Chapter 14: The Endocrine System Flashcards
What is the primary function of the endocrine system?
To produce hormones that directly enter the bloodstream and travel to specific organs or tissues of the body called targets to maintain homeostasis.
What are hormones?
Specialized chemicals released by the body.
Define antagonistic:
Acting in opposition, mutually opposing.
Define electrolytes:
Salts and minerals that conduct electrical impulses in the body. These control fluid balance in the body and are important in muscle contraction, energy generation, and almost every biochemical reaction in the body.
Define glucagon:
Hormone produced by pancreatic alpha cells that stimulates the liver to change stored glycogen to glucose. Glucagon is antagonistic to insulin, and is used to reverse hypoglycemic reactions in insulin shock.
Define glucose:
Simple sugar that is the end product of carbohydrate digestion; major source of energy for living organisms.
Define sympathomimetic:
Agent that mimics the effects of the sympathetic nervous system. Ex: epinephrine or norepinephrine.
What are some other names for the pituitary gland?
Hypophysis or master gland
What is the function of the pituitary gland?
Pea-sized organ located at the base of the brain that regulates many body activities and stimulates other organs to secrete their own specific hormones.
What are the 2 distinct lobes of the pituitary gland?
Adenohypophysis and neurohypophysis
What is the adenohypophysis?
Anterior lobe of the pituitary gland; produces at least 6 hormones triggered by the action of the hypothalamus.
What is the neurohypophysis?
Posterior lobe of the pituitary gland; secretes 2 hormones produced by the hypothalamus.
Tell me about the adrenocorticotropic hormone (ACTH):
Secreted by the adenohypophysis; affects the adrenal cortex by promoting the secretion of corticosteroids, specifically cortisol. Hyposecretion is rare; hypersecretion causes Cushing disease.
Tell me about the follicle-stimulating hormone (FSH):
Secreted by the adenohypophysis; affects the ovaries/testes and stimulates production of their respective gametes. Hyposecretion causes failure of sexual maturation and hypersecretion has no known significant effects.
Tell me about growth hormone (GH), otherwise known as somatotropin:
Secreted by the adenohypophysis; regulates growth of bone, muscle, and other body tissues, and increases use of fats for energy. Hyposecretion during childhood may cause pituitary dwarfism, hypersecretion during childhood causes gigantism, and hypersecretion in adulthood causes acromegaly.
Tell me about luteinizing hormone (LH):
Secreted by the adenohypophysis; promotes ovulation and stimulates production of estrogen/progesterone in the ovaries or testosterone in the testes. Hyposecretion in nursing mothers causes poor lactation, hyposecretion causes failure of sexual maturation, and hypersecretion has no known significant effects.
Tell me about prolactin (PRL):
Secreted by the adenohypophysis; promotes lactation in breast tissue in conjunction with other hormones. Hypersecretion in nursing mothers can cause excessive lactation (galactorrhea).
Tell me about the thyroid-stimulating hormone (TSH), otherwise known as thyrotropin:
Secreted by the adenohypophysis; stimulates the thyroid gland to secrete thyroid hormones. Hyposecretion in infants causes cretinism, hyposecretion in adults causes myxedema, and hypersecretion causes Graves disease.
Tell me about the antidiuretic hormone (ADH):
Secreted by the neurohypophysis; stimulates the kidneys to increase water reabsorption. Hyposecretion causes diabetes insipidus (DI), and hypersecretion causes syndrome of inappropriate antidiuretic hormone (SIADH).
Tell me about oxytocin:
Secreted by the neurohypophysis; stimulates the uterus to contract and initiate labor, and stimulates the mammary glands to secrete milk.
Tell me about the thyroid gland:
H-shaped organ that lies in the neck just below the larynx; largest gland of the endocrine system. Composed of 2 lobes separated by a strip of tissue called the isthmus.
What hormones does the thyroid secrete?
The thyroid hormone (TH) is the body’s major metabolic hormone as it increases the rate of O2 consumption. The 2 iodine-containing hormones secreted by the thyroid are thyroxine (T4) and triiodothyronine (T3).
Tell me about calcitonin:
Secreted by the thyroid; regulates calcium levels in the blood in conjunction with parathyroid hormones.
Tell me about thyroxine (T4) and triiodothyronine (T3):
Increases energy production from all food types, and increases the rate of protein synthesis.
Tell me about the parathyroid glands:
Consists of at least 4 separate glands on the surface of the thyroid. These secrete that parathyroid hormone (PTH), which targets the bones (reabsorption of calcium from the bones to the blood), the kidneys (increases calcium absorption and phosphate excretion), and the small intestine (increases absorption of calcium and phosphate).
Tell me about the adrenal glands:
Also known as suprarenal glands; paired organs covering the superior surface of the kidneys. These are divided into the adrenal cortex and adrenal medulla.
Tell me about the adrenal cortex:
Outer portion of the adrenal gland that secretes 3 distinct hormones: mineralocorticoids, glucocorticoids, and sex hormones.
Tell me about mineralocorticoids:
Secreted by the adrenal cortex; main one is aldosterone, which is essential to life. These act on the kidneys and cause them to conserve Na+ and K+ to conserve electrolyte balance and reduce water output.
Tell me about glucocorticoids:
Secreted by the adrenal cortex; main one is cortisol, which influences the metabolism of carbohydrates, fats, and proteins. These help regulate the concentration of glucose in the blood. It also stimulates the breakdown of fats to release fatty acids in the blood to reduce use of glucose to maintain blood sugar between meals.
Tell me about sex hormones:
Secreted by the adrenal cortex; these are androgens, estrogens, and progestins that help maintain secondary sex characteristics.
Tell me about the adrenal medulla:
Inner portion of the adrenal gland, and secretes 2 closely related hormones, epinephrine (adrenaline) and norepinephrine (noradrenaline). Both of these are considered sympathomimetic agents that are released when the body experiences crisis.
Tell me about the pancreas:
Lies inferior to the stomach and functions as an endocrine and exocrine gland. Exocrine function is it secretes digestive enzymes into the small intestine via the large pancreatic duct. The endocrine role is secretion of 2 hormones through the islets of Langerhans, glucagon and insulin.
Tell me about glucagon and insulin:
Glucagon is produced by the alpha cells of the pancreas and functions to turn glucose into glycogen to be used by the body. Insulin is produced by the beta cells of the pancreas, and clears glucose from the blood to prevent hyperglycemia. These 2 hormones function antagonistically.
Tell me about the pineal gland:
Small, pinecone-shaped organ located deep in the brain just behind the thalamus. Exact function of this gland is unknown, but there are signs it secretes melatonin.
Tell me about the thymus:
Butterfly-shaped gland at the base of the neck formed mostly of lymphatic tissue. This functions as part of both the immune and endocrine systems.
adren/o
adrenal/o
Adrenaline glands
calc/o
calcium
crin/o
secrete
gluc/o
glyc/o
glycos/o
sugar; sweetness
home/o
same; alike
kal/i
potassium
pancreat/o
pancreas
parathyroid/o
parathyroid glands
thym/o
thymus gland
thyr/o
thyroid/o
thyroid gland
toxic/o
poison
-crine
secrete
-dipsia
thirst
-gen
forming, producing, origin
-toxic
pertaining to poison
-uria
urine
eu-
good
exo-
outside
poly-
many, much
Define hypersecretion:
Overproduction of a hormone.
Define hyposecretion:
Underproduction of a hormone.
How is hyposecretion of a hormone usually treated?
With drug therapy
How is hypersecretion of a hormone usually treated?
With surgery
What is endocrinology?
Branch of medicine concerned with endocrine glands and hormones.
What is an endocrinologist?
Physician who specializes in the diagnosis and treatment of endocrine disorders.
What is hypothyroidism?
Deficiency of the thyroid hormone
What is cretinism?
Hypothyroidism in infants. If left untreated, this condition may lead to mental retardation, impaired growth, low body temp, and abnormal bone formation.
What is myxedema?
Hypothyroidism in adults. Signs and sx include edema, low blood levels of T3 and T4, weight gain, cold intolerance, fatigue, depression, arthralgia/myalgia, and sluggishness.
What is hyperthyroidism?
Overproduction of thyroid hormones. Can be autoimmune (Graves disease) or toxic nodular/multinodular. Signs and sx include elevated metabolic rate, abnormal weight loss, excessive perspiration, muscle weakness, exophthalmos, goiter, and emotional instability. Tx includes drug therapy or surgery.
What is Graves disease?
Most common form of hyperthyroidism; also called thyrotoxicosis or autoimmune hyperthyroidism. This is an autoimmune disease where auto-antibodies are produced that stimulate excess thyroid hormone.
What is toxic nodular/multinodular hyperthyroidism?
Hyperthyroidism caused by nodules that develop on the thyroid gland.
What is hypoparathyroidism?
Insufficient production of parathyroid hormone (PTH) that is either caused by parathyroid dysfunction or elevated blood calcium levels. This may result from injury or surgical removal of the glands. Primary effect of this disease is hypocalcemia which causes tetany.
What is hypocalcemia?
Decreased levels of calcium in the blood.
What is tetany?
Muscle twitches and spasms.
What is hyperparathyroidism?
Excessive production of the parathyroid hormone. Commonly caused by a benign adenoma. This may cause osteitis fibrosa cystica, osteoporosis, and calcium deposits in the kidney.
What is osteitis fibrosa cystica?
Demineralization of bones.
What is osteoporosis?
Porous bones that are highly susceptible to fracture or deformity.
What is Addison disease?
Also called corticoadrenal insufficiency; uncommon disorder caused by deficiency of cortical hormones that results from damage or atrophy to the adrenal cortex. This interferes with the body’s ability to handle internal and external stress. Signs and sx include weakness, anorexia, GI sx, hypocalcemia, hypotension, hyponatremia, and hypokalemia. Early tx has a good prognosis, and the body will continue to deteriorate until tx is received.
What is Cushing Syndrome?
A cluster of sx produced by excessive amounts of cortisol, adrenocorticotropic hormone (ACTH), or both circulating in the blood. It alters carb/protein metabolism, affects electrolyte balance, edema, and results in higher blood glucose levels. Causes may include long-term use of steroids to tx autoimmune disease, adrenal tumor, and Cushing disease.
What is Cushing disease?
Hypersecretion of ACTH caused by an adenoma of the anterior pituitary gland.
What is a pheochromocytoma?
Most common neoplasm of the adrenal medulla that causes it to hypersecrete epinephrine and norepinephrine. Most of these are encapsulated and benign.
What is diabetes?
It is a general term that refers to diabetes mellitus (DM). This is a chronic metabolic disorder that results from the body’s inability to produce insulin, or it’s inability to process insulin properly. When the body cells are deprived of glucose with this disease, they start to metabolize proteins and fats, causing ketones to enter the blood, which leads to ketosis.
What’s ketosis?
Abnormal condition of high levels of ketones in the blood due to increased fat metabolism.
What is DM type 1?
An autoimmune disease, usually diagnosed in children or young adults, where the body doesn’t produce a sufficient amount of insulin. Requires monitoring blood sugar levels with a glucometer, and multiple insulin shots daily.
What is DM type 2?
Either the body’s cells are insulin-resistant, or the pancreas is deficient in producing insulin. In both cases, the body’s cells don’t absorb glucose, which causes hyperglycemia. Most common form of diabetes that usually occurs later in life. Tx includes exercise, weight loss, and oral medication.
Tell me about pancreatic cancer:
Most cancers of the pancreas are adenocarcinomas. Pain is a prominent sx of pancreatic cancer, because the pancreas has a rich supply of nerves. Prognosis is poor with a 2% chance of survival in 5 years, and pancreatic cancer is the 4th leading cause of cancer death in the U.S. Etiology is unknown, but risk factors include cigarette smoking, occupational exposure, high fat diet, and heavy coffee intake.
Tell me about pituitary tumors:
These are abnormal growths that appear on the pituitary gland that may cause excessive or deficient production of hormones that regulate important bodily functions. Sx may include compression of nerves that can result in vision problems. Tx includes a hypophysectomy (surgical removal).
What is a transsphenoidal hypophysectomy?
Removal of the pituitary tumor through the nose and sphenoid sinuses.
Tell me about thyroid carcinoma:
Malignancy that usually begins with a painless, hard nodule and enlarged thyroid. Can either cause hypothyroidism or hyperthyroidism. Tx includes surgery and radiation.
Disorder characterized by excessive thirst (polydipsia) and polyuria due to inadequate production of the antidiuretic hormone (ADH).
Diabetes insipidus (DI)
Increased formation and secretion of urine. Commonly occurs in DM or in those with high alcohol or coffee consumption.
Diuresis
Diabetes that develops during pregnancy. Blood glucose levels usually return to normal after delivery, however, it places the mother at risk for DM2.
Gestational diabetes
Pituitary gland disorder that generally involves hyper/hyposecretion of GH; commonly results from a pituitary tumor.
Growth hormone (GH) disorder
Hypersecretion of GH in adults, resulting in enlargement of bones in extremities and head.
Acromegaly
Hyposecretion of GH during childhood, resulting in extreme shortness and stature (final height 3’-4’) but normal body proportions. Tx includes administration of GH during childhood before skeletal growth is complete.
Dwarfism
Hypersecretion of GH during childhood, resulting in abnormal increase in length of long bones and extreme height (up to 8’ tall) but with normal proportions.
Gigantism
Excessive distribution of body hair, especially in women. Common causes include abnormalities in androgen production, meds, and tumors.
Hirsutism
Increased levels of blood calcium. Main cause is overactivity of 1 or more parathyroid glands.
Hypercalcemia
Increased levels of blood potassium. Requires immediate tx, because it can lead to cardiac arrest and death.
Hyperkalemia
Abnormal increase in the volume of blood plasma. Commonly result of retention of large amounts of sodium and water by the kidneys.
Hypervolemia
Decreased levels of blood sodium. Commonly caused by drinking too much water when exercising, which dilutes the sodium in the blood.
Hyponatremia
Tumor of the islets of Langerhans of the pancreas, causing excess insulin production, which leads to hypoglycemia. Also called pancreatic tumor.
Insulinoma
Genetic disorder with multiple benign fibrous tumors that grow anywhere in the nervous system, including the brain, spinal cord, and peripheral nerves. Some of these may become cancerous.
Neurofibromatosis (NF)
Abnormal accumulation of body fat, usually 20% or more of an individual’s ideal body weight. Associated with increased risk of illness, disability, and death.
Obesity
Total pituitary impairment that brings about a progressive and general loss of hormone activity.
Panhypopituitarism
Crisis of uncontrolled hyperthyroidism caused by increased amount of thyroid hormone being released into the bloodstream; also called thyroid crisis or thyrotoxic crisis. Medical emergency that may be fatal if left untreated.
Thyroid storm
Masculinization or development of male secondary sex characteristics in a woman.
Virilism
Measures the degree of forward displacement of the eyeball as seen in Graves disease.
Exophthalmometry
Blood test used to diagnose and manage DM1 and DM2. Reflects the avg blood sugar level in a patient for the past 2-3 months by measuring the percentage of hemoglobin coated with sugar.
A1c test
Test that measures the glucose levels in a blood sample following a fast of at least 8 hours. Helps diagnose DM and monitor glucose levels in diabetic patients.
Fasting Blood Sugar (FBS)
Screening test in which a dose of glucose is administered and blood samples are taken at regular intervals following the dose to determine how quickly glucose is cleared from the blood. Performed to diagnose pre-diabetes and gestational diabetes.
Glucose Tolerance Test (GTT)
Diagnostic test in which insulin is injected into the vein, causing severe hypoglycemia to assess growth hormone (GH) and cortisol reserve. Sx of low blood glucose causes release of GH and cortisol. The test measures GH and cortisol levels at specified intervals.
Insulin Tolerance Test (ITT)
Test that detects an increase/decrease in thyroid function. Measures levels of thyroid-stimulating hormone (TSH), triiodothyronine (T3), and thyroxine (T4).
Thyroid Function Test (TFT)
Measures blood calcium levels to detect bone and parathyroid disorders, malabsorption, or overactive thyroid. Hypercalcemia indicates hyperparathyroidism, hypocalcemia indicates hypoparathyroidism.
Total calcium test
Nuclear imaging procedure that combines a thyroid scan with RAIU procedure to evaluate the structure and physiologic functioning of the thyroid.
Radioactive iodine uptake (RAIU) scan
Excision of 1 or more of the parathyroid glands, usually to control hyperparathyroidism.
Parathyroidectomy
Excision of the entire thyroid gland (thyroidectomy), a part of it (subtotal thyroidectomy), or a single lobe (thyroid lobectomy). Performed for goiter, tumors, or hyperthyroidism that does not respond to drug therapy.
Thyroidectomy
Endoscopic surgery to remove a pituitary tumor through an incision in the sphenoid sinus without disturbing brain tissue.
Transsphenoidal hypophysectomy
Lifelong therapy using a fine needle and syringe to inject insulin in patients with DM1. Tx includes a mixture of long-acting and rapid-acting insulins to keep blood glucose in a target range. Accompanied by monitoring blood glucose levels with a glucometer.
Insulin injection therapy
Tx for DM1 that uses a device that continually delivers insulin through an intradermal catheter. The pump delivers a basal rate of insulin continuously over a 24-hr period.
Insulin pump therapy
Medication that treats hyperthyroidism by impeding the formation of T3 and T4 hormones. These are administered in preparation for a thyroidectomy, in a thyrotoxic crisis, and for tx of Graves disease.
Antithyroids
Medication that replaces hormones lost in adrenal insufficiency (Addison disease). Also widely used to suppress inflammation, control allergic reactions, cancer tx, and reduce rejection in transplantation.
Corticosteroids
Medication that increases skeletal growth in children and GH deficiencies in adults. Help increase spinal bone density and help manage growth failure in kids.
Growth hormone replacements
Medication that lowers blood glucose levels by promoting its entrance into body cells and converting glucose to glycogen. Used to tx DM1 and DM2 that cannot be controlled with oral meds.
Insulin
Medication that treats DM2 by stimulating the pancreas to produce more insulin and decrease peripheral resistance to insulin. Not used to tx DM1.
Oral antidiabetics
Medication that replaces or supplement thyroid hormones. Also used to tx certain types of thyroid cancer.
Thyroid supplements
ACTH
Adrenocorticotropic (stimulating) hormone
ADH
antidiuretic hormone
DI
diabetes insipidus
DKA
diabetic ketoacidosis
DM
diabetes mellitus
FBS
fasting blood sugar
FSH
follicle-stimulating hormone
GH
growth hormone
GTT
glucose tolerance test
ITT
insulin tolerance test
LH
luteinizing hormone
PRL
prolactin
PTH
parathyroid hormone; also called parathormone
RAI
radioactive iodine
RAIU
radioactive iodine uptake
SIADH
Syndrome of inappropriate antidiuretic hormone
T3
triiodothyronine
T4
thyroxine
TFT
thyroid function test
TH
thyroid hormone
TSH
thyroid-stimulating hormone
NF
neurofibromatosis
