Pnb 2xb3 Study guides, Class notes & Summaries

How many neurons are in the human brain? ~~> about 100 billion What percentage of the brain do we use? ~~> 100% What is the brain's power in watts? ~~> 20 W What is the size of a typical neuron? ~~> 10 um (cell body diameter) What is the most common neurotransmitter? ~~> Glutamate What is the voltage of a neuron at rest? ~~> -65mV What is the name of the neuro-electrical impulse? 2 | P a g e | © copyright 2024/2025 | Grade A+ Master01 | September, 2024/20...

Merkell cells - ~~> - slowly adapting - 25% of mechanosensory afferents in hand - highest spatial resolution - edges, points, corners, curvature - static indentation ** Meissener - ~~> - rapidly adapting -40% of mechanosensory innervation in hand - skin motion, indentation, low frequency vibrations for textured objects*** - more than 4x more sensitive than Merkell to skin deformation, but larger receptive fields so less spatial resolution - ie. tea set plate etchin...

Mitosis ~~> process of one cell dividing in two (Embryonic) Stem Cells ~~> precursors to all types of cells Pluripotent ~~> potential to become any type of cell Ectoderm ~~> brain and skin (outer layer) Mesoderm ~~> muscle, blood, bone, cartilage (middle layer) Germline ~~> sperm and eggs Endoderm 2 | P a g e | © copyright 2024/2025 | Grade A+ Master01 | September, 2024/2025 | Latest update ~~> lung, gut, and liver (inside layer) Day 18 of gestation ...

dermatome - ~~> the area of skin supplied by the sensory axons of a single spinal nerve dorsal horn - ~~> the POSTERIOR column of grey matter in the spinal cord (shape differs depending on spinal segment) - contains SENSORY neuron cell bodies ventral horn - ~~> the ANTERIOR column of grey matter in the spinal cord (shape differs depending on spinal segment) - contains MOTOR neuron cell bodies 3 types of primary somatosensory afferent axons - ~~> 1) Aβ 2) Aδ 3...

Sound waves are ___; compression is __ of a wave, rarefaction is ___ ~~> longitudinal - move like a slinky; top; bottom Period ~~> the time taken for one up-down cycle (wavelength) Wavelength ~~> the distance b/w two peaks/an up-down cycle Universal wave equation ~~> speed = distance/time = wavelength/period Higher pitch = ~~> higher frequency - but perception depends on the environment Sound frequency ~~> - longer wavelengths = lower frequency - basilar membr...

DCML - 1) mechanosensory receptors send info to fibers in gracile & cuneate pathways 2) fibers travel to caudal medulla, synapse at dorsal column nucleus (and switch sides) 3) exit DCN as arcuate fibers, cross the midline to form medial lemniscus carries through pons, midbrain, brainstem 4) synapse at thalamus (VPL) 5) internal capsule takes axons to post-central gyrus/S1, some to S2. Meissener - - rapidly adapting -40% of mechanosensory innervation in hand - skin motion, indentation, lo...

Higher pitch = - ️️higher frequency - but perception depends on the environment Wavelength - ️️the distance b/w two peaks/an up-down cycle Middle ear - ️️everything inside the tympanic membrane and before the oval window LSO - ️️- monitors intensity differences for high-frequency sound - head blocks frequencies that have wavelengths smaller than the head - produces a sound shadow (in humans - higher than 2kHz) - the ipsilateral LSO starts firing more when there is a sound ...

RAPID-adapting mechanoreceptors - ️️Meissner and Pacinian (dynamic phase QUICKLY becomes static phase) dorsal root ganglion (DRG) - ️️(part of the PNS) cluster of cell bodies in the dorsal root of a spinal nerve (when the action potential reaches the DRG, it splits into 2 - one travels toward the cell body and the other continues down the axon) dorsal horn - ️️the POSTERIOR column of grey matter in the spinal cord (shape differs depending on spinal segment) - contains SENSORY n...

For an on-center ganglion cell, what causes it to maximally fire? ~~> light in the center and darkness in the surround What is the spontaneous level of activity or baseline for a ganglion cell? ~~> when the entire field is in the dark color opponency ~~> the center and surround cones can be of different types (red,green,blue...) fixating the eyes on an object ~~> turning the eyes so that the image falls on the fovea of each eye monocular vision portion of the visual fie...

Spina bifida - ️️neural tube fails to close caudally - risk factor: insufficient folate (vitamin B9) consumption during pregnancy - needed for production of DNA and RNA and for mitosis - exposed nerves can result in infection, affect bladder and bowel function, and paralysis Day 20 of gestation - ️️neural groove develops; part of the mesoderm becomes somites which become bones Pluripo Endoderm - ️️lung, gut, and liver (inside layer) tent - ️️potential to become any type o...