Neuronal Components

Question 1

Types of neurons 3

Answer 1

1. multipolar neuron
   (A neuron with one axon and many dendrites attached to its soma.
 - example: cortical stellate neutron)
2. bipolar neuron
   (A neuron with one axon and one dendrite attached to its soma.
   Example: retinal bipolar cell )
3. unipolar neuron
   (A neuron with one axon attached to its soma; the axon divides, with one branch receiving sensory information and the other sending the information into the central nervous system.
   Example: dorsal root ganglion cell)

Question 2

sensory neuron

Answer 2

A neuron that detects changes in the external or internal environment and sends information about these changes to the central nervous system.


Question 3

motor neuron

Answer 3

A neuron located within the central nervous system that controls the contraction of a muscle or the secretion of a gland.


Question 4

interneuron

Answer 4

A neuron located entirely within the central nervous system.

Question 5

soma

Answer 5

The cell body of a neuron, which contains the nucleus.

Question 6

dendrite

Answer 6

The branched, treelike structure attached to the soma of a neuron; receives information from the terminal buttons of other neurons.

Question 7

synapse

Answer 7

A junction between the terminal button of an axon and the membrane of another neuron.

Question 8

axon

Answer 8

The long, thin, cylindrical structure that conveys information from the soma of a neuron to its terminal buttons

Question 9

terminal button

Answer 9

The bud at the end of a branch of an axon; forms synapses with another neuron; sends information to that neuron.

Question 10

neurotransmitter

Answer 10

A chemical that is released by a terminal button; has excitatory or inhibitory effect on another neuron.


Question 11

membrane

Answer 11

A structure consisting principally of lipid molecules that defines the outer boundaries of a cell and also constitutes many of the cell organelles, such as he Golgi apparatus.


Question 12

nucleus

Answer 12

A structure in the central region of a cell, containing the nucleolus and chromosomes.


Question 13

nucleolus

Answer 13

A structure within the nucleus of a cell that produces the ribosomes.

Question 14

mitochondrion

Answer 14

An organelle that is responsible for extracting energy from nutrients.


Question 15

adenosine triphosphate (ATP)

Answer 15

A molecule of prime importance to cellular energy metabolism; its breakdown liberates energy.


Question 16

endoplasmic reticulum

Answer 16

Parallel layers of membrane found within the cytoplasm of a cell. Rough endoplasmic reticulum contains ribosomes and is involved with production of proteins that are secreted by the cell. Smooth endoplasmic reticulum is the site of synthesis of lipids and provides channels for the segregation of molecules involved in various cellular processes.


Question 17

golgi apparatus

Answer 17

A complex of parallel membranes in the cytoplasm that wraps the products of a secretory cell.

Question 18

exocytosis

Answer 18

The secretion of a substance by a cell through means of vesicles; the process by which neurotransmitters are secreted.


Question 19

lysosome

Answer 19

An organelle surrounded by membrane; contains enzymes that break down waste products.


Question 20

cytoskeleton

Answer 20

Formed of microtubules and other protein fibers, linked to each other and forming a cohesive mass that gives a cell its shape.


Question 21

microtubule

Answer 21

A long strand of bundles of protein filaments arranged around a hollow core; part of the cytoskeleton and involved in transporting substances from place to place within that cell.

Question 22

ribosome

Answer 22

A cytoplasmic structure, made of protein, that serves as the site of production of proteins translated from mRNA.


Question 23

chromosome

Answer 23

A strand of DNA, with associated proteins, found in the nucleus; carries genetic information.


Question 24

deoxyribonucleic acid (DNA)

Answer 24

A long, complex macromolecule consisting of two interconnected helical strands; along with associated proteins, strands of DNA constitute the chromosomes.


Question 25

gene

Answer 25

The functional unit of the chromosome, which directs synthesis of one or more proteins.

Question 26

messenger ribonucleic acid (mRNA)

Answer 26

A macromolecule that delivers genetic information concerning the synthesis of protein from a portion of a chromosome to a ribosome.


Question 27

enzyme

Answer 27

A molecule that controls a chemical reaction, combining two substances or breaking a substance into two parts.


Question 28

cytoplasm

Answer 28

The viscous, semiliquid substance contained in the interior of a cell.

Question 29

axoplasmic transport

Answer 29

An active process by which substances are propelled along microtubules that run the length of the axon.


Question 30

anterograde

Answer 30

In a direction along an axon from the cell body toward the terminal buttons.


Question 31

retrograde

Answer 31

In a direction along an axon from the terminal buttons toward the cell body.


Question 32

astrocyte

Answer 32

A glial cell that provides support for neurons of the central nervous system, provides nutrients and other substances, and regulates the chemical composition of the extracellular fluid.


Question 33

phagocytosis

Answer 33

The process by which cells engulf and digest other cells or debris caused by cellular degeneration.


Question 34

oligodendrocyte

Answer 34

A type of glial cell in the central nervous system that forms myelin sheaths.


Question 35

myelin sheath

Answer 35

A sheath that surrounds axons and insulated them, preventing messages from spreading between adjacent axons.

Question 36

blood-brain barrier

Answer 36

A semipermeable barrier between the blood and the brain produced by the cells in the walls of the brain’s capillaries.


Question 37

area postrema

Answer 37

A region of the medulla where the blood-brain barrier is weak; poisons can be detected there and can initiate vomiting.