BIOL 1040 - Chapter 26

Hormones and the Endocrine System; BIOL 1040 (General Biology II) - Exam 3

Endocrine System

The organ system consisting of ductless glands that secrete hormones and the molecular receptors on or in target cells that respond to the hormones. Cooperates with the nervous system in regulating body functions and maintaining homeostasis.

Hormone

In animals, a regulatory chemical that travels in the blood from its production site, usually an endocrine gland, to other sites, where target cells respond to the regulatory signal.

Endocrine Gland

A ductless gland that synthesizes hormone molecules and secretes them into the interstitial fluid, from which they diffuse into the bloodstream.

Target Cell

A cell that responds to a regulatory signal, such as a hormone.

Neurosecretory Cell

A nerve cell that synthesizes hormones and secretes them into the blood and also conducts nerve signals.

Endocrine Disruptors

A chemical, usually synthetic, that interferes with the endocrine system’s normal functions.

Pineal Gland

An outgrowth of the vertebrate brain that secretes the hormone melatonin, which coordinates daily and seasonal body activities such as the sleep/wake circadian rhythm with environmental light conditions.

Hypothalamus

The master control center of the endocrine system, located in the ventral portion of the vertebrate forebrain. The hypothalamus functions in maintaining homeostasis, especially in coordinating the endocrine and nervous systems; secretes hormones of the posterior pituitary and releasing hormones that regulate the anterior pituitary.

Pituitary Gland

An endocrine gland at the base of the hypothalamus; consists of a posterior lobe, which stores and releases two hormones produced by the hypothalamus, and an anterior lobe, which produces and secretes many hormones that regulate diverse body functions.

Posterior Pituitary

An extension of the hypothalamus composed of nervous tissue that secretes hormones made in the hypothalamus; a temporary storage site for hypothalamic hormones.

Anterior Pituitary

An endocrine gland, adjacent to the hypothalamus and the posterior pituitary, that synthesizes several hormones, including some that control the activity of other endocrine glands.

Releasing Hormone

A kind of hormone secreted by the hypothalamus that promotes the release of hormones from the anterior pituitary.

Inhibiting Hormone

A kind of hormone released from the hypothalamus that prompts the anterior pituitary to stop secreting on or more hormones.

Thyroid-Stimulating Hormone (TSH)

A protein hormone secreted by the anterior pituitary that stimulates the thyroid gland to secrete thyroid hormone.

Prolactin (PRL)

A protein hormone secreted by the anterior pituitary that stimulates human mammary glands to produce and release milk and produces other responses in different animals.

Growth Hormone (GH)

A protein hormone secreted by the anterior pituitary that promotes development and growth and stimulates metabolism.

TRH (TSH-releasing hormone)

A peptide hormone that triggers the release of THS (thyroid-stimulating hormone), which in turn stimulates the thyroid gland.

Thyroid Gland

An endocrine gland located in the neck that secretes thyroid hormone.

Thyroid Hormone

A combination of two different water-soluble hormones (T3 and T4) secreted by the thyroid gland that affects many functions of the body, including metabolic rate, heart rate, blood pressure, and tolerance to the cold.

Goiter

An enlargement of the thyroid gland resulting from a dietary iodine deficiency.

Gonad

A sex organ in an animal that secretes sex hormones and produces gametes; an ovary or testis.

Estrogen

One of several chemically similar steroid hormones secreted by the gonads; maintains the female reproductive system and promotes the development of female body features.

Progesterone

A steroid hormone that contributes to the menstrual cycle and prepares the uterus for pregnancy.

Androgen

A steroid sex hormone secreted by the gonads that promotes the development and maintenance of the male reproductive system and male body features.

Testosterone

An androgen hormone that stimulates and embryo to develop into a male and promotes male body features.

Pancreas

A gland with dual functions: The digestive portion secretes digestive enzymes and an alkaline solution into the small intestine via a duct. The endocrine portion secretes the hormones insulin and glucagon into the blood.

Insulin

A protein hormone, secreted by the pancreas, that lowers the level of glucose in the blood. It is antagonistic with glucagon.

Glucagon

A peptide hormone, secreted by the pancreas, that raises the level of glucose in the blood. It is antagonistic with insulin.

Antagonistic Hormones

Two hormones that have opposite effects.

Diabetes Mellitus

A human hormonal disease in which body cells cannot absorb enough glucose from the blood and become energy starved; body fats and proteins are then consumed for their energy. Type 1 (insulin-dependent) diabetes results when the pancreas does not produce insulin; Type 2 (non-insulin-dependent) diabetes results when body cells fail to respond to insulin.

Hyperglycemia

An abnormally high level of glucose in the blood that results when the pancreas does not secrete enough insulin or cells do not respond to insulin. Is a characteristic of diabetes.

Adrenal Gland

One pair of endocrine glands, located atop each kidney in mammals, composed of an outer cortex and a central medulla.

Adrenal Medulla

The central portion of an adrenal gland, controlled by nerve signals; secretes the fight-or-flight hormones epinephrine and norepinephrine.

Adrenal Cortex

The outer portion of an adrenal gland, controlled by ACTH from the anterior pituitary gland; secretes hormones called glucocorticoids and mineralocorticoids.

Epinephrine

A hormone (also called adrenaline) secreted by the adrenal medulla in response to stress from a physical threat that prepares body organs for action (fight or flight); also serves as a neurotransmitter.

Norepinephrine

A hormone (also called noradrenaline) secreted by the adrenal medulla in response to stress from physical threat that prepares body organs for action (fight or flight); also serves as a neurotransmitter.

Adrenocorticotropic Hormone (ACTH)

A protein hormone secreted by the anterior pituitary gland that stimulates the adrenal cortex to secrete corticosteroids.

Corticosteroid

A hormone synthesized and secreted by the adrenal cortex. The corticosteroids include the mineralocorticoids and glucocorticoids.

Mineralocorticoids

A corticosteroid hormone secreted by the adrenal cortex that helps maintain salt and water homeostasis and may increase blood pressure in response to stress from low blood sugar or decreased blood volume or blood pressure.

Glucocorticoid

A corticosteroid hormone secreted by the adrenal cortex that increases the blood glucose level and helps maintain the body’s response to stress from low blood sugar or decreased blood volume or blood pressure.