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Endo I Hormones
From hormone table in study guide
46
Medical
Graduate
02/13/2011

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Term
TRH (Thyrotropin-releasing hormone)

Gland of origin

Major actions

Disorders
Definition
Hypothalamus

Stimulates secretion of TSH and prolactin

Tertiary hypothyroidism – TRH producing areas of hypothalamus are impaired (by tumor, infarction, congenital, etc) which effects TSH levels (low) which effects T3/4 levels (low)
Term
Corticotrophin-releasing hormone
CRH


Gland of origin

Major actions
Definition
Hypothalamus

Stimulates secretion of ACTH, maintins the ability of corticotrophs to make & secrete ACTH in acute response to CRH
Term
Gonadotropin-releasing hormone
GnRH


Gland of origin

Major actions

Disorders
Definition
Hypothalamus

Stimulates secretion of LH and FSH
Term
Growth hormone releasing hormone
GHRH


Gland of origin

Major actions

Disorders
Definition
Hypothalamus

Stimulates secretion of growth hormone
Term
Somatotropin release-inhibiting hormone
(somatostatin)
SRIF


Gland of origin

Major actions
Definition
Hypothalamus
(also found in delta cells in pancreatic islet tissue)

Inhibits secretion of growth hormone
Inhibits secretion of insulin, glucagon

Normal or elevated in diabetes (hyperglycemia, ketosis)
Term
Prolactin-inhibiting factor
(dopamine)
PIF

Gland of origin

Major actions
Definition
Hypothalamus

Inhibits secretion of prolactin
Term
Thyroid stimulating hormone
TSH

Gland of origin

Stimulus/suppresion

Major actions

Disorders
Definition
Anterior pituitary

Stimulated by cold, suppressed by stress or i/c FT3

Stim siz, # of follicular cells
Tropic (stim T3/T$ synth & sec)
Trophic (maintains gland health)
Stimulates all steps in hormone synth & sec - effects primarily mediated by membrane receptors, Gs-alpha, cAMP, PKA
I/c the efficiency of the iodine pump with dietary I intake is low

Secondary Hyperthyroidism – too much TSH leads to excess T3/4 (pituitary in origin)
- Graves’ dz due to ab against TSH; always presents with exophthalmos; Grave’s is most common cause for hyperthyroidism
- due to iodine excess, has an anti-TSH-like effect

Secondary Hypothyroidism – too little TSH leads to def T3/4 (pituitary in origin: tumor, infarction, congenital)
- due to iodine deficiency – low TSH leads to goiter b/c no T3/4 can be produced
Term
Follicle-stimulating hormone
FSH


Gland of origin

Major actions

Disorders
Definition
Anterior pituitary

Stimulates growth of ovarian follicles and estrogen secretion
Promotes sperm maturation in the testes

Excess –amenorrhea, impotence
Insufficiency –hypogonadism, delayed adolescence
Term
Luteinizing hormone
LH


Gland of origin

Major actions
Definition
Anterior pituitary

Stimulates ovulation, formation of corpus luteum, and synthesis of extrogen and progesterone (ovary)
Stimulates synthesis and secretion of testosterone (testes)
Term
Growth hormone
(somatotropin)
GH

Gland of origin

Stimuli for release

Inhibitors (neg feedback)

Major actions

Disorders
Definition
Anterior pituitary

AA (esp arginine)
ingestion of protein meal
starvation (i/c ghrelin)
hypoglycemia
exercise, stress, trauma
sleep

IGF-I
Somatostatin

Cell growth in size and #
Protein synthesis (i/c AA transport into cells, i/c ribosomal pr synth, i/c RNA synth, d/c protein catabolism)
Lipolysis (HSL), "spares blood glucose"
Inhibits CHO use (blood glucose rises)
-inhibition of glucose uptake into m
-stim of gluconeogenesis in liver
Release of IGF-I (somatomedin) from liver & kidney --> bone growth
Osmotic diuresis secondary to i/c [glucose]
Secretion of somatostatin

Gigantism – excess GH in childhood
Acromegaly – excess GH in adult (octreotide used in treatment)
Dwarfism – lack of GH
Lorons dwarfism - GH levels are normal, but receptors are defective/absent
Term
Prolactin

Gland of origin

Major actions

Disorders
Definition
Anterior pituitary

Stimulates milk production and breast development

Panhypopituitarism –ALL anterior pituitary hormones are destroyed
Excess –galactorrhea, amenorrhea, impotence
Insufficiency –no lactation
Term
Adrenocorticotropic hormone
ACTH


Gland of origin

Major actions

Disorders
Definition
Anterior pituitary

Stimulates synthesis and secretion of adrenal cortical hormones (membrane R, adenylylcyclase, cAMP_

Secondary Cushing’s – too much ACTH due to pituitary tumor leading to hypercortisolism; *hyper-pigmentation often present*
Secondary Addison’s/adrenal insufficiency – enzyme deficiencies lead to excess ACTH
Term
β-endorphin

What class of hormones does this belong to?

Gland of origin

Synthesis?
Definition
An endogenous opioid - analgesia, i/c GI tone, tolerance, physical dependence

Anterior pituitary

Synth as part of POMC (along with ACTH are released during stress, suppressed by cortisol)
Term
Melanocyte-stimulating hormone
MSH

Gland of origin

Major actions

Disorders
Definition
Anterior pituitary (POMC)

Stimulates melanocytes to secrete melanin

circulating MSH activity is regulated along with ACTH; secretion is inhibited by cortisol

Patients with disorders resulting in high ACTH secretion develop hyperpigmentation (b/c of relationship b/t cortisol, ACTH, and MSH)
Term
Oxytocin

Gland of origin

Stimulus for release

Major actions

Disorders
Definition
Originates in the PVN/SON, stored in the posterior pituitary

Suckling
distention of the uterus & cervix and mvmts of infant during pregnancy
stimulation of cervix during sex

Milk ejection/letdown
Parturition (freq & force of uterine contractions i/c in presence of estrogen)
Sperm transport

Too much oxytocin could lead to premature delivery
Oxytocin’s weak ADH activity can cause water intoxication during long infusions and can precipitate HTN during acute administration
Term
Antidiuretic hormone – vasopressin
ADH

Gland of origin

Stimulus for release

Major actions

Disorders
Definition
Synth in SON & PVN, stored in posterior pituitary

I/c ECF osmolarity (esp NaCl)
D/c BP or volume
Trauma, pain, anxiety, nicotine, barbiturate anesthetics

Stimulates H2O reabsorption by renal collecting ducts (V2 receptors)
Venous constriction (V1 receptor, IP3)

Factors that increase ADH secretion:
↑ serum osmolarity, volume contraction, pain, nausea, hypoglycemia, nicotine, opiates, antineoplastic drugs
Factors that decrease ADH secretion:
↓ serum osmolarity, ethanol, α-agonists

Too little ADH: diabetes insipidus -> idiopathic; surgical, traumatic and secondary to hypothalamus tumors or vascular lesions; nephrogenic (no renal ADH receptors); psychogenic polydypsia
Too much ADH: syndrome of inappropriate ADH secretion -> usually due to non-pituitary tumor secreting excess ADH
Term
Thyroxine (T4)
Triiodothyronine (T3)

Gland of origin

Major actions

Inhibitors

Disorders
Definition
Thyroid gland

Skeletal growth
↑ O2 consumption
Heat production
↑ protein , fat, and carbohydrate use
Maturation of nervous system (perinatal)

Block organification: goitren (cabbage), propylthiouracil (PTU)
Compete for iodine pump: thiocyanate, perchlorate, lithium

Primary Hyperthyroidism – excess hormone secretion (thyroid in origin)
-> Graves: autoimmune form; exophthalmous, pretibial myxedema
-> Thyroiditis caused by leakage of T3/4 due to damage to thyroid
-> iodine excess blocks T4 synthesis and acts as anti-TSH
-> thyroid adenomas (single nodular goiters) secrete excess T3/4 w/o pituitary control
-> enhanced beta adrenergic activity

Primary Hypothyroidism – reduced T3/4 secretion (usually due to an attack on the thyroid)
- primary: iodine def, genetic loss, bacterial/viral damage (Hashimoto's, de Quervain's - deQ can start out as hyper, end up hypo), surgical/radioactive damage
- secondary: pit problem/low TSH - brain/AP tumor crowds or destroys TSH producing regions; pit infarc due to trauma/hemorrhage/post-partum hemorrhage (Sheehans), congenital
- tertiary - TRH producing regions of HT are impaired

-> Cretinism (congenital) – neonatal hypothyroidism, leads to permanent mental retardation
-> Hashimoto’s throiditis due to no T3/4 and high TSH caused by autoimmune dz that destroys the thyroid
-> iodine deficiency can lead to low T4 (high T3)
Term
Calcitonin

Gland of origin

Major actions

Disorders
Definition
Thyroid gland – parafollicular cells

↓ serum [Ca2+]
promotes bone formation (osteoblasts)
Ca++ filtration -> renal excretion
Term
Parathyroid hormone
PTH


Gland of origin

Major actions

Disorders (hypo-/hypercalcemia)
Definition
Parathyroid gland (chief cells)

↑ serum [Ca2+]
↓ serum [Pi]
bone resorption, renal Ca reabsorption

Hypocalcemia sx: hyper-reflexia, paraesthesias, m cramps, laryngeal spasm
Hypocalcemia caused by:
- hypoparathyroidism, due to low PTH
- Pseudo-hypoparathyroidism – secondary hyperparathyroidism due to resistance to PTH
- Mg deficiency (d/c ability to secrete PTH, common in alcoholic liver disease)
- Vit D deficiency (nursing home pts)
- Renal failure (-> vit D def, tx give active 1,25 form)

Hypercalcemia sx: hypophosphatemia, skeletal wasting, personality/neural/GI disturbances
Causes:
– primary hyperparathyroidism, caused by parathyroid adenoma or glandular hyperplasia
- hypervitaminosis D
- non-endocrine causes
Term
Catecholamines
Epi
NE
DA

Gland of origin

Synthesis

Major actions

Disorders
Definition
Adrenal medulla

Tyrosine -TH-> LDopa --> DA -DBH-> NE -PNMT-> Epi

NE
i/c HR, contractility, CO, constricts peripheral blood vessels, i/c systolic + diastolic -> i/c MAP

Epi
i/c HR, contractility, CO, dilation of skeletal BV, constriction of GI & skin BV, slight i/c systolic + d/c diastolic -> n/c MAP
inhibits insulin secretion

DA
inhibits prolactin
same CV effects as Epie & NE
can support circulation during shock with fewer episodes of secondary renal failiure


Relax intestines & bladder, contract sphincters
Stimulate axillary sweating

Denervation super sensitivity
Orthostatic HTN – can result from degeneration of preganglionic SNS nerves -> secondary lack of catecholamines
Pheochromocytoma – causing excess catecholamines - tx adrenergic blockers
Thyrotoxicosis – similar to catecholamine excess - tx beta-blockers
Term
Glucocorticoids
(cortisol)

Gland of origin

Activator

Major actions

Disorders

What happens when there are enzyme deficiencies in tfhe cortisol pathway?

which drug blocks 11-beta hydroxylase?
Definition
Adrenal cortex (zona fasciculata)

Stress (--> CRH -> ACTH -> cortisol)

Stimulates gluconeogenesis (i/c [glucose])
Anti-inflammatory (suppresses COX)
Immunosuppression
Inhibits pr synth (except in liver) --> negative N balance
Lipolytic
Stabilizes lysosomal membranes
Helps effects of catecholamines
Reduces effects of histamine


Primary Cushing’s syndrome – hypercortisolism due to adrenal hyperplasia; *pigmentation will be normal*
Addison’s dz - low/absent cortisol, can lead to Addisonian crisis

Adrenogenital syndrome – excess secretion of adrenal androgens due to enzyme defect w/ subsequent ACTH induced adrenal hyperplasia
; i/c intermediates (androgens, estrogens, progestins, mineralcorticoids)
super excess ACTH -> hyperpigmentation

11-b HL converts 17-OH DOC to cortisol
METYRAPONE blocks it
prevents cortisol synth -> adrenal i/c 11-DOC (precursor), confirms secondary adrenocortical insufficiency
Term
Aldosterone (mineralcorticoid)

Gland of origin

Major actions

Stim for secretion

Inhibitors (drugs)

Disorders
Definition
Adrenal cortex (zona glomerulosa)

↑ renal Na+ reabsorption
↑ renal K+ secretion
↑ renal H+ secretion

*Ang II* -> zona glomerulosa -> stim aldo
I/c K+ -> zona glomerulosa
SNS i/c renin release
(D/c Na, ACTH, peptidase-ATIII)

Losartin - ang-II R antagonist
Captropril - ACE inhibitor
Spironolactone - aldo antagonist

Conn’s: primary hyper-aldosteronism -> increased aldosterone levels; increased Na+, GFR, blood pressure; continued K+ loss
Addison’s dz – adrenocortical insufficiency -> due to no aldosterone
Term
1,25-dihydroxycholecalciferol
(Vitamin D3 active form)


Gland of origin

Major actions

Disorders
Definition
Kidney (activation site)

↑ intestinal Ca2+ absorption
↑ bone resorption
*calbindin* synthesis (an intestinal transport pr, facilitates absorption of dietary Ca++)

activated in kidneys by low Pi (created by PTH)
1-alpha-hydroxylase generates 1,25 dihydroxy-D3
Term
Insulin

Stimulus for secretion

Inhibitors of secretion

Gland of origin

Major actions

Disorders
Definition
Pancreas (β cells)

I/c blood glucose, AA (esp arg)
Vagal (ACh) stimulation
Glucagon

Catecholamines (via alpha R)
Somatostatin

↓ blood [glucose], [amino acid], [fatty acid]
stimulates transport of glucose into cells via facilitated diffusion (i/c glut-4 receptors on muscle, adipose)
glucose utilization
glycogen synthesis (muscle)
AA transport (active)
protein synthesis (muscle)
lipogenesis (adipose)
K+, Mg+ transport into cells
decreases catabolic processes
Term
Glucagon

Gland of origin

Stimulus for secretion

Inhibitors of secretion

Major actions

Disorders
Definition
Pancreas (α cells)

falling blood [glucose]
i/c [AA] (protective)
Catecholamines (via beta R)
PNS stimulation
Circulating ketones

Somatostatin

↑ blood [glucose], [fatty acid]
glycogenolysis
gluconeogenesis
HSL: provides FA
stimulates insulin release
Term
Estradiol

Gland of origin

Major actions

Disorders
Definition
Ovary

Growth and development of female reproductive organs
Follicular phase of menstrual cycle
Term
Progesterone

Gland of origin

Major actions

Disorders
Definition
Ovary

Luteal phase of menstrual cycle
Term
Testosterone

Gland of origin

Major actions

Disorders
Definition
Testes

Spermatogenesis
Male secondary sex characteristics
Term
Human chorionic gonadotropin
HCG


Gland of origin

Major actions

Disorders
Definition
Placenta

↑ estrogen and progesterone synthesis in corpus luteum
Term
Human placental lactogen
HPL


Gland of origin

Major actions

Disorders
Definition
Placenta

Stimulates protein synthesis and overall growth, and milk production and breast development during pregnancy
Term
IGF's
Definition
Peptide GF, i/c glucose utilization by connective tissues

IGF-1: plasma conc doesn't d/c like insulin during hypoglycemia
Term
Hypopituitarism

causes

defects?
Definition
congenital, necrosis secondary to vascular failure/hemorrhage (Scheehans Syndrome), space occupying tumors, head trauma

lack of GH in childhood - dwarfism

non pituitary origins of dwarfism:
- Laron's dwarfism - resistance to hormone, production OK
- bad/poor IGF-I
- inadequate thyroid production
- inadequate insulin production
- too much androgen in childhood (causes premature closure of epiphyseal plates)
Term
Effect of iodine def on TSH

Effect of iodine excess on TSH
Definition
Def:
more MITs, fewer DITs --> i/c T3 synth --> d/c T3 (more severe def) --> i/c TSH --> trophic, thyroid enlarges into a GOITER

excess:
blocks thyroid hormone synth, has an anti-TSH-like effect, used prior to surgery to minimize operative complications (thyroid storm)
Term
Estrogen: effect on thyroid hormone

Androgen effect?

Estrogen's effect on cortisol
Definition
Stimulate i/c in TBG --> more T3/T4 is bound, less is free --> i/c TSH --> normal FT3/FT4 (euthyroid), but bound hormone remains i/c

Opposite to estrogen - lowered TBF - ultimately euthyroid, but low totals

I/c CBG -> d/c fCortisol (also raises central set point of cortisol neg feedback -> i/c fCortisol & totals

men treated with estrogens > pregnancy > contraceptives
Term
Catecholamine receptors:

Alpha-1

Role in fight-or-flight response

effects, catecholamine(s)
Definition
primarily via IP3
vasoconstriction
intestinal smooth m relaxation

D/c blood flow to nonessential vascular beds - fast - NE

Epi, NE
Term
Catecholamine receptors:

Alpha-2

effects, catecholamine(s)
Definition
mainly presynaptic
inhibition of NE release via inhibition of cAMP

Epi, NE
inhibit insulin secretion
Term
Catecholamine receptors:

beta-1

Role in fight-or-flight response

effects, catecholamine(s)
Definition
via i/c cAMP

cardiostimulatory
lipolytic (HSL)

provide i/c blood flow, HR, contractility, SV, CO all i/c

Epi, NE
Term
Catecholamine receptors:

beta-2

Role in fight-or-flight response

effects, catecholamine(s)
Definition
via i/c cAMP

bronchodilatory

open vascular beds in skeletal m
dilate airway to i/c O2 delivery
provide energy: release of stored glucose & FA, stim cAMP, i/c glycogenolysis & lipolysis

Epi
vasodilatory (skeletal m)
lipolytic, glycogenolytic, gluconeogenesis (liver)
Term
Catecholamine receptors:

beta-3

effects, catecholamine(s)
Definition
via i/c cAMP

most important in adipose

Little bit of both, more NE
lipolytic, lower glucose uptake
Term
Alpha agonists
Definition
phenylephrine
methoxamine
Term
Alpha antagonists
Definition
prazocin (alpha1)
phentolamine (alpha1&2)
Term
Beta agonists
Definition
isoproterenol
salbutamol (beta2)
dobutamine (beta1
Term
Beta antagonists
Definition
propranolol, atenolol (beta1)
metoprolol (beta1&3)
esmolol (beta1)
pindolol (beta1&2)
Term
Termination of catecholamine effects
Definition
1. Neuronal reuptake (Type I) - blocked by cocaine, psych meds
2. Non-neuronal reuptake (type 2) - blocked by corticosteroids
3. COMT - transfers donor methyl groups to catechol rings --> metanephrine, normetanephrine, 3-methoxytyramine
4. MAO - oxidative deamination - MAOI available
Term
How to predict Ca++ correction
Definition
Difference in albumin x 0.8 + measured Ca++
Term
Dexamethasone Suppression Test

Normal?
Cushing's?
ACTH producing tumor?
Definition
Normal: low dose suppresses cortisol levels

Cushing's: low dose has no effect, high dose suppresses cortisol

ACTH tumor: neither high nor low suppresses cortisol
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