What are hormones?

Hormones are tiny chemicals used by your body to signal from one gland to the entire body in order to ensure that the internal environment is uniform.   Hormone systems influence our metabolism, health, growth, aging and finally ,who we are. Hormones influence our mood, our hunger, sex drive and is the body’s way of signalling to different parts of the body.

What are the signals that the body needs to send?

Signals are communications between the center and remote parts of the body and is essential to maintain the integrity of the whole body. Imagine you are going ballroom dancing..Your head shoulders knees and toes need to know about each other and need to move in a coordinated manner. Furthermore, the temperature, blood pressure and internal climate needs to be exactly right for optimal function. This is a very complex set of messages that need to move to different areas at different speeds. some messages are urgent (eg your head must move in the same direction as your toes while dancing) others not so urgent, (Blood pressure and heart rate must change appropriately)

How does the body signal?

There are two main methods of signalling Rapid (nervous system) and slow ( Hormone system)

If you step on a nail, your body knows this instantly and this is the rapid signalling pathway (Nervous system). you will immediately feel the pain,withdraw the foot, use your hand to pull out the nail and the less stoic ones a among us (me included may shout out a four letter expletive or shed a tear.

The body also needs to communicate other non urgent messages (eg I have just eaten food, I am having a terrible day at work). These are required for slower changes required to adapt. In the first example, the glucose levels will rise after a meal and insulin has to be secreted. In the second example, your stress hormones have to rise to meet the demands of office work.

The nervous system is the rapid signalling pathway (e-mail) and hormones are the snail mail

What are hormones?

Hormones are small chemicals (about 2000 – 5000 atoms each) and are present in very tiny amounts in your blood. These act on very specific cells and make the cell change its behavior. for example 1 molecule of Glucagon Like Peptide – 1 (GLP- 1 )will act on the beta cell in the pancreas and make it produce more insulin.

What amounts  of these substances are present in your blood?

These hormones are present  in very tiny amounts  For example your thyroid hormone concentration in your blood is similar to 1 spoon of sugar dissolved in 1000 Olympic sized swimming pools (5 picograms/decilitre). Hence tests need to be done carefully at the correct time of the day to make an interpretation.

What are these different hormones?

Most hormones are regulated by two mechanisms.

a) Balancing – activity of a cell is usually balanced by two opposing hormones eg insulin and glucagon have opposing actions, Parathyroid and calcitonin.

b) Feedback – The target cell usually sends back a signal to the hormone gland that the levels are correct. For examples Thyroid hormone (Thyroxine)and Thyroid Stimulating hormone ( TSH)

We use these principles to identify if the hormone levels are right or not..More later..



Thyroid hormone





Growth Hormone


Produced by







Pituitary Gland

Pituitary Gland

Acts On

Liver, Muscle, Fatty Tissue

Liver Muscle Heart

Brain, muscle, Bone

Blood vessels, Heart

Womb, Breast, Blood vessels

Womb, Breast

(Growth) Muscle, all internal organs

Breast tissue, Hypothalamus (brain)