Neuro 3000 Exam 3

CNS

brain and spinal cord, encased in bone

PNS

all parts outside CNS

cerebrum

two hemispheres, each receives input and controls movement from opposite, contralateral

cerebellum

same amt of cells as cerebrum, connections to cerebrum and spinal cord, each receives input and controls movement from same, ipsilateral

brain stem

relay center, essential for life, regulates body temp, breathing, and consciousness

spinal cord

encased in vertebral column, spinal nerves are part of PNS

pyramidal decussation

point at junction of medulla and spinal cord where moto fibers from medullary pyramids, continue into spinal cord as corticospinal tract

anterior, rostral

front

posterior, caudal

rear

lateral

side

medial

middle

dorsal

top, back

ventral

bottom, belly

superior

above

inferior

below

superficial

surface

deep

far from surface

bilateral symmetry

only seen on coronal plane or horizontal plane

gyri

ridges

sulci

valleys between ridges, central sulcus, lateral sulcus/sylvian fissure, parieto-occipital sulcus

fissure

deeper than a sulcus, major division, longitudinal - separates left + right hemispheres, transverse - separates cerebrum from cerebellum

grey matter

cortex, made up of myelinated axons

white matter

made up of myelinated axons

nucelus

a mass of neurons, usually deep in brain

dorsal and ventral roots in CNS

dorsal and ventral roots of spinal cord are myelinated by oligodendrocytes and protected by meninges

dorsal and ventral roots in PNS

once they enter PNS, Schwann cells take over both functions

dorsal roots

sensory

ventral roots

motor

somatic nervous system

voluntary behaviors, cell body of motor neurons in CNS, axons in PNS

autonomic (visceral) nervous system

involuntary behaviors, portion of NS that supplies motor innervation to structures that are not under voluntary control, mostly smooth muscle

ganglion

a collection of neuron cell bodies in PNS

dorsal root ganglia

contain cell bodies of sensory neurons entering the spinal cord via dorsal root

preganglionic neurons of sympathetic system

emanate from thoracic and anterior lumbar regions of spinal cord

preganglionic neurons of parasympathetic system

emanate from various cranial nerves at anterior end (brain) and sacral regions in the posterior (lower end of spinal cord)

autonomic division

increases/decreases blood pressure by regulating heart rate and diameter of blood vessels, can command contraction and relaxation of muscles that form the intestinal and vascular walls (smooth muscle), dilate/constrict pupils, stimulate/inhibit digestion, sympathetic- fight or flight, parasympathetic- rest and digest

cranial nerves

numbered by Galen, anterior to posterior, originate from brain stem (III-XII) but also cerebrum (I-II), and mainly innervate the head, relay info from the brain to regions of head, neck, and GI track

blastulation

raw, undecided cells, where ES cells come from, blastocysts can become anything

neurodevelopment days 2-10

cleavage to blastocyte, zygote divides into many cells

neurodevelopment days 11-15

gastrulation and neural induction, formation of three primary “derm” layer

gastrulation

embryo forms 3 layers, mesoderm (middle), ectoderm (top)- nervous, endoderm (bottom)

ectoderm

nervous system and skin, formed before gastrulation

endoderm

internal organs, formed before gastrulation

mesoderm

muscle and skeleton, forms during gastrulation

neural induction

decide to become nervous system, mesoderm tells neurectoderm to become neural fate (nervous system)

noggin

morphogen, inhibits BMP4 (tells cells to become skin), main neural inducer produced by mesoderm, without the neurectoderm would become epidermis (skin), used to help convert ES to neurons in culture

morphogen

substance governs the pattern of tissue development in the process of pattern formation, establishing positions of cell types within tissue

neurodevelopment days 16-25

neurulation and formation of neural tube, neural crest forms giving rise to sensory neurons

neurulation

neural tube formation - becomes brain and spinal cord

neural crest cells

break off during closure of neural tube - becomes sensory neurons, autonomic neurons, gliai cells, Schwann cells, and other

neurodevelopment days 26+

organogenesis and brain patterning

anterior-posterior (AP) patterning

front-back, divides into forebrain, midbrain, hindbrain, spinal cord

AP patterning day 28

3 primary vesicles appear- prosencephalon (forebrain), mesencephalon (mindbrain), and rhombencephalon (hindbrain)

retinoic acid (RA)

morphogen that controls AP patterning, small lipophilic, acts as posteriorizer- spinal cord/brainstem

dorsal-ventral (DV) patterning

top-bottom, tectum, dorsal- sensory, tegmentum, ventral- motor

notochord

releases SHH, eventually becomes part of the bone and muscle of spinal cord

sonic hedgehog

morphogen, controls DV patterning, SHH protein, initiates the formation of nervous system and floor plate, ventralizer

Shh gradient

high amts- ventral motor neurons, low amts- dorsal interneurons, gradient helps with DV subregions that rises to neurons

floor plate

also expresses SHH along with notochord, gradient

neurodevelopment day 36

forebrain (prosencephalon) expands and adds telencephalic vesicles, eyes begin to form, hindbrain (rhombencephalon) develops into metencephalon which is the futures pons and cerebellum, and myelencephalon which is the future medulla, cranial nerves begin to form, 3rd and 4th ventricles

differentiation of the telencephalon

telencephalic cerebral hemispheres swell and envelop the diencephalon, optic cup develops from the optic vesicle that emanates from the diencephalon which gives rise to the retina

retina

only organ in the CNS

neocortex

dorsal telencephalon, highly expanded in primates and humans

basal (ventral) telencephalon

includes basal ganglia (striatum- including substanra nigra- dopametrigic) and amygdala

diencephalon

becomes the thalamus and hypothalamus

cortical white matter

down, descending info, motor commands

internal capsule

project up to cortex, ascending information, sensory commands, peripheral to cortex

forebrain

seat of perceptions, conscious awareness awareness, cognition, and voluntary actions

projections from axons from the thalamus

via the internal capsule ex. right foot thumbtack, relayed to left cortex by left thalamus via left internal capsule

corpus callosum

how the two hemispheres communicate, white matter tract

cortical neurons

send axons back to brainstem through internal capsule, or project up to spinal cord, or project to basal ganglia to control movemnt

basal ganglia

only part of CNS that uses the term ganglia

neurodevelopment days 49-90

forebrain (prosencephalon) develops into the diencephalon which is the future thalamus and hypothalamus and the telencephalon which is the future cerebral cortex and develops rapidly and covers the diencephalon

neurodevelopment months 6-9

gyri and sulci form, cerebellum develops folia