Chapter 1: Bio Psychology

When the membrane is at rest, the concentration gradient tends to draw sodium ions ____ the cell, and the electrical gradient draws them ____ the cell.

into... into

The sodium-potassium pump moves sodium ions ____ and moves potassium ions ____.

out of the cell... into the cell

When the membrane is at rest, the concentration gradient tends to draw potassium ions ____ the cell, and the electrical gradient draws them ____ the cell.

out of... into

An advantage of the blood-brain barrier is that it keeps out most ____. A disadvantage is that it also keeps out ____.

viruses... most nutrients

Which of the following is one way of stating the all-or-none law?

All stimuli that exceed the treshold produce equivalent responses in the axon.

Which kind of glia cell wraps around the synaptic terminals of axons?

Astrocytes

To which part or parts of a neuron does the all-or-none law apply?

Axons

Identify the four major structures that compose a neuron.

Dendrites, soma (cell body), axon, and presynaptic terminal

Which is not one of the four major structures that compose a neuron?

Glia

Which of these chemicals cross the blood-brain barrier by active transport?

Glucose and amino acids

Which chemicals cross the blood-brain barrier by active transport?

Glucose, amino acids, purines, choline, certain vitamins, iron, and a few hormones.

What does an afferent axon do?

It brings information into a structure

What does the myelin sheath of an axon accomplish?

It enables action potentials to travel more rapidly

What makes brain cancers so difficult to treat?

Nearly all chemotherapy drugs fail to cross the blood-brain barrier

Is it true that we use only 10 percent of our brains? If so, what does that mean?

No, the statement is false and nonsensical

When the neuron's membrane is at rest, sodium ions are more concentrated ____ the cell, and potassium ions are more concentrated ____.

Outside...Inside

After the action potential reaches its peak, the potential across the membrane falls toward its resting level. What accounts for this recovery?

Potassium ions move out because their channels are open and the concentration gradient pushes them out.

Which chemicals cross the blood-brain barrier by passively?

Small, uncharged molecules such as oxygen, carbon dioxide, and water cross the blood--brain barrier passively. So do chemicals that dissolve in the fats of the membrane.

When the membrane is at rest, are the sodium ions more concentrated inside the cell or outside? Where are the potassium ions more concentrated?

Sodium ions are more concentrated outside the cell, and potassium is more concentrated inside,

During the rising portion of the action potential, which ions are moving across the membrane and in which direction?

Sodium ions move in

Identify one major advantage and one disadvantage of having a blood-brain barrier.

The blood--brain barrier keeps out viruses (an advantage) and also most nutrients (a disadvantage)

Which animal species would have the longest axons?

The longest axons occur in the largest animals. For example, giraffes and elephants have axons that extend from the spinal cord to the feet, nearly two meters away.

Santiago Ramon y Cajal was responsible for which discovery?

The nervous system is composed of separate cells.

What are the widely branching structures of a neuron called? And what is the long, thin structure that carries information to another cell called?

The widely branching structures of a neuron are called dendrites, and the long thin structure that carries information to another cell is called an axon

When the membrane is at rest, what tends to drive the potassium ions out of the cell? What tends to draw them into the cell?

When the membrane is at rest, the concentration gradient tends to drive potassium ions out of the cell, and the electrical gradient draws them into the cell. The sodium--potassium pump also draws them into the cell.

Under what conditions does an axon produce an action potential?

Whenever the membrane's potential reaches the treshold

Which of the following is something glia do not do?

conduct action potentials

Which species probably has the longest axons?

giraffes

What is the brain's main source of fuel?

glucose

Suppose a neuron has a resting potential of -70 mV. If the potential goes to -80 mV, the change would be a ________.

hyperpolarization