Nervous System

Front 1

nervous system divisions

Back 1

central nervous system - brain + spinal cord

peripheral nervous system - all nerves + ganglia outside of CNS

Front 2

nervous system cell groups

Back 2

neurons - transmitting cells

neuroglia - supporting cells, different types for CNS & PNS

Front 3

Neuroglia

Back 3

"nerve glue", brace, protect, myelinate neurons. don't transmit signals

Front 4

CNS Neuroglia

Back 4

Microglia - act as phagocytes

Oligodendrocytes - myelinate neurons

Astrocytes - control chemical environment around neurons

Ependymal Cells - circulate cerebrospinal fluid

Front 5

PNS Neuroglia

Back 5

Schwann cells - myelinate neurons

Satellite Cells - surround neuron cell body

Front 6

Neurons

Back 6

Cell body - neurofibrils, nissl bodies

Neuron processes - dendrites, axon

Front 7

Neurofibrils

Back 7

intermediate filaments in neuron that provide tensile strength

Front 8

Nissl Bodies

Back 8

specialized ER - protein synthesis

Front 9

Cell Body Clusters

Back 9

CNS - nuclei

PNS - ganglia

Front 10

Dendrites

Back 10

receive signals to cell body - can be more than one

Front 11

Axon

Back 11

generate and transmit action potential - only one per neuron - can have many branches

Front 12

Axon features

Back 12

Axon hillock - junction b/w cell body and axon

Axon terminals - ends of axon, where neurotransmitters are stored

Myelin Sheath - whitish fatty proteins covering & insulating some axons

Front 13

Neuron Properties

Back 13

Excitability - ability to respond to stimuli and convert into nerve impulses

Conductivity - ability to transmit impulse to other neurons, muscles or glands

-exhibit longevity

-amitotic

Front 14

Myelin

Back 14

whitish fatty proteins covering some axons - insulate fibers and increase speed of transmitting nerve impulse

Front 15

Myelin Sheath (PNS)

Back 15

concentric rings of plasma membrane of schwann cell wrapped around axon

Front 16

Neurilemma

Back 16

last concentric ring of schwann cell myelin sheath containing nucleus

Front 17

Nodes of Ranvier

Back 17

gaps between nodes in myelin sheath

Front 18

Structural classification of neurons

Back 18

based on number of processes extending from cell body

unipolar - single process extending from cell body - divides into central and peripheral prcoess

bipolar - 2 processes - one axon, one dendrite

multipolar - many processes - one axon, many dendrites

Front 19

Functional classification of neurons

Back 19

Based on direction of impulse in relation to CNS

sensory(afferent) neurons - carry impulse from sensory receptors towards CNS

motor(efferent) neurons - carry impulse from CNS to organs, muscles, and glands

Association neurons - conduct impulses within CNS

Front 20

Nerve

Back 20

bundle of axons in PNS wrapped in connective tissue

Front 21

Tract

Back 21

bundle of axons in CNS wrapped in connective tissue

Front 22

Mixed/Sensory/Motor nerves

Back 22

Mixed - both efferent/afferent processes

Sensory - only afferent processes

Motor - only efferent processes

Front 23

Nerve structure

Back 23

Axon is covered by endoneurium, group of endoneurium covered nerve fibers covered by perineurium called a fascicle, group of fascicles with blood vessels covered by epineurium froms a nerve (same for tract)

Front 24

Nerve Impulse Steps

Back 24

-resting state -> stimulation/depolarization -> generation of nerve impulse -> repolarization -> return to resting state

Front 25

Resting membrane potential

Back 25

High Na+ concentration outside of cell, high K+ concentration inside of cell -> more negative on inside than outside

Front 26

Depolarization

Back 26

Neuron activated by threshold stimulus, sodium gates open and Na+ enters cell -> cell interior becomes less - and eventually +

Front 27

Generation of Action potential

Back 27

After certain charge is reached - the threshold potential - an action potential is generated in an all or none fashion - called a nerve impulse

Front 28

Repolarization

Back 28

Potassium gates open and K+ leaves the cell - membrane repolarizes

Front 29

Return to resting state

Back 29

The sodium potassium pump reestablishes the concentration gradient and the resting membrane potential - allows neuron to fire again

Front 30

Absolute refractory period

Back 30

sodium gates are still open - unable to create another action potential

Front 31

Relative refractory period

Back 31

when going through repolarization the sodium gates are closed - a very strong stimulus can generate another action potential