chapter 8 dendrites

Question 1

Dendrites or

Answer 1

trees

Question 2

Dendrites des

Answer 2

are short, often highly branching cytoplasmic extensions that are tapered from their bases at the neuron cell body to their tips.

Question 3

Most dendrites are extensions of the neuron cell body, but
dendrite-like structures also project from the peripheral ends of some sensory
axons.

Answer 3

.

Question 4

Dendrites usually receive

Answer 4

information from other neurons or from

sensory receptors and transmit the information toward the neuron cell body.

Question 5

axon des

Answer 5

a single long cell process extending from the neuron cell body.

Question 6

The area where the axon leaves the neuron cell body is

called the

Answer 6

axon hillock.

Question 7

Axons of sensory neurons conduct

Answer 7

action potentials towards the CNS

Question 8

axons of motor

neurons conduct

Answer 8

action potentials away from the CNS.

Question 9

Axons also conduct

Answer 9

action potentials from one part of the brain or spinal cord to another part.

Question 10

An axon may remain unbranched or

Answer 10

may branch to form collateral (ko-LAT-er-

uhl) axons.

Question 11

Axons can be surrounded by a highly specialized insulating layer
of cells

Answer 11

myelin sheath

Question 12

neurons can be

classified on the basis of their

Answer 12

function as well as their structure.

Question 13

“sensory neuron”

Answer 13

indicates that it is carrying

information to the CNS from a specific receptor in the body.

Question 14

“motor neuron”

Answer 14

it is sending

information to an effector of the body from the CNS.

Question 15

three categories of neurons exist, based on the

arrangement of their processes/structure

Answer 15

Multipolar, bipolar, pseudo unipolar

Question 16

Multipolar neurons

Answer 16

have many dendrites and a single axon. Most of
the neurons within the CNS and nearly all motor neurons are
multipolar.

Question 17

Bipolar neurons have two processes:

Answer 17

one dendrite and one axon.

Question 18

Bipolar neurons are located

Answer 18

in some sensory organs, such as in the

retina of the eye and in the nasal cavity.

Question 19

Pseudo-unipolar neurons des 1

Answer 19

have a single process extending from the

cell body.

Question 20

Pseudo-unipolar neurons des 2

Answer 20

This process divides into two extensions, a short distance

from the cell body.

Question 21

This process divides into two extensions a short distance

from the cell body. One

Answer 21

One extends to the periphery, and the other

extends to the CNS.

Question 22

This process divides into two extensions a short distance

from the cell body. One

Answer 22

One extends to the periphery, and the other

extends to the CNS.

Question 23

The two extensions function

Answer 23

as a single axon with

small, dendrite-like sensory receptors at the periphery.

Question 24

The axon receives sensory information at the periphery and transmits that
information in the form of action potentials to the CNS.

Answer 24

.

Question 25

most sensory | neurons are

Answer 25

pseudo-unipolar.

Question 26

Glial cells (GLEE-al), or

Answer 26

neuroglia (nyu-ROH-glee-ah; nerve glue),

Question 27

Glial cells des

Answer 27

are the supportive cells of the CNS and PNS, meaning these cells do not conduct action potentials.

Question 28

Instead, glial cells carry out

Answer 28

different activities that enhance | neuron function and maintain normal conditions within nervous tissue.

Question 29

Glial cells are far more numerous than neurons.

Answer 29

.

Question 30

Most glial cells retain the ability to | divide, whereas neurons do not.

Answer 30

.

Question 31

In the CNS, there are four types of glial cells.

Answer 31

astrocytes, (2) ependymal cells, (3) microglia, and (4) | oligodendrocytes.

Question 32

The glial cells of the PNS include

Answer 32

Schwann cells and (2) | satellite cells.

Question 33

Astrocytes (ASS-troh-sites)

Answer 33

serve as the major supporting cells in the CNS.

Question 34

In this role, astrocytes can

Answer 34

stimulate or inhibit the signaling activity of nearby | neurons.

Question 35

In addition, astrocytes participate with the

Answer 35

blood vessel endothelium to form a permeability barrier, called the blood-brain barrier, between the blood and the CNS.

Question 36

Astrocytes help limit

Answer 36

damage to neural tissue; however, the repair process can form a scar that blocks regeneration of damaged axons .

Question 37

Ependymal (ep-EN-dih-mal) cells

Answer 37

line the fluid-filled cavities | (ventricles and canals) within the CNS.

Question 38

Some ependymal cells produce

Answer 38

cerebrospinal fluid

Question 39

others, with cilia,

Answer 39

help move the cerebrospinal fluid | through the CNS.

Question 40

Microglia (my-KROH-glee-ah)

Answer 40

act as immune cells of the | CNS.

Question 41

They help protect the brain by

Answer 41

removing bacteria and cell debris.

Question 42

Oligodendrocytes (OL-ih-goh-DEN-droh-sites)

Answer 42

provide an insulating | material that surrounds axons

Question 43

in pns, Schwann cells

Answer 43

provide insulating | material around axons.

Question 44

Satellite cells

Answer 44

found around the cell bodies of | certain neurons of the PNS.

Question 45

Satellite cells 2 des

Answer 45

These cells provide support and nutrition to the neurons and protect the neurons from heavy-metal poisons, such as lead and mercury.

Question 46

Myelin sheaths

Answer 46

specialized layers that wrap around the axons of some | neurons.

Question 47

These myelin sheaths are formed by the cell processes of

Answer 47

oligodendrocytes in the CNS and Schwann cells in the PNS

Question 48

Axons with these myelin sheaths

Answer 48

are called myelinated axons, Each oligodendrocyte process or Schwann cell repeatedly wraps around a segment of an axon to form a series of tightly wrapped cell membranes.

Question 49

Myelin is an excellent insulator

Answer 49

that prevents almost all ion movement across the cell membrane.

Question 50

Gaps in the myelin sheath, called

Answer 50

nodes of Ranvier

Question 51

nodes of Ranvier

Answer 51

occur about every millimeter between the myelinated areas.

Question 52

_____ can occur at the nodes of Ranvier.

Answer 52

Ion movement

Question 53

Myelination of an axon | increases

Answer 53

the speed and efficiency of action potential generation along the axon.

Question 54

Unmyelinated axons

Answer 54

lack the myelin sheaths; however, these axons rest in indentations of the oligodendrocytes in the CNS and the Schwann cells in the PNS

Question 55

A typical small nerve, which consists of axons of multiple | neurons, usually contains

Answer 55

more unmyelinated axons than myelinated axons.