Chapter 2 - Neurons and Glia Flashcards
(26 cards)
Nissl stain
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.
Cytoarchitecture
the arrangement of neurons in different parts of the brain.
Golgi stain
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).
Watery fluid inside the cell
cytosol
A salty potassium rich solution.
Where is dna contained within a cell?
Inside chromosomes within the nucleus
What is DNA transcripted to?
mRNA
What does the golgi apparatus do?
Sorts newly synthesized proteins for delivery to appropriate locations in the neuron.
ATP
adenosine triphosphate
What does ATP do?
It is used to fuel most of the biochemical reactions of the neuron.
How can neurons be classified?
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)
What is a golgi type 1 neuron?
A projection neuron wth long axons.
What is a golgi type 2 neuron?
A neuron with local circuits with short axons.
What are astrocytes?
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.
How many neurons and glia are in the adult human brain?
Roughly 85 billion of each type.
What is the average size of most brain cells?
0.01-0.05mm in diameter
Describe the properties of the axon.
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.
Describe the properties of the dendrite.
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.
Describe the contents of the soma.
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.
What is the cytoplam?
Everything within the membrane except the nucleus.
Describe the nucleus?
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.
Describe genes and gene expression.
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.
What is transcription?
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.
What are promoters and terminators of a gene?
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.
What are exons and introns?
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.
