cells of the nervous system (1.2)

Question 1

central nervous system vs peripheral nervous system

Answer 1

cns: all incased in bone (brain and spinal cord); interprets sensory input, movement, and complex cognitive processes
pns: located outside of the skull and spine; brings sensory information to cns, carries motor signals out of the cns

Question 2

neurons

Answer 2

specialized cells for the reception, conduction, and transmission of electrochemical signals

Question 3

flow of information (dendrites, cell body (soma), axon, myelin, cell membrane, synapse)

Answer 3

dendrites: receives input from other neurons
cell body (soma): processed information; where proteins are made
axon: transmits the output of processing to other neurons
myelin: the fatty insulation around many axons
cell membrane: semi-permeable membrane that encloses the neuron
synapse: gap between adjacent neurons across which chemical signals are transmitted

Question 4

similarities (5) and differences (2) of the nucleus in comparison with other cells

Answer 4

similarities: nucleus (holds genetic information), ribosomes (where proteins are synthesized), mitochondria (makes ATP/energy), membrane (protects the cell), microtubules (“train tracks” that transport material)
differences: stop dividing after birth; have specialized structures to receive and transmit information (dendrites and axons)

Question 5

cell membrane (lipid bilayer, ways for info to talk (channel and signal proteins))

Answer 5

lipid bilayer: two layers of fat molecules with embedded proteins; selective permeability
channel protein: form aqueous pore so liquids can pass
signal protein: know what is there but nothing passes

Question 6

visualizing neurons (Golgi stain, Nissl stain)

Answer 6

Golgi stain: silver stains some neurons black; allows for visualization of shape and connectivity of neurons (CNS)
Nissl stain: selectively stains cell bodies (nuclei and ribosomes); indicates the number of neurons in an area

Question 7

visualizing neurons (tract tracing techniques (anterograde and retrograde))

Answer 7

anterograde: trace axons projecting away from cell bodies
retrograde: trace axons projecting into an area of cell bodies

Question 8

pontine nuclei

Answer 8

nuclei of the pond involved in motor activity; gives information to cerebellum from cerebral cortex

Question 9

electron microscopy vs two photon microscopy

Answer 9

electron microscopy: provides information about the details of neuronal structure (3D —> axons tend to synapse to dendritic spines)
two photon microscopy: uses focused laser beams to scan living tissue (cannot see synapse; key to understanding how NS works); dendritic spines remodeled over time

Question 10

neuroanatomical structures

Answer 10

clusters of cell bodies: nuclei and grey matter (CNS); ganglia (PNS)
bundles of axons: tracts and white matter (CNS); nerves (PNS)

Question 11

unipolar vs multipolar neurons

Answer 11

unipolar: one process extending from cell body
multipolar: more than two processes extending from cell body

Question 12

functional classes of neurons (sensory, motor, interneuron)

Answer 12

sensory: unipolar (PNS); information from tissues and organs
motor: multipolar (PNS); information to effector cells
interneuron: multipolar (CNS) with short axon or no axon; integrate neural activity within a single brain structure

Question 13

connections between neurons directions (afferent vs efferent) and type (2)

Answer 13

directions: afferent (approaching) and efferent (exiting)
type: axon-dendrite (most common) and axon-soma, axon-axon, dendrite-dendrite

Question 14

functions of glial cells

Answer 14

helper cells (outnumber neurons); provide structural/metabolic support to neurons

Question 15

classes of glial cells (5)

Answer 15

Oligodendrocytes: (CNS) create myelin sheaths around axons; do not allow regrowth; myelinate everything in their vicinity
Schwann cells: (PNS) create myelin sheaths; can guide axons regeneration (regrowth) after damage; myelinate one part of one neuron
Microglia: (CNS) respond to injury or disease by multiplying, engulfing cellular debris or entire cells, and triggering inflammatory responses (white blood cells do this in pns)
Astrocytes: (CNS) star-shaped; control microenvironment (i.e. cover blood vessels, contract or relax blood vessels); contact many neurons; maintain proper chemical state outside; send nutrients (glucose); form barrier to unwanted substances; control blood flow
Satellite cells: (PNS) flattened shape; control microenvironment; contact one neuron; maintain proper chemical state outside; send nutrients (glucose)

Question 16

tripartite synapses (astrocytes and satellite cells participate)

Answer 16

modulate neurotransmission by responding to neurotransmitters and secreting gliotransmitters