What hormones does the medulla produce?
What stimulates it?
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Epinephrine
Norepinephrine
Autonomic Nervous System stimulates the adrenal glands
,Describe the overall steps of endocrine communication
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1. Starts w/stimulation -- usually a change in internal/external environment
2. Endocrine cells produce hormones
3. The signal (hormone) travels through blood circulation
4. The hormone reaches a target cell w/receptors for the hormone
5. Ligand binds to receptor
6. Creates a signal transduction
7. Signal transduction leads to a physiologic response
Describe long loop feedback
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T3/T4 supresses secretion of TSH by acting directly on the cells that
secrete TSH or indirectly by acting on the hypothalamic neuroendocrine
cells that stimulate the secretion of TSH via TRH
Describe Thyroid Follicular Cell Hormones
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Tetraiodothyronine (T4) and Triiodothyronine (T3)
Tyrosine based hormones
Responsible for regulation of cellular metabolism
T4 (pro T3) is the major form in the blood -- has a longer half life than T3
, T4/T3 ratio is 14/1
T3 is three to four times more potent than T4
Describe characteristics of steroid hormones
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Synthesized from cholesterol
Non-Polar, lipophillic
Require blood carrier proteins for transport
Cytoplasmic and/or nuclear receptors
Change gene expression regulation directly
2 classes -- corticosteroids and sex steroids
Describe the biosynthesis of T3/T4
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1. Thyroglobulin is synthesized in the RER and enters the lumen of the
thyroid follicle by receptor mediated exocytosis
2.A Na/Iodide symporter pumps Iodide into the follicular cell
3.Iodide enters the follicular lumen by the transporter Pendrin
4.Iodide is oxidized to Iodine by thyroid peroxidase
5.Iodine iodinates the thyroglobulin
, 6.Iodinated thyroglobulin enters back into the follicular cell through
receptor mediated endocytosis
7. Proteases cleave the iodinated thyroglobulin into T3 and T4 molecules
8. T3 and T4 enter the blood
Describe the overall hormone pathway of growth hormone
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Hypothalamus produces growth hormone releasing hormone which acts
on the adenohypophysis
Growth Hormone is released by the anterior pituitary
Growth hormone triggers the liver to release insulin like growth factor
(somatomedin) -- primary growth mediator for different tissues through
paracrine/autocrine/endocrine actions
Growth hormone also acts directly on muscle tissues, bone tissues, nerve
tissues, and other tissues to stimulate growth
Describe the biosynthesis of steroid hormones
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What stimulates it?
Give this one a try later!
Epinephrine
Norepinephrine
Autonomic Nervous System stimulates the adrenal glands
,Describe the overall steps of endocrine communication
Give this one a try later!
1. Starts w/stimulation -- usually a change in internal/external environment
2. Endocrine cells produce hormones
3. The signal (hormone) travels through blood circulation
4. The hormone reaches a target cell w/receptors for the hormone
5. Ligand binds to receptor
6. Creates a signal transduction
7. Signal transduction leads to a physiologic response
Describe long loop feedback
Give this one a try later!
T3/T4 supresses secretion of TSH by acting directly on the cells that
secrete TSH or indirectly by acting on the hypothalamic neuroendocrine
cells that stimulate the secretion of TSH via TRH
Describe Thyroid Follicular Cell Hormones
Give this one a try later!
Tetraiodothyronine (T4) and Triiodothyronine (T3)
Tyrosine based hormones
Responsible for regulation of cellular metabolism
T4 (pro T3) is the major form in the blood -- has a longer half life than T3
, T4/T3 ratio is 14/1
T3 is three to four times more potent than T4
Describe characteristics of steroid hormones
Give this one a try later!
Synthesized from cholesterol
Non-Polar, lipophillic
Require blood carrier proteins for transport
Cytoplasmic and/or nuclear receptors
Change gene expression regulation directly
2 classes -- corticosteroids and sex steroids
Describe the biosynthesis of T3/T4
Give this one a try later!
1. Thyroglobulin is synthesized in the RER and enters the lumen of the
thyroid follicle by receptor mediated exocytosis
2.A Na/Iodide symporter pumps Iodide into the follicular cell
3.Iodide enters the follicular lumen by the transporter Pendrin
4.Iodide is oxidized to Iodine by thyroid peroxidase
5.Iodine iodinates the thyroglobulin
, 6.Iodinated thyroglobulin enters back into the follicular cell through
receptor mediated endocytosis
7. Proteases cleave the iodinated thyroglobulin into T3 and T4 molecules
8. T3 and T4 enter the blood
Describe the overall hormone pathway of growth hormone
Give this one a try later!
Hypothalamus produces growth hormone releasing hormone which acts
on the adenohypophysis
Growth Hormone is released by the anterior pituitary
Growth hormone triggers the liver to release insulin like growth factor
(somatomedin) -- primary growth mediator for different tissues through
paracrine/autocrine/endocrine actions
Growth hormone also acts directly on muscle tissues, bone tissues, nerve
tissues, and other tissues to stimulate growth
Describe the biosynthesis of steroid hormones
Give this one a try later!
