Neurons And Glia Flashcards
1
Q
Levels of analysis in neuroscience
A
- atoms
- molecules
- individual cells
- pairs of cells connected by synapses
- networks of interacting cells
- systems in the brain that regulate behaviour
- behaving animal
- groups of animals
2
Q
Alzheimer’s disease
A
- neurodetengerative
- loss of short term memory, decline in cognitive functions
- 50% of people over 85 develop Alzheimer’s
- cost of treatment will increase 10fold due to aging population
3
Q
Neurons
A
- functional unit of NS
- most anatomically diverse cell in the body
- all contain dendrites, cell body, and axon
4
Q
Neuronal diversity
A
- pioneering cell-staining method introduced by Camille Golgi and utilized by S. Ramon Y Cajal
- Golgi stain: tissue a shin with silver salts, a few neurons take up the silver and are stained black
-more recently developed fluorescent dyes can be injected into individual neurons using specialized equipment
5
Q
Signalling
A
- principle function
- facilitated by dendrites, axons, and synapses
- intracellular: from one part of cell to another
- intercellular: communication between cells
6
Q
Axon
A
- tube-like process exiting from axon hillock on the soma
- interneurons have relatively short axons
- projection neurons have longer axons
- the axon transmits electrical signals rapidly along its length
7
Q
The synapse
A
- where pre-synaptic axon terminals (synaptic boutons) meet post-synaptic dendrites
- site of intercellular information transfer
- ‘synapse’ comes from Greek work ‘connect’
- coined by sir Charles Sherrington
- hypothesized it’s existence from spinal cord reflexes years before anatomical correlate
8
Q
Dendrites
A
- some dendritic trees can be highly branched
- usually acts as synaptic input site
- integrates information from other cells
- some dendrites have numerous finger-like projections called dendritic spines
- highly plastic structures
9
Q
Neuronal structure
A
- maintained or changed by the cytoskeleton
- cytoskeleton is highly plastic during developmental (atonal path finding/ growth cone), and acts as a highway for molecular motors
- dendrites composed of microtubules (tubulin) and actin
- axon composed up intermediate filaments (neurofilament) and microtubules
- synaptic boulb composed of actin mainly and microtubules
10
Q
Genes and the brain
A
-source of neuronal diversity not well understood
-partially under genetic control
-genes influence neuronal structure/function which influences behaviour
-unsure how genes influence neuronal structure, how neurons produce behaviour, and how environment and genes interact to alter neuronal function
-
11
Q
Complexity of brain
A
- makes brain-gene interactions hard to understand
- human brain: ~100billion neurons
- 10^15 synapses in the neocortex
- a typical neuron has ~5,000-100,000 synapses
- thousands of different neuronal types
- 20,000 protein-coding genes in human genome
- not all involved in brain function (about 14,000 are)
12
Q
Genes, nervous system and behaviour
A
- genetic control of neuronal structure/function not straight forward
- seems that complexity of human brain results from extra genes unique to humans?
- NO
- mice have more genes than humans but less neurons and fewer synapses
- eg. Drosophila axon guidance receptor (DSCAM) undergoes alternate splicing when being transcribed which creates a receptor with 38,016 possibilities… double the number of predicted genes in entire genome
13
Q
Neuronal system and diversity
A
- originally begin as progenitor cells
- generation of neuronal diversity causes 20^9 neuronal types and subtypes
- cell death and selective pressure based on experience causes more variation
- cell maturation and signal amplification by changes in synaptic activity created dynamic diversity mediated by activity
14
Q
Example where genes can be tied to NS
A
- autosomal recessive primary microcephaly (MCPH)
- results in a small both otherwise normal cerebral cortex associated with mild to moderate mental retardation
- most common cause is a homozygous mutation of a gene called ASPM
- ASPM (abnormal spindle like microcephaly associated) gene is essential for normal mitotic spindle function in embryonic neuro lasts
- mouse version (ASPM) expressed specifically in primary sites of prenatal cerebral cortical neurogenesis
- across species, ASPM homologs differ in number of IQ domains
- c. Elegans: 2 repeats
- drosophila (asp): 24 repeats
- mice (Aspm): 61 repeats
- humans (ASPM): 74 repeats
- seems like more IQ domains in this gene leads to bigger brains
15
Q
Glia
A
- Glia outnumber neurons 3:1
- 3 broad categories
- atroglia
- Oligodenroglia
- microglia
-glial cells retain their ability to divide throughout life
