Psych Chapter 3.2

What are the 2 basic cell types in the nervous system?

Neurons and glial cells

What do glial cells do in the nervous system?

provide the scaffolding on which the nervous system is built, help align neurons to allow for communication, provide insulation, transport nutrients and waste, mediate immune responses.

What are neurons?

Interconnected information processors that are essential for all tasks of the nervous system.

What are the 7 basic components of a nueron.

1. semi-permeable membrane

2. dendrites

3. myelin sheath

4. cell body (soma)

5. axon

6. nodes of ranvier

7. terminal buttons

What is the function of the semipermeable membrane of a neuron?

Allows for smaller and lower charged molecules to pass through while stopping larger/ highly charged molecules.

What is the function of dendrites?

Serve as input sites where signals are recieved from other neurons.

What is the myelin sheath composed of and what is its function?

A neuron’s myelin sheath is comprised of glial cells, and its function is to insulate and facilitate the travel of signals.

What is the soma of a neuron?

The soma (aka cell body) contains the nucleus.

What is the axon of a neuron?

The major extension from the soma that sends signals received by dendrites down to the terminal buttons.

What are the nodes of ranvier?

Gaps in the myelin sheath?

What is the function of a neuron’s terminal buttons?

The terminal buttons contain synaptic vesicles that house neurotransmitters that pass signals along to the next neuron.

What is the synaptic cleft?

The gap between neurons where electrical signals are converted into chemical signals, allowing communication to occur between neurons.

What are receptors?

Proteins on the cell surface of dendrites to which neurotransmitters can attach (lock and key model).

What provides energy for a signal?

Membrane potential: difference in charge on each side of a semipermeable membrane (extracellular fluid is differently charged than intercellular fluid)

During a state of resting potential, the charge ____ the cell is ___ than the charge outside.

inside, more negative

At resting potential sodium (Na+) is more highly concentrated ___ the cell.

outside

At resting potential potassium (K+) is more highly concentrated ___ the cell.

inside

How does depolarization begin to occur between neurons?

Neurotransmitters from nearby neurons attach to receptors on dendrites, causing membrane potential to change. Depolarization occurs when membrane potential becomes less negative (excitation), making the neuron more likely to fire.

What is hyperpolarization?

When neurotransmitter activity increases membrane potential, inhibiting signals.

What is the threshold of excitation?

The point at which level of charge is strong enough to activate a neuron.

What happens to Na+ ions when the threshold of excitation is reached.

They come flooding into the cell, allowing the neuron to become momentarily positive and generating action potential that pushes a neurotransmitter signal through the neuron.

What happens is an electrical signal is not strong enough to reach the treshhold of excitation.

The signal is not sent (all or none principle)

Put the following levels of membrane potential in order for the process of action potential. Repolarization, hyperpolarization, resting potential, peak action potential, threshold of excitement.

1. Resting potential

2. Threshold of excitement

3. Peak action potential

4. Repolarization

5. Hyperpolarization

What is reuptake?

Excess neurotransmitters that are not able to bind to a receptor are pumped back up into the neuron that released them.

What is acetylcholine?

A major neurotransmitter involved in muscle action and memory. Increases arousal and cognition.

What are beta-endorphins?

Major neurotransmitters involved in pain and pleasure. Reduce anxiety and tension.

What is dopamine?

Involved in mood, sleep, and learning. Increases pleasure, decreases appetite.

What is GABA?

Neurotransmitter involved in brain function and sleep. Decreases anxiety and tension.

What is glutamate?

Neurotransmitter involved in increasing memory and learning.

What is norepinephrine?

Neurotransmitter involved in alertness, fight or flight, and heartrate. Increases arousal, decreases appetite.

What is serotonin?

Neurotransmitter involved in mood and sleep. Increases mood, decreases appetite.

What is an agonist?

Chemical that mimics a neurotransmitter at the reception site.

What is an antagonist?

Chemical that blocks a neurotransmitter’s activity at the reception site.

What does a reuptake inhibitor do?

Prevent unused neurotransmitters from being pumped back into the neuron.