chapter 4 Flashcards
what r the 2 types genes
sex linked and all other
two ways genes can change
mutation: heritable change in a dna molecule
micro deletion / duplication - part of a chromosome that might appear once may appear twice or not at all
explain the 2 widely studied mechanisms of epigenetic
histone remodelling -histone changes she and influences the shape of adjacent DNA ..can influence or decrease gene expression\
DNA methylation: methyl group attaches and tends to reduce adjacent DNA expression
overtime what happens to intelligence correlations between adopted siblings
decreases
genes account for about ____ percent of characteristics
50
what is PKU ? how can it be influenced
genetic inability to metabolize the amino acid phenylalanine …changes in diet can fix
how do genes produce behavior
produce proteins that increase the probability that a behavior will develop under certain circumstances
explain maturation of the brain
begins to form when an embryo is 2 weeks
- dorsal surface thickens, forming a neural tube surrounding a fluid filled cavity
- the forward end enlarges and differentiates into the hind brain, midbrain and forebrain
- the rest of the neural tube becomes the spinal cord
what are the 5 stages of development of neurons
proliferation, migrarton, diffraction, myelination, synaptogeniss
3 parts of proliferation
production of new cells/neruons
early in development the cells lining the ventricles divide
some cells become stem cells that continue to divide
what is important about migration
chemicals known as immunoglobulins and chemokine guide neuron migration
what chemicals guide migration
immunoglobulins and chemokine
what is differation
forming of the axon and dendrites that gives the neuron its distinctive shape …axon grows first
what order does myelination occur
spinal cord, hind brain, mid brain, forebrain
what is synaptogenisis..whats important about time
the formation of the synapses between neurons ..occurs throughout life as neurons are constanty forming new connections and discarding ……slows significantly later in lifetime
what does newer research on new neurons later in life say
stem cells: undifferentiated cells found in the interior of the brain that generate “daughter cells “ that can transform into glia or neurones
stem cells differentiate into new neurons in the adult hippocampus of mammals and faccilitate learning
what did sherry’s research with newts show about axons
that they follow a chemical trail to reach their approximate target …by taking out eyes and rotating and then allowed them to recover
describe duane syndrome
the nerves controlling the eye muscles send some of their axons to the wrong destinations
-try to turn eye message goes to muscle to contact
describe competition among axons
when axons initially reach their target they form synapses with several cells
-post synaptic cells strengthen connection with some cells and eliminate connection with others
it depends on the pattern of incoming axons
what are neurotropins
chemicals that promote the survival and activity of neurons….axons that are not exposed to neurotropins undergo apoptosis …matches axons to number of receiving cells…impotant for healthy brain
what’s an example of a neurotropic
never growth factor: released by muscles that promotes the survival and growth of axons
what does alcohol exposure cause physiologically
short dendrites with fewer branches, suppression of glutamate and enchantment of gaba…less excitation and exposure to neurotropins than usual and undergo apoptosis
what allows for more surface area for connections
dendrites continuously grow new spines
the gain and loss of spines indicates
new connections which relates to learning
what is an example of effects of special experiences
blind people improve attention to touch and sounds…occipital lobe can adapt to also process tactile and verbal information…touch activates occipital cortical area
what is another special experience in relation to music
temporal lobe right hemisphere of musicians is 30 percent larger than non musicians….thicker grey matter precentral gyrus
results suggest that practicing a skill reorganizes brain to maximize performance of that skill
what is the condition where reorganization of brain goes to far in musicians..what happens
focal hand dystonia ..fingers become clumsy fatigue and make involuntary movements ,,,,result of extensive reorganization of the sensory thalamus and cortex so touch responses to one finger over lap another
some recovery of brain damage relies on what
growth of new branches of axons and dendrites
5 examples of brain damage
tumors: abnormal proliferation cells
infections: tissue surrounding, fluid surrounding meininges
exposure to toxic substances or radiation …carbon dioxide
degenerative disease…parkkinsons
closed head injuries
what is a stroke or cerebrovascular accident
temporary loss blood flow ro the brain
-common cause brain damage in the elderly
what are the two types of strokes
ischia: most common..result of a blood clot or an obstruction of an artery ..also tia :transient ischemic attack.mini stroke
hemorrhage: less frequent, ruptured artery ..neurons flood excess blood and chemical…neurons loose oxygen,,,,usually permanent
what do strokes cause?
edema: accumulation of fluid in the brain resulting in increased pressure and likelihood of further strokes
-disruption sodium potassium pimp
-release glutamate
sodium other things enter cell
blocks metabolism in mitochondria
kills the neuron
how do we save neurons from death
blocking glutamate synapses and calcium entry thus blocking cell death
3 stroke treatments?
tissues plasminogen activator…breaks up loot clots can reduce effects of ischmic strokes
blocking glutamate synapses and calcium entry
therapeutic hypothermia …cooling protects brain after ischmeia by reducing overstimulation apoptosis and inflammation….used a lot in cardiac arrest and is most successful
what is diaschsis
decreased activity of surviving neurons after damage to other neurons. occurs cause activity in one area stimulates areas in others
describe axonal regrowth in brain recovery
axons cannot regenerate but collateral sprouting can occur from an intact axon
descrive denervation supersensitivity
tightened sensitive to a neurotransmitter after the destruction of an incoming axon,,,can cause chronic pain
what is it called when there’s an illusion of an extra limb
supernumerary
explain phantom limb
the continuation of sensation amputates body part. the cortex reorganizes itself by become responsive to other parts of the body..original axons degenerate leaving vacant synapses into which the axons….brain confuses it for that area of the body
explain deafferented limb and what often people do
limbs that have lost their afferent sensory input. they can be used but harder so usually use something else
