Chapter 52: Assessment of the Endocrine System

Vocabulary flashcards covering endocrine system structure, function, hormone regulation, physiological rhythms, and diagnostic testing.

Hormones

Chemical substances produced by endocrine glands that control and regulate the activity of specific target cells or organs.

Lock-and-Key Mechanism

The process by which hormones exert specific effects on target cells by recognizing target tissues and attaching to specific receptor sites.

Negative Feedback

The most common endocrine feedback system, relying on blood levels of a hormone or regulated chemical compound to increase or decrease hormone release from a gland.

Positive Feedback

A hormonal regulation system that continuously increases hormone levels until an external mechanism stops their release, such as the action of the ovarian hormone estradiol.

Catecholamines

Hormones secreted by the Sympathetic Nervous System (SNS) in response to stress to stimulate heart and lung function.

Circadian Rhythm

A 24-hour diurnal sleep-wake or dark-light cycle during which specific hormone levels (such as GH, TSH, prolactin, and cortisol) fluctuate predictably.

Ultradian Rhythm

A hormonal secretion rhythm occurring in cycles longer or shorter than 24 hours, such as menstrual cycles.

TSH (Thyroid-Stimulating Hormone) Test

The most sensitive and accurate laboratory test for evaluating thyroid gland function.

Free T4

Unbound thyroxine that provides a more accurate reflection of thyroid function than total T4.

Parathyroid Hormone (PTH)

The single hormone secreted by the parathyroid glands that regulates blood levels of calcium and phosphate.

24-Hour Urine Collection

A diagnostic urine study method used to assess adrenal cortex function by eliminating the impact of diurnal fluctuations in blood hormone levels.