Download MBBS (Bachelor of Medicine and Bachelor of Surgery) Latest Hormone 2 Lecture PPT
HORMONES
o Term hormone was introduced by Starling and
Bayliss in 1905.
o Hormones are the chemical messengers produced by
endocrine gland and transported by blood to other
tissue or organ where these stimulate a change in
some metabolic activity.
o They are produced from by one type of cell and have
regulatory effect on the activities of other type of cell
or on itself.
o The tissue or organ stimulated by a specific hormone
are called Target Tissue/ Target organ
o .
Hormones act on specific cells and organs called
target cell or target organ.
o Target cell or organ is that cell which has specific
receptors for the hormone which bind to them
with or without any demonstratable biochemical
or physiological response
o Concentration of hormone is very low in blood
but..
o Presence of receptors on target tissue
Specific binding between hormone and receptor
Very high local concentration
o Makes the target tissue highly specific to
hormones
The "information pathway". Information flows from the gene to the
primary transcript to mRNA to protein.
Hormones can affect any of the steps involved and can affect the rates
of processing, degradation or modification of the various products
CLASSIFICATION OF HORMONES BY
MECHANISM OF ACTION
I. Hormones that bind to intracellular receptors
1. Androgens
2. Calcitriol (1,25[OH]2-D3)
3. Estrogens
4. Glucocorticoids
5. Mineralocorticoids
6. Progestins
7. Retinoic acid
8. Thyroid hormones (T3 and T4)
II. HORMONES THAT BIND TO CELL SURFACE
RECEPTOR
A. The second messenger is cAMP
? 2-Adrenergic catecholamines
? -Adrenergic catecholamines
? Adrenocorticotropic hormone (ACTH)
? Antidiuretic hormone (vasopressin)
? Calcitonin
? Human Chorionic gonadotropin, (HCG)
? Corticotropin-releasing hormone
? Follicle-stimulating hormone (FSH)
? Glucagon
? Luteinizing hormone (LH)
? Melanocyte-stimulating hormone (MSH)
? Parathyroid hormone (PTH)
? Somatostatin
? Thyroid-stimulating hormone (TSH
B. The second messenger is cGMP
? Atrial natriuretic factor
? Nitric oxide
C. The second messenger is calcium or
phosphatidylinositols (or both)
? Acetylcholine (muscarinic)
? 1-Adrenergic catecholamines
? Angiotensin II
? Antidiuretic hormone (vasopressin)
? Cholecystokinin
? Gastrin
? Gonadotropin-releasing hormone
? Oxytocin
? Thyrotropin-releasing hormone (TRH
D. The second messenger is a kinase or phosphatase
cascade
? Adiponectin
? Chorionic somatomammotropin
? Epidermal growth factor (EGF)
? Erythropoietin (EPO)
? Fibroblast growth factor (FGF)
? Growth hormone (GH)
? Insulin
? Insulin-like growth factors I and II
? Leptin
? Nerve growth factor (NGF)
? Platelet-derived growth factor
? Prolactin
HORMONES
STIMULUS
PROPERTY
GROUP I
GROUPII
1.HORMONES
Adrenal steroids, thyroid Hypothalamic
hormones,
hormones, sex hormones, pituitary
hormones,
calcitriol ,retinoids
pancreatic
hormones,
Adrenal hormones
2.Chemical nature
Steroids,
iodothyronines, Peptides & polypeptides,
retinoids
proteins,
glycoproteins,
Catecholamines
3.Solubility
Hydrophobic,
Water Hydrophilic Water soluble
insoluble
4.Transport Protein
Required
Not required
5.Receptors location
Cytoplasm and nucleus
Cell membrane
6.Mediators of action
Hormone
-Receptors cAMP
Complex
cGMP
Ca ++
Phosphoinositides,
kinase Cascade etc.
ACTION OF GROUP I HORMONES
MECHANISM OF GROUP I HORMONE
ACTION
?
The DNA Sequences of Several Hormone Response Elements
Another member of the steroid receptor superfamily, the retinoid X
receptor (RXR), forms heterodimers with VDR, TR, and RARE, and
these constitute the functional forms of these transacting factors.
cAMP affects gene transcription through the CRE
This post was last modified on 30 November 2021