Lab 12 HW

A bundle of axons in the CNS is called a ________.

tract

Neuron fibers (axons) running through the central nervous system form __________ of white matter.

tracts

What is true about tracts and nerves?

tracts lack connective tissue coverings

Nervous tissue is made up of __________ main cell types.

two

Sensory or afferent neurons are typically of this type.

unipolar

Functional classification of neurons is based on ________.

whether the signal carried is traveling toward or away from the CNS

Neurons can be classified according to structure. __________ neurons have many processes that issue from the cell body.

Multipolar

These neurons transmit impulses from CNS to effectors.

motor neurons

Interneurons (association neurons) in the brain are likely to be ________ neurons.

multipolar

The gaps in the sheath that insulates axons are called ________.

myelin sheath gaps

These nervous system cells are highly specialized to transmit messages throughout the body.

neurons

These glial cells play a role in capillary-neuron exchanges and control the chemical environment around neurons.

astrocytes

These support cells are found in the central nervous system.

astrocytes and ependymal cells

This part of the neuron generates and conducts action potentials.

axon

The outermost connective tissue covering of a nerve is called the ________.

epineurium

Vesicles in the axon terminal contain ________.

neurotransmitters

Groups of axons within a nerve are bound into fascicles by a coarse connective tissue called ________.

perineurium

Amyotrophic lateral sclerosis is a neurodegenerative disease in which motor neurons are progressively destroyed. Excess levels of the neurotransmitter glutamate have been implicated in this process. Which type of neuroglia would play a role in controlling glutamate levels in the chemical environment of neurons?

Astrocytes

Neurons can be classified according to function. __________ or motor neurons carry electrical signals from the central nervous system primarily to muscles or glands.

Efferent

What is true of a mixed nerve?

It contains both afferent and efferent axons

You are examining a neuron under the microscope. It appears as a round cell without visible processes. What is true of this neuron?

It is likely to be a unipolar neuron, it is located in the PNS (peripheral nervous system), and it is most likely to be a sensory neuron.

Peripheral neuropathy has a variety of causes. Worldwide, the most common cause is leprosy, also known as Hansen's disease. Would you expect peripheral neuropathy to cause damage to tracts or to nerves? Why?

Nerves are damaged in the periphery as a result of a bacterial infection.

A demyelinating disease affects ________.

Schwann cells

The formation of myelin in the peripheral nervous system is accomplished by these cells.

Schwann cells

The dendrites share this characteristic with the neuron cell body.

They receive synapses from many other neurons.

Axons are the neuron processes that generate and conduct nerve impulses.

True

You have lost the sensation, but not movement, in one of your hands due to a problem with your spinal cord neurons. Based upon these symptoms, what type of neuron was most likely affected?

afferent neuron

Within a nerve, each axon is surrounded by a covering called the __________.

endoneurium

The ________ forms synapses, or junctions, with other neurons or effector cells.

axon terminal

This type of sensory neuron is quite rare.

bipolar

At an axon terminal, the electrical signal from one cell ________.

causes the release of chemical neurotransmitter molecules that cause an electrical signal in the next cell

Axons give rise to branches called ________.

collaterals

A nerve ________.

consists of axons wrapped in connective tissue in the PNS

These glial cell line cerebrospinal fluid-filled cavities in the CNS.

ependymal cells

These branching neuron processes serve as receptive regions and transmit electrical signals toward the cell body. They are __________.

dendrites

A cluster of neurons in the peripheral nervous system is called a ________.

ganglion

Myelin is important in ________.

insulating axons and increasing the conduction velocity of action potentials

Chromatophilic substance, found within the cell bodies of neurons, is involved in the metabolic activities of the cell and is composed of ________.

rough endoplasmic reticulum

Neuroglia of the peripheral nervous system include __________.

satellite cells and Schwann cells

Cell bodies of these neurons lie in ganglia in the peripheral nervous system (PNS).

sensory neurons

Oligodendrocytes form myelin around ________.

several axons in the central nervous system