Endocrine System

The endocrine system consists of network of glands, which we called endocrine glands. Endocrine glands function as hormones producer. And what is hormone by the way? Hormones are chemical messenger that transmit message to regulate physiological events and they are transported by the bloodstream.

Before that, an endocrine system is the body's main system for communicating, controlling and coordinating body's work. It mainly works for the nervous system, the reproductive system and other systems.

The endocrine glands are:

1) The hypothalamus 

2) adrenal gland

3) pituitary gland 

4) thyroid gland

Functions of the Hypothalamus

- hypothalamus connected to the pituitary gland in which it keeps track of the hormone level, if hormone level is high, it inhibits hormone production, and vice versa. 

-Hypothalamus secretes FSHRH (Follicle stimulating hormone releasing hormone) and LHRH (Luteinising hormone releasing hormone)

Hypothalamus triggers the pituitary gland to produce hormones. Pituitary gland is by right consists of the anterior and posterior pituitary gland. Anterior is facing in front meanwhile posterior is facing behind. There are a wide difference between both anterior and posterior. 

The anterior side produces hormone prolactin and growth hormone, which is directed to the body. It also produces TSH (thyroid stimulating hormone), ACTH (adrenocorticotropic Hormone), Gonadotropic Hormone (FSH, LH), but these ones are not directed toward targeted organ or cells, rather, it stimulates other target gland to produce another hormone like stimulating thyroid gland. 

Posterior side of the pituitary gland, acts as storage site. In which, the hormones oxytocin and ADH are produced by the hypothalamus, but they are stored in the posterior side. So, we can conclude that posterior side does not produce hormones. 

Now let us look at the functions of the hormones mentioned above:

a) growth hormone-assist in growth

b) prolactin-development of mammary gland

c) TSH-stimulate thyroid gland to produce thyroid hormone

d) oxytocin- important in the contraction of uterus during labour

e) ADH- reabsorption of water from collecting tubules. 

 

Function of Thyroid Glands

Thyroid gland produces thyroid stimulating hormone. So, before we get closer to TSH,  we know that we have both the endocrine and exocrine systems. What are the differences? 

Endocrine system consists of endocrine glands that produce hormones which then brought through the bloodstream, meaning 'inside' the body whereas exocrine system consists of exocrine glands that secrete hormones 'outside'. The secretion passes through a system of ducts that lead to the exterior of the body. 

Fine, how does the thyroid stimulating hormone stimulated?

Thyroid Hormones are actually divided into 2 types, the T3 and T4. 

• T3 stands for triiodothyronine, and it is in the active form, which take up 3 molecules of iodine to generate thyroid hormone. 
•  T4 stands for thyroxine the most common type of thyroid, which is mostly produced.

At a target organ, T4 is converted in T3 which is an active form.

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