Thyroxine and Antithyroids

Thyroxine and Antithyroids

Hormones:

The word harmones is derived from hormao which means to excite or
to rouse or set in motion.

It is defined as a chemical substance which is formed in one organ
or released from one group of cell and carried in blood stream to another organ
or group of cell, to exert specific regulatory effect.

The word hormones are secreted by endocrine gland.

The word derived from Greek word endon=within and crinein = to set
a part.

Like vitamins, hormones are effective in very low concentration.

They do not have any cumulative action as they are destroyed and
excreted as soon as their function are over.

Some hormones function quickly and are destroyed quickly e.g.
adrenaline.

Some work slowly and destroyed slowly e.g –Thyroxine. 

Classifications of Hormones:

A. Chemically
hormones are classified as

Amino acid
derivatives:
-e.g. Thyroxine, Liothyronine.

Polypeptides:-e.g.
Insulin,
Oxytocin, Vasopressin 

Proteins: e.g.
–growth hormones

Glycoprotein’s:-e.g.  FSH (follicle stimulating hormone, (LH)
Leutinising hormones.

Steroids:
e.g:
Testosterone, Progesterone, And Oestradiol.

Miscellaneous:

a. Hormones
are classified according to source (origin).

1. Thyroids
hormones (hormones are secreted by thyroids gland) e.g. –

Thyroxine, Liothyronine, calcitonin

2. Pituitary
hormones:

Hormones secreted by anterior pituitary: e.g. ACTH, TSH, FSH, LH,
GH.

Hormones secreted by posterior pituitary: e.g Oxytocin,
Vasopressin 

3. Adrenal gland hormones:

Secreted
by cortex: e.g. –
Glucocorticoids like Cortisone, Hydrocortisone
Mineral corticoids like aldosterone

Secreted
by medulla:
adrenaline

4. Pancreatic
hormones:

Secreted
by alpha cell of islets of langerhans: –
e.g. glucagon

Secreted
by beta cell of islets of langerhans: e.g
. Insulin

5. Parathyroid hormones secreted by
parathyroid gland

6. Hormones
secreted by thymus gland – e.g
Thymine

7. Hormones
secreted by hypothalamus:

Releasing
factor for stimulation: e.g.
Thyrotropin, (release TSH).
Adrenocorticotrophin (release ACTH), leutotrophin releasing hormones etc.

Releasing
factor for inhibition of TSH, GH, FSH, etc.

Thyroxine

Structure
of Thyroxine: