unit 2 :( Flashcards
i hate this unit
homology
suggests relationships/similarities among species that evolved from a shared ancestor
homoplasy
similar features that evolved seperately
darwin’s 4 observations
- reproduction increases population unless limits factor it
- individuals in a species are not identical
- some variation among individuals is inherited
- not all offspring survive to reproduce
basic similarities across vertebrate nervous systems
- development from hollow dorsal neural tube
- bilateral symmetry
- segmentation
- hierarchial control
- seperate systems
- functional specialization
social brain hypothesis for cortex size
larger cortex necessary for handling complex social relationships
what did darwin do?
natural selection
what did mendel do?
created laws of inheritance
what did de vries do?
mutations occur in genes, which induces changes in organism’s characteristics
6 stages of development in neural system
- neurogenesis
- cell migration
- differentiation
- synaptogenesis
- neural cell death
- synapse rearrangement
neurogenesis
cells from inner neural tube divide and the type of cell is determined by intrinsic and extrinsic
intristic
genetic
extrinsic
cell-cell interactions
are vertebrates focused on intrinsic or extrinsic?
more focused on extrinsic and they are both with most of the neurons they will ever have
are invertebrates more focused on intrinsic or extrinsic?
intrinsic
cell migration
depends on CAMS
when does cell migration happen in primates?
done by birth
when does cell migration happen in rodents?
still some cell migration after birth
differentiation
genes determine cell fate and nearby cells can also induce fate
what happens to undifferentiated cells?
they can be placed into a new environment and develop (stem cells)
synaptogenesis
growth of axons and dendrites, which have growth cones at ends
what is axon growth guided by?
chemoattractants and chemorepellants
neuronal cell death
apoptosis
what keeps cells alive?
cell-cell interactions
synapse rearrangement
synapses are retracted and added
apoptosis process
- influx of Ca2+ ions from outside the cell and release of Ca2+ ions from internal stores, raising intracellular Ca2+ levels
- increased Ca2+ causes mitochondria to release Diablo protein into cell
- diablo binds to proteins that stop apoptosis, so they can no longer block caspases
- cascade of capsases destroy proteins and DNA
- Bel-2 proteins can stop apoptosis by preventing release of Diablo
can glial cells be made after birth?
yes because myelination mostly happens after birth
epigentics
regulation of gene expression
methylation
gene expression reduced for DNA with an extra methyl group
alzheimers process
- Amyloid precursor protein releases the beta-amyloid extracellularly is removed.
- Beta-amyloid forms clumps (plaques). Plaques accumulate on axons and dendrites = impaired function
- The plaques also accumulate inside the cell which form neurofibrillary tangles.
- Basal forebrain neurons cease the production of acetylcholine-> dementia
Apoptosis -> loss of basal forebrain produced acetylcholine -> dementia
labeled lines
brain recognizes different senses due to action potentials traveling along separate nerve tracts
tonic receptors
no decline in AP frequency
phasic receptors
decrease AP frequency
what does S1 do?
receive touch information from opposite side of body
what does S2 do?
map both sides of body
pacinian corpuscle
- detects vibration
- fast adapting
meissner’s corpuscle
-light touch
- fast adapting
merkel’s disc
-fine touch
- slow adapting
ruffinis ending
- stretch
- slow ending
what does the dorsal column system of spinal cord do?
delivers touch info to the brain
what does the ventral column of the spinal cord do?
motor
TRPV1
responds to painful heat, including capsaicin
is TRPV1 a C fiber or a-delta fiber?
C fiber
CMR1
responds to menthol and to cool temps
is CMR1 a C fiber or a-delta fiber?
C fiber
C fibes
thin, unmyelinated axons that conduct slowly and produce lasting pain
TRP2
responds to even higher temps, not capsaicin
are TRP2 a C fiber or a-delta fiber?
A-delta fiber
A-delta fiber
thick, myelinated axons that conduct quickly
what brain structure is involved in pain perception?
periaqueductal grey
what pathway doesn’t pass through the thalamus?
olfactory
where do the pathways terminate?
cingulate cortex
what type of pain modulation system do we have?
descending
steps of auditory transduction
- outer ear (pinna) amplifies sound
- sound waves arrive at tympanic membrane (eardrum)
- movement of tympanic membrane results in movement of inner ear ossicles (malleus, incus, stapes)
- movement of stapes at oval window establishes pressure waves in perilymph (fluid in cochlea)
- basilar membrane separates perilymph in coclea, organ of corti (contains hair cells) found on basilar membrane
- when perilymph/basilar membrane vibrates, hair cells bend and produce signals that are send to CNS
what does the actual transducing?
hair cells
inner hair cells
responsible for perception of sound
outer hair cells
fine tune organ of corti in response to messages from brain
hair cells have little hairs on them called ______
stereocilia
stereocilia
move back and forth in response to movement of the basilar membrane
what happens when tip links move back and forth?
ion channels open, leading to depolarization
place theory
pitch is identified based on the specific place on the basilar membrane where sound waves stimulate the most activity
volley theory
pitch is encoded by firing frequency of neurons
volley theory is more correct with ______
lower frequencies
intensity differences
relies on lateral superior olive
- receives loudness
latency differences
relies on medial superior olive
- time
conduction deafness
problem in outer or middle ear prevents transmission of vibrations
sensorineural deafness
auditory nerve is unable to conduct signals
central deafness
issue with CNS
utricle and saccule
detect linear forces (horizontal and vertical)
semicircular canal
detecting rotational forces
salty
sodium transported across cell membrane causing depolarization
sour
depends on acidity (H ions) causes depolarization
sweet
detected by two members of T1R receptor family (GCPR)
bitter
toxic substances and T2R receptors
umami
one kind of receptor responds to glutamate, another to amino acids
photoreceptors
rods and cones
rods
dim light
cones
bright light (color, near fovea)
bipolar cells
on center and off center
amacrine and horizontal cells
lateral inhibition enables us to see borders clearly
ganglion cells
only one that fires AP and on-center/off-center
if light hits on center…
cell is activated
if light hits off center…
inhibits NT release
pathway of vision to brain
retinal ganglion cells»LGN of thalamus» V1
which layer receives monocular LGN input?
layer 4
feedback control
starts with disturbance in periphery, sends signal BACK to CNS
feedforward
more proactive, CNS uses information in advance to correct muscle contraction before disturbance occurs
what makes muscles contract?
myosin and actin
fast twitch fibers
react quickly but tire quickly (from large motoneurons)
slow twitch fibers
slower response but tire less quickly (from small motorneurons)
supplementary motor area
for voluntary movement
premotor cortex
crucial for movements guided by external stimuli
extrapyramidal system
cerebellum and basal ganglia
- modulate activity rather than having direct control over movements
basal ganglia
determine amplitude and direction of movement
basal ganglia
guides movement by inhibiting neurons
parkinsons
death of substantia nigra dopamine
huntingtons
caused by single dominant HTT gene, which produces huntingtin - due to trinucleotide repeats
what hormones does the posterior pituitary release?
oxytocin and vasopressin
oxytocin
involved in reproductive and parenting behavior, and milk-letdown reflex
vasopressin
increases blood pressure and inhibits urine formation
6 tropic hormones that anterior pituitary releases
- adrenocorticiotropic hormone
- thyroid-stimulating hormone
- follicle-stimulating hormone
- lutenizing hormone
- Prolactin
- Growth Hormone
lutenizing hormone
stimulates follicles to form corpora lutea or promotes testosterone release
adrenal glands
consists of adrenal cortex and adrenal medulla
what do adrenal glands release?
amine hormones (epinephrine and norephinephrine) and steroid hormones (glucocorticoids and mineralcorticoids)
pineal gland
secretes melatonin
