Overview – The Endocrine System Flashcards by Katie Keller

List the hormone glands of the brain

Pineal gland

Hypothalamus

Pituitary gland

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List all the components of the endocrine system

Hormonal Glands of the Brain (Pineal gland, Hypothalamus, Pituitary gland)

Thyroid gland

Parathyroid gland

Thymus gland

Adrenal glands

Kidneys

Pancreas

Ovaries

Testes

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Which endocrine organ is described below?

Shaped like a pine cone

Located in pocket near the splenium of the corpus collosum

Site of melatonin synthesis

Pineal Gland

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Which endocrine organ is described below?

Most inferior portion of diencephalon

Releases hormones that target the pituitary gland

Produces ADH and oxytocin

Produces releasing hormones

Regulates water balance, body temperature, and appetite

Hypothalamus

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Which endocrine organ is described below?

Called the “Master gland”

Attached to the lower surface of the hypothalamus by the infundibular stalk

Pituitary Gland

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The anterior pituitary gland is responsible for which hormones?

GH
ACTH
TSH
Prolactin
FSH
LH

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The posterior pituitary gland stores which hormones from the hypothalamus?

Neurohormones (Continuous with brain)

Antidiuretic hormone (ADH)/ Vasopressin

oxytocin

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Which portion of the pituitary gland is continuous with the brain?

posterior pituitary gland

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Which portion of the pituitary gland is the Rathke’s pouch located?

anterior pituitary gland

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Postpartum necrosis of the pituitary gland due to massive blood loss, hypovolemic shock, or both during delivery

Consider if a patient has failure to lactate after delivery and amenorrhea

Sheehan’s necrosis

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Which endocrine organ is described below?

Located in the base of the neck on both sides of the lower part of the
larynx and upper part of trachea

Two lateral lobes connected by an isthmus

Thyroid Gland

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What are the two types of the thyroid gland?

Follicular cells
Parafollicular cells

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This thyroid gland cell type produce T3 and T4 – important role in body’s metabolism

Follicular cells

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This thyroid gland cell type secretes calcitonin

Parafollicular cells

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Which thyroid hormone is described below?

Large protein that is a storage form of the thyroid hormones

Thyroglobulin

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Which thyroid hormone is described below?

Formed from the hydrolysis of Tg

70% bound to TBG

Thyroxine (T4)

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Which thyroid hormone is described below?

Formed from the hydrolysis of Tg

80% bound to TBG

Triiodothyronine (T3)

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Which thyroid hormone is described below?

Glycoprotein that is synthesized and secreted by the liver

Each molecule of TBG has a single binding site for a thyroid hormone molecule

Thyroxine-binding globulin

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Which thyroid hormone is described below?

Secreted by the hypothalamus

Stimulates anterior pituitary release TSH

Thyrotropin Releasing Hormone (TRH)

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Which thyroid hormone is described below?

Secreted by the pituitary and stimulates thyroid hormone production

Levels as low as 0.01 mU/L may be detected

Best screening test for hypo or hyperthyroidism

Levels may be depressed with: thyroid hormone administration, severe
nonthyroidal illness, primary hyperthyroidism, older age >60

Levels can be suppressed with: pregnancy, acute psychiatric illness,
glucocorticoids, NSAIDs, or narcotics

Thyroid Stimulating Hormone (TSH)

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Less than what percentage of the T4 and T3 in blood is in the free form (in equilibrium with the large protein-bound portion)?

less than 1%

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Which thyroid hormone is the major secretory product of the thyroid gland and is the predominant thyroid hormone in the blood?

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When concentrations of free T4 and T3 fall in the blood, which part of the pituitary secretes TSH to raise the concentration?

the anterior pituitary gland

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What percentage of circulating T3 is derived from peripheral deiodination of T4?

90%

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Which thyroid hormone is the the most active hormone?

Which hormone is a direct measurement of the serum concentration of free (unbound) thyroxine, representing only about 0.025% of the total?

FT4

Why is evaluation with the free thyroxine immunoassay (FT4) better than with the T4 immunoassay?

Better than T4 immunoassay or free thyroxine index since it is not affected by variations in protein binding

What does the T4 immunoassay measure?

Measures total serum thyroxine, both bound and free

What is the T4 immunoassay result affected by?

Affected by altered thyroxine binding, therefore, is usually run with resin T3U to calculate the free thyroxine index

Indirect inverse test of thyroid binding proteins It is high when the patient’s proteins are low or thyroxine is high

T3 Resin Uptake

What assessment is an indirect measure of the quantity of thyroxine binding proteins (thyroid binding prealbumin, albumin, and TBG) in plasma?

T3 Uptake (T3U)

What is the T3 resin uptake assessment used for?

Used to correct for binding changes that effect the total serum thyroxine to create the free thyroxine index

Which thyroid assessment is described below? Product of T4 and resin T3 uptake (T4 x T3 uptake) helps correct for abnormalities of thyroxine binding A good free T4 assay is more accurate

Free Thyroxine Index

Four parathyroid glands are located in what relation to the thyroid gland?

posterior

Which hormone is described below? Primary regulator of calcium Secretion stimulated by falling free calcium levels Secretion suppressed by rising free calcium levels

PTH

What is the role of PTH?

PTH increases the serum calcium concentration

What are the main physiological effects of PTH?

It increases the osteoclastic activity in bone, with increased delivery of calcium and phosphorus to the circulation It increases the renal tubular reabsorption of calcium in the glomerular filtrate It inhibits the net absorption of phosphate and bicarbonate by the renal tubule It stimulates the synthesis of 1,25-dihydroxycholecalciferol by the kidney, thus secondarily enhancing intestinal absorption of calcium

Only what percentage of total calcium circulates in blood?

You must adjust normal range of total serum calcium based on what?

serum albumin Serum calcium is largely bound to albumin; therefore, ionized calcium should be determined or the serum calcium level should be corrected for serum albumin level

What is the corrected calcium equation?

Corrected calcium (mg/dL) = measured total Ca (mg/dL) = 0.8(4.0 – serum albumin [g/dL], where 4.0 represents the average albumin level in g/dL Ca = 8.0mg/dL , albumin 3.0m/dL 8.0 + 0.8 (4.0 – 3.0) Corrected calcium = 8.8mg/dL

What is a fat-soluble hormone that increases the absorption of calcium from the intestine?

Vitamin D

Which vitamin is not really aa vitamin since it can be made by the action of sunlight on the skin?

Vitamin D

Which endocrine organ is described below? Located in the mediastinal cavity anterior to and above the heart Produces T-lymphocytes

Thymus gland

Which endocrine organ is described below? Paired pyramid-shaped organs located on the upper poles of each kidney Composed to two separate endocrine organs

Adrenal Glands

What is the outer portion of the adrenal glands called?

Cortex

What is the inner portion of the adrenal glands called?

Medulla

The adrenal cortex secretes what hormones?

Mineralocorticoids Glucocorticoids Androgens

The adrenal medulla secretes what hormones?

Epinephrine Norepinephrine

What are the three layers that make up the adrenal cortex?

Zona Fasciculata Zona Glomerulosa Zona Reticularis

Using what as the starting material, the cells of the adrenal cortex secrete a variety of steroid hormones that fall into the three classes?

cholesterol

The most abundant glucocorticoid is what?

cortisol (also called hydrocortisone)

Glucocorticoids are produced in what portion of the adrenal cortex?

Produced in the Zona Fasciculata

Get their name from their effect of raising the level of glucose 🡪 stimulate gluconeogenesis in the liver

Glucocorticoids

What are the major metabolic effects of cortisol?

Carbohydrate metabolism Fat Metabolism Protein Metabolism

List some short term (high dose) adverse effects of glucocorticoids?

Cerebral edema GI bleed Glaucoma Mood disorder Pancreatitis Sodium and water retention Diabetes mellitus Hypertension Hypokalemic alkalosis Increased BUN Proximal myopathy

List some long term adverse effects of glucocorticoids?

Amenorrhea Aseptic necrosis of bone Centripetal obesity Mood disorders Osteoporosis Diabetes mellitus Cataracts Growth failure Hyperlipidemia Hypertension Muscle weakness seizures

Mineralcorticoids are produced in what portion of the adrenal cortex?

Zona Glomerulosa

What get their name from their effect on mineral metabolism?

The mineralcorticoids

What is the most important mineralcorticoid?

aldosterone

In females, what is a major source of androgens?

the adrenal cortex

The adrenal cortex secretes precursors to androgens such as what?

testosterone

Androgens are produced in what portion of the adrenal cortex?

Zona Reticularis

Which endocrine organ is described below? Pair of purple-brown organs situated towards the back of the abdominal cavity (retroperitoneal cavity) Each is lateral to the spinal column Form urine from blood plasma Major regulators of water, electrolytes, and acid-base content of the blood

Kidneys

Which endocrine organ is described below? Located behind the stomach and in front of the first and second lumbar vertebrae Endocrine and exocrine gland Has a role in digestion and hormone production

Pancreas

Islets of Langerhans alpha cells secrete what?

secrete glucagon

Islets of Langerhans beta cells secrete what?

secrete insulin

Islets of Langerhans delta cells secrete what?

secrete somatostatin

This hormone inhibits the secretion of insulin, glucagon, growth hormone from the anterior pituitary, and gastrin from the stomach

somatostatin

Which endocrine organ is described below? Almond shaped glands, located on both sides of the uterus Controlled by gonadotropins LH and FSH

Ovaries

What is the function of the ovaries?

Production of reproductive cell - ovum Production of hormones - Estrogen, progesterone

Which endocrine organ is described below? Male gonad One of two reproductive glands located in the scrotum

Testes

What is the function of the testes?

Male reproductive glands - Spermatozoa Male hormones - Testosterone, inhibin