B1 Hormones

What are hormones?

Hormones are basically chemicals that are made and released by glands called endocrine glands. These messages go into the bloodstream where they cause certain parts of the body to do something. Different messages for different parts of the body.

So where are these endocrine glands then?





There are lots of them and they send chemical messages to specific target organs.

1. Pituitary gland releases anti-diuretic hormone which causes the kidneys to produce more concentrated urine. This is part of homeostasis which helps keep our water levels constant.
2. Adrenal gland makes the hormone adrenaline which speeds up the heartbeat.
3. The pancreas releases the hormone glucagon which raises blood glucose levels and also the hormone insulin which lowers blood glucose levels. This is a big topic which you will have to learn especially linked to diabetes Types 1 and 2.
4. The male testes release the hormone testosterone which causes the development of the male reproductive organs during puberty.
5. The female ovaries make the hormone oestrogen which causes the development of the female reproductive organs during puberty.

Now, let's get back to the the control of blood sugar levels.

You eat, in fact you may usually eat your lunch at break-time. 

Carbohydrates in your food are mainly digested into a type of sugar called glucose. So, eating carbohydrates (like bread, flour, cakes. potatoes etc) increase the glucose levels whereas exercise, in fact respiration uses up glucose so the blood sugar levels drop.

Note, energy stored in food is released in respiration. Respiration is not breathing!

So, all the time your glucose levels are going up and down depending on what you are doing. Homeostasis is keeping the internal environment stable - in this case it is to do with keeping the blood sugar levels the same.

Now, this topic is about hormones,
so it's basically a gland sending a chemical message to tell something else what to do.

It's the pancreas that makes the hormones

.

The 2 hormones are called insulin and glucagon.

The target organ is the liver.

The pancreas then is telling the liver what to do by sending it 2 messages.

1. Insulin tells the liver that there is too much glucose in the blood so it has to remove some. The liver takes the glucose out and stores it as glycogen.
2. Glucagon tells the liver that there is not enough glucose in the blood (the glucose has gon!) so the liver breaks down the glycogen stored earlier back into glucose.