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Hormones and the Endocrine System StudyGuide

Endocrine system

A collection of glands and groups of cells thats secrete hormones that regulate growth,development, and homeostsis


Chemical "messengers" of the endocrine system that are released into the blood

Protein hormones

Class of hormones that cannot pass through the cell membrane; less likely to be stored in the body

Steroid hormone

Class of hormones that can pass through the cell membrane; can be stored in the body


Local hormones that do not enter the bloodstream

Positive feedback

Process that amplifies a small change (reinforce change)

Negative feedback

A response that opposes the original stimulus

One messenger model

Mechanism of hormone action used by steroid hormones which bring their message directly into the cell

Two messenger model

Mechanism of hormone action used by protein hormones; attach to cell membrane receptors which activate enzymes in the cell to produce the desired effect


Excessive hormone production by an endocrine gland


Deficient hormone production by an endocrine gland

Pituitary gland

The master gland of the endocrine system

Growth hormone

Hormone secreted by anterior pituitary gland that stimulates growth of bones

Luteinizing hormone

A protein hormone secreted by the anterior pituitary that stimulates ovulation in females and androgen production in males.


Peptide hormone released by anterior pituitary which promotes lactation.

Follicle stimulating hormone

Secreted in increasing amounts during puberty, by the anterior pituitary gland, to stimulate development of reproductive cell follicles

Adrenocorticotropic hormone

A peptide hormone released from the anterior pituitary, it stimulates the production and secretion of steroid hormones by the adrenal cortex.


A hormone produced by the hypothalamus and released from the posterior pituitary. It induces contractions of the uterine muscles during labor.

Antidiuretic hormone

Hormone secreted by the posterior pituitary gland which aids in water reabsorption by the kidney


Part of the brain which links the endocine and nervous system, and controls the pituitary gland.


Hypersecretion of the gh in adults which causes an overgrowth of bones in the hands, feet, and face

Thyroid gland

Gland found in neck that regulates rate of metabolism; produces thyroxine


Produced by the thyroid gland and decreases the blood calcium levels by stimulating calcium deposit in the bones. The antagonist of the parathyroid hormone.


Secreted by parathyroid glands and controls calcium and phosphate metabolism


Condition affecting nerves causing muscle spasms as a result of low amounts of calcium in the blood caused by a deficiency of the parathyroid hormone


A condition in which the body's bones become weak and break easily; may be caused by hypersecretion of parahormone

Adrenal gland

One of a pair of ductless glands, located above the kidneys, consisting of a cortex, which produces steroidal hormones, and a medulla, which produces epinephrine and norepinephrine.


Outer part of kidney which produces corticosteroids; helps body deal with longtern stress


Inner part of kidney which produces epineprine and norepinephrine


Secreted from the adrenal cortex, aids the body during stress by regulating glucose, carbohydrates, and fat levels


A corticosteroid hormone that is secreted by the cortex of the adrenal gland, regulates mineral balance in blood and controls fluid volumes

Cushing syndrome

Excessive production of cortisol by adrenal cortex with symptoms of abnormal fat deposits and wasting away of muscle


Located partially behind the stomach in the abdomen, and it functions as both an endocrine and exocrine gland. It produces digestive enzymes as well as insulin and glucagon


A hormone secreted by the beta cells of the islets of langerhans of the pancreas responsible for regulating the metabolism of glucose


Hormone secreted by alpha cells of the pancreas; raises blood glucose levels


A condition in which the pancreas fails to produce enough insulin or the body's cells cannot use it properly, characterized by excessive thirst, weight loss/gain, frequent urination.


A general term for female steroid sex hormones that are secreted by the ovary and responsible for typical female sexual characteristics


A hormone produced by the ovaries which acts with estrogen to bring about the menstral cycle.


The male sex hormone produced by the testes which promotes the maturation of the reproductive system accessory structures, and development of the male secondary sex characteristics.

Pineal gland

A small mass of tissue near the center of the brain; it secretes the hormone melatonin.


Hormone secreted by the pineal gland, used to regulate sleep patterns.

Thymus gland

Gland located near the heart; it aids in the body's defence against infection by making antibodies

Adrenal cortex

Part of the adrenal gland that produces three mayor groups of steroid hormones called corticosteroids.

Adrenal gland

An endocrine gland located adjacent to the kidney in mammals; composed of two glandular portions: an outer cortex, which responds to endocrine signals in reacting to stress and effecting salt and water balance, and a central medulla, which responds to nervous inputs resulting from stress.

Adrenal medulla

The inner region of the adrenal gland. The adrenal medulla is part of the sympathetic nervous system, and releases epinephrine (adrenaline) and norepinephrine into the blood when stimulated. These hormones augment and prolong the effects of sympathetic stimulation in the body.

Adrenocorticotropic hormone (acth)

A tropic hormone that is produced and secreted by the anterior pituitary and that stimulates the production and secretion of steroid hormones by the adrenal cortex.


Male sex hormone that is produced in the testes and responsible for typical male sexual characteristics

Antagonistic hormones

Hormones that have opposing physiological properties, but that work together. Ex. Insulin & glucagon have opposite effects on blood sugar levels. Other hormone pairs: parathyroid & calcitonin melanocyte & melatonin oxytocin & pitocin etc.

Anterior pituitary

Produces and secretes several peptide hormones that regulate many physiological processes including stress, growth, and reproduction


Produced by the thyroid gland and decreases the blood calcium levels by stimulating calcium deposit in the bones. The antagonist of the parathyroid hormone.


Stress hormone that activates the body and prepares us to respond to stressful circumstances

Diabetes mellitus

Condition that occurs when the pancreas produces too little insulin, resulting in an increase in the level of blood glucose

Endocrine gland

A ductless gland that secretes hormones directly into the bloodstream

Endocrine system

The body's "slow" chemical communication system; a set of glands that secrete hormones into the bloodstream


Any of several hormones produced in the brain and anterior pituitary that inhibits pain perception.


Adrenaline; activates a sympathetic nervous system by making the heart beat faster, stopping digestion, enlarging pupils, sending sugar into the bloodstream, preparing a blood clot faster


A sex hormone, secreted in greater amounts by females than by males. In nonhuman female mammals, estrogen levels peak during ovulation, promoting sexual receptivity.


The antagonist of insulin. Its release is stimulated by low blood glucose levels. It stimulates the liver, its primary target organ, to break down its glycogen stores to glucose and subsequently to release glucose to the blood.


Steroid hormone secreted by the adrenal cortex; regulates glucose, fat, and protein metabolism.


Enlargement of the thyroid gland caused by thyroid dysfunction, tumor, lack of iodine in the diet, or inflammation (goiter = throat)


Female or male reproductive organ that produces sex cells and hormones; ovary or testis

Growth hormone (gh)

Anterior pituitary: increases bone and muscle growth, increases cell turnover rate


A chemical that serves as a messenger. Each hormone is secreted by a gland and travels to one or more target organs, where it brings about responses.


Abnormally low blood sugar usually resulting from excessive insulin or a poor diet


A neural structure lying below the thalamus; directs eating, drinking, body temperature; helps govern the endocrine system via the pituitary gland, and is linked to emotion

Inhibiting hormone

A kind of hormone released from the hypothalamus that makes the anterior pituitary stop secreting hormone


Hormone produced by the pancreas that is released when stimulated by elevated glucose levels. This hormone decreases blood sugar levels by accelerating the transport of glucose into the body cells where it is oxidized for energy or converted to glycogen or fat for storage.

Local regulator

A secreted molecule that influences cells near where it is secreted.


Hormone secreted by the adrenal cortex; regulates salts (electrolytes) and water balance in the body. Aldosterone is an example.

Neurosecretory cell

A specialized nerve cell that releases a hormone into the bloodstream in response to signals from other nerve cells; located in the hypothalamus and adrenal medulla.


Noradrenaline; chemical which is excitatory, similar to adrenaline, and affects arousal and memory; raises blood pressure by causing blood vessels to become constricted, but also carried by bloodstream to the anterior pituitary which relaxes acth thus prolonging stress response


Located partially behind the stomach in the abdomen, and it functions as both an endocrine and exocrine gland. It produces digestive enzymes as well as insulin and glucagon

Parathyroid glands

There are four and they are embedded in the surface of the thyroid, function in the homeostasis of calcium ions. They secrete parathyroid hormone (pth), which raises blood levels of calcium and thus has an effect opposite to that of the thyroid hormone calcitonin.

Parathyroid hormone (pth)

Increases blood calcium levels; stimulates kidneys & intestines to absorb more calcium; breaks down bones

Pineal gland

Located in the center of the brain, functioning to secrete melatonin and serotonin

Pituitary gland

The endocrine system's most influential gland. Under the influence of the hypothalamus, the pituitary regulates growth and controls other endocrine glands

Posterior pituitary

Aka neurohypophysis; does not synthesize hormones; stores and releases peptide hormones oxytocin and adh which are produced by neurosecretory cells of hypothalamus; hormone secretion is stimulated by action potentials from hypothalamus.


Female hormone that stimulates the uterine lining during pregnancy and is also used in treatment of abnormal uterine bleeding and for hormone replacement therapy

Prolactin (prl)

Promotes development of glandular tissue during pregnancy and produces milk after birth of an infant

Releasing hormone

Hormone secreted by the hypothalamus that regulates the release of other hormones from the anterior pituitary

Steroid hormone

A hormone derived from cholesterol. Steroids are generally hydrophobic and can easily cross the plasma membrane of cells, thus receptors for steroids are found intracellularly. Once this steroid binds to its receptor, the receptor-steroid complex acts to regulate transcription in the nucleus.

Target cell

Any cell that is acted on directly by effector t cells, effector cells or molecules. For example, virus-infected cells are the targets of cytotoxic t cells, which kill them, and naive b cells are the targets of effector cd4 t cells, which help to stimulate them to produce antibodies.


The most important of the male sex hormones. Both males and females have it, but the additional testosterone in males stimulates the growth of the male sex organs in the fetus and the development of the male sex characteristics during puberty

Trh-releasing hormone

Hormone released by the hypothalamus that controls the release of thyroid-stimulating hormone from the anterior pituitary.

Triiodothyronine (t3)

Thyroid gland; regulates growth and development of the body and controls metabolism and body temperature.

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