hormone diversity
TRANSCRIPT
Diversity of Endocrine system
By
Dr. Kamal Modi
3rd year Resident
Biochemistry dept.
Communication system
Nervous system ---> fixed
Endocrine system ----> mobile
Target cell
Any cell in which the hormone (ligand) binds to its receptor, whether or not a biochemical or physiologic response has yet been determined.
How Target cell discriminate between Hormone and other similar molecules ????
Ans: Receptors
All receptors have at least two functional domains.
1) A recognition domain binds the hormone ligand
2) second region generates a signal that couples hormone recognition to some
intracellular function.
Group 1
Hormones that bind to intracellular receptors
Lipophilic
Require transport proteins
E.g. Steroids, Iodothyronines Retinoids
Group 2
Bind to cell surface receptors
Hydrophilic E.g Catecholamines
LH, FSH, HCGInsulin, Glucagon
Mediates through cAMP, cGMP,Ca, Kinase Cascade
Hormone synthesized in Various cellular arrangements.
In discrete organ designed solely for this purpose.
Thyroid Adrenal Pituitary
T3, T4 Gluco-corticoidsMineralo-corticoids LH
FSHTSHGH
In specialized cells within other organs.
Small intestineThyroid Kidney
Glucagon Calcitonin Angiotensin II
Requires the parenchymal cells of more than one organ.
Skin Liver Kidney
Calcitriol
Hormones are Chemically diverse
synthesized from a wide variety of chemical building blocks.
hormone is the precursor molecule for another hormone.
Amino acid tyrosine is the starting point in the synthesis of the catecholamines and of the thyroid hormones tetraiodothyronine (thyroxine; T4) and triiodothyronine (T3).
T3 and T4 are unique in that they require the addition of iodine for bioactivity.
Many hormones are polypeptides or glycoproteins.
Hormones Are Synthesized & ModifiedFor Full Activity in a Variety of Ways
synthesized in final form and secreted immediately. E.g. hormones derived from
cholesterol.
synthesized in final form and stored inthe producing cells. E.g. Catecholamines
synthesized from precursor molecules in the producing cell, then are processed and
secreted. E.g. Insulin
Converted to active forms from precursor molecules in the periphery (T3 and DHT).
Thank you...