LESSON 7: ENDOCRINOLOGY
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CLINICAL CHEMISTRY 2
Elevation of products = decrease of
activity of system and production rate
TERMINOLOGIES
ENDOCRINE SYSTEM
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May also be termed as neuroendocrine
system
Made of a network of ductless glands
that releases chemical signals
(hormones) into interstitial connective
tissue (blood) and carried to a target
tissue
Secretion usually being controlled by
feedback mechanism rather than by
degradation
Most glands consist of cords of
parenchymal cells
Sagittal view showing blood supply of the
pituitary
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Circadian rhythm – a change in the level
of a hormone every 24 hours
Ex.: Cortisol, GH, Aldosterone, prolactin,
TSH, testosterone, LH, and FSH
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Infradian rhythm – rhythms that are
longer than circadian rhythms
Ex.: menstrual cycle: variations in the FSH
and LH are on a monthly cycle
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Ectopic hormones – hormones that
were produced from a non-endocrine
source
Ex.: Some benign and malignant tumors
manufacture hormones similar to the
hormone produced by the endocrine gland
CLASSIFICATION OF HORMONES
HORMONES
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Function: Maintenance of the
homeostasis of chemical composition of
extracellular fluid, and control
metabolism, growth, fertility and
response to stress
• Regulation:
1. POSTIVE FEEDBACK MECHANISM:
-elevation of products = elevation of
activity of system and production
rate
2. NEGATIVE FEEDBACK MECHANISM:
1. Steroid hormones
- Precursor: Cholesterol
- Examples: estrogen,
progesterone, testosterone,
cortisone, vitamin D, and
aldosterone
2. Protein hormones
- Composed of amino acids and
are usually produces by the
partial hydrolysis of proteins
- Examples: pituitary gland
hormones, parathormone,
placental and pancreatic
hormones
3. Amine hormones
- Derived from tyrosine
- Examples: T3 and T4 ( secreted
by thyroid glands, and
sympathomimetic
hormones(secreted by adrenal
medulla)