# Hormones

Source: https://projectgcse.co.uk/biology/human_biology/hormones

> We offer many resources for students revising for their GCSEs including: GCSE revision notes and practice questions, a GCSE bookshop, GCSE help and advice and the take a break section.

Hormones are chemical substances which are produced in one part of an organism which have effect on another part. Below are the main hormones:

#### **Plant hormones**

- Natural growth hormone, auxin is responsible for phototropism.
- Plant hormones are also used artificially for rooting.
- Rooting powder is put onto cuttings to make them root quicker.

#### **Animal hormones**

- Produced in endocrine glands which pass hormones directly into the blood where they are distributed to different parts of the body.
- The Pancreas produces insulin.

#### **Adrenal glands**

- Situated at the top of the kidneys.
- Produces adrenaline, the hormone produced when you are scared or excited.
- Adrenaline stimulates faster breathing, increased heart rate, more glucose and widening of blood vessels so more oxygen can be transported to the parts of the body that need it

#### **Reproductive organs**

- Produce sex hormones.
- Oestrogen from the ovary to cause secondary sexual characteristics and menstrual cycle.
- Testosterone from testes causes male secondary sexual characteristics.