Toxic Responses of the Endocrine System Flashcards
The endocrine system consists of an _______________ that secretes a hormone, the hormone itself, and a _______________ that responds to the hormone.
endocrine gland; target tissue
A hormone is a chemical substance produced by a __________ endocrine gland that is secreted into the blood.
ductless
What are the hormone-producing glands?
pituitary, thyroid and parathyroid, adrenals, gonads, and pancreas
What are the 3 classes of hormones?
amino acid derivatives, peptide hormones, and steroids
The examples of this class of hormones are catecholamines and thyroid hormones. What class are these?
amino acid derivatives
An example of this class of hormone are pancreatic hormones. What class are these?
peptide hormones
This class of hormone consists of derivatives of cholesterol
steroids
Endocrine glands are ________ and ___________ devices that are capable of responding to changes in the internal and external environment and coordinate multiple activities that maintain ____________
sensing; signaling; homeostasis
What are the two major subdivisions of the pituitary gland?
pars distalis and pars nervosa
this subdivision is also known as the adenohypophysis or anterior pituitary
pars distalis
this subdivision is also known as the neurohypophysis or posterior pituitary
pars nervosa
This is the largest subdivision of the pituitary gland and it receives peptides from the hypothalamus through a capillary portal system
pars distalis
This subdivision of the pituitary gland has its cell bodies in the hypothalamus with their axons stretching to the posterior lobe of the pituitary
pars nervosa
T/F: the anterior pituitary is an extension of your hypothalamus
False. Posterior pituitary
The pars distalis receives peptides from the hypothalamus through the _________________________
hypothalamo-hypophyseal vessels (a capillary portal system)
What are the hormones secreted by the anterior pituitary gland?
Growth hormone (GH), somatotrophic hormone (STH), prolactin (PRL), luteinizing hormone (LH), follicle-stimulating hormone (FSH), thyrotropic hormone (TTH), adenocorticotropic hormone (ACTH), melanocyte-stimulating hormone (MSH)
What are the hormones secreted by the posterior pituitary gland?
antidiuretic hormone (ADH), and oxytocin
this hormone, secreted by the posterior pituitary gland, enhances water absorption by the kidney and causes contraction of the cardiovascular smooth muscles
antidiuretic hormone (ADH)
this hormone, secreted by the posterior pituitary gland, stimulates contraction of smooth muscles for milk let-down
oxytocin
To maintain appropriate homeostasis, the endocrine organ must constantly monitor the systemic hormone concentration, accomplished in the form of ______________________
negative feed-back loops
this pituitary toxicant inhibits prolactin, LH, and FSH secretion
cadmium
this pituitary toxicant inhibits the release of LH and FSH as well as TSH.
Environmental contaminants (polychlorinated biphenyls & polybrominated diphenylethers)
these environmental toxicants increase prolactin and LH levels
Methoxychlor, dieldrin, eldosulfan
these pituitary toxicant decrease LH and FSH
lead and mercury
this pituitary toxicant is a chemical used in the treatment of alcoholics, increases the ACTH precursor mRNA in the anterior pituitary
cynamide
this pituitary toxicant reduces pulsatile LH and suppresses the pituitary response to exogenous GnRH.
coumestrol
these pituitary toxicants stimulate pituitary proliferation
Flame retardants tetrabromo- and tetrachlorobisphenol A
this hormone plays a key role in gonadal function, in synergy with follicle-stimulating hormone (FSH)
leutinizing hormone (LH)
this hormone stimulates follicular growth and ovulation
follicle-stimulating hormone (FSH)
T/F: cynamide increases the ACTH precursor mRNA in the anterior pituitary when co-administered with anti-angina drugs.
False. cynamide increases the ACTH precursor mRNA in the anterior pituitary when co-administered with ethanol.
T/F: The adrenals are two small glands situated on the superior poles of the kidneys.
True
What is the major physiological role of the adrenal gland?
management of stress.
What are the two distinct regions of the adrenal gland
the outer cortex and the interior medulla
What are the functions of the adrenal cortex?
immune system, inflammation, water and electrolyte balance, carbohydrate and protein metabolism
What are the three zones of the adrenal cortex?
Zona Glomerulosa, Zona Fasciculata, and Zona Reticularis
This zone of the adrenal cortex produces mineralocorticoid aldosterone
Zona Glomerulosa
These two zones of the adrenal cortex produces glucocorticoids, corticosterone, and cortisol as well as adrenal androgens
Zona Fasciculata, and Zona Reticularis
This synthesizes and secretes catecholamines, epinephrine, and norepinephrine
Inner medulla
These adrenocortical toxicants (xenobiotics) target the Zona Fasciculata and Reticularis
7,12-dimethylbenz[a]anthracene, acrylonitrite, thioacetamide, and basic polyglutamic acid
These adrenocortical toxicants directly target glucocorticoid secretion
Spironolactone, ketoconazole, and various Polychlorinated biphenyls
These adrenocortical toxicants causes increased secretion of endogenous glucocorticoids
Ethanol, cannabinoids, cocaine, and cytotoxic anticancer drugs
It is a functional extension of the nervous system.
Adrenal medulla
The adrenal medulla is composed of _____________, which are the site of catecholamine synthesis and secretion.
chromaffin cells
In the adrenal medulla, sympathetic and cholinergic stimulation of the cell bodies results in the secretion of _____________, which behave as hormones.
catecholamines
T/F: Catecholamines affect all tissues, but are more pronounced in the heart, liver, skeletal muscles, adipocytes, bronchial smooth muscle and vascular smooth muscles
True
T/F: In adrenal medulla toxicity, the toxins that target the chromaffin cells are toxins that block voltage-gated ion channels and bacterial toxins resulting in the blockage of exocytosis of secretory granules thereby preventing catecholamine release
True
What is the most common pathological changes in adrenal medulla toxicity?
proliferative lesions classified as nodular hyperplasia
This is characterized by having large benign adrenal medullary proliferative lesions
pheochromacytoma
T/F: pheochromacytoma is also caused by having too much adrenaline from the adrenal gland
True
This is the most powerful mitogenic stimulus to cause chromaffin cell proliferation in the adrenal medulla in rats, which is due to impaired calcium homeostasis resulting in hypercalcemia
vitamin D
In long-term animal studies, pheochromocytomas often are accompanied by _______ or toxic effects in other organs.
tumors
This gland is located below the larynx
thyroid gland
The thyroid gland secretes two hormones known as thyroxine (T4) and triiodothyronine (T3) from the ______________.
thyroid follicle
are important regulators of overall metabolism, with their primary target tissues including the liver, kidney, heart, brain, pituitary, gonads, and spleen
T4 and T3
Thyroid toxicity consists of ______________ or ____________, or a significant impairment in brain development and function
hypothyroidism; hyperthyroidism
This thyroid toxicant is one of the best characterized thyroid disrupting chemicals.
Polychlorinated biphenyls
T/F: Polychlorinated biphenyls interfere with the thyroid system that leads to serious ophthalmic defects.
False. Polychlorinated biphenyls interfere with the thyroid system that leads to serious neurocognitive defects.
T/F: Polychlorinated biphenyls decrease the level of thyroid hormone by inhibiting synthesis and/or increasing the metabolism.
True
These thyroid toxicants are structurally similar with polychlorinated biphenyls (PCBs) which also leads to neurocognitive defects.
Polybrominated diphenyl ethers (PBDEs)
This thyroid toxicant inhibits thyroid hormone levels, possibly leading to hypothyroid-like outcomes.
perchlorate
these thyroid toxicants increase thyroid volume and induce antibodies that attack the thyroid gland, resulting in autoimmune thyroid disease.
Pesticide mixtures containing dichlorodiphenyltrichloroethane (DD)
These thyroid toxicants may alter the levels of T3 and T4 in adult men and pregnant women (hypothyroidism)
phthalates
this thyroid toxicant blocks T3 action by antagonizing the binding of T3 to its receptor.
bisphenol A
These thyroid toxicants decrease T3 and T4 levels by potentially upregulating phase II enzymes in liver and deiodinases in the thyroid.
perfluorinated chemicals (perfluorooctanoic sulfonate and perfluorooctanoic acid)
T/F: Humans have four parathyroid glands that are embedded in the surface of the thyroid gland.
True
T/F: Parathyroid glands are composed mainly of chromaffin cells that produce parathyroid hormone (PTH)
False. They are composed of mainly chief cells that produce parathyroid hormone (PTH).
This hormone helps maintain normal plasma calcium levels
parathyroid hormone (PTH)
When the parathyroids are removed or damaged, PTH levels drop, causing a major drop in circulating calcium levels. In turn, this can lead to _______________ and ________.
tetanic convulsions; death
These parathyroid toxicants lead to parathyroid cancer
Lead, rotenone, malathion, and hexachlorobenzene
T/F: Chemicals cause death of the parathyroid cells, resulting in a reduced size and limited release of PTH
True
The parathyroid hormone (PTH) is a polypeptide hormone that is derived from a precursor molecule called ______________________________
preproparathyroid hormone
T/F: Xenobiotics may interfere with the normal synthesis of PTH.
True
These parathyroid xenobiotics inhibit PTH secretion
Aluminum and cadmium
This causes decreased PTH levels in pregnant rats
Alcohol consumption
This causes rise in PTH levels and abnormally high calcium levels.
Lithium
What is the main physiological role of the parathyroid gland?
control circulating calcium levels
T/F: PTH works in concert with calcitonin (CT) and vitamin D.
True
T/F: PTH increases circulating calcium levels by increasing calcium release from the bone through mineralization.
False. Demineralization
T/F: PTH inhibits the hepatic reabsorption of phosphate, which aids in increasing the solubility of calcium.
False. Renal reabsorption
T/F: PTH enhances magnesium reabsorption, inhibits bicarbonate ion reabsorption, and facilitates the exchange of sodium ions by the tubules.
False. Blocks the exchange of sodium ions by the tubules.
This is also Known as the Islets of Langerhans
Endocrine pancreas
T/F: Islet cells are sensors of ____________ homeostasis that respond to changes in their nutrient and hormonal environment.
glucose
What is the major physiological function of the endocrine pancreas?
primary homeostatic regulator of fuel metabolism, particularly circulating glucose
T/F: Insulin, Glucagon, and Somatostatin are pancreatic hormones
True
This pancreatic hormone functions as a hormone release inhibitor.
somatostatin
This pancreatic hormone is a primary hormone with action counterregulatory to insulin, stimulates catabolic processes to prevent hypoglycemia.
glucagon
This pancreatic hormone stimulate anabolic processes (energy storage).
Insulin
This pancreatic hormone can be stimulated by epinephrine, norepinephrine, and amino acids, arginine, leucine, and alanine.
Glucagon
This pancreatic hormone lowers blood levels of glucose, fatty acids, and amino acids and promote their conversion to their storage form
Insulin
What is the storage form of glucose after insulin action
glycogen
What is the storage form of fatty acids?
triglycerides
What is the storage form of amino acids?
proteins
T/F: insulin and somatostatin inhibits glucagon secretion
True
This is a pancreatic hormone, responsible for the regulation of neuroendocrine function to inhibit secretion of growth hormone in the anterior pituitary.
somatostatin
The insulin-secreting ___________ are particularly sensitive to chemical attack.
beta cells
T/F: The clinical consequences of insulin deficiency are more severe than those that would result from glucagon deficiency
True
T/F: The other counterregulatory hormones that oppose insulin action can compensate for or reduce glucagon regulation.
True
T/F: Insulin resistance and defective function of pancreatic beta cells usually occur sometime after the development of Type 2 Diabetes.
False. Insulin resistance and defective function of pancreatic beta cells usually occur sometime BEFORE the development of Type 2 Diabetes.
Insulin resistance is associated with increasing circulating levels of ________ and ________
dioxins and mercury.
T/F: Endocrine glands are collections of specialized cells that synthesize, store, and release their secretions directly into the bloodstream
True
T/F: Toxicants can influence the synthesis, storage, and release of hypothalamic-releasing hormones, adenohypophyseal releasing hormones, and the endocrine gland–specifc hormones.
True
T/F: Each type of endocrine cell in the adenohypophysis is under the control of a specific releasing hormone from the hypothalamus.
True
