Endocrine System Flashcards
The endocrine system is responsible for the production and release of __________.
hormones
__________ hormones are associated with proteins in the bloodstream.
Lipid soluble
Endocrine hormones act on __________ cells.
target
The degree of association between lipid-soluble hormones and proteins can vary with the __________.
environment (pH, ions, etc.)
The __________ form of a lipid-soluble hormone is the active form.
free
Lipid-soluble hormones generally act via __________ receptors.
intracellular
Lipid-soluble hormones generally affect the synthesis of specific __________ within the cell.
proteins
__________ hormones act via specific receptors on the target cell membrane.
Hydrophillic
Hydrophilic hormone-receptor interaction activates __________ systems within the cell.
second messenger
The three chemical categories of endocrine hormones are amine, peptide, and __________.
steroid
Ultrashort-loop feedback regulation occurs when a hormone inhibits its own __________.
secretion
The two aspects of the dose-response relationship are responsiveness and __________.
sensitivity
Responsiveness refers to the __________ response.
maximum
Sensitivity refers to the concentration of hormone that produces __________ the maximum response.
half
A __________ effect occurs when one hormone allows another hormone to exert its full effect.
permissive
True or False: Both lipid-soluble and lipid-insoluble hormones act as first messengers.
True
Signal transduction mechanisms for lipid-insoluble hormones involve __________.
GPCRs
Signal transduction mechanisms for lipid-soluble hormones involve __________ hormone receptors.
steroid
G-protein coupled receptors produce more __________ effects, while steroid hormone receptors produce __________ response effects.
rapid, slower
The two types of enzyme-linked (catalytic) receptors are receptor tyrosine kinase and __________.
tyrosine kinase-associated receptor
The signal transduction mechanism for tyrosine kinase involves a __________ of intracellular signaling.
cascade
Steroid hormone receptors bind to specific DNA sequences called __________.
steroid response elements
True or False: Endocrine hormones are synthesized as needed and/or produced and stored for release as needed.
True
The steps in hormone signaling include stimulus, stimulus detection, hormone release, hormone processing, hormone detection at the effector cell, intracellular events, and __________ to the hormone signal.
response
The endocrine system consists of various __________ located throughout the body.
glands
Endocrine glands release hormones directly into the __________.
bloodstream
The __________ gland is often referred to as the “master gland” because it controls many other endocrine glands.
pituitary
The __________ gland produces hormones that regulate metabolism.
thyroid
The __________ glands produce hormones that regulate calcium levels in the blood.
parathyroid
The __________ glands produce hormones that regulate stress response.
adrenal
The __________ produces insulin and glucagon, which regulate blood sugar levels.
pancreas
The __________ produce estrogen and progesterone in females, and testosterone in males.
gonads (ovaries and testes)
Hormones travel through the bloodstream to reach their __________ cells.
target
Hormone receptors are specific __________ that bind to particular hormones.
proteins
Hormone binding to its receptor triggers a __________ of events within the target cell.
cascade
__________ feedback loops help to maintain hormone levels within a normal range.
Negative
__________ feedback loops amplify hormone production.
Positive
Endocrine disorders can result from either __________ or __________ of hormone production.
overproduction, underproduction
__________ is a condition characterized by high blood sugar levels due to insufficient insulin production or insulin resistance.
Diabetes
__________ disease is an autoimmune disorder that causes an overactive thyroid gland.
Graves’
__________ is a condition characterized by low thyroid hormone levels.
Hypothyroidism
__________ syndrome is caused by an overproduction of cortisol by the adrenal glands.
Cushing’s
__________ disease is caused by an underproduction of cortisol by the adrenal glands.
Addison’s
__________ hormone is essential for growth and development.
Growth
__________ hormones, such as estrogen and testosterone, play a key role in sexual development and reproduction.
Sex
The endocrine system interacts closely with the __________ system to regulate various bodily functions.
nervous
__________ are chemical messengers that act over short distances between neurons or between neurons and target cells.
Neurotransmitters
__________ are hormones produced by neurons that are released into the bloodstream.
Neurohormones
The __________ is a brain region that links the nervous and endocrine systems.
hypothalamus
True or False: Thyroid hormone is hydrophilic.
False, it’s lipophilic
The hypothalamus and the pituitary gland make up the _____.
Hypothalamic-pituitary axis
The posterior pituitary is also known as the _____.
Neurohypophysis
The anterior pituitary is also known as the _____.
Adenohypophysis
The _____ neurons produce primarily ADH.
superoptic
The _____ neurons primarily produce oxytocin.
paraventricular
_____ are carrier proteins that transport hormones from the hypothalamic nuclei to the posterior pituitary.
Neurophysins
ADH secretion is stimulated by signals from _____ and _____.
osmoreceptors, baroreceptors
Oxytocin and ADH use the _____ signaling pathway.
JAK/STAT
_____ from the hypothalamus stimulates GH secretion.
Growth hormone-releasing hormone (GHRH)
Somatostatin is also known as _____.
Somatotropin release-inhibiting hormone (SRIF)
Somatostatin (SRIF) _____ the release of growth hormone.
inhibits
Growth hormone secretion exhibits a _____ pattern of release.
cyclical/pulsatile
Growth hormone acts directly on target tissues and indirectly via the production of _____.
Insulin-like growth factor 1 (IGF-1)
The cells in the anterior pituitary that secrete growth hormone are called _____.
somatotrophs
The cells in the anterior pituitary that secrete prolactin are called _____.
lactotrophs
The growth hormone receptor utilizes the _____ signaling pathway.
JAK/STAT
GHRH acts on the anterior pituitary to stimulate the synthesis and release of _____.
growth hormone
The posterior pituitary hormones are synthesized in the _____.
hypothalamus
The posterior pituitary stores and releases _____ and ______.
ADH, oxytocin
A key difference between the anterior and posterior pituitary is their connection to the hypothalamus. The posterior pituitary has a _____ connection, while the anterior pituitary has a _____ connection.
neural, vascular
_____ increases water reabsorption in the kidneys.
ADH
_____ stimulates uterine contractions and milk ejection.
Oxytocin
Insulin-like growth factor 1 (IGF-1) primarily mediates the effects of _____ on _____ growth.
growth hormone, bone and soft tissue
Increased blood osmolarity stimulates the release of _____.
ADH
Decreased blood pressure stimulates the release of _____.
ADH
Suckling stimulates the release of _____.
oxytocin
Stress inhibits the release of _____.
growth hormone
Growth hormone promotes _____ nitrogen balance.
positive
Growth hormone increases _____ levels in the blood.
glucose
Growth hormone stimulates the production of _____ in the liver.
IGF-1
IGF-1 promotes _____ growth.
bone and soft tissue
The hypothalamic-pituitary axis is an example of a _____ system.
neuroendocrine
The hypothalamus releases _____ hormones that regulate the anterior pituitary.
releasing and inhibiting
_____ acts on the kidneys to conserve water.
ADH
_____ can stimulate milk production in lactating mothers.
Prolactin
Growth hormone deficiency in childhood can lead to _____.
dwarfish
Growth hormone excess in adulthood can lead to _____.
acromegaly
The hypothalamic neurons that produce ADH are located in the _____ nucleus.
superoptic
The hypothalamic neurons that produce oxytocin are located in the _____ nucleus.
paraventricular
Neurophysins are _____ proteins.
carrier
The primary target organ of ADH is the _____.
kidney
The primary target organs of oxytocin are the _____ and _____.
uterus, mammary glands
Cortisol is an example of a ____________.
glucocorticoid
Somatostatin inhibits the anterior pituitary to release _____.
growth hormone
The primary target of GHRH is the _____.
anterior pituitary
The primary target of somatostatin is the _____.
anterior pituitary
GHRH acts under a _______ feedback loop by stimulating somatostatin, an inhibitor.
negative
The growth hormone receptor is a _____ receptor.
cell surface/membrane
Growth hormone acts via ______ receptors.
tyrosine kinase
Growth hormone synthesis requires ________ transcription factor.
Pit-1
The Islets of Langerhans are clusters of endocrine cells found in the _____.
pancreas
The Islets of Langerhans contain alpha cells that secrete _____, beta cells that secrete _____, delta cells that secrete _____, and PP cells that secrete _____.
Glucagon, insulin, somatostatin, pancreatic polypeptide
_____(three) cells in the Islets of Langerhans are connected by gap junctions, allowing for coordinated hormone release.
Alpha, beta, and delta
Blood flows from the _____ cells to the _____ cells in the Islets of Langerhans.
beta, alpha
_____ is a peptide hormone that is co-secreted with insulin and can be used to determine endogenous insulin levels.
C-peptide
Insulin secretion is stimulated by an increase in blood _____.
glucose
The _____ effect refers to the phenomenon where oral glucose elicits a greater insulin response than intravenous glucose.
incretin
Two important incretin hormones are _____ and _____.
GIP, GLP-1
Insulin binding to its receptor on target cells leads to _____ of the receptor.
down regulation
Insulin secretion oscillates with a period of _____ minutes.
3-6
The insulin receptor is a _____ receptor.
tyrosine kinase
Insulin signaling activates a cascade of intracellular events, including the phosphorylation of _____.
Insulin receptor substrates (IRS)
In most tissues, insulin promotes _____ uptake.
glucose
Insulin promotes _____ synthesis in the liver and skeletal muscle.
glycogen
Insulin stimulates _____ and carbohydrate oxidation.
glycolysis
Insulin promotes _____ synthesis.
protein
In adipose tissue, insulin promotes _____ synthesis and storage.
fat
Insulin promotes the synthesis of _____, an enzyme that breaks down triglycerides in lipoproteins.
Lipoprotein lipase (LPL)
_____ is a peptide hormone produced by alpha cells that opposes the actions of insulin.
Glucagon
_____ is the most potent insulinotropic hormone known.
GLP-1
Glucagon promotes _____ breakdown in the liver.
glycogen
Glucagon stimulates _____ in the liver.
gluconeogenesis
Glucagon promotes the oxidation of _____ to produce ketone bodies.
fats
Glucagon has no direct effect on _____.
muscle
_____ is produced by delta cells and inhibits both insulin and glucagon secretion.
Somatostatin
_____ is produced by PP cells and regulates pancreatic secretion activities (both endocrine and exocrine).
Pancreatic polypeptide
_____ is a condition characterized by hyperglycemia (high blood glucose).
Diabetes mellitus
_____ diabetes is characterized by the autoimmune destruction of beta cells, resulting in an absolute deficiency of insulin.
Type 1
_____ diabetes is characterized by insulin resistance and a relative deficiency of insulin.
Type 2
In diabetes, the body switches to burning _____ for energy, leading to the production of acidic ketone bodies.
fatty acids
The low pKa of ketone bodies can lead to _____.
metabolic acidosis
Diabetic ketoacidosis is a life-threatening complication of diabetes, primarily seen in individuals with _____ diabetes.
type 1
Increased blood glucose in diabetes leads to _____ diuresis, resulting in excessive urine production and dehydration.
osmotic
The breakdown of fats for energy in diabetes leads to an increase in blood _____.
fatty acids
In diabetes, there is an increase in blood _____ due to protein breakdown for energy.
amino acids
The accumulation of ketoacids in the blood leads to _____.
diabetic ketoacidosis
Hyperkalemia in diabetes is caused by a shift of _____ out of cells.
potassium
Insulin is synthesized as a precursor molecule called _____.
preproinsulin
Preproinsulin is cleaved to form _____, which is further cleaved to produce insulin and C-peptide.
proinsulin
The primary target organs for glucagon action are the _____ and _____.
liver, adipose tissue
A protein-rich meal stimulates the release of _____.
pancreatic polypeptide
Fasting, exercise, and acute hypoglycemia stimulate the release of _____.
pancreatic polypeptide
_____ and intravenous glucose inhibit pancreatic polypeptide secretion.
Somatostatin
Glucose-counterregulatory controls help to maintain blood glucose levels within a narrow range, especially during periods of _____.
fasting/hypoglycemia
In response to hypoglycemia, the hormone _____ is released from the adrenal medulla.
epinephrine
_____ from the adrenal cortex is released in response to hypoglycemia.
Cortisol
Growth hormone is released from the _____ in response to hypoglycemia.
anterior pituitary
_____ release is also increased during hypoglycemia to promote glycogen breakdown.
Glucagon
The overall effect of glucose-counterregulatory controls is to _____ blood glucose levels.
increase
The symptoms and complications of diabetes are primarily caused by _____.
hyperglycemia and the accumulation of ketone bodies
The adrenal glands are located on top of the _____.
kidneys
The outer portion of the adrenal gland is called the _____.
adrenal cortex
The inner portion of the adrenal gland is called the _____.
adrenal medulla
The adrenal cortex is responsible for the production of _____.
steroid hormones
The adrenal medulla is responsible for the production of _____.
catecholamines
The two main catecholamines produced by the adrenal medulla are _____ and _____.
epinephrine, norepinephrine
Approximately 80% of the adrenal medulla’s output is _____.
epinephrine
The enzyme that converts norepinephrine to epinephrine is _____.
phenylethanolamine N-methyltransferase (PNMT)
_____ and _____ are enzymes that break down catecholamines.
Monoamine oxidase (MAO), catechol-O-methyltransferase (COMT)
Catecholamines are stored in _____ within chromaffin cells.
chromaffin granules
The transporter responsible for moving catecholamines into chromaffin granules is called _____.
vesicular monoamine transporter (VMAT)
There are two main types of adrenergic receptors: _____ and _____.
alpha (α), beta (β)
Alpha-1 receptors are typically coupled to _____ G proteins.
Gq
Alpha-2 receptors are typically coupled to _____ G proteins.
Gi
Beta-1, Beta-2, and Beta-3 receptors are typically coupled to _____ G proteins.
Gs
Activation of Beta-1 receptors in the heart increases _____, _____, and _____.
heart rate, contractility, conduction velocity
Activation of Beta-2 receptors in the lungs causes _____.
bronchodilation
Epinephrine stimulates _____ release from the liver, increasing blood glucose levels.
glucose
Epinephrine promotes _____ breakdown in adipose tissue, providing free fatty acids for energy.
lipolysis (fat)
Catecholamines can suppress the _____ system.
immune
The three main categories of adrenocortical steroid hormones are _____, _____, and _____.
glucocorticoids, mineralocorticoids, adrenal androgens
The primary glucocorticoid produced by the adrenal cortex is _____.
cortisol
The primary mineralocorticoid produced by the adrenal cortex is _____.
aldosterone
The precursor molecule for all adrenocortical steroid hormones is _____.
cholesterol
______ inhibitors are a common therapeutic for excess catecholamines.
VMAT
The rate-limiting step in adrenocortical steroid hormone synthesis is the conversion of cholesterol to _____ by the enzyme _____.
pregnenolone, P450scc (cholesterol desmolase)
_____ is the primary regulator of cortisol synthesis.
Adrenocorticotropic hormone (ACTH)
_____ is released from the hypothalamus and stimulates the release of ACTH from the anterior pituitary gland.
Corticotropin-releasing hormone (CRH)
_____ stimulates the adrenal cortex to produce cortisol.
ACTH
Cortisol exerts negative feedback on both the _____ and the _____, inhibiting CRH and ACTH release.
hypothalamus, anterior pituitary gland
Cortisol secretion exhibits a _____ pattern, with levels highest in the _____ and lowest in the _____.
diurnal (circadian), morning, evening
Cortisol increases blood glucose levels by stimulating _____ and _____.
gluconeogenesis, glycogenolysis
Cortisol is essential for maintaining _____ and responding to _____.
blood pressure, stress
_____ disease is caused by adrenal insufficiency, resulting in a deficiency of cortisol and aldosterone.
Addison’s
_____ syndrome is caused by excessive cortisol production.
Cushing’s
The most common defect in congenital adrenal hyperplasia (CAH) is a deficiency in the enzyme _____.
21-hydroxylase
The _____ response to stress is mediated by the release of catecholamines from the adrenal medulla.
short-term (immediate)
The _____ response to stress is mediated by the release of cortisol from the adrenal cortex.
long-term
During stress, the hypothalamus releases _____, which triggers the release of ACTH.
CRH
________ is required for estrogenic activity (in the A ring).
Aromaticity
______ starts steroidogenesis.
ACTH
Cortisol binds to _____ receptors.
glucocorticoid receptors (GR)
The cortisol-receptor complex translocates to the _____ and binds to specific DNA sequences called _____, regulating gene expression.
nucleus, glucocorticoid response elements (GREs)
The adrenal medulla is derived from _____.
neural crest cells
The adrenal cortex is derived from _____.
mesoderm
The zona glomerulosa is the outermost layer of the adrenal cortex and produces _____.
mineralocorticoids
The zona fasciculata is the middle layer of the adrenal cortex and produces _____.
glucocorticoids
The zona reticularis is the innermost layer of the adrenal cortex and produces _____.
adrenal androgens
Pheochromocytoma is a tumor of the _____ that causes excessive catecholamine release.
adrenal medulla
Primary adrenal insufficiency is caused by destruction of the _____.
adrenal cortex
The thyroid gland is located in the _____.
neck
The thyroid gland is responsible for producing the hormones _____, _____, and _____.
thyroxine (T4), triiodothyronine (T3), calcitonin
_____ cells in the thyroid gland produce T3 and T4.
Follicular
_____ cells in the thyroid gland produce calcitonin.
Parafollicular
Thyroid hormones are crucial for regulating _____, _____, and _____.
growth, development, metabolism
The synthesis of thyroid hormones requires _____.
iodine
Iodine is transported into follicular cells by the _____ transporter.
sodium-iodide symporter (NIS)
Within the follicular cell, iodine is oxidized by the enzyme _____.
thyroid peroxidase (TPO)
Oxidized iodine is then attached to tyrosine residues in the protein _____.
thyroglobulin (Tg)
Two iodinated tyrosine residues are coupled to form either _____ or _____.
T4, T3
T4 is the _____ form of thyroid hormone, while T3 is the _____ form.
major secreted, more active
Most T3 is generated from T4 by the action of enzymes called _____.
iodothyronine deiodinases
Thyroid hormones are transported in the blood bound to carrier proteins, primarily _____.
thyroxine-binding globulin (TBG)
Only _____ thyroid hormone is biologically active.
free (unbound)
_____ is a type of iodothyronine deiodinase that converts T4 to T3 in peripheral tissues.
D1
_____ is a type of iodothyronine deiodinase that inactivates T4 and T3.
D3
The hypothalamus releases _____, which stimulates the anterior pituitary to release _____.
thyrotropin-releasing hormone (TRH), thyroid-stimulating hormone (TSH)
_____ binds to receptors on follicular cells, stimulating the synthesis and release of T3 and T4.
TSH
T3 and T4 exert _____ feedback inhibition on the hypothalamus and anterior pituitary, regulating their own secretion.
negative
High levels of iodine can transiently _____ thyroid hormone synthesis, a phenomenon known as the _____.
inhibit, Wolff-Chaikoff effect
Thyroid hormones bind to _____ receptors in the cell.
nuclear
The thyroid hormone receptor forms a heterodimer with the _____ receptor.
retinoic acid X (RXR)
The thyroid hormone-receptor complex binds to specific DNA sequences called _____, regulating gene expression.
thyroid hormone response elements (TREs)
Thyroid hormones increase _____ by stimulating the synthesis of _____ in mitochondria.
basal metabolic rate (BMR), uncoupling proteins
Thyroid hormones promote _____ synthesis, particularly in the developing nervous system.
protein
Thyroid hormones enhance the effects of _____ by increasing the expression of beta-adrenergic receptors.
catecholamines
Hypothyroidism is a condition characterized by _____ levels of thyroid hormones.
low
In infants, severe hypothyroidism can lead to _____, a condition characterized by impaired mental and physical development.
cretinism
The most common cause of hypothyroidism worldwide is _____.
iodine deficiency
Hyperthyroidism is a condition characterized by _____ levels of thyroid hormones.
high
_____ disease is an autoimmune disorder that causes hyperthyroidism.
Graves’
A key feature of Graves’ disease is _____, a protrusion of the eyeballs.
exophthalmos
_____ is a severe and life-threatening complication of hyperthyroidism.
Thyroid storm
A _____ scan uses radioactive iodine to visualize the thyroid gland and assess its function.
radioactive iodine uptake (RAIU)
Hypothyroidism is typically treated with _____ hormone replacement therapy.
levothyroxine (synthetic T4)
Radioactive iodine therapy can be used to _____ the thyroid gland in cases of hyperthyroidism.
destroy
A _____ is an enlargement of the thyroid gland.
goiter
True or False: Goiters can occur in both hyperthyroidism and hypothyroidism.
True
A “cold nodule” on a thyroid scan indicates an area of _____ iodine uptake, which can be suggestive of _____.
decreased, thyroid cancer
_____ is a protein that transports cholesterol into the mitochondria of steroid-producing cells, including thyroid follicular cells.
Steroidogenic acute regulatory protein (StAR)
