Ch 6 The Endocrine System: Endocrine Glands and Hormone Action

Flashcards covering key vocabulary related to the endocrine system, including primary and secondary endocrine organs, the hypothalamus-pituitary axis, tropic hormones, feedback loops, and specific endocrine glands and their secretions.

Endocrine System

A system of endocrine glands and hormones that regulate body functions.

Primary Endocrine Organs

Organs whose primary function is to secrete hormones, including pineal gland, hypothalamus, pituitary gland, thyroid gland, parathyroid glands, thymus, adrenal gland, pancreas, ovaries, and testes.

Secondary Endocrine Organs

Organs that have endocrine functions secondary to their main roles, including heart, stomach, liver, kidney, small intestine, placenta, and skin.

Pineal Gland

A primary endocrine organ located in the brain.

Hypothalamus

A key brain region that connects the nervous and endocrine systems and regulates the pituitary gland.

Pituitary Gland

An endocrine gland located at the base of the brain, divided into anterior and posterior lobes, regulated by the hypothalamus.

Anterior Pituitary

The front lobe of the pituitary gland, responsible for secreting several tropic hormones.

Posterior Pituitary

The rear lobe of the pituitary gland, which stores and releases hormones produced by the hypothalamus.

Infundibulum

The stalk that connects the hypothalamus to the pituitary gland.

Neurosecretory Cells

Specialized neurons in the hypothalamus that produce and release hormones into the posterior pituitary or portal system.

Supraoptic Nucleus

A cluster of neurosecretory cells in the hypothalamus that secrete oxytocin.

Paraventricular Nucleus

A cluster of neurosecretory cells in the hypothalamus that secrete ADH (antidiuretic hormone).

Hypothalamic-Pituitary Portal System

A specialized vascular system that directly connects the hypothalamus and the anterior pituitary, allowing transport of hypothalamic hormones.

Median Eminence

The region of the hypothalamus where releasing and inhibiting hormones are secreted into the portal system.

Tropic Hormone

A hormone that stimulates the secretion of another hormone from an endocrine gland.

PRH (Prolactin-Releasing Hormone)

A hypothalamic tropic hormone that stimulates prolactin secretion from the anterior pituitary.

PIH (Prolactin-Inhibiting Hormone)

Also known as dopamine, a hypothalamic hormone that inhibits prolactin secretion.

TRH (Thyrotropin-Releasing Hormone)

A hypothalamic tropic hormone that stimulates TSH secretion from the anterior pituitary.

TSH (Thyroid-Stimulating Hormone)

An anterior pituitary tropic hormone that stimulates the thyroid gland to produce thyroid hormones.

CRH (Corticotropin-Releasing Hormone)

A hypothalamic tropic hormone that stimulates ACTH secretion from the anterior pituitary.

ACTH (Adrenocorticotropic Hormone)

An anterior pituitary tropic hormone that stimulates the adrenal cortex to produce cortisol.

GHRH (Growth Hormone-Releasing Hormone)

A hypothalamic tropic hormone that stimulates GH secretion from the anterior pituitary.

GHIH (Growth Hormone-Inhibiting Hormone)

Also known as somatostatin, a hypothalamic hormone that inhibits GH secretion.

GH (Growth Hormone)

An anterior pituitary hormone that acts on the liver and other tissues to produce insulin-like growth factors, promoting growth.

GnRH (Gonadotropin-Releasing Hormone)

A hypothalamic tropic hormone that stimulates LH and FSH secretion from the anterior pituitary.

LH (Luteinizing Hormone)

An anterior pituitary tropic hormone that acts on the gonads to stimulate the production of estrogens, progesterone (female) and androgens (male).

FSH (Follicle-Stimulating Hormone)

An anterior pituitary tropic hormone that acts on the gonads to stimulate the production of estrogens, progesterone (female) and androgens (male).

Prolactin

An anterior pituitary hormone that primarily targets the breasts to stimulate milk production.

Negative Feedback Loop

A regulatory mechanism in which the end product of a pathway inhibits an earlier step in the pathway, maintaining homeostasis.

Short Loop Negative Feedback

Inhibitory feedback where an anterior pituitary hormone inhibits hormone secretion from the hypothalamus.

Long Loop Negative Feedback

Inhibitory feedback where a hormone from a peripheral endocrine gland inhibits hormone secretion from both the hypothalamus and the anterior pituitary.

Thyroid Gland

A primary endocrine organ located in the neck, anterior to the trachea, that produces thyroid hormones.

Parathyroid Glands

Small endocrine glands usually located on the posterior surface of the thyroid gland, primarily involved in calcium regulation.

Adrenal Gland

A primary endocrine organ located superior to the kidneys, consisting of an outer cortex and an inner medulla.

Adrenal Cortex

The outer region of the adrenal gland, responsible for secreting steroid hormones like aldosterone and cortisol.

Adrenal Medulla

The inner region of the adrenal gland, responsible for secreting catecholamines like epinephrine and norepinephrine.

Pancreas

A primary endocrine organ located in the abdomen, which has both exocrine and endocrine functions.

Islet of Langerhans

Endocrine cell clusters within the pancreas that secrete hormones.

Alpha Cell

A type of endocrine cell in the pancreatic islets that secretes glucagon.

Beta Cell

A type of endocrine cell in the pancreatic islets that secretes insulin.

Delta Cell

A type of endocrine cell in the pancreatic islets that secretes somatostatin.

F Cell

A type of endocrine cell in the pancreatic islets that secretes pancreatic polypeptide.

Aldosterone

A hormone secreted by the adrenal cortex that increases potassium excretion by the kidneys in response to high blood potassium levels.

Insulin

A hormone secreted by pancreatic beta cells that increases glucose uptake by cells, thereby lowering blood glucose levels.