8/14/2019 POS - Stress and the PFC

1/2

Nathaniel Kan

Perspectives on Science Problem Set 4

1. Identify three parts of a typical neuron and explain briefly the functions of each.

There are three parts to the neuron: the dendrite, the soma and the axon. The

dendrites are like the branches of the tree-like neuron structure. The dendritescontain receptors which bind to molecules called neurotransmitters. These

neurotransmitters are signals from other neurons. When a neurotransmitter is

bound the neuron changes, which alters the likelihood that the neuron will send asignal to next neuron in the chain. This is how neurons communicate.

The soma is the cell body of the neuron cell. It contains the normal organelles just

like other cells in the body, and functions to keep the cell alive and well,

producing proteins and replicating DNA.

The axon is the long trunk-like structure of the neuron. It sends the signals out

from the cell, which travel to close neurons. The axon sends out signals when a

sufficient electrical change builds up in the axon.

2. In general terms, identify a pharmacological strategy for treating a patient who

has excessive levels of a neurotransmitter.

The general practice for assisting patients with excessive levels of a

neurotransmitter, such Dopamine, is giving the patient a drug which blocks

receptor sites on the dendrites. These drugs do that by bonding to the receptor

sites themselves. Another way to treat syndromes where there are excessive levelsof a neurotransmitter, such as Tourettes, where there is an excess of DA, is to

supply a drug which blocks the release of the neurotransmitter.

3. The nervous system has evolved a mechanism for stress-induced inhibition of

certain thought processes. How might the ability to inhibit thought provide a

selective advantage?

It can be a selective advantage to inhibit thought in stressful situations. In

situations which are stressful, sometimes it is definitely best to react and act onreflex. The body can naturally act better in certain situations than it can in others,

for example, if a hungry predator attacks a human, it would be best toautomatically run, as opposed to thinking and then deciding that running would bea good idea. The mind can be trained to react in certain ways without thinking in

certain situations. One example of this is soldiers, who react automatically and do

as they are trained without thinking in combat.

8/14/2019 POS - Stress and the PFC

2/2

4. Your adrenal organs synthesize hormones that play an important role in thestress response. If you labeled these hormones and injected them into your arm,

would you expect to find label in the prefrontal cortex? The amygdala? Explain.

You would definitely find the label in the amygdala. The amygdala is the portion

of the brain that deals with fear and situations you perceive as dangerous. Thesehormones, upon detection by the amygdala, cause the brain to react in natural

reflexive ways to defend the individual.

You would also find these labels in the prefrontal cortex. The PFC deals with

retrieving memory, both recent and long term, guiding behavior based on past

rewards and punishments, Theory of Mind (the ability to know what another

person is thinking), and social conscience. During stressful situations, the PFCreceives hormones which cause it to shut down. This is because during stressful

situations it is much more important to act immediately on reflex than it is to

think about the situation. These hormones, the same ones which would be injected

in the arm during the experiment, send the signal to stop thinking.