Controlled mostly by GHRH more than GHIH GHRH attaches to GCPR on the GH cells, activates adenylate cyclase, etc...increases Ca into cell and causes vesicle release also controlled by Gherlin and IGF-1

Endocrine Hormones Flashcards by Maggie McDonell

Cell types of the pituitary gland:

Somatotropes release __________

Growth hormone

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Cell types of the pituitary gland:

Corticotropes release ________

adrenocorticotropic hormone

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Cell types of the pituitary gland:

Thyrotropes

Thyroid stimulating hormone

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Cell types of the pituitary gland:

Gonadotropes release _______

Leuteninzing hormone, follicle stimulating hormone

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Cell types of the pituitary gland:

Lactotropes release ______

prolactin

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Hormones that come from the anterior pituitary gland

Thyrotropin
Growth hormone
Corticotropin
follicle stimulating
luteinizing
prolactin

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What stimulates release of hormones from the posterior pituitary gland?

posterior: nerve signals that originate in the hypothalamus

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What controls release of hormones from the anterior pituitary gland?

hormones secreted within the hypothalamus called hypothalamic releasing and hypothalamic inhibitory hormones
brought to the anterior pituitary through small blood vessels called the hypothalamic-hypophysial portal vessels
the hormones act on the glandular cells to control their secretions

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osmoreceptor

found in hypothalamus. Shrinks and expands depending on osmolarity of blood going by

Shrink = increased signals, increased ADH

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Growth hormone physiologic effects

promotes growth of many body tissues (increased size and number of cells)
promotes protein synthesis
increased use of fatty acid for energy
decreased use of glucose

* GH enhances body protein, uses up fat stores, and conserves carbohydrates

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What does Growth hormone need in order to have effect?

insulin

carbohydrates

*to provide the energy needed for the metabolism of growth and enhance transport of some amino acids into cells

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How much does the amount of growth hormone change throughout the lifespan?

you will have 25% of what you had as an adolescent when you are elderly

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What stimulates release of growth hormone?

starvation (especially severe protein deficiency)
hypoglycemia or low concentration of fatty acids in the blood
exercise
exciement
trauma
ghrelin (tells you you are hungry)
increased during first 2 hours of deep sleep

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GH regulation

Controlled mostly by GHRH more than GHIH
- GHRH attaches to GCPR on the GH cells, activates adenylate cyclase, etc…increases Ca into cell and causes vesicle release
also controlled by Gherlin and IGF-1

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GH summary

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What are the two major thyroid hormones and the percent which you find them in?

Thyroxine (T4)- 93%

Triiodothyronine (T3)- 7%

Which thyroid hormone is more potent?

Triiodothyronine is 4x as potent

it is present in smaller quantities and has a shorter DOA

What is thyroglobulin?

A vesicle containing thyroid hormones

Formation of a thyroid hormone

Iodide enters cuboidal cell surrounding colloid.
conversion of iodide to an oxidized form of iodine which can then combine directly with the amino acid tyrosine.
1. Enzyme peroxidase makes oxidation happen faster
over time the iodotyrosines become coupled with each other.
This thyroxine remains in the thyroglobulin molecule

How is Thyroid hormone transported?

upon enteing blood, more than 99% of T4 and T3 are bound to proteins
- thyroxine-binding globulin (mostly)
- thyroxine-binding prealbumin
- albumin
this affinity for proteins acts as a reservoir for the thyroid hormones, releasing them slowly into the tissues

Thyroid hormone receptors:

Attached to DNA or very close to them
the thyroid hormone receptor forms a heterodimer with retinoid X receptor (RXR) at specific thyroid hormone response elements on the DNA
This activates receptor and starts the transcription process
Make a bunch of mRNA then RNA
actions of thyroid hormones result from the functions of these new proteins

generally, what do thyroid hormones do?

increase the metabolic activities of almost all the tissues of the body

** number and size of mitochondria increase

How is thyroid hormone stimulated?

hypothalamus secretes thyrotropin releasing hormone (TRH)
this activates the anterior pituitary to secrete thyroid stimulating hormone (TSH)
TSH increases all the known secretory activities of the thyroid glandular cells
T4 and T3 (more T4) go to target organs

How is thyroid hormone negatively controlled?

Increased thyroid hormone in the body fluids decreases the secretion of TSH from the anterior pituitary

what does the medulla of the adrenal gland produce?

catecholamines

what does the cortex of the adrenal gland produce?

* 2 major types of hormones * mineralcorticoids * corticosteroids * 1 minor type of hormone * androgenic hormones

What are the three layers of the adrenal cortex? And what do they each secrete?

1. zona glomerulosa- thin cells just under capsule 1. secrete aldosterone in response to extracellular ang II and K. 2. zona fasciculata- middle and widest zone (75%) 1. secretes glucocorticoids (cortisol and corticosterone 2. secretes andrenal androgens 3. secretion controlled by ACTH 3. zona reticularis- inner zone 1. secretes androgens

Actions of Aldosterone

1. retains Na and excretes K into tubule in exchange 2. causes secretion of H ions in exchange for Na in the intercalated cells of collecting ducts 1. decreases the H concentration and causes metabolic alkalosis

what role do intercalated cells play? alpha vs beta?

* they are involved with acid/base homeostasis * alpha- secreces acid (H), reabsorbs HCO3 * beta- secretes HCO3, reabsorbs (H)

What do principle cells do?

* mediate Na/K balance in the collecting duct with Na/k channels in the cells membrane

Aldosterone pathway

* triggered by RAAS system when low circulating volume is sensed * released directly when high K is sensed * increases number of Na/K exchangers and Na/Cl symporters * water follows Na * fluid balance increases

What do thiazide diuretics antagonize?

anything that aldosterone does. thiazide diuretics: decrease Na/K channels decrease Na/Cl symporter water follows and is secreted

What does cortisol do?

* increases gluconeogenesis * antagonizes insulin's effects to inhibit gluconeogenesis * increases protein mobilization * increases fat mobilization * removes the GLUT4 from cell membranes, causing insulin resistance * suppresses immune system

What percentage of cortisol binds to plasma proteins? How long is the half life?

90-95% has a long half life 60-90 minutes

How much circulating aldosterone is bound to proteins? What is the half life?

60% shorter half life of 20minutes

what is the normal plasma and ISF concentration of ionized Ca? What is the ionized Ca used for?

1.2 mmol/L 50% Used for most important functions

What is the concentration of bound Ca in plasma and ISF? How is this Ca used?

1 mmol/L the Ca bound to proteins is used as a reservoir/backup supply

What do you need/needs to function to be able to absorb Ca?

Vitamin D liver function, kidney function

What stimulates the secretion of parathyroid hormone? Where is it released from?

decreased blood calcium