1. Cellular Communication

2. In multicellular organisms, cells need to communicate with each other to coordinate their activities. This helps to maintain homeostasis.

3. Neurotransmitters and hormones are the primary “communicators”

4. Cells have receptor molecules (proteins) that have unique shapes.
(Think Lock and Key)

5. These receptor molecules receive the chemical messages from other cells.

6. In nerve cells the “key” is a neurotransmitter

7. In other types of cells the “key” is a hormone

8. If signals are blocked, cellular communication is interrupted and may upset the homeostasis of the organism.

9. Which letter represents a receptor molecule?

13. When a nerve impulse moves along nerve cell (A), it reaches a synapse and a neurotransmitter is released. 
Some neurotransmitters ‘switch on’ the next cell (B) and the nerve impulse moves through that cell.
Other neurotransmitters ‘switch off’ the next cell (B) and the impulse does not move on.
Alcohol binds to sites in the brain and other parts of the nervous system. The effect of this is to switch off nerve cells and slow down our reactions. This is why alcohol is a sedative and can be dangerous.

14. Imagine you are sleeping and you hear a loud crash
Imagine you are sleeping and you hear a loud crash! You jump up, your heart is pounding and you are breathing quickly.
Explain briefly, using what you have learned about cell communication, what caused these reactions. Start with your ear receiving the stimulus: