BIO 114 - Exam #3

nuclei

clusters of neuron cell bodies in CNS

ganglia

clusters of neuron cell bodies in PNS

nerves

bundles of neuron processes in PNS

tracts

bundles of neuron procceses in CNS

myelin

a whitish protein-lipid substance that speeds nerve impulse transmission

what happens when myelin becomes damaged?

the electrical signals traveling along your nerves are slowed, disrupted, or blocked completely

 What glial cells produce myelin in the CNS and PNS?

oligodendrocytes = CNS; schwann cells in PNS

astrocytes

blood-brain barrier that separates CNS from circulation; provides structure and repairs damages neural tissues

oligodendrocytes

forms thin sheet of myelin that wraps around an axon, electrically insulating it to increase speed that action potentials travel

microglia

engulf cellular wastes and pathogens

ependymal cells

ine cavities in CNS that are filled with CSF, create CSF in some parts of CNS, and circulate CSF within and around CNS

satellite cells

 surround and support neuron cell bodies in PNS

schwann cells

myelinates one segment of single axon; can enclose portions of several unmyelinated axons

white matter

regions of brain and spinal cord with dense collections of myelinated fibers; associated with tracts

gray matter

neuron cell bodies and nonmyelinated fibers, a lot of it in outer cortex of brain and inner part of spinal cord; associated with nuclei

electrical voltage

potential energy (measured in V or mV) generated by separated charge

The resting membrane potential (the voltage across the cell membrane when the cell is at rest) is typically what, and where is the charge more negative?

Negative, meaning the charge is more negative on the inside of the cell compared to the outside of the cell

Can ions, like Na+ and K+, easily travel across the phospholipid bilayer of the cell membrane?

These ions cannot easily travel across cell membranes without large channel proteins called ion channels. Chemical gradients of ions create electric potential, especially Na+ and K+

concentration gradients

 ions diffuse from where they are at high concentration to where they are low concentration

electrical gradients

ions move towards opposite electrical charges and away from like electrical charges

threshold voltage

voltage at which voltage-gated ion channels open; this level of depolarization triggers an action potential

hyperpolarization

occurs when membrane potential becomes more negative, and this decreases the likelihood of an action potential

depolarization

 occurs when membrane potential becomes more positive, or you could think of it as less negative, and this increases the likelihood of an action potential. It occurs when positively charged ions move into the cell.

all or none law

action potential either happens completely or does not happen at all

repolarization

 occurs when positively charged ions move out of the cell, causing the membrane voltage to fall back to its normal negative voltage

thick axon or a myelinated axon

conducts action potentials faster

synapse

A junction between 2 neurons or between neuron and effector cell

neurotransmitter

A chemical that binds to receptors on the next neuron or effector cell