Summary
Hormones are chemical substances produced by glands and carried by the blood to alter the activity of specific target organs. The endocrine system consists of glands that produce hormones, which only affect cells with complementary receptors.
- Hormone — a chemical substance produced by a gland and carried by the blood to alter the activity of target organs. Example: Adrenaline is a hormone that prepares the body for 'fight or flight' situations.
- Endocrine Glands — glands that produce hormones and release them into the bloodstream. Example: The adrenal gland releases adrenaline.
- Adrenaline — a hormone secreted in 'fight or flight' situations, increasing blood glucose concentration and pulse rate. Example: Adrenaline increases respiration in muscle cells.
- Insulin — a hormone that regulates blood glucose levels. Example: Insulin helps lower blood glucose concentration.
- Oestrogen — a hormone involved in the development of female secondary sexual characteristics. Example: Oestrogen regulates the menstrual cycle.
- Testosterone — a hormone involved in the development of male secondary sexual characteristics. Example: Testosterone promotes muscle growth.
Exam Tips
Key Definitions to Remember
- Hormone: Chemical substance produced by a gland and carried by the blood.
- Endocrine Glands: Glands that produce hormones.
- Adrenaline: Hormone for 'fight or flight' response.
Common Confusions
- Mixing up glucagon and glycogen.
- Confusing the speed of nervous and hormonal responses.
Typical Exam Questions
- What is the role of adrenaline in the body? Adrenaline prepares the body for 'fight or flight' by increasing blood glucose and pulse rate.
- How do hormones differ from nervous signals? Hormones are chemical messages in the blood, while nervous signals are electrical impulses.
- What is the function of insulin? Insulin regulates blood glucose levels.
What Examiners Usually Test
- Effects of adrenaline on the body.
- Differences between nervous and hormonal control systems.