Properties of Hormones
() They have low molecular weight.
(i) They are soluble in water and blood.
(iii) They have no cumulative effect.
(iv) They can act in very low concentration.
(v) They are non-antigenic.
(vi) They may act slowly or quickly
(vi) Hormone controlled reactions are not reversible.
(vii) Their excess or deficiency leads to disorders.
(ix) They do not provide energy or building materials.
(x) Many hormones are produced in inactive form called
prohormones, e.g., insulin is secreted as proinsulin.
Classification of Hormones
On the basis of chemical nature, hormones can be classified as:
(i) Amino acid derivative hormones The hormones epinephrine (adrenaline), norepinephrine
(noradrenaline) and thyroxine are derived from the amino acid tyrosine.
(ii) Peptide hormones The hormones oxytocin and vasopressin (ADH) are composed of peptides.
Proteinlypeptide) hormones-The somato-tropic, thyrotropic and gonadotropic hormones, insulin,
glucagon, parathormone, human chorionic gonadotropin, human chorionic somatomammotropin (hCS) and relaxin.
(iii) are made up of proteins.
(iv) Steroid hormones The hormones secreted by the
adrenal cortex, testes and ovaries are composed of steroids. Placental estradiol and progesterone are alsco
steroid hormones.
ENDOCRINE GLANDS
The endocrine system comprises of the endocrine glands and hormone producing diffused tissues or cells located in
different parts of our body.
The endocrine glands in our body are pituitary, pineal, thyroid.
