Chapter 2 - Neurons and Glia

Question 1

Nissl stain

Answer 1

Franz Nissl, a german neurologist discovered a way to dye to color brain tissue.

They stain the nuclei of all cells and also stain clumps of material surrounding the nuclei of neurons. These clumps are called nissl bodies and the stain is know as the Nissl stain.

It distinguishes neurons and glia from each other.

Question 2

Cytoarchitecture

Answer 2

the arrangement of neurons in different parts of the brain.

Question 3

Golgi stain

Answer 3

Camillo Golgi 1873. Is achieved by soaking brain tissue in a silver chromate solution. The stain shows that neurons have at least two distinguishable parts: a central region containing the nucleus and and thin tubes that radiate away from the central region. The thin tubed are called neurites (axons and dendrites).

Question 4

Watery fluid inside the cell

Answer 4

cytosol

A salty potassium rich solution.

Question 5

Where is dna contained within a cell?

Answer 5

Inside chromosomes within the nucleus

Question 6

What is DNA transcripted to?

Answer 6

mRNA

Question 7

What does the golgi apparatus do?

Answer 7

Sorts newly synthesized proteins for delivery to appropriate locations in the neuron.

Question 8

ATP

Answer 8

adenosine triphosphate

Question 9

What does ATP do?

Answer 9

It is used to fuel most of the biochemical reactions of the neuron.

Question 10

How can neurons be classified?

Answer 10

Number of neurites (unpolar, bipolar, mutlipolar), based on dendrites (main ones are stellate cells and pyramidal cells or spiny/aspinous), based on connections (primary sensory neurons, motor neurons, interneurons) based on axon length (Golgi type 1, golgi type 2) or based on neurotransmitter (e.g. cholinergic)

Question 11

What is a golgi type 1 neuron?

Answer 11

A projection neuron wth long axons.

Question 12

What is a golgi type 2 neuron?

Answer 12

A neuron with local circuits with short axons.

Question 13

What are astrocytes?

Answer 13

A type of glia. These cells fill the spaces between neurons. They regulate the chemical content of the extracellular space. They regulate neurotransmitters in the synaptic cleft.

Question 14

How many neurons and glia are in the adult human brain?

Answer 14

Roughly 85 billion of each type.

Question 15

What is the average size of most brain cells?

Answer 15

0.01-0.05mm in diameter

Question 16

Describe the properties of the axon.

Answer 16

There is usually a single axon from the neuron. This has a uniform diameter throughout its length, and any branches generally extend at right angles. They act as “wires” that carry the output of the neurons.

Question 17

Describe the properties of the dendrite.

Answer 17

They are rarerly longer than 2mm. many of them extend from the cell body. They generally taper to a fine point (become thinner towards the end). Dendrites acts as the antennae of the neuron and receiving incoming signal.

Question 18

Describe the contents of the soma.

Answer 18

The cell body is about 20 micrometers in diameter. Inside the cell is cytosol (a potassium rich fluid) that is separated from the outside by the neuronal membrane. Within the soma, there are membrane-enclosed organelles same one you find in all animal cells.

Question 19

What is the cytoplam?

Answer 19

Everything within the membrane except the nucleus.

Question 20

Describe the nucleus?

Answer 20

It is spherical, centrally located and bout 5-10 micrometers in diameter. It is contained within a double membrane, the nuclear envelope, which is perforated by pored about 0.1 micrometers across. Within the nucleus are chomosomes that contain the DNA. The DNA contains genes that are parts of the dna used to assemble the cell.

Question 21

Describe genes and gene expression.

Answer 21

Gene expression is the reading of DNA. The final product of gene expression is the synthesis of proteins. This protein syntehsis occurss in the cytoplasm.

Question 22

What is transcription?

Answer 22

The process of assembling a piece of mRNA that contains the information of a gene. The mRNA (messenger RNA) consists of four different nucleic acids strung together in various sequences to form a chain.

Question 23

What are promoters and terminators of a gene?

Answer 23

The promoter is the region where the RNA-synthesizing enzyme, RNA polumerase, binds to initate transcription. The terminator, also called the stop sequence, is a sequence of DNA that the RNA polymerase recognizes as the end for transcription.

Question 24

What are exons and introns?

Answer 24

Exons are the parts that are coded into mRNA. Introns are stretches of DNA within the gene that cannot be used to code for protein. During RNA splicin the introns are removed from the transcription after the initial transcript.

Question 25

Why do neurons differ from other cells in the body?

Answer 25

Because of the specific genes they express as proteins.

Question 26

Describe the funciton of the rough endoplasmic reticulum in neurons.

Answer 26

Many ribosomes, where protein synthesis occurs, are attached to stacks of membrane (rough ER). Rough ER is very prominent in neurons, far more than in glia or non-neuronal cells.