Chapter 2: Neurons and Gila Flashcards
What are the two main types of cells in nervous system?
Neurons and gila
How many neurons are there in human brain?
86 billion
How many gila are there in human brain?
85 billion
What do neurons do?
They sense changes in environment, communicate changes to other neurons and command our body’s responses
What do gila do?
They insulate, support and nourish neighbouring neurons
What is the consistency of brain tissue like?
Jello-O, not firm enough to make thin slices
How do scientist harden brain tissue?
Immersing them in formaldehyde
What does a microtome do?
Make very thin slices
What is Nissl stain?
Basic dyes that stain the nuclei of all cells as well as Nissl bodies
What is Nissl bodies?
Clumps of material surrounding nuclei of neurons
Why is Nissl stain useful?
- Distinguishes between neurons and gila
2. Enable the study of cytoarchitecture (arrangement) of neurons in different parts of brain
What is golgi stain?
Soaking brain tissue in silver chromate solution
What do golgi stain show?
Neurons have two parts:
- Central region that contains cell nucleus called cell body, soma and perikaryon
- Numerous thin tubes that radiate from central region called neurites and have two types: axons and dendrites
How many axons does a cell body give rise to?
1
What are axons like?
Uniform diameter throughout its length, any branches from it generally extend at right angles
What are dendrites like?
Rarely longer than 2mm, dendrites extend from cell body and taper at fine point
What is neuron doctrine?
Neurites of different neurons are not continuous with each other and communicate by contact, not continuity
What is cell body/soma like?
- 20μm (micrometer) in diameter
- has watery fluid inside cell called cytosol
- cytosol is separated from outside by neuronal membrane
- contain same organelles found in all animal cells
What is cytosol?
Salty, potassium rich solution
What are the organelles found in all animal cell?
Nucleus, rough endoplasmic reticulum, smooth endoplasmic reticulum, Golgi apparatus, mitochondria
What is cytoplasm?
Everything inside cell membrane, including organelles but excluding nucleus
What is the size of nucleus?
5-10 μm (micrometer)
What is nucleus like?
- contained with nuclear envelope
- inside nucleus are chromosomes which contain DNA
What is nuclear envelope?
- double membrane containing nucleus
- perforated by pores about 0.1 μm across
What distinguishes a neuron from other cells?
Specific parts of DNA used to assemble cell called genes
What are the size of genes?
0.1 to several micrometers in length
What is gene expression?
Reading of DNA
What is the final product of gene expression?
Proteins
What is protein synthesis?
Assembly of protein molecules
Where do protein synthesis occur?
In the cytoplasm
How does protein synthesis work?
DNA never leaves the nucleus, hence an intermediary (mRNA) carries the genetic message to sites of protein synthesis in the cytoplasm
What does mRNA work?
Four different nuclei acids strung together in various sequences to form a chain, the different sequences represent the information in the gene
What is transcription?
Process of assembling a piece of mRNA that contains information of a gene
What is the name of resulting mRNA after transcription?
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