Hormones types

1. Classification of
Hormones
Subject: BIO-103
Lecturer: Nishafa Shahzad

2. Classification of Hormones
Hormones can be classified into four groups depending upon their chemical
nature
1. Peptide hormones
2. Steroid hormones
3. Amino acid derivatives
4. Fatty acid derivatives

3. 1. Peptide Hormones
• These are the short chains of amino acids which are produced as large
polypeptide precursors and processed before being secreted.
• Peptide hormones are inactivated by gastric acid and peptidases; thus,
unlike steroid hormones, they cannot be given orally.
• Glycoproteins (composed of peptides and carbohydrate moeities) are more
stable and last longer than peptide hormones in circulation.
• Examples: gonadotropins, insulin, etc.

4. Synthesis of peptide hormones
• Peptide hormones are described in the DNA.
• A large majority of protein synthesis happens within the endoplasmic
reticulum.
• Large protein complexes known as ribosomes read the messenger RNA and
convert the message into a sequence of amino acids.
• Peptide hormones can be any length, from only a few amino acids to several
hundred.They are released through two pathways specifically
i)Regulated secretion
ii)Constitutive secretion

5. Continue…
• In constitutive secretion, the cells create hormones through signals
received by the DNA.
• In regulated secretion, the body may produce many of these. Biological
containers called vesicles then store the excess hormones. They then
become ready for release anytime the body needs them.

6. 2. Steroid Hormones
• Derivatives of cholesterol
• Transported by carrier proteins
• They are typically lipid-soluble and can be administered via the oral route
• They cross the cell membrane, enter cells, and bind to intracellular
receptors (cytoplasm and nucleus).This will then alter the transcription and
translation of certain proteins.
• Examples: testosterone, aldosterone, etc.

7. Action of steroid hormones
• Steroid hormone exerts their functions by diffusing through the cell
membrane, binding their receptors, inducing a conformational change in
the receptor, associating with DNA, interacting with cofactors, and altering
gene expression.
• The primary role of steroid receptor complex is to bind to specific loci in the
genome and regulate rates of gene transcription, but in addition steroid can
also modulate the expression of some gene post-transcriptionally.

9. 3. Amino acid derivatives
• Also called amine hormones
• Derived from amino acids tyrosine and tryptophan
• Thyroid hormones behave similarly to steroid hormones (binds to
intracellular receptors)
• Catecholamines behave similarly to peptide hormones
• Examples: epinephrine and norepinephrine.

10. 4. Fatty acid derivatives
• Fatty acids are the building blocks of fats as
they are derived by the breakdown of
emulsified fats.
• Fatty acid derivatives are eicosanoids which
are a large group of molecules derived from
polyunsaturated fatty acids.
• Example: prostaglandins.

11. Biological importance of hormones
• These messengers control most major bodily functions , from simple basic
needs like hunger to complex systems like reproduction , and even emotions
and other tissues .
• They include body growth and development , metabolism ( or production of
energy ) , sexual function and reproduction .
• The hormones are important in our daily life routine and playing important
role by controlling sleep-wake cycle , menstural cycle .
• They help in regulating mood.
• Hormones are important to maintain our body temperature .