Nerve Cells and Nerve Impulses

Question 1

Cells that receive information and transmit it to other cells

Answer 1

Neurons

Question 2

The average adult human brain contains approximately _____________ neurons.

Answer 2

86 billion

Question 3

Who are recognized to be the founders of neuroscience?

Answer 3

Charles Sherrington & Santiago Ramon y Cajal

Question 4

The cerebral cortex has around _______ neurons.

Answer 4

16 billion

Question 5

The cerebellum has at least _______ neurons.

Answer 5

69 billion

Question 6

The spinal cord has around _______ neurons.

Answer 6

1 billion

Question 7

What did Cajal’s research on nerve cells demonstrate?

Answer 7

Nerve cells remain separate instead of merging into one another

Question 8

The surface of a cell and the structure that separated the inside of the cell from the outside environment

Answer 8

Cell membrane

Question 9

Most chemicals cannot cross the membrane, but protein channels in the membrane permit _______________.

Answer 9

Water, oxygen, sodium, potassium, calcium, chloride, and other chemicals

Question 10

Cell structure that contains the chromosomes

Answer 10

Nucleus

Question 11

Cell structure that performs metabolic activities, providing the energy that the cell uses for all activities

Answer 11

Mitochondrion

Question 12

Cell structure that have genes separate from those in the nucleus of a cell

Answer 12

Mitochondrion

Question 13

Sites within a cell that synthesize new protein molecules

Answer 13

Ribosomes

Question 14

Building materials of a cell that facilitate chemical reactions

Answer 14

Proteins

Question 15

Where can ribosomes be found?

Answer 15

Floating freely within the cell or attached to the endoplasmic reticulum

Question 16

A network of thin tubes that transport newly synthesized proteins to other locations

Answer 16

Endoplasmic reticulum

Question 17

The most distinctive feature of a neuron

Answer 17

Shape

Question 18

Describe a motor neuron

Answer 18

Soma in the spinal cord
Receives excitation through its dendrites
Conducts impulses along its axon to a muscle

Question 19

Describe a sensory neuron

Answer 19

Soma located on a stalk off the main trunk
Specialized at one end to be highly sensitive to a particular type of stimulation
Conducts touch information from the skin to the spinal cord

Question 20

Branching fibers that get narrower near their ends

Answer 20

Dendrites

Question 21

The term dendrite comes from the Greek root word ______

Answer 21

Tree

Question 22

Covers the dendrite’s surface where it receives information from other neurons

Answer 22

Synaptic receptors

Question 23

The greater the surface area of a dendrite, ___________

Answer 23

The more information it can receive

Question 24

Short outgrowths located on dendrites that increase the surface area available for synapses

Answer 24

Dendritic spines

Question 25

Cell structure that contains the nucleus, ribosomes and mitochondria

Answer 25

Cell body or soma

Question 26

Soma is the Greek word for _____

Answer 26

Body

Question 27

Cell bodies of neurons range in diameter from ____________

Answer 27

0.005 mm to 0.1 mm in vertebrates Up to a millimeter in invertebrates

Question 28

A thin fiber of constant diameter which conveys an impulse toward other neurons, an organ, or a muscle

Answer 28

Axon

Question 29

The term axon comes from the Greek word _______

Answer 29

Axis

Question 30

Axons can be ____________ in length

Answer 30

More than a meter

Question 31

Insulating material that covers vertebrate axons and separated by Nodes of Ranvier

Answer 31

Myelin sheaths

Question 32

Invertebrate axons do not have ___________

Answer 32

Myelin sheaths

Question 33

The end of each branch in an axon that releases chemicals that cross through the junction between the neuron and another cell

Answer 33

Presynaptic terminal (end bulb or bouton)

Question 34

What is an afferent axon?

Answer 34

Axon that brings information to a structure

Question 35

What is an efferent axon?

Answer 35

Axon that carries information away from a strcture

Question 36

Every sensory neuron is ________

Answer 36

Afferent

Question 37

Every motor neuron is ______

Answer 37

Efferent

Question 38

What is an interneuron or an intrinsic neuron?

Answer 38

Neuron wherein its cell's dendrites and axon are contained entirely within a single structure

Question 39

The ______ of a neuron determines its connections with other cells, thereby determining its function

Answer 39

Shape

Question 40

Which part of the brain are glia are more abundant than neurons?

Answer 40

Cerebral cortex

Question 41

Star-shaped glia that wraps around the synapses of functionally related axons

Answer 41

Astrocytes

Question 42

What are the functions of an astrocyte?

Answer 42

Shields neurons from chemicals Synchronizes closely related neurons Generate rhythms such as the rhythm for breathing Dilates blood vessels to bring more nutrients into the brain areas that have heightened activity

Question 43

The hypothesis that the tip of an axon releases chemicals that cause the neighboring astrocyte to release chemicals of its own, thus magnifying or modifying the message to the next neuron

Answer 43

Tripartite synapse

Question 44

Glial cells that act as part of the immune system and proliferate after brain damage, removing viruses and fungi, dead or damaged neurons, and the weakest synapses from the brain

Answer 44

Microglia

Question 45

Glial cells that build the myelin sheaths that surround and insulate axons and supply an axon with nutrients necessary for proper functioning

Answer 45

Oligodendrocytes and Schwann cells

Question 46

Where are oligodendrocytes located?

Answer 46

The brain and spinal cord

Question 47

Where are Schwann cells located?

Answer 47

The periphery of the body

Question 48

Glial cells that guide the migration of neurons and their axons and dendrites during embryonic development

Answer 48

Radial glia

Question 49

The mechanism that excludes most chemicals from the vertebrate brain

Answer 49

Blood-brain barrier

Question 50

A protein-mediated process that expends energy to pump chemicals from the blood into the brain

Answer 50

Active transport

Question 51

Which chemicals are actively transported into the brain

Answer 51

Glucose, amino acids, purines, choline, a few vitamins, and iron

Question 52

Vertebrate neurons depend almost entirely on __________ (brain's main fuel)

Answer 52

Glucose

Question 53

Why do neurons depend heavily on glucose?

Answer 53

Glucose is the only nutrient that crosses the blood-brain barrier in large quantities

Question 54

Neurons need a steady supply of _________ to metabolize glucose

Answer 54

Oxygen