The Endocrine System
- Uses hormones to through the blood to bring about changes in the body in response to environmental changes.
- Made up of endocrine glands (note different to exocrine glands such as sweat glands and salivary glands). Endocrine glands are groups of cells that are specialised to secrete hormones.
Click on the box below to practice matching the glands to the hormones they secrete.
Hormones
- Chemical messengers
- Chemically different (proteins, steroids, glycoproteins, polypeptides, amines or tyrosine derivatives) but work the same
- secreted into the blood, spread out to the whole body but only affect target organs that have complementary receptors on their cells (target cells).
- The way a hormone works on it's target cells, is determined by the hormones chemical characteristics.
Steroid Hormones
The Adrenal Glands
The adrenal cortex produces hormones vital to life; Glucocorticoids (cortisol, corticosterone), Mineralocorticoids (aldosterone) and Androgens.
The adrenal medulla produces hormones that are non-essential; Adrenaline and Noradrenaline.
First and second messengers.
First messengers bind to a cell surface membrane receptor and initiate an effect inside the cell. They usually release another molecule in the cell cytoplasm which is known as the second messenger. This second messenger can change the activity inside the cell.
eg G - protein, adenyl cyclase and cAMP
One example of a hormone that uses this method of signal transduction is glucagon.
eg 2 Insulin receptor
Introduction to the pancreas
Watch the video below until 5:54 to learn the roles of the cell clusters in the Pancreas.
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