Classification of Hormones

Presented By

Younis Ahmad Hajam

Pre- Ph.D Student

Department of Zoology,

Guru Ghasidas Vishwavidayalaya, Bilaspur.

Hormone(Greek term “to spur on.”)

Hormones are the chemical substances produced by specializedtissue (endocrine gland) and secreted into the blood, where they arecarried to the target organs or cells.

Main endocrine glands are:• Hypothalamus(Master of master gland)

• Pituitary gland (Master gland)

• Pineal gland (Neuroendocrine gland)

• Thyroid gland

• Adrenal gland

• Gonads

• Endocrine part of pancreas (islets of langerhens)

Hormone features

• Chemical messengers

• Secreted by a specific gland

• Secreted directly into the blood stream

• Carried by the blood

• Acts on a specific target site distant from site of

secretion

• Secreted in minute quantities

• Acts via specific receptors to exert specific actions

Functions of Hormones

• Hormones coordinate all the biological activities within an organism, these activities include :– Metabolism

– Growth

– Reproduction

– Behavioral activities

• Affect contraction, relaxation, and metabolism of muscles.

• Stimulate or inhibit cellular proliferation.

• Regulate excretion and reabsorption of inorganic cations and anions from the kidneys.

• Have permissive actions on the action of the hormones.

Hormone classification

Basis of hormone classification

On the basis of solubility

On the basis of chemical nature

On the basis of the function

I. On the basis of solubility.

i. Lipid soluble hormones: Steroids and thyroid hormones.

ii. Water soluble hormones: Peptides, proteins, amines.

Water soluble

hormones

Lipid soluble

hormones

gene

mRNA

peptide hormones

amino acid

derivatives

(epinephrine,

norepinephrine)

storage

secretion

cholesterol

steroid hormone

amino acid

derivative

(thyroid

hormone)

free hormone

free hormone

binding protein

diffusion

plasma membranereceptors

protein

target

DNA

mRNA

cellular response

Time

HormoneLevel

Time

HormoneLevel

phosphorylation

ion flux

second

messengers

(cAMP,

cGMP)

stimulus

secretion

synthesis synthesis

cellular response

Water soluble and lipid soluble hormones

Steroid Hormones Receptors are mainly in the nucleus

Glucocorticoidsreceptors are mainly in the cytoplasm

Steroid Hormones

Release from bloodcirculation

steroid

progestrone

Diffuses into cytoplasm

DNASteroid

receptor

Rough endoplasmic reticulum

mRNA

Protein synthesis

secretion

Uterine glandular endothelial cells

II. On the basis of their chemical nature

• Peptides: ACTH, Calcitonin, Glucagon, Vasopressin,Oxytocin.

• Proteins: Insulin, and Parathormone (PTH).

• Amino acid derivatives: Catecholamine (epinephrine and nor-epinephrine), thyroid hormones and melatonin.

• Steroids: (Derived from cholesterol) Hormones of adrenalcortex and sex steroids.

• Glycoproteins: FSH &LH

• Derivatives of polyunsaturated fatty acids Derivatives :Prostaglandins.

IV. On the basis of function

• Kinetic hormones: Those hormones which are involved in the

migration of pigment granules (melanin), muscle contraction

(oxytocin).

• Metabolic hormone: Those hormones which helps in the

control of metabolic functions e. g. thyroxin (T4 and T3, insulin,

growth hormone, parathyroid hormones etc.

• Morphometric hormones: Hormones which controls growth

and differentiation, e.g. Growth hormone, FSH, LH and

androgens (testosterone).

Mechanism of hydrophilic hormones via cyclic

AMP second messenger pathway

PIP2 AS SECOND MESSENGER

Behavioral hormones

• Hormones like testosterone develops secondary characters in

males

• Estrogen and progesterone helps in the development of the female

characters like breast development, deposition of fat in the hips,

deepening of voice etc.

• Maternal behavior is controlled by gonadal hormones and by

pituitary hormones

• Group behavior is effected by the release of pheromones into the

environment.

Signaling molecules act via following ways-

• Endocrine

• Paracrine

• Autocrine

• Intracrine

• Neuroendocrine

• Ectocrine (Pheramones)

Modes of delivery

Blood vessel

Distant target cells

Hormone secretion into blood by endocrine gland

Secretory cell Adjacent target cell

Target sites on same cell

Autocrine

Endocrine

Paracrine