Where biology and psychology come together (if you couldn’t tell already by the name of the unit).

Neurons

A nerve cell. The basic building block of the nervous system. Connects the central nervous system with muscles, glands, and sensory organs

It is good for AP Psychology students to memorize only the following parts of a neuron:

1. Cell Body (Soma)

   Contains the nucleus and chromosomes, produces energy

2. Cell membrane

   Protects the cell

3. Dendrites

   Receives information from other neurons and sends it to the cell body

4. Axon (+Nodes of Ranvier)

   Carries information to the axon terminal (Nodes of Ranvier are the small gaps of the axon that arent covered by the myelin sheath)

5. Myelin Sheath

   Fatty tissue that makes information travel to the axon terminal quicker

6. Axon Terminal

   Sends the electrical signal to the next neuron

7. Synaptic Gaps

   The junction between the axon tip of the sending neuron and the receiving dendrite

Neurons can be found in the brain and the nervous system

Action Potential

A neural impulse or a brief electrical charge that travels down the axon.

Threshold- the level of stimulation required to trigger a neural impulse

Refractory period- a period of inactivity after a neuron fires

All-or-nothing response- a neuron’s reaction of either firing with full potential or not

There are three main parts/stages to a neuron’s firing:

1. Resting potential

2. Depolarization

3. Repolarization

A neuron will go through 1. then 2. then 3. and finally back to 1.

During depolarization, (you can see in the graph above) neurons gain Na and during repolarization, neurons release K. You should know this but it is unlikely it will be on your test.

Sensory Neurons and Motor Neurons

A sensory neuron is first activated when your sensory receptors feel something. In the example above, it is heat. An impulse will then travel down your sensory neuron, through your interneurons (neurons that connect your sensory and motor neuron, they are located in your brain and spinal cord). The impulse will then travel down your motor neurons after being transferred through your interneurons. Because your motor neurons control your muscles, this impulse will result in you moving. For the example above, it would be to quickly move your finger away from the fire after it burns you.

To summarize: In these neurons, incoming/outgoing information travel likewise:

Sensory Neuron: sensory receptors → brain and spinal cord

Motor Neuron: brain and spinal cord → muscles and glands

Neurotransmitters

chemical messengers that cross synaptic gaps between neurons.

You are required to memorize 7 neurotransmitters in AP Psychology. Here is a memorization technique that helped me with this.

Key terms about neurotransmitters:

Reuptake- a neurotransmitter’s reabsorption by the sending neuron

Endorphins- neurotransmitters linked to pain control and to pleasure

Agonist- a molecule that increases a neurotransmitter’s action

Antagonist- a molecule that blocks/inhibits a neurotransmitter’s action

Do not get agonist and antagonist mixed up! Here’s a memorization tip: an antagonist in a story is an evil character. Think that blocking or inhibiting a neurotransmitter’s action is bad or evil and link antagonist with blocking/inhibiting.

Endorphins: neurotransmitters linked to pain control and pleasure

Nervous Systems

the body’s speedy, electrochemical communication network, consisting of all nerve cells of the peripheral nervous system and central nervous system

AP Psychology test takers should be familiar with all of these nervous systems, especially the autonomic nervous system’s sympathetic and parasympathetic nervous systems.