Neurons and the Nervous System

Question 1

Cell Body

Answer 1

Nucleus with chromosomes

Question 2

Dendrites

Answer 2

Receive information from other neurons

Question 3

Axon

Answer 3

Transmits information to other neurons, muscles, and glands

Question 4

Myelin

Answer 4

Insulating layer of fatty material

Composed of glial cells

Helps the efficient transmission of signals to other cells

Question 5

Nodes of Ranvier

Answer 5

Gaps within the myelin sheath

Question 6

Action Potential

Answer 6

A neural impulse that travels down an axon like a wave

Stimulates the release of neurotransmitters into the synapse

“All-or-none”—electrical impulse is the same no matter how much stimulation the neuron receives

Question 7

Resting Potential

Answer 7

High concentration of K+ inside neuron
Lower concentration of K+ outside neuron
Higher concentration of Na+ outside neuron

K+ channels in cell membrane open in resting state
K+ moves out of neuron, leaving a -70 mv charge

Question 8

The Action Potential is Initiated

Answer 8

The electrical charge reaches a threshold

K+ channels close
Na+ channels open
Na+ flows into the neuron
+ charge inside the neuron increases

Charge inside the neuron is +40 millivolts

Question 9

The Action Potential Travels Down the Axon

Answer 9

Intracellular fluid is positively charged (+40 millivolts)

Adjacent Na+ channels open
The action potential travels down the axon membrane

K+ channels open
K+ moves out of the cell
Intracellular fluid becomes negative again
K+ channels close

Question 10

Na+/K+ Pump Restores Ion Balance

Answer 10

Na+ and K+ channels close
Na+ concentration is higher inside the cell
K+ concentration is lower inside the cell
Na+/K+ pump restores resting state charge

Question 11

The Refractory Period

Answer 11

Another action potential can’t occur during the refractory period

After the action potential reaches +40 mv, membrane channels return to original state

The neuron can now generate another action potentia

Question 12

Reuptake

Answer 12

Neurotransmitters are absorbed back into the presynaptic neuron

Question 13

Enzyme Deactivation (Disassembly)

Answer 13

Neurotransmitters are broken down by enzymes in the synapse

Question 14

Autoreceptors

Answer 14

Neurotransmitters bind to autoreceptor sites on the presynaptic neuron

Question 15

Agonists

Answer 15

Chemical that binds to receptor
Triggers responses
Enhances neurotransmitter action

Question 16

Antagonists

Answer 16

Chemical that binds to receptor

Blocks receptor

Question 17

Peripheral Nervous System

Answer 17

Gathers information from the body and sends CNS decisions out to the body

Connects the central nervous system to the body’s organs and muscles

Autonomic nervous system
Somatic nervous system

Question 18

Central Nervous System

Answer 18

The body’s decisionmaker.

Question 19

Sensory Neurons

Answer 19

Carry messages IN from the body’s tissues and sensory receptors to the CNS for processin

Question 20

Motor Neurons

Answer 20

Carry instructions OUT from the CNS out to the body’s tissues

Question 21

Interneurons

Answer 21

(In the brain and spinal cord) Process information between the sensory input and motor output.

Question 22

The Autonomic Nervous System

Answer 22

Sympathetic Nervous System
Parasympathetic Nervous System

Arousal
Returning the body to its resting state

Question 23

Endocrine System

Answer 23

Sends molecules as messages through the bloodstream

A set of glands that produce chemical messengers called hormones

Question 24

EEG (Electroencephalogram)

Answer 24

Recording of the electrical waves sweeping across the brain’s surface

Useful in studying seizures and sleep.

Question 25

Structural Neuroimaging Techniques

Answer 25

Produce images of the soft tissue in the brain

Question 26

CAT Scan (Computed Axial Tomography)

Answer 26

Uses thousands of x-ray images to construct an image. The x-rays are taken at slightly different angles.

Question 27

MRI (magnetic resonance imaging)

Answer 27

Makes images from signals produced by brain tissue after magnets align the spin of atoms

Question 28

Functional Neuroimaging Techniques

Answer 28

Show brain activity in living participant

Question 29

Functional MRI (magnetic resonance imaging)

Answer 29

Compares successive MRI images taken a split second apart, and shows changes in the level of oxygen in blood flow in the brain

Question 30

PET (positron emission tomography)

Answer 30

Allows us to see what part of the brain is active by tracing where a radioactive form of glucose goes while the brain performs a given task

Question 31

Excitatory Messages

Answer 31

INCREASE firing of post-synaptic neuron

Question 32

Inhibitory Messages

Answer 32

DECREASE firing of post-synaptic neuron