12. ENDOCRINE SYSTEM

Adrenal cortex: Outer section of each adrenal gland; secretes Cortisol, Aldosterone,

and sex hormones.

Adrenal medulla: Inner section of each adrenal gland; secretes epinephrine and

norepinephrine.

Ovaries: Located in the lower abdomen of a female; responsible for egg production

and estrogen and progesterone secretion.

Pancreas: Located behind the stomach. Islet cells secrete hormones from the

pancreas. The pancreas also contains cells that are exocrine in function. They secrete

enzymes, via a duct into the small intestine to aid digestion.

Parathyroid gland: Four small glands on the posterior of the thyroid gland. Some

patients may have 3 to 5 parathyroid glands.

Pituitary gland: Located at the base of the brain in the sella turcica; composed of

an anterior lobe and a posterior lobe. It weighs only 1/16th of an ounce and is a half

inch across.

Testes: Two glands enclosed in the scrotal sac of a male; responsible for sperm

production and testosterone secretion.

Thyroid gland: Located in the neck on either side of the trachea; secretes

thyroxine.

Adrenaline: Secreted by the adrenal medulla; increases heart rate and blood

pressure.

Adrenocorticotropic hormone: Secreted by the anterior lobe of the pituitary

gland; also called adrenocorticotropin. ACTH stimulates the adrenal cortex.

Aldosterone: Secreted by the adrenal cortex; increases salt reabsorption.

Androgen: Male hormone secreted by the tests and to a lesser extent by the

adrenal cortex.

Antidiuretic hormone: Secreted by the posterior lobe of the pituitary gland. ADH

increases reabsorption of water by the kidney.

Calcitonin: Secreted by the thyroid gland, decreases blood calcium levels.

Cortisol: Secreted by the adrenal cortex; increases blood sugar. It is secreted in

times of stress and has an anti-inflammatory effect.

Epinephrine: Secreted by the adrenal medulla; increases heart rate and blood

pressure and dilates airways. It is part of the body’s “fight or flight” reaction.

Estradiol: Estrogen secreted by the ovaries.

Estrogen: Female hormone secreted by the ovaries and to the lesser extent by the

adrenal cortex. Examples are Estradiol and estrone.

Follicle-stimulating hormone: Secreted by the anterior lobe of the pituitary gland.

FSH stimulates hormone secretion and egg production by the ovaries and sperm

production by the testes.

Glucagon: Secreted by alpha islet cells of the pancreas, increases blood sugar by

conversion of glycogen to glucose.

Growth hormone; somatotropin: Secreted by the anterior lobe of the pituitary

gland; stimulates growth of bones and soft tissues.

Insulin: Secreted by beta islet cells of the pancreas. Insulin lowers blood sugar by

transport and conversion of glucose to glycogen.

Luteinizing hormone: Secreted by the anterior lobe of the pituitary gland;

stimulates ovulation in females and testosterone secretion in males.

Norepinephrine: Secreted by the adrenal medulla; increases heart rate and blood

pressure.

Oxytocin: Secreted by the posterior lobe of the pituitary gland; stimulates

contraction of the uterus during labor and child birth.

Parathormone: Secreted by the parathyroid gland; increase blood calcium.

Progesterone: Secreted by the ovaries; prepares the uterus for pregnancy.

Prolactin: Secreted by the anterior lobe of the pituitary gland; promotes milk

secretion.

Somatotropin: Secreted by the anterior lobe of the pituitary gland; growth

hormone.

Testosterone: Male hormone secreted by the testes.

Thyroid-stimulating hormone: Secreted by the anterior lobe of the pituitary gland’

TSH acts on the thyroid gland to promote its functioning. Note: TSH is not secreted

by the thyroid gland.

Thyroxine: Secreted by the thyroid gland; also called tetraiodothyronine. T4

increases metabolism in cells.

Triiodothyronine (T3): Secreted by the thyroid gland; T3 increases metabolism in

cells.

Vasopressin: Secreted by the posterior lobe of the pituitary gland; Antidiuretic

hormone.

Catecholamines: Hormones derived from an amino acid and secreted by the

adrenal medulla. Epinephrine is a catecholamine.

Corticosteroids: Hormones produced by the adrenal cortex.

Electrolyte: Mineral salt found in the blood and tissues and necessary for proper

functioning of cells; potassium, sodium, and calcium are electrolytes.

Glucocorticoid: Steroid hormone secreted by the adrenal cortex, regulates glucose,

fat, and protein metabolism. Cortisol raises blood sugar and is part of the stress

response.

Homeostasis: Tendency of an organism to maintain a constant internal

environment.

Hormone: Substance, secreted by an endocrine gland that travels through the blood

to a distant organ or gland where it influences the structure or function of that organ

or gland.

Hypothalamus: Region of the brain lying below the thalamus and above the

pituitary gland. It secretes releasing factors and hormones that affect the pituitary

gland.

Mineralocorticoid: Steroid hormone secreted by the adrenal cortex to regulate

mineral salts and water balance in the body. Aldosterone is an example.

Receptor: Cellular or nuclear protein that binds to a hormone so that a response

can be elicited.

Sella turcica: Cavity in the skull that contains the pituitary gland.

Sex hormones: Steroids produced by the adrenal cortex to influence male and

female sexual characteristics.

Steroid: Complex substance related to fats and of which many hormones are made.

Examples of steroids are estrogens, androgens, glucocorticoids, and

mineralocorticoids.

Sympathomimetic: Pertaining to mimicking or copying the effect of the

sympathetic nervous system/ adrenaline is a Sympathomimetic hormone.

Target tissue: Cells of an organ that are affected or stimulated by specific

hormones.

Hyperthyroidism: Overactivity of the thyroid gland

Graves’s disease: Because metabolism is faster, the condition is marked by an

increase in heart rate, higher body temperature, hyperactivity, weight loss, and

increased peristalsis.

Exophtalmos: Swelling of tissue behind the eyeball, pushing it forward.

Goiter: Enlargement of the thyroid gland is goiter. Goiter occurs when low iodine

levels lead to low T3 and T4 levels.

Nodular goiter: In this type of goiter, hyperplasia occurs as well as nodules and

adenomas occur.

Myxedema: This is advanced hypothyroidism in adult. Atrophy of the thyroid gland

occurs, and practically no hormone is produced. The skin becomes dry and puffy.

Cretinism: Extreme hypothyroidism during infancy and childhood leads to a lack of

normal physical and mental growth.

Tetany: Muscle and nerve weakness with spasms of muscles due to hypocalcemia.

Cushing syndrome: Group of symptoms produced by excess Cortisol from the

adrenal cortex. In includes obesity, moon-like fullness of the face, and excess

deposition of fat in the thoracic region of the back, hyperglycemia, hypernatremia,

hypokalemia, osteoporosis, and hypertension.

Addison disease: Hypofunctioning of the adrenal cortex. Patient experiences

malaise, weakness, muscle atrophy, severe loss of fluids and electrolytes.

Pheochromocytoma: Benign tumor of the adrenal medulla.

Hyperinsulinism: Excess secretion of insulin causes hypoglycemia.

Diabetes mellitus: Lack of insulin secretion or resistance of insulin in promoting

sugar, starch, and fat metabolism in cells.

Type 1 diabetes: Onset in childhood, involves destruction of the beta islet cells of

the pancreas and complete deficiency of insulin in the body.

Type 2 diabetes: It’s a separate disease from type 1 and has a different inheritance

pattern. Patients usually are older, and obesity is very common. The islet cells are

not initially destroyed, and there is a relative deficiency of insulin secretion.

Acromegaly: Enlargement of the extremities caused by hypersecretion of the

anterior pituitary after puberty.

Gigantism: Hypersecretion of growth hormone from the anterior lobe of the

pituitary gland before puberty, leading to abnormal overgrowth of body tissues.

Dwarfism: Congenital hyposecretion of growth hormone.

Panhypopituitarism: All pituitary hormones are deficient.

Diabetes insipidus: Insufficient secretion of Antidiuretic hormone. Deficient

Antidiuretic hormone causes the kidney tubules to fail to hold back needed water and

salts.

Fasting blood sugar: Measures circulating glucose level in a patient who has fasted

at least 4 hours.

Serum and urine tests: Measurement of hormones, electrolytes, glucose and other

substances in serum and urine as indicators of endocrine function.

Exophthalmometry: Measurement of eyeball protrusion.