Endocrine System Flashcards
What are the organs of the endocrine system?
1) pineal gland
2) hypothalamus (neuroendocrine organ)
3) pituitary gland
4) thyroid gland
5) parathyroid gland
6) thymus
7) adrenal glands
Contains endocrine tissue:
8) pancreas
9) gonads (ovary & testes)
10) placenta
What is the major functions that are controlled by the hormones?
1) Reproduction
2) Growth & development
3) maintenance of electrolyte, water, and nutrient balance of the blood
4) regulation of cellular metabolism and energy balance
5) mobilization of body defenses
What is a hormone?
Long distance chemical signals which travel trough the blood or lymph
What is meant by autocrines?
Short-distance chemical signals which exert their effects on the same cells which secreted them
What is meant by paracrines?
Short-distance chemical signals, acting locally within the same tissue affecting cells other than the ones which secreted them (somatostatin released by cells of the pancreas which inhibits the secretion of insulin by other cells of the pancreas)
What is the difference between the endocrine and the nervous system?
1) NS is rapid while Endocrineeis slow
2) NS has short duration response while endocrine has a long-duration
3) NS acts via action potential & neurotransmitters, endocrine via hormones
4) NS specific locations, Endocrine diffuse location
5) NS short distances, Endocrine long distances
What are the types of hormones?
1) Water soluble:
Proteins, peptides, amino-acid based (cannot cross the plasma membrane)
2) Lipid soluble:
Steroid based synthesized from cholesterol (can cross plasma membrane secreted only the gonadal and adrenocortical hormones)
How do hormones act?
1) water soluble via second messengers except thyroid hormone
2) steroid hormones via activating specific genes
What does a hormone typically do?
1) alters the plasma membrane permeability/membrane potential via opening or closing ion channels
2) stimulates the synthesis of enzymes and other proteins within the cell
3) activates or deactivates enzymes
4) stimulates mitosis
How does water-soluble hormones act?
- They act on receptors on the plasma membrane coupled via
G-proteins
1) Hormone (1st Messenger) bind to a receptor on the cell membrane
2) Receptor activates a G-protein, providing it with GTP
3) G-protein activates the enzyme Adenylate Cyclase
4) Adenylate cyclase converts ATP into cAMP (which is the 2nd messenger)
5) cyclic AMP (cAMP “2nd Messenger”) activates protein kinases which triggers responses of target cell
How does lipid-soluble hormones act?
Steroid & thyroid hormones act on receptors inside the cell, directly activating the gene:
1) steroid hormone diffuses through the plasma membrane and binds to an intracellular receptor
2) the receptor-hormone complex enters the nucleus
3) receptor-hormone complex binds to a specific DNA region
4) binding of the receptor-hormone complex initiates the transcription of the gene to mRNA
5) MRNA directs protein synthesis
What are the types of stimuli that causes hormonal release?
1) Humoral stimulus
2) Neural stimulus
3) Hormonal stimulus
What is the mechanism of the humoral stimulus, what type of hormones does it release, from which gland?
It is the release of hormones via the alteration of critical ions or nutrients.
It can release PTH (parathyroid hormone) which is secreted by the parathyroid gland due to the decrease in the level of Ca2+ in the blood other examples includes (Insulin “increased blood glucose”, aldosterone “low Na+ or High “K+” blood levels)
FYI (humor means moisture/body fluid)
What is the mechanism of the neural stimulus, what type of hormones does it release, from which gland?
The release of hormones via neural input due to action potentials
(preganglionic sympathetic fibers - stimulates the medulla of adrenal gland - secrete epinephrine and norepinephrine, in response to stress
What is the mechanism of the hormonal stimulus, what type of hormones does it release, from which gland?
The release of hormone via a tropic hormone
Hormone from the hypothalamus targets - Anterior pituitary gland which secretes hormones that stimulates other endocrine glands (thyroid, adrenal cortex, gonads) it is called “hypothalamic-pituitary- target endocrine organ”
Which type of mechanism regulates most of the synthesis and release of hormone?
Negative feedback mechanism except for some (oxytocin)
How does the nervous system modulate hormone secretion?
In certain situation like when you are under stress, the NS can override the effects of the hormone stimulus releasing more than the normal amount of a certain hormone like when you are under stress it releases more glucose for our cell to be ready for vigorous activity if required
What is required from the cell to respond to a hormone?
It must have the receptor for that hormone either in its interior or on its plasma membrane for that hormone to bind, ACTH receptors are only found on the adrenal cortex, while thyroxine hormone receptor is found on nearly all body cells
What is the action of a hormone?
It stimulates the cell to preform “gene determined” functions acting as a molecular trigger
What determine the degree of target cell activation
1) blood levels of that hormone
2) relative number of receptor
3) affinity (the strength of the binding)
What is meant by up-regulation and down-regulation?
Up-regulation is when the numbers of a specific hormone receptor increases due to low levels of that hormone in the body Dow-regulation is exactly the opposite
Can hormones influence the number of receptors that respond to other hormones?
Yes! Progesterone can down-regulate estrogen while osteogen up-regulates progesterone receptors
How does a hormone circulate in the blood?
1) free
2) bound to a protein carrier (lipid-soluble hormones)
What are the types of hormone interactions?
1) permissiveness
2) synergism
3) antagonism
What is meant by permissiveness?
Where one hormone cannot exert its full effects unless the presence of another hormone (reproductive system needs the thyroid hormone)
Wha is meant by synergism?
When more than one hormone exert the same effect on the target cell and their effects are amplified. (Glucagon & epinephrine, causes the release of glucose from the blood)
What is meant by antagonism?
When one hormone opposes the effect of another hormone due to the competition for the same receptors (insulin and glucagon)
What is the sources of lipid soluble hormones?
1) Adrenal cortex
2) gonads
3) thyroid gland
What are the lipid-soluble hormones?
All steroid hormones + thyroid hormone
Where is the pituitary gland seated, and what connects it to the hypothalamus?
Seated on the sella turcica of sphenoid bone connected to the hypothalamus via the infudibulum
What is the structure of the pituitary gland?
1) posterior pituitary
2) anterior pituitary
Describe the structure and function of the posterior pituitary gland
Composed largely of neural tissue Forming the neurohypophysis (PPG + Infundibulum), releasing neurohormone (secreted via neurons) which is stored hormones made in the hypothalamus
Describe the structure of the anterior pituitary gland
Originates from epithelial tissue, adhering to the neurohypophysis, no direct neural connection with the hypothalamus, but communicates via vascular connection (primary capillary plexus in the infundibulum communicates inferiorly via the small hypophyseal portal veins with a secondary capillary plexus in the anterior lobe “hypophyseal portal system AKA unusual arrangement of blood vessels in which a capillary bed feeds into veins, which in turn feed into a second capillary bed”) which controls its secretion of hormones, ensuring that the minute quantities of hormones released by the hypothalamus arrive rapidly
at the anterior pituitary without being diluted by the systemic circulation
Hypothalamus/pituitary hormones are what based?
Amino acid based
How does the hypothalamus control the release of hormones from the posterior pituitary?
1) Hypothalamic neurons synthesize oxytocin or antidiuretic hormone (ADH)
2) Oxytocin and ADH are transported down the axons of the hypothalamic-hypophyseal tract to the posterior pituitary
3) Oxytocin and ADH are stored in axon terminals in the posterior pituitary
4) When associated hypothalamic neurons fire, action potentials arriving at the axon terminals cause oxytocin or ADH to be released into the blood
via Action potentials that travel down the axons of hypothalamic neurons, causing hormone release from their axon terminals in the posterior pituitary
How does the hypothalamus control the release of hormones from the anterior pituitary?
1) When appropriately stimulated, hypothalamic neurons secrete releasing or inhibiting hormones into the primary capillary plexus
2) Hypothalamic hormones travel through portal veins to the anterior pituitary where they stimulate or inhibit release of hormones made in the anterior pituitary
3) In response to releasing hormones, the anterior pituitary secretes hormones into the secondary capiIlary plexus. This in turn empties into the general circulation
Via Hypothalamic hormones released into special blood vessels (the hypophyseal portal system) control the release of anterior pituitary hormones
What hormones is released from the posterior pituitary?
1) oxytocin
2) antidiuretic hormone (ADH)
What are the hormones that are released from the anterior pituitary gland?
1) Growth hormone (GH)
2) Thyroid-stimulating hormone (TSH)
3) Adrenocorticotropic hormone (ACTH)
4) Follicle-stimulating hormone (FSH)
5) Leutinizing hormone (LH)
6) Prolactin (PRL)
Which neuron synthesizes oxytocin?
Paraventricular neurons (composed of nine amino acids)
Which neuron synthesizes ADH?
Supraoptic neurons (composed of nine amino acids)
Where is the oxytocin released from?
Its a nonapeptide, released from the paraventricular nucleus in the hypothalamus
Where is the ADH released from?
ADH or vasopressin, its a nonapeptide released from the supraoptic nucleus of the hypothalamus
Where is the growth hormone released from?
A protein released from he somatotropic cells of the anterior pituitary gland
Where is the thyroid stimulating hormone released from?
“Glycoprotein” Released from the thyrotropic cells in the anterior pituitary
Where is the adrenocorticotropic hormone released from?
Peptide released from the corticotropic cells of the anterior pituitary gland
Where is the follicle stimulating hormone released from?
A glycoprotein release from gonadotropic cells of the anterior pituitary
Where is the leutinizing hormone released from?
Glycoprotein, released from the gonadotropic cells of the anterior pituitary gland
Where is the prolactin released from?
A protein, released from prolactin cells in the anterior pituitary
What stimulates the release of oxytocin?
Stimulated by stretching of the uterine cervix, breast suckling
Inhibited by lack of neural stimuli
What stimulates the release of ADH?
Stimulated by
1) increased solute concentration
2) decreased blood volume
3) pain
4) some drugs
5) low BP
Inhibited by:
1) alcohol
2) adequate hydration
What stimulates the release of GH?
Stimulated by:
1) low GH levels
2) deep sleep
3) hypoglycemia
4) increase amino acids
5) low fatty acids
6) exercise
Inhibited by:
1) feedback inhibition by GH & Insulin GF
2) hyperglycemia
3) hyperlipidemia
4) obesity
5) emotional deprivation (increased GHIH, decrease GHRH)
What stimulates the release of TSH?
Stimulated by:
1) TRH
2) cold temperature in infants
Inhibited by:
1) feedback inhibition via thyroid hormone, anterior pituitary and hypothalamus via GHIH
What stimulates the release of ACTH?
Stimulated by:
1) CRH
2) Fever
3) hypoglycemia
Inhibited by:
1) feedback inhibition via glucocorticoids
What stimulates the release of FSH?
Stimulated by:
1) GnRH (gonadotropin releasing hormone)
Inhibited by:
1) feedback inhibition via estrogens and testosterone
What stimulates the release of LH?
Stimulated by:
1) GnRH (gonadotropin releasing hormone)
Inhibited by:
1) feedback inhibition via estrogens, progesterone and testosterone
What stimulates the release of PRL?
Stimulate by:
1) decreased PIH
2) estrogen
3) birth control pills
4) breast feeding
5) dopamine-blocking drugs
Inhibited by:
1) PIH (dopamine)
Which organ is targeted by oxytocin?
1) uterus
2) breast
Which organ is targeted by ADH?
Kidneys
Which organ is targeted by GH?
1) liver
2) muscle
3) bone
4) cartilage
Which organ is targeted by TSH?
Thyroid gland
Which organ is targeted by FSH?
1) ovaries
2) testes
Which organ is targeted by LH?
1) ovaries
2) testes
Which organ is targeted by PRL?
Breast
What are the effects the hyposecretion of oxytocin?
Unknown
What are the effects the hyposecretion of ADH?
Diabetes insipidus
What are the effects the hyposecretion of GH?
Pituitary dwarfism in children
What are the effects the hyposecretion of TSH?
Hypothyroidism (can cause myxedema)
What are the effects the hyposecretion of ACTH?
Its very rare
What are the effects the hyposecretion of FSH?
Failure of sexual maturation
What are the effects the hyposecretion of LH?
Failure of sexual maturation
What are the effects the hyposecretion of PRL?
Poor milk production in nursing women
What are the effects the hypersecretion of oxytocin?
Unknown
What are the effects the hypersecretion of ADH?
SIADH (syndrome of inappropriate ADH secretion)
What are the effects the hypersecretion of GH?
1) Gigantism in children
2) acromegaly in adults
What are the effects the hypersecretion of TSH?
Hyperthyroidism
What are the effects the hypersecretion of ACTH?
Cushing’s disease
What are the effects the hypersecretion of LH & FSH?
No important effect
What are the effects the hypersecretion of PRL?
1) Inappropriate milk production (galactorrhea)
2) cessation of menses in females; incompetence in males
Which organ is targeted by ACTH?
Adrenal cortex
What is diabetes insipidus?
A result of ADH deficiency, marked by intense thirst & huge urine output can be due to pituitary tumor, blown to the head which might damage the hypothalamus or posterior pituitary
What is syndrome of inappropriate ADH?
Hypersecretion of ADH, causes retention of fluid causing headaches, disorientation (due to brain edema), weight gain
In children due to meningitis, adults can be due to neurosurgery, hypothalamic injury, cancers, general anesthesia, or due to certain drugs you can manage it by restricting fluids and monitoring sodium levels in blood.
What is gigantism?
The hypersecretion of the growth hormone in children, which is usually due to anterior pituitary tumor
What is acromegaly?
Hypersecretion of the growth hormone after the closure of the epiphyseal plate in adults enlarging their extremities which is usually due to anterior pituitary tumor
What is pituitary dwarfism?
HYPO-SECRETION of the growth hormone in children which slows the growth of bones
What is hyperprolactinemia?
Hypersecretion of prolactin which is mainly due to anterior pituitary tumor causing inappropriate lactation, lack of menses, infertility in females, and incompetence in males
What is a tropic hormone and what are four examples of them?
Hormones that regulates the secretory action of other endocrine glands:
1) thyroid stimulating hormone
2) adrenocorticotropic hormone
3) follicle stimulating hormone
4) lutenizing hormone
What are the effects of the GH?
1) Increases blood glucose and has other anti-insulin effects
2) Increases fat breakdown and release
3) Increases skeletal growth
4) Increases cartilage growth at extraskeletal tissues, promotes protein synthesis and cell growth and proliferation
What does the thyroid gland control?
Metabolism
What is the location and structure of the thyroid gland?
The Largest pure endocrine gland, butterfly shaped located anterior to the neck inferior to the larynx its two lobes are connected by the isthmus tissue, has superior and inferior blood supply, composed internally of spherical follicles formed by squamous/cuboidal epithelial cells producing thyroglobulin storing colloid in its lumen which consists of thyroglobulin with attached iodine deriving the thyroid hormone, it has also parafollicular cells which produces calcitonin found on tissue that surrounds the thyroid follicle
What is the body’s major metabolic hormone?
Thyroid hormone
What are the types of thyroid hormones?
1) T4 (two iodine-containing amine, the major hormone produced by the thyroid follicles)
2) T3 (triiodothyronine, usually produced due to the conversion of T4 to T3 at the target tissue)
What is the difference between T4 & T3?
Both are constructed from two linked tyrosine amino acids, but T4 has four bound iodine atoms, and T3 has three
What is the function and mechanism of the thyroid hormone?
It initiated the transcription of mRNA for protein synthesis, entering the target cell through its lipid membrane (protein hormone, but lipid soluble) and binding to its receptor inside the cell it has various effects:
1) calorigenic effects, increases basal metabolic rate and body heat production via turning on the genes concerned with glucose oxidation
2) regulates tissue growth & development
3) maintains BP via increasing adregenic receptors in BV
How is the thyroid hormone synthesized?
1) TSH from anterior pituitary bind to receptors on the follicular cells
2) release stored thyroid, then restock “synthesize” the colloid in the lumen
Synthesized via:
1) thyroglobulin is synthesize and discharged into the follicle lumen
2) iodide is trapped actively from the blood
3) iodide gets oxidized to iodine
4) iodine gets attached to tyrosine in colloid forming DIT & MIT
5) iodinated tyrosine are linked together forming T4 & T3
6) Thyroglobulin colloid is endocytosed and combined with a lysosome
7) Lysosomal enzymes cleave T4 and T3 from thyroglobulin and hormones diffuse into bloodstream
How does the thyroid hormone targets its cells?
In the blood it is bound to plasma protein (thyroxine-binding globulins)
What is myxedema?
Full-blown hypothyroid syndrome, causing low metabolic rate, child feeling, constipation, thick dry skin, puffy eyes, edema, lethargy, and mental sluggishness, if the myxedema was due to lack of iodine a goiter (enlarged thyroid gland will appear) treatment can involve iodine supplements
What is Graves’ disease?
Hyperthyroid pathology, it is an autoimmune disorder where the patients immune system makes antibodies agains the thyroid follicular cells mimicking the TSH stimulating TH release, symptoms may include:
1) elevated metabolic rate
2) sweating & rapid irregular heartbeat
3) nervousness
4) protrusion of the eyeballs
5) weight loss
Treatments include surgically removing the thyroid gland or ingesting radioactive iodine, which destroys the most active thyroid cells
What is calcitonin?
A polypeptide secreted by the parafollicular (C cells) of the thyroid gland due to increase Ca+2 LEVELS, pharmacologically calcitonin has a bone-sparing effect and is given therapeutically to patients to treat Paget’s disease and sometimes osteoporosis inhibits osteoclast activity, inhibiting bone resorption and release of Ca+2 from the bony matrix, and stimulates Ca+2 uptake and incorporation into bone matrix.
What are the hormones that increase blood glucose levels?
GH
Glucagon
Thyroid hormone
Glucocorticoids (braking down glycogen in liver, & enhances gluconeogenesis)
What is the precursor for ACTH?
Proopimelanocortin (increases pigmentation)
What is the role of androgens?
In males it’s converted into testosterone, and in female into estrogen
What does the adrenal medulla release?
1) epinephrine
2) norepinephrine
What is the functions & structure of the parathyroid glan
- tiny, yellow-brown
- usually four to eight
- two glandular cells, oxyphil cells and large numbers of smaller parathyroid cells (secrete parathyroid hormone “PTH”)
what is the function of the parathyroid hormone?
- protein hormone
- the most important hormone controlling calcium levels (which is important for transmission of nerve impulses,
muscle contraction, and blood clotting)
What is the mechanism of the parathyroid hormone (PTH)?
- Falling blood Ca2+ levels trigger PTH release, and rising
blood Ca2+ levels inhibit its release - PTH increases Ca2+ levels in blood by stimulating three target organs: (skeleton, kidneys, and the intestine) stimulating:
1) osteoclasts (bone-resorbing cells) to digest some of the calcium-rich bony matrix and release ionic calcium and
phosphates to the blood
2) Enhances the kidney’s reabsorption of Ca2+ from the forming urine into the blood
3) Promotes activation of vitamin D, thereby increasing absorption of Ca2+ by intestinal mucosal cells. Vitamin D is required for absorption of Ca2+ from food, but first the kidneys must convert it to its active vitaminD3 form, calcitriol (1,25-dihydroxycholecalciferol). Which is stimulated by PTH
What is meant by hyperparathyroidism?
Excess PTH, often due to parathyroid tumor, where Calcium leaches from the bones, softening and deforming as fibrous connective tissue replaces their mineral salts. Which can become a osteitis fibrosa cystica, where the bones have a moth-eaten appearance on X rays and tend to fracture spontaneously, this disease can:
1) depress the nervous system
2) forms kidney stones
3) accumulate in soft. Tissue impairing vital organ function
What is meant by hypoparathyroidism?
- PTH deficiency, due to parathyroid gland trauma or removal during thyroid surgery
- The resulting hypocalcemia (low blood Ca2+) makes neurons more excitable and accounts for the classic signs and symptoms of tingling sensations, tetany (twitching muscle), and convulsions.
- If Untreated it may lead to respiratory paraly-sis and death
Where is the location of the pancreas, & from which cells is it composed?
Behind the stomach in the abdomen, composed of endocrine and exocrine gland cells
What is the pancreatic acinar cells?
Forms the bulk of the pancreas, produces an enzyme rich juice which is arrived to the S.I during digestion
What is the pancreatic islet (islet of langerhans)?
Cell clusters that produces glucagon (by Alpha cells) and insulin (by beta cells), they act as a sensor, they also synthesize:
1) somatostatin
2) pancreatic polypeptide
What is glucagon?
A 29-amino acid polypeptide, hyperglycemic agent, mainly targets the liver
What are the effects of glucagon?
1) Breakdown of glycogen to glucose (glycogenolysis)
2) Synthesis of glucose from lactic acid and from noncarbohydrate molecules (gluconeogenesis)
3) Release of glucose to the blood by liver cells, causing blood glucose levels to rise
4) lowers amino-acid levels in blood
What stimulates the release of glucagon?
1) “Humoral stimuli” the falling levels of blood glucose, prompts the alpha cells to secrete glucagon
2) sympathetic nervous system stimulation
3) rising amino acid levels
What suppresses the release of glucagon?
1) rising blood glucose levels
2) insulin
3) somatostatin
What is insulin?
51-amino-acid, protein consisting of two amino acid chains linked by disulfide (-S-S-) bonds, synthesized as part of a larger polypeptide chain called proinsnlin. Enzymes then excise the middle portion of this chain, releasing functional insulin, just before the beta cell releases insulin, which is a hypoglycemic hormone
what are the effects of insulin?
1) promotes protein synthesis and fat storage
2) enhances membrane transport of glucose
3) Inhibits the breakdown of glycogen to glucose
4) Inhibits the conversion of amino acids or fats to glucose.
5) participates in neural development, feeding behavior, learning & memory
What stimulates the secretion of insulin?
1) Elevated blood glucose levels
2) Rising blood levels of amino acids and fatty acids
3) Acetylcholine released by parasympathetic nerve fibers
4) Hyperglycemic hormones (such as glucagon, epinephrine, growth hormone, thyroxine, or glucocorticoids). This effect is indirect and occurs because all of these hormones increase blood glucose levels
what suppresses the release of insulin?
Activation of:
1) somatostatin
2) sympathetic nervous system
What is the mechanism of how insulin works?
It activates receptors (tyrosine kinase enzyme), phosphorylating specific proteins, promoting glucose uptake, which hen the insulin triggers enzymatic activities that:
1) Catalyze the oxidation of glucose for ATP production
2) Join glucose molecules together to form glycogen
3) Convert glucose to fat (particularly in adipose tissue)
And in muscle tissue it:
4) stimulates amino acid uptake and protein synthesis
What is diabetes mellitus type 1?
The result of the hyposecretion/hpoactivity of insulin, it is due to the absence of insulin
what is type 2 diabetes mellitus?
When insulin is present but its effects are deficient
What are the cardinal signs of diabetes mellitus?
1) polyuria (as excessive glucose in kidney inhibits water reabsorption), which decreases blood volume & causes dehydration
2) polydipsia (due to stimulation of the hypothalamus by the dehydration caused by polyuria)
3) polyphagia (as body cannot use the glucose it breaks down protein & fat to produce energy, stimulating appetite “lipidemia”)
What is lipidemia & what can it lead to?
Increased blood fat level due to the inability of cells to use sugars as cellular fuels mobilizing more fats, in severe cases of diabetes mellitus not only blood fat levels increases but also their metabolites (acetoacetic acid, acetone, and others called “ketones”) rises causing ketoacidosis (low blood pH) & ketone bodies begins to spill in the urine causing ketouria, severe ketoacidosis is life threatening NS respond by rapid deep breathing (hyperpnea) to blow of CO2 increasing blood pH, also electrolytes are also ridden of as ketone bodies are negatively charged they take with them sodium and potassium ions leading to abdominal pain and vomiting, if untreated ketoacidosis can impair the heart cause coma and death
What is hyperinsulinism?
Excessive insulin production can be due to islet cell tumor, or more commonly, by an overdose of insulin, which leads to hypoglycemia triggering the release of hyperglycemic hormones, causing:
1) anxiety
2) nervousness
3) tremors
4) weakness
Insufficient glucose delivery to the brain causes disorientation, unconsciousness, and even death, it is easily treated by ingesting sugar
What is the gonads?
The male testes & female ovaries
What does the gonads produce?
Steroid hormones identical to those produced by the adrenal cortical cells, ovaries produce progesterone and estrogen (estrogen is responsible for the maturation of the reproductive organs and the appearance o the secondary sex characteristics of females at puberty) estrogen & progesterone acts together to promote breast development and cyclic changes in the uterine mucosa “menstrua cycle”, while the testes produces testosterone which initiates the maturation of the secondary sex characteristics and sex drive & maintains normal sperm production
What is the placenta and what hormones does it secretes?
A temporary endocrine organ, it secretes estrogen, progesterone, & hCG (Human chorionic gonadotropin)
Endocrine glands derived from the mesoderm produces what type of hormones?
Steroid hormones
What are the hormones that are vulnerable to environmental pollutants?
1) sex hormones
2) thyroid hormone
3) glucocorticoids (Interference with glucocorticoids, which turn on many genes that may suppress cancer, may help to explain high cancer rates in populations exposed to various types of toxins)
Which hormone production does not decline with age?
Parathyroid hormone (PTH), which have bone demineralizing effect and osteoporosis
