Endocrine System

 

Endocrine System


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Body parts

Pituitary gland, hypophysis cerebri

Approximately the size of a pea and located at the base of the brain.  The pituitary is divided into two lobes.

Anterior love or adenohypophysis

Produces and secretes the following hormones:

Growth hormone (GH)

Regulates the growth of the body;

Adrenocorticotropic hormone (ACTH)

Stimulates the adrenal cortex;

Thyroid-stimulating hormone (TSH)

Stimulates the thyroid gland;

Gonadotropic hormones

Affect the male and female reproductive systems;

Follicle-stimulating hormone (FSH), luteinizing hormone (LH)

Regulate development, growth, and function of the ovaries and testes;

Prolactin or lactogenic hormone (PRL)

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

Antidiuretic hormone (ADH)

Stimulates the kidney to reabsorb water;

Oxytocin

Stimulates uterine contractions during labor and postpartum.

Hypothalamus

Located near the pituitary gland in the brain.  The hypothalamus secretes “releasing” hormone that functions to stimulate or inhibit the release of pituitary gland hormones.

Thyroid gland

Largest endocrine gland.  It is located in the neck below the larynx and comprises bilateral lobes connected by an isthmus.  The thyroid gland secretes the hormones triiodothyronine (T3) and thyroxine (T4), which require iodine for their production.  Thyroxine is necessary for body cell metabolism.

Parathyroid glands

Four small bodies lying directly behind the thyroid.  Parathormone (PTH), the hormone produced by the glands, helps maintain the level of calcium in the blood.

Islets of Langerhans

Clusters of endocrine tissue found throughout the pancreas, made up of different cell types that secrete various hormones, including insulin and glucagons.  Non-endocrine cells found throughout the pancreas perform non-endocrine functions such as digestion.

Adrenal glands, suprarenals

Paired glands, one of which is located above each kidney.  The outer portion is called the adrenal cortex, and the inner portion is called the adrenal medulla.  The following hormones are secreted by the adrenal glands.

Cortisol

Secreted by the cortex.  It aids the body during stress by increasing glucose levels to provide energy (also called hydrocortisone).

Aldosterone

Secreted by the cortex.  Electrolytes (mineral salts) that are necessary for normal body function are regulated by this hormone.

Epinephrine (adrenaline), norepinephrine (noradrenaline)

Secreted by the medulla.  These hormones help the body to deal with stress by increasing the body pressure, heartbeat, and respirations.

 

Combining Forms

aden/o

gland

adren/o, adrenal/o

adrenal glands

cortic/o

cortex (the outer layer of a body organ)

endocrin/o

endocrine

parathyroid/o

parathyroid glands

thyroid/o, thyr/o

thyroid gland

acr/o

extremities, height

calc/i

calcium

dips/o

thirst

kal/i

potassium

natr/o

sodium

 

Suffixes

-drome

run, running

 

Medical Terms – not built from word parts

Acidosis

Condition brought about by an abnormal accumulation of acid products of metabolism, seen frequently in uncontrolled diabetes mellitus.

Addison disease

Chronic syndrome resulting from a deficiency in the hormonal secretion of the adrenal cortex.  Symptoms may include weakness, darkening of skin, loss of appetite, depression, and other emotional problems.

Cretinism

Condition caused by congenital absence or atrophy (wasting away) of the thyroid gland, resulting in hypothyroidism.  The disease is characterized by puffy features, mental deficiency, large tongue, and dwarfism.

Cushing syndrome

Group of symptoms attributed to the excessive production of cortisol by the adrenal cortices (pl. Of cortex).  This syndrome may be the result of a pituitary tumor.  Symptoms include abnormally pigmented skin, “moon face”, pads of fat on the chest and abdomen, “buffalo hump” (fat on the upper back), and wasting away of muscle.

Diabetes insipidus (DI)

Result of decreased secretion of antidiuretic hormone by the posterior lobe of the pituitary gland.  Symptoms include excessive thirst (polydipsia) and large amounts of urine (polyuria) and sodium being excreted from the body.

Diabetes mellitus (DM)

Chronic disease involving a disorder of carbohydrate metabolism.  Diabetes mellitus is caused by underactivity of the islets of Langerhans in the pancreas, which results in insufficient production of insulin.  When the disease is not controlled or is untreated, the patient may develop ketosis, acidosis, and finally coma.

Gigantism

Condition brought about by overproduction of growth hormone by the pituitary gland before puberty.

Goiter

Enlargement of the thyroid gland.

Graves disease

A disorder of the thyroid gland characterized by the presence of hyperthyroidism, goiter, and exophthalmos.

Ketosis

Condition resulting from uncontrolled diabetes mellitus, in which the body has an abnormal concentration of ketone bodies (compounds that are a normal product of fat metabolism).

Myxedema

Condition resulting from a deficiency of the thyroid hormone thyroxine.  A severe form of hypothyroidism in an adult.  Symptoms include puffiness of the face and hands, coarse and thickened skin, enlarged tongue, slow speech, and anemia.

Tetany

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.

Thyrotoxicosis

A condition caused by excessive thyroid hormones.

Radioactive iodine uptake test (RAIU)

A nuclear medicine scan that measures thyroid function.  Radioactive iodine is given to the patient orally, after which its uptake into the thyroid gland is measured.

Thyroid scan

A nuclear medicine test that shows the size, shape, and position of the thyroid gland.  The patient is given a radioactive substance to visualize the thyroid gland.  An image is recorded as the scanner is passed over the neck area.  Used to detect tumors and nodules.

Fasting blood sugar (FBS)

A blood test to determine the amount of glucose in the blood after fasting for 8 to 10 hours.  Elevation indicates diabetes mellitus.

Thyroid-stimulating hormone level (TSH) (thyrotropin)

A blood test that measures the amount of thyroid-stimulating hormone in the blood.  Used to diagnose hyperthyroidism and to monitor patients on thyroid replacement therapy.

Thyroxine level (T4)

A blood study that gives the direct measurement of the amount of thyroxine in the patient’s blood.  A greater-than-normal amount indicates hyperthyroidism; a less-than-normal amount indicates hypothyroidism.

Exophthalmos

Abnormal protrusion of the eyeball.

Hormone

A chemical substance secreted by an endocrine gland that is carried in the blood to a target tissue.

Isthmus

Narrow strip of tissue connecting two large parts in the body, such as the isthmus that connects the two lobes of the thyroid gland.

Metabolism

Sum total of all the chemical processes that take place in a living organism.

 

Abbreviations

DI

diabetes insipidus

DM

diabetes mellitus

FBS

fasting blood sugar

RAIU

radioactive iodine uptake

T4

thyroxine level

 

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