We had seen in the beginning of this chapter that control and coordination is brought about by the Nervous system and Endocrine system .
Till now we discussed the nervous system. Let us move on to discussing the Endocrine system.
Endocrine system is involved in chemical coordination.
- Endocrine system is associated with Hormones .
- Hormones are your body's chemical messengers .
- They travel in your bloodstream to tissues or organs .
- They play an important role in growth, development, metabolism, reproduction etc.
- Hormones are secreted in response to external as well as internal stimuli
Consider the following situation;
A boy who is very scared of darkness got locked in a dark room.
There are broadly 2 possible ways to deal with this situation
- Fight - To actively deal/ cope with the situation
- Flight - To run away
Both the above activities are complicated and utilize energy in a controlled manner .
Now you must be wondering, why not rely on the nerve impulses to deal with this situation?
- The answer is that nerve impulses reach only a limited number of tissues in the body .
- But on the other hand, the chemical signals reach all the cells and the body prepares for a wide range of activities.
- Special molecules on the surface of cells recognise information, and even transmit it
Coming back to the situation discussed above,
A hormone called adrenaline is released by the adrenal glands into the blood when the body is in a stressful situation .
The following processes are carried out once adrenaline is released.
- Heart beats faster , resulting in supply of more oxygen to our muscles
- Blood to the digestive system and skin is reduced due to contraction of muscles around small arteries in these organs
- This diverts blood to our skeletal muscles
- The breathing rate increases because of the contractions of the diaphragm and the rib muscles.
All these together help to deal with the situation.
Glands are organs which produce and release substances that perform specific functions in the body.
A few glands, hormones produced and functions in humans are as follows:
Let us look at a few examples in detail to understand the importance of hormones ;
When you go to the grocery store, have you seen the label “Iodized salt” on some of the salt bottles?
Why is the salt enriched with iodine?
- If you take a look at the table above, you will see that the thyroid gland produces thyroxine hormone . Also from the image, you will know that the thyroid gland is located near the neck.
- Thyroxine is involved in metabolism of carbohydrates, proteins and fats and helps to balance the amounts required for optimum growth.
- Iodine is very important for the thyroid gland to be able to produce thyroxine.
- So when there is a deficiency or decrease in the amount of Iodine in our diet , we might suffer from goiter .
- Thus salt is enriched with Iodine
- One of the symptoms of goiter is a swollen neck.
Have you seen people who are very short or very tall?
These people are referred to as dwarfs and giants respectively and the phenomena are known as dwarfism and gigantism respectively.
This is due to the growth hormone secreted by the pituitary glands .
Deficiency of hormone leads to Dwarfism and excess secretion of growth hormone results in gigantism.
You must have heard the song Baby by Justin Bieber. If you compare his voice when the song was released and now, you will notice a difference.
This is due to puberty and is a result of testosterone secretion by testes in males and estrogen secretion by ovaries in females .
You must be familiar with the word insulin
It is a hormone produced by the pancreas
Insulin is responsible for regulating blood sugar levels
If it is not secreted properly the blood sugar level increases causing harm .
This condition is called diabetes .
This is why doctors advise people with this condition to not consume sugary food.
Now we know hormones are secreted precisely at the right time.
But what is the mechanism that regulates this behind it?
The timing and amount of hormone released are regulated by feedback mechanisms.
- If blood sugar levels rise , pancreatic cells respond by producing more insulin
As the blood sugar level drops , insulin secretion also drops.
- Similarly like we discussed earlier, when we are in a stressful situation, adrenaline is produced at the right time to cope with the situation .