Studied by 9 people
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levels of causality
relational, necessary, sufficient
levels of analysis
molecular, cellular, systems, behavioral, cognitive
early evidence
hominid skulls have evidence of tool inflicted wounds, shows they knew brain was important
Galen
studied brain by studying its structure
cerebellum was hard to touch so must control hard body parts
cerebrum soft so must control sensations and memories
Rene Descartes
mind brain division. I think therefor I am
mind brain division
pineal gland is only unimpaired midline brain structure (rene thought it was to communicate with spirits)
White matter
mylenated axons
grey matter
neuronal cell bodies
Stimulating nerve and muscle tissue
electrical current could contract muscles, found that electricity controls functions
doctrine of specific nerve energies
all nerves carry the same electrical signal but different nerves carry different information
Ventral root damage
motor paralysis
Dorsal root damage
impaired sensory functions
flourens
provided first evidence of localization of function in the brain
phrenology
bumps on skull signals a map
brocas area
can speak but can understand
found because there was damage to a specific part of the left side of the brain
lateralization
evolution requires
variability, heritability, different survival
natural selection
darwin -how have species evolved
sexual selection
darwin - mate selection often acts against natural selection, female selects mates that have signals of fitness
animal research
researcher must be novel, number of animals must be minimal possible, least amount of pain and distress, principle investigator is qualified, lowest species available is being used, must have nesessary and sufficient levels of causality
why is anatomy important
structure and function relationship
functional anatomy
Nissl stain
stain every cell just see cell body
golgi stain
see the neurites (dendrites and axons)
only taken up by some neurons
cajals contribution
neural circuitry, neurons are discontinuous
neuron doctrine
neurons adhere to cell theory, based on golgi stain but confirmed with electron microscopy
cell theory
individual cells are the basis of an organism, what the organism does depends on what the cells do
synaptic distance
20nm
ratio of neurons to glial cells
1:1
macroglial cells
astrocytes
oligodendrocytes
schwann cells
ependymal cells
astrocytes
nutrition to neurons, seal around synaptic junctions, clean up and fill damaged brain tissue, maintain chemical composition of extracellular fluid outside neurons, communicate btwn neurons and surrounding vasculature
mylenating glia
serve to insulate axonal segments from the surronding extracellular fluid
where do neurons regenerate
peripheral nervous system do, do not in brain or spine
oligodendroglial cells
in the central nervous system -brain and spinal cord
schwann cells
in the peripheral nervous system, promote axonal regeneration
ependymal cells
line the ventricles of the brain and cilia pump cerebral spinal fluid
contribute to axon guidance during developmetn
migroglia
change structure and funtion
serve as phages -clean up dead brain tissue
part of brains immune response
produced in bone marrow
pyramidal cell
basilar and apical dendrites
stellate cell
dendrites in radial pattern
5 types of neuronal classification
number of neurites
dendric arborization
their connections
axon length
gene expression
gene expression
dominant use for classification
after a genetic difference is known between neurons a neon protein can be introduced that can be identified
cell membrane thickness
5nm
cell membrane
boundary of the cell
phospholipid bilayer with both hydrophilic and hydrophobic components
detects chemical signals, detects voltage differences, sometimes allows for passage of ions
hydrophilic head
attracted to water, suspends itself in fluids
hydrophobic tails
float together in continuous thin fatty layer
cytoplasm
fills the space within the cell membranes
includes the cytosol and the organelles
cytosol
rich in potassium ions and has lower concentrations of other ion
nucleus
command and control center
every cell has all the genes it matters how the genes are expressed to determine funtcion
STEM cells
cells early in development that can differentiate into any type of cell
different cell types have different transcription factors
length of DNA uncoiled
2 meters
gene expression
goal of gene expression is to build proteins in the cell
what is a protien
sequence of amino acids (20 make up all protiens)
How do you get amino acids
9 come from diet the rest can be made by the body
triplet
a sequence of 3 nucleotides in the DNA defines the amino acid
protein synthesis steps
replication, DNA, transcription (rna synthesis) mRNA, cytoplasm, ribosome, rough ER, translation, protein
transcription
DNA to mRNA
translation
mRNA to protein (happens in 2-3hrs)
DNA central dogma
DNA is the molecule of hereditary, DNA codes for mRNA, mRNA codes for proteins
nuclear pores
allow for transport of specialized elements into and out of the nucleus
gene
a sequence of nucleotides that encode for a specific protien
exons
sections of rna that are code for proteins
introns
noncoding regions of RNA
splice variants
occur when different exons are removed with the introns
promoter region
transcription initiation
terminator region
transcription stops
Three bases on mRNA
codon
three bases on +RNA
anti-codon (matching nucleotide sequence that transports the mRNA to a ribosome
free floating ribosomes
produce proteins for use in the cytoplasm (allows for synaptic plasticity)
polyribosomes
multiple copies of same segment of mRNA
Rough ER
covered with ribosomes to make protiens
smooth er
produces lipid molecules and keeps calcium (high levels can kill the cell)
golgi apparatus
edits proteins and packages them into vesicles to prepare them for transport
mitochondria
site of cellular respiration, generates ATP, have own mitochondrial DNA
cytoskeleton
internal scaffolding of neuronal membrane, (bones of neuron), vesicles transported via microtubules and microfilaments
three bones of neuron
microtubules (20nm), microfilaments (10nm), neurofilaments (5nm)
microtubule associate proteins
anchor microtubules together, (TAU, a map, accumulates in the cell body causing neurofibrillary tangles, kills the cell =alzheimers)
axon parts
axon hillock, axon proper, axon terminal
axon hillock
initial segment
axon proper
middle
axon vs soma
no rough er or free ribosomes, unique protein and chemical composition, creates need for ventricles
axon terminal
no microtubules, has synaptic vesicles, lots of membrane bound proteins, large number of mitochondria (uses lots of energy)
kinesin
anterograde transport -cell body to terminal (away from cell center)
dynein
retrograde transport -terminal to cell body
synapse connections
axo-somatic, axo-dendric, axo-axonic
ion
atom or molecule carrying an electrical charge (cation or anion)
anion
negative charge
cation
positive charge
ion channels
proteins that allow free passage of specific ions into and out of the neuron
leak
ion channels always open
gated
ion channels voltage, chemical, both, or some other stimulus to open
ion transporters
proteins that maintain the normal distribution of ions inside and outside the cell
peptide
chain of amino acids
protein structure primary
AA sequence and amino groups with variable R group
protein structure secondary
alpha helix
protein structure tertiary
3D folding of polypeptide
protein structure quartenrnary
different subunits that make up the channel protein
Na+/K+ transporter
move against concentration gradient, energy dependent process, ion concentration differences are how cells store electrical charge,
ratio of potassium inside the cell to outside
20:1
electrical potentials
create electrical gradients allowing for the possibility of allowing ions to flow in a preffered direction
membrane potential of a neuron
rests at -70mV
diffusion
similar ions don’t like to be together and if able to move they will go down a concentration gradient until they achieve equilibrium
electrostatic pressure
draw to regions that are oppositely charged
