Neural Substrates Exam 2

UMN

1st order, brain or brainstem origination, exert control over LMN

LMN

2nd order, spinal or cranial nerves, transmit to the muscle

glial cells

support and protect nerve cells role in communication

- framework for neurons to function, remove debris after neuron death, myelin sheath and CSF production

- processes= tentacles

neurons

basic functional unit of the central nervous system

- axons and dendrites

astroctye

- CNS glia, support

oligodendrocyte

- CNS glia, insulation, myelination

microglia

- CNS glia, immune surveillance, phagocytosis

ependymal cell

- CNS glia, creating CSF

satellite cell

- PNS glia, support

schwann cell

- PNS glia, insulation, myelination

astroctye function

- star shaped, multiple processes extend from cell

- provides structure/ support

- attach/ interact with neurons, blood vessels or the pia matter

- contribute to maintaining the blood brain barrier

blood brain barrier

thick layer of cells in brain capillary walls to prevent substances from entering the brain, preventing non nutritive contamination, BBB prevents other contamination

oligodendrocytes function

- few processes extend from cell body

- wraps neuron axon in myelin

- covers multiple axon segments may or may not cover segments of the same axon

schwann cells function

- single cell surrounds one neuron axon segment

Multiple scelrosis

CNS

- body marks myelin as an "enemy"

- destroys myelin, scar tissue

- somatic and autonomic impairments

Guillian Barre Syndrome

PNS

- autoimmune response, may follow respiratory or digestive tract infection

- sudden onset in lower extremities progresses to upper extremities

- cause unknown

microglia

- smallest glial cells

- digest damaged/ diseased cells and dead nuerons

- act like macrophages in other parts of the body

ependymal cells

- assists with filtering blood to make CSF

- single layer tightly compact cells; looks like epithelial cells

- has cilia layer that moves CSF through the ventricles

- line the ventricles

choroid plexus

network of capillary vessels in the ventricles covered by thing layer of ependymal cells that produce CSF

what are the types of neurons

- sensory neurons, motor neurons, interneurons

interneuron

received information, processes, sends info)

cell body= soma

control center, nucleus

axon

one per nucleus, outgoing signal, electrical signal conduction to action potential

dendrites

incoming signals

axon terminals

neurotransmitter location

node of ranvier

myelin sheath gap, thought to increase signal transmission speed

where are neurons in CNS function

white matter: myelinated axons

gray matter: nerve cell bodies, dendrites, glia cells, axon terminals

where are neurons in CNS location

brain: thin layer of gray matter on surface and found in small clusters; white matter deeper in cortex

spinal cord: gray matter in the H - shaped center, white matter surrounds

depolarization

strong perturbation evokes gated channels opening and ion movement

action potential

if depolarization reaches threshold of change from -70 mV to -55 mV then action potential is intiated at the axon hillock

conduction

process of how a neuron body communicates with its axon terminals, electrical signal traveling down an axon = action potential

resting potential

neuron is polarized, ion channels (protein structure in membrane) are closed has minimal exchange of Na+ and K+

depolarization

when resting potential of -70mV becomes more positive about +30 mV evokes action potential approx -55mV opens sodium voltage gated ion channels, Na+ rushes into the sodium voltage gated channel making intercellular more positive, the sodium channel then closes

repolarization

occurs by K+ channel opening to flow out, restores intercellular to its resting potential level of -70 mV

refractory period

if repolarizing it undershoots and becomes too negative during this brief period it cannot fire another action potential

sodium potassium pump functions

maintaining sodium to potassium gradient, cells need energy to provide influx

sodium potassium pump non gated channels

extracellular Na+ enters cell, intracellular K+ leaves cell

Na+ K+ Pump

drives out 3 Na+ ions and intakes 2 K+ ions (voltage gated channel), keeps intracellular polarity with more negative charge