CH 14: Endocrine

Pineal Gland

A cone-shaped gland located in the brain; secretes melatonin; called the biological clock.

tetany

A deficiency of parathyroid hormone causes this life-threatening hypocalcemic condition. Characterized by sustained muscle contraction and an inability to ventilate (breathe).

Cushing's syndrome

A person who takes high doses of steroids over an extended time will develop this group of signs and symptoms.

Positive Feedback Control

A self-amplication (give me more) in which a change is the stimulus for an even greater change in the same direction.

ACTH

A tropic hormone that is suppressed by increasing plasma levels of cortisol. Tropic hormone that stimulates the adrenal cortex to secrete cortisol.

Growth Hormone

Also called somatotropic hormone, this anterior pituitary hormone stimulates the growth of the musculoskeletal system.

cretinism

An infant born with a deficiency of thyroid hormones develops this condition, characterized by a severe delay in both physical and mental development. Requires replacement doses of T3 & T4.

Grave's disease

Antithyroid drugs and surgery are used to treat this form of hyperthyroidism.

Pancreas

Beta and alpha cells of the islets of Langerhans. Secretes insulin and glucagon.

Addison's disease

Condition that is caused by a deficiency of adrenocortical steroids. If untreated, this deficiency disease will progress to adrenal shock. Requires replacement doses of steroids, especially mineralocorticoid.

giantism

Condition that is caused by a hypersecretion of somatotropic hormone in a child.

dwarfism

Condition that is caused by a hyporsecretion of somatotropic hormone in a child.

acromegaly

Condition that is caused by hypersecretion of growth hormone in an adult (after the fusion of the epiphyseal discs).

pheochromocytoma

Condition that results from a tumor of the adrenal medulla, which causes a very high (and dangerous) blood pressure.

Steroids

Cortisol, aldosterone, and testosterone.

Second Chemical Messengers

Cyclic adenosine monophosphate. (cAMP)

Target Tissue (organ)

Describes a specific tissue or organ to which a hormone binds.

exophthalmos

Describes the bulging or protruding eyes that characterize hyperthyroidism.

Hormones

Endocrine secretions that are classified as proteins, protein-like substances, or steroids.

Catecholamines

Epinephrine and norepinephrine; sympathomimetic hormones.

Biorhythm(s)

Ex. 1) cortisol secretion is highest in the morning (8AM), lowest in the evening (midnight). 2) Circadian rhythm. 3) Jet lag and night shift work alter this pattern of hormone secretion. 4) Menstrual cycle.

Negative Feedback Control

Ex. Corticotropin-releasing hormone (CRH) stimulates the release of adrenocorticotropic hormone (ACTH), which in turn stimulates the secretion of cortisol; as the blood level of cortisol increases, it shuts off the further secretion of ACTH and CRH.

Ovaries

Gonads that secrete estrogen and progesterone.

Parathyroid Hormone

Hormone that acts on three target organs (bones, kidneys, and intestine) to increase the blood levels of calcium. Stimulates osteoclastic activity. A decrease in plasma calcium is the stimulus forts release.

Receptor(s)

Hormones bind to these special areas in the cell or on the surface of the cell membrane of target tissue.

Tropic Hormones

Hormones that are "aimed at" a target.

Releasing Hormone

Hypothalamic hormones that control the hormonal secretion of the anterior pituitary gland.

Gonadotropins

Include follicle-stimulating hormone (FSH) and luteinizing hormone (LH).

Parathyroid Glands

Low plasma levels of calcium stimulate these glands to secrete parathyroid hormone (PTH). Glands that are sometimes embedded within the thyroid gland; removal causes hypocalcemia tetany.

myxedema

the adult form of hyperthyroidism that is treated with thyroid hormone. Requires replacement doses of T3 & T4.

Glucagon

Pancreatic hormone that increases blood glucose levels.

Calcitonin

Parafollicular cells, thyroid gland, stimulate osteoblastic activity.

Oxytocin

Posterior pituitary hormone that enhances labor. Post. pit. hormone that is involved in the release of milk from the breast (the milk let-down reflex).

ADH

Posterior pituitary hormone that stimulates the the kidneys to reabsorb water. Also called vasopressin.

diabetes mellitus

Results from a deficiency in insulin; the person becomes hyperglycemic and glucosuric. Condition that is treated with replacement doses of insulin. If untreated, this condition progresses to ketoacidosis.

diabetes insipidus

Results from deficiency of ADH that has causes the person to urinate up to 25 L/day of pale urine.

Thyroid Gland

Secretes T3, T4, and calcitonin. Uses iodine to synthesize its hormone. Target gland of TSH.

Posterior Pituitary Gland (neurohypophysis)

Secretes antidiuretic hormone (ADH) and oxytocin.

Hypothalamus

Secretes releasing hormones.

Adrenal Medulla

Secretes the catecholamines, epinephrine, and norepinephrine. Secretion of this gland contribute to the sympathetic flight-or-fight response.

Adrenal Cortex

Secretes the steroids - glucocorticoids, mineralocorticoids, and androgens. Secretes the hormones that are concerned with sugar, salt, and sex. Target gland for ACTH.

Prolactin

Stimulates the breasts to make milk; also called lactogenic hormone.

T3 & T4

TSH stimulates the thyroid gland to release these hormones. Iodine-Containing hormones that regulate basal metabolic rate (BMR).

Testes

The gonad that secretes testosterone.

Anterior Pituitary Gland (adenohypophysis)

The hypothalamus and this gland are parts of the hypothalamic-hypophyseal portal system. Secretes tropic hormones such as thyroid-stimulating (TSH), ACTH, growth hormone (somatotropic hormone), and the gonadotropins.

Insulin

The only hormone that lowers blood glucose. The stimulus for its release is an increasing blood glucose level.

Thymus Gland

This gland plays and important role in immunity and involutes, or shrinks, after puberty.

goiter

This results from an iodine-deficient diet, which causes hyperplasia or overgrowth of the thyroid gland.

Endocrine Glands

Type of glands that secrete hormones; ductless glands.

Exocrine Glands

Types of glands that secrete into ducts.