Hormones in Humans (Cambridge (CIE) O Level Biology): Revision Note
Did this video help you?
Hormones & Their Associated Glands
What is a Hormone?
A hormone is a chemical substance produced by a gland and carried by the blood
The hormone alters the activity of one or more specific target organs i.e. they are chemicals which transmit information from one part of the organism to another and bring about a change
The glands that produce hormones in animals are known collectively as the endocrine system
The endocrine system diagram
The endocrine glands secrete hormones into the blood
Important hormones in the human body table
Hormone | Source | Effect |
|---|---|---|
Adrenaline | Adrenal glands | Increases heart and breathing rate, dilates pupils |
Insulin | Pancreas | Lowers blood glucose levels |
Glucagon | Pancreas | Raises blood glucose levels |
Testosterone | Testes | Male sex hormone that develops secondary male sexual characteristics |
Oestrogen | Ovaries | Female sex hormone that develops secondary female sexual characteristics |
Progesterone | Ovaries | Female sex hormone that plays a role in the menstrual cycle |
LH | The pituitary gland | Female sex hormone that plays a role in the menstrual cycle |
FSH | The pituitary gland | Female sex hormone that plays a role in the menstrual cycle |
Transport around the body
Endocrine glands have a good blood supply as when they make hormones they need to get them into the bloodstream (specifically the blood plasma) as soon as possible so they can travel around the body to the target organs to bring about the response
Hormones only affect cells with target receptors that the hormone can bind to. These are either found on the cell membrane, or inside cells. Receptors have to be complementary to hormones for there to be an effect.
The liver regulates levels of hormones in the blood; transforming or breaking down any that are in excess.
Hormones travel in the blood to target organs
Examiner Tips and Tricks
You do need to be able to identify the following glands on a diagram:
The adrenal glands
The pancreas
The pituitary gland
The testes
The ovaries
Comparison of Nervous & Hormonal Control
| Nervous system | Endocrine system |
|---|---|---|
Made up of | Nerves (bundles of neurones), brain, spinal cord | Glands |
Type of message | Electrical | Chemical hormone |
Speed of action | Very fast | Slower |
Duration of effect | Short - until the nerve impulse stops | Long - until the hormone is broken down in the body |
You've read 0 of your 5 free revision notes this week
Sign up now. It’s free!
Did this page help you?