendocrine system; regulates both nervous and endocrine responses to internal and
external stimuli
negative feedback system:
control system in which increasing levels of a hormone lead to decreased levels of releasing and
stimulating hormones, leading to decreased hormone levels, which stimulates the release of releasing and stimulating hormones;
allows tight control of the endocrine system
neuroendocrine system:
the combination of the nervous and endocrine systems, which work closely together to maintain regulatory
control and homeostasis in the body
pituitary gland:
gland found in the sella turcica of the brain; produces hormones, endorphins and encephalins and stores two
hypothalamic hormones
posterior pituitary:
lobe of the pituitary that receives antidiuretic hormone and oxytocin via nerve axons from the hypothalamus and
stores them to be released when stimulated by the hypothalamus
releasing hormones or factors:
chemicals released by the hypothalamus into the anterior pituitary to stimulate the release of anterior
pituitary hormones
Test your current knowledge of the endocrine system with a PrepU Practice Quiz!
Learning objectives
Upon completion of this chapter, you should be able to:
1.
Label a diagram showing the glands of the traditional endocrine system and list the hormones produced
by each.
2.
Describe two theories of hormone action.
3.
Discuss the role of the hypothalamus as the master gland of the endocrine system, including influences on the
actions of the hypothalamus.
4.
Outline a negative feedback system within the endocrine system and explain the ways that this system
controls hormone levels in the body.
5.
Describe the hypothalamic–pituitary axis (HPA) and what would happen if a hormone level was altered within
the HPA.
Introduction to the
endocrine system
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