How the brain forms before birth

1. The brain starts to form about three weeks after conception, long before birth.
2. A ridge of cells folds into a hollow neural tube, and that tube becomes the brain and the spinal cord.
3. Neurons are produced from the walls of the tube and then migrate to their proper place, so the layers of the brain are laid down in a set order.
4. A baby is born with almost every neuron it will ever have.

The nervous system

1. The nervous system is the network that detects information, processes it and controls the body.
2. Central nervous system: the brain and the spinal cord, where information is processed and decisions are made.
3. Peripheral nervous system: the nerves branching out to the muscles, skin and organs, carrying messages in from the senses and instructions back out.
4. Both divisions grow from the same early neural tissue, the walls of the neural tube.

The three main divisions of the brain

1. Cerebrum
   1. This is the large, folded outer part, and by far the biggest of the three.
   2. It handles thinking, memory, language, the senses and voluntary movement.
   3. Its sub-parts include the frontal lobe for planning and self-control, the temporal lobes for hearing and language, and the hippocampus for laying down new memories.
2. Cerebellum
   1. This sits underneath, at the back of the brain.
   2. It co-ordinates balance, posture and smooth, skilled movement, so riding a bike eventually feels automatic.
3. Brainstem
   1. This joins the brain to the spinal cord, and its sub-parts include the pons and the medulla.
   2. It controls automatic functions such as breathing, heart rate and arousal.

Neurons and synapses

1. Neurons: nerve cells that carry information around the body as electrical impulses.
   1. Dendrites receive the signal and the axon carries it away from the cell body.
   2. Axons become wrapped in myelin, a fatty insulating layer that makes the impulse travel much faster.
2. Synapses: the tiny gaps between one neuron and the next.
   1. When the impulse reaches the end of the axon, the neuron releases chemicals called neurotransmitters into the gap.
   2. The neurotransmitters cross the synapse and bind to receptors on the next neuron.
   3. If enough of them bind, that neuron fires its own electrical impulse and the message carries on.

How synapses change with experience

1. Development after birth is mainly the forming of synapses between neurons that are already there.
2. In the first years of life synapses form faster than at any later point, so a toddler's brain holds more connections than an adult's.
3. Connections used again and again are strengthened.
4. Connections that are rarely used are pruned away.
   1. The paths worn across a school field work the same way, where the routes hundreds of pupils walk every day become clear tracks and the ones nobody uses grow over.
5. Myelin keeps being added through childhood and adolescence, so signals travel faster and thinking speeds up.

Turning this into marks

1. When two divisions of the brain are asked for, give each one a function of its own rather than one function reworded.
2. Name neurotransmitters and receptors when you describe a synapse, because saying the message travels to the next neuron does not secure the knowledge mark.
3. The mark most often lost is naming a brain part with no function attached, so pair every structure with what it does.
4. In a question on development after birth, the marks are for synapse formation, pruning and myelin.