Introduction to Cell:Cell Signalling Systems

Question 1

What is Endocrine signalling?

Answer 1

• Signalling molecules (such as hormones and growth factors) act on a distant group of target cells
• Usually carried in the blood

Question 2

What is Paracrine signalling?

Answer 2

Signalling molecules only affects the target cells adjacent to the signalling cell e.g. neurotransmitters

Question 3

What is Autocrine signalling?

Answer 3

The cells releases and responds to the signalling substance
e.g. growth factors in tumour cells

Question 4

What SIX steps are involved in cell-to-cell communication?

Answer 4

1. Synthesis of signalling molecule
2. Release
3. Transport to the target cell
4. Detection by target cell (via receptors)
5. Change in the target cell
6. Removal and termination of the signal

Question 5

What are the THREE broad categories of signalling molecules?

Answer 5

1. Small lipophilic / hydrophobic molecules that bind to intracellular receptors
2. Hydrophilic molecules which bind cell surface receptors
3. Other lipophilic molecules which bind cell surface receptors