Synapses and the Reflex Arc

Question 1

How do synapses work?

Answer 1

1. A nerve impulse reaches the end of the synapse.
2. This triggers the release of chemical transmitters, serotonin, which carry the chemical signal across the synapse.
3. Only specific chemicals can bind to the receptor molecules on the membrane of the next neurone, so this triggers a new impulse.

Question 2

Hormonal communication systems transport …. signals called …. such as oestrogen. These are carried in the ….. and cause …. long-lasting effects. Nervous communication systems are made up of cells called neurones. They link receptor cells, (in the eyes), with … cells, (in the muscles). Nerve cells carry … impulses for …. short-lived responses.

Answer 2

Chemical, hormones, blood, slow, effector, electrical, fast

Question 3

What are some features of the reflex arc?

Answer 3

The reflexes are automatic responses.
Only 2-3 neurones involved - sensory, relay, motor.
The same direction is used each time so no information is processed!
The reflex arc carries signals from the receptor to the effector.

Question 4

How does the reflex arc work?

Answer 4

1. A reflex is detected. An impulse is sent to the CNS.
2. In the CNS, the brain or spinal cord, a sensory neurone carries the impulse to a relay and then motor neurone.
3. The motor neurone carries the impulse to the effector, causing the muscle to contract.

Question 5

How does ecstasy work?

Answer 5

This blocks sites in the brain where serotonin is removed. This causes an increased concentration, altering mood, pain, aggression, and appetite. This increases transmission and elevates the mood.
Ecstasy does not bind to receptor molecules as only specific molecules such as serotonin can to trigger NEW IMPULSES.