Hormonal Control (SQA National 5 Biology): Revision Note

Hormones

• The hormonal control system regulates many of the body’s slower, longer-lasting processes by using chemical messengers called hormones

• Hormones are produced by a gland and carried by the blood

• They are chemicals that transmit information from one part of the organism to another and alter the activity of one or more specific target organs

• The following hormones are of great importance in humans:

  • Insulin

  • Glucagon

• A response to a stimulus can be a rapid action via electrical impulses in the nervous system or a slower response via hormones in the endocrine system

The endocrine system

• The endocrine system is made up of endocrine glands responsible for the release of hormones into the blood

  • The pancreas is an endocrine gland that secretes insulin and glucagon to allow the regulation of blood glucose

Target tissues

• Chemical hormones travel throughout the body, but only affect specific target tissues

• This is because the cells in a target tissue have complementary receptor proteins on their cell membranes that match the shape of a particular hormone

• When the hormone binds to its receptor, it triggers a specific response in those cells

• Other tissues without these receptors remain unaffected