Endocrine System

Vocabulary flashcards for the endocrine system.

Endocrine System

A system of ductless glands that synthesize and secrete hormones into the blood, which are then transported throughout the body to target cells with specific receptors, triggering a response.

Local Hormones

Hormones that do not circulate in the blood and bind to neighboring cells or the cells that release them.

Eicosanoids

Fatty acids within the phospholipid bilayer of the membrane that act as local hormones.

Autocrine stimulation

Effects on the same cell where a messenger was formed

Paracrine stimulation

Effects on neighboring cells

Endocrine System Functions

Regulating development, growth, and metabolism; maintaining homeostasis of blood composition and volume; controlling digestive processes; controlling reproductive activities.

Endocrine Organs

Organs with a solely endocrine function, such as the pituitary, pineal, thyroid, parathyroid, and adrenal glands.

Hormonal Stimulation

The release of a hormone in response to another hormone (e.g., TSH).

Humoral Stimulation

The release of a hormone in response to changes in the level of a nutrient or ion in the blood (e.g., insulin).

Nervous Stimulation

The release of a hormone in response to neuron stimulation (e.g., adrenal medulla).

Steroids

Lipid-soluble hormones derived from cholesterol, including gonadal steroids, cortisol, and calcitriol.

Biogenic Amines

Modified amino acids that act as hormones, including catecholamines, thyroid hormone, and melatonin. Most are water-soluble, except for thyroid hormone.

Proteins

Water-soluble chains of amino acids that include small peptides, large polypeptides and glycoproteins. (antidiuretic hormone, insulin, glucagon)

Lipid-soluble hormones

Hormones such as steroids and thyroid hormone, require carrier molecules for transport in the blood.

Water-soluble hormones

Hormones that are free in the blood, though a few use carrier proteins to prolong their life.

Half-Life

The time required for half of a hormone to be eliminated from the blood, influenced by enzymatic degradation, removal from blood, and target cell uptake.

Up-regulation

An increase in the number of receptors on a target cell in response to a reduced hormone concentration in the blood; increasing sensitivity

Down-regulation

A decrease in the number of receptors on a target cell in response to elevated hormone concentration in the blood; decreasing sensitivity

Synergistic interactions

Interaction where hormones work together to produce a greater effect.

Permissive interactions

Interaction where the first hormone allows the action of second hormone.

Antagonistic interactions

Interaction where one hormone causes the opposite effect of another hormone.

Pituitary Gland

An endocrine gland with two lobes: the neurohypophysis (posterior lobe) which stores and releases hormones from the hypothalamus, and the adenohypophysis (anterior lobe), which synthesizes and secretes hormones.

Hypothalamus

Brain region that controls the anterior pituitary by secreting regulatory hormones through the hypophyseal portal system.

Releasing hormones

Hormones secreted by the hypothalamus to increase secretion of anterior pituitary hormones.

Inhibiting hormones

Hormones secreted by the hypothalamus to decrease secretion of anterior pituitary hormones.

Tropic Hormones

Hormones of the anterior pituitary including thyroid stimulating hormone (TSH), Prolactin (PRL), Adrenocorticotropic hormone (ACTH), Follicle-stimulating hormone (FSH) and Leutenizing hormone (LH), and Growth hormone (GH)

Growth hormone (GH)

Stimulates linear growth, muscle hypertrophy and the release of nutrients from storage into the blood; its release is influenced by age, time of day, nutrient levels, stress and exercise.

Gigantism

A condition caused by hypersecretion of GH before the epiphyseal plates have fused and a person becomes abnormally tall.

Acromegaly

A condition caused by hypersecretion of GH after the epiphyseal plates have fused, leading to bone thickening in the face, hands, and feet.

Pituitary dwarfism

A condition caused by hyposecretion of GH and a person does not grow to normal height.

Follicular cells

Cells in the thyroid glad that produce and release thyroid hormone (TH)

Parafollicular cells

Cells in the thyroid gland that make calcitonin.

Thyroid hormone (TH)

Hormone that increases metabolic rate and protein synthesis in targets, stimulates synthesis of sodium-potassium pumps, and is calorigenic.

Hyperthyroidism

A condition resulting from excessive secretion of thyroid hormone.

Hypothyroidism

A condition resulting from decreased secretion of thyroid hormone.

Goiter

An enlarged thyroid gland, often caused by iodine deficiency.

Mineralocorticoids

Hormones produced by the adrenal cortex which regulate electrolyte levels.

Glucocorticoids

Hormones secreted by the adrenal cortex which affect glucose metabolism.

Gonadocorticoids

Sex hormones secreted by the adrenal cortex.

Cushing syndrome

A condition resulting from chronic exposure to excessive glucocorticoid hormones.

Addison disease

A condition due to deficiency of mineralocorticoids and glucocorticoids.

Pancreatic islets (of Langerhans)

Clusters of endocrine cells in the pancreas, containing alpha cells that secrete glucagon, and beta cells that secrete insulin.

Insulin

A hormone that lowers blood glucose levels by increasing glucose uptake into cells.

Glucagon

A hormone that raises blood glucose levels by stimulating glycogenolysis and gluconeogenesis in the liver.

Diabetes mellitus

A disease resulting from inadequate uptake of glucose.

Type 1 diabetes

Diabetes caused by absent or diminished release of insulin by the pancreas; requires daily injections of insulin.

Type 2 diabetes

Diabetes due to decreased insulin release or insulin effectiveness; often associated with obesity.

Hypoglycemia

A condition with blood glucose levels below 60 mg/dL.