U3 Endocrine system: Hormones

Question 1

Define hormone

Answer 1

Chemical substances that are secreted by endocrine glands, transported through the body via the blood then bind to receptors on target cells to change the activity of those cells

Question 2

Compare steroid hormones and protein/amine hormones

Answer 2

Steroid hormones
- Lipid soluble: can pass through cell membrane

1. Enters target cell by diffusion through the cell membrane
2. Combines with a receptor protein in the cytoplasm, forming a hormone-receptor complex
3. Hormone-receptor complex enters the nucleus, altering gene expression (protein synthesis)

Protein/amine hormones
- Water soluble: can’t pass through cell membrane

1. Attaches to receptor on the cell membrane of target cell, forming a hormone-receptor complex
2. The formation of the hormone-receptor complex causes a secondary messenger substance to diffuse through the cell and activate a particular enzyme
3. The enzyme has an effect on cellular function

Question 3

How do hormones change the functioning of cells?

Answer 3

By changing the quantity, type or activities of proteins (including enzymes)