Endocrine System

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Endocrine System
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Nervous and Endocrine System
fast
slow
Electrical/Chemical
Chemical
Change amplitude
Freq of Action Pot.
Short term
Long term
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• Endocrine System
• A. Hormones

1. Amines
derivatives of amino acid
tyrosine
Thyroid Gland and
Adrenal medulla
Thyroxine (T4)
Epinephrine Triiodothyronine (T3)
Norepinephrine
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2. Peptides and proteins
most hormones
synthesized in Rough ER
3. Steroids
cholesterol - precursor
Glands Adrenal Cortex / Gonads
B. Control of Hormone secretion
1. Change in plasma concentration

• of ions (ex. Calcium)

• of organic nutrients (ex. Glucose)

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2. Neurons

• hormones regulated by ANS

ex. Parasympathetic -gt increase
insulin Sympathetic -gt
release of catecholamines

• regulated by CNS

ex. Neurons in hypothalamus
3. Hormonal control

• Tropic hormones -gt hormone -gt release other
  hormones

Ex. TSH -gt Thyroid (T3/T4)
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C. Hormone transport
1. Peptides, catecholamines dissolve
2. Steroids, thyroid hormones lipid
soluble
free hormone binding protein
hormone-protein

• only free enter target

D. Hormone removal
1. Excretion
2. Metabolism
excreted
reused

• broken down

3. Conjugation -gt molecule added
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III. Hormone action
A. Hormone receptors
1. Down regulation

• reduce receptors w/prolonged exposure

• due to receptor synthesis

phagocytosis
2. Up regulation -

• increase receptors w/ exposure

• receptor synthesis

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B. Receptor classes
1. Extracellular membrane bound
a. Controls channels
b. Synthesis of 2nd messenger
c. Activate G protein

• control channels

• 2nd messenger

d. Phosphorylate receptor
2. Intracellular receptors

• binds w/hormone inside

• specific region of DNA -gt protein synthesis

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