Nervous System Overview, Neurons, Neuroglia

Front 1

what are the characteristics of afferent neurons?

Back 1

sensory, input
carry signals into CNS

Front 2

what are the characteristics of efferent neurons?

Back 2

motor, output
carry signals from CNS

Front 3

define interneurons

Back 3

interconnect groups of neurons in CNS
-process signals between afferent and efferent

Front 4

define CNS

Back 4

brain and spinal cord
within cranium and vertebral column

Front 5

define PNS

Back 5

nerves and ganglia
throughout body

Front 6

what structures make up the forebrain?

Back 6

diencephalon
telencephlon
brainstem

Front 7

what structures make up telencephlon?

Back 7

basal ganglia, limbic system, olfactory system and neocortex or cerebral cortex

Front 8

what structures make up the diencephalon?

Back 8

- includes thalamus and hypothalamus

Front 9

what structures make up brainstem? what activities does it coordinate?

Back 9

medulla, pons and midbrain
-receives sensory input from head and neck, provides motor control to muscles of head and neck, autonomic control to muscles of head, neck and visceral organs
integrates vital functions such as consciousness, sleep, respiration, circulation, muscle tone and eye movement

Front 10

what are some important roles of cerebellum?

Back 10

coordinating and fine-tuning muscle activity, learning automatic movements

Front 11

what direction runs rostral? caudal?

Back 11

rostral- towards front; anterior
caudal- towards back; posterior

Front 12

what direction is cephalad?

Back 12

towards nose

Front 13

what direction is caudad?

Back 13

towards butt

Front 14

define visceral (autonomic) motor component. what are the 3 components?

Back 14

complex which controls smooth muscle, cardiac muscle and secretory glands
-sympathetic nervous system
-parasympathetic system
-enteric nervous system

Front 15

define sympathetic nervous system

Back 15

system of arousal which responds to stress or demand for activity
fight vs flight

Front 16

define parasympathetic nervous system

Back 16

system of maintenance and repair which controls homeostatic functions necessary for well being

Front 17

define enteric nervous system

Back 17

controls digestive process and coordinates contraction of gut

Front 18

what cells are afferent neurons of PNS derived from?

Back 18

neural crest cells

Front 19

what are the cells from CNS derived from?

Back 19

neuroectoderm

Front 20

what is the term for a clump of neurons in PNS? in CNS

Back 20

ganglia- PNS
nuclei- CNS

Front 21

gray vs white matter?

Back 21

gray matter- cell bodies
white matter- axonal tracts

Front 22

describe bone protection of PNS and CNS

Back 22

PNS- outside of bones
CNS- protected by bone- within skull and vertebral canal

Front 23

what does spinal cord include?

Back 23

sensory axons, motor neuron cell bodies, pre-ganglionic sympathetic and parasympathetic neurons, interneurons, ascending sensory and descending motor tracts

Front 24

what is function of neurons?

Back 24

responsible for electrical signal generation and transmission

Front 25

what are the glial membranes that wrap around axons?

Back 25

myelin

Front 26

how is gray matter organized in CNS

Back 26

into clusters of funtionally related neurons and their dendrites called nuclei
-on surface of hemispheres and cerebellum gray matter is organized as layers of cell bodies

Front 27

define outward fold of cortex and the furrow between these
what is the term for these folds in cerebellum?

Back 27

fold- gyrus
furrow- sulcus
cerebellum folds- folia

Front 28

what are the 4 lobes of the brain; where is central sulcus located?
lateral fissure?

Back 28

frontal, parietal, occipital, temporal
central sulcus- frontal and parietal lobes
lateral fissure- temporal and frontal, parietal

Front 29

what is the border of occipital lobe?

Back 29

from parieto-occipital sulcus and preoccipital notch

Front 30

define fasicles, cortex, nerves

Back 30

fasicles- tracts, bundles of axons in CNS
cortex- layers of neurons
nerves- bundles of axons in PNS

Front 31

what is the term for a cell body? describe it and its function

Back 31

soma
metabolic support, abundant RER, most mitochondria
process information

Front 32

function of dendrites
axons

Back 32

dendrites- receive information from other neurons
axons- send out info

Front 33

dendritic spine function

Back 33

where receptor is located
specialized site for synaptic contact

Front 34

define synaptic bouton

Back 34

vesicles contain neurotransmitters
-end of axon branch, terminal

Front 35

what do dendrites contain

Back 35

fine filaments, mitochondria, some RER and free ribosomes

Front 36

define orthograde

Back 36

molecules synthesized in some are transported to synaptic endings

Front 37

where does self-regenerating wave of electrical activity propagate from? (pt of initiation at cell body)

Back 37

axon hillock

Front 38

what is the motor molecule for anterograde transport? retrograde?

Back 38

kinesis
dynein- retro

Front 39

what is significance of extracellular fluid in synaptic cleft?

Back 39

provides diffusion path for transmitter between two cells

Front 40

what is characteristic of sensory system receptor neurons? (connections)

Back 40

branch out and make multiple, divergent connections with neurons
stimulus activates sensory neurons which sends to many sources

Front 41

what is characteristic of motor neurons? (targets of what?)

Back 41

motor neurons are targets of progressively converging connections; to elicit single response

Front 42

what 2 processes do bipolar cells give rise to?

Back 42

oval-shaped soma that gives rise to 2 processes
-dendrite that conveys info from periphery of body and axon that carries info towards CNS

Front 43

what are characteristics of multipolar neuron- motoneuron

Back 43

single axon and typically many dendrites emerging from various points around cell body

Front 44

define unipolar neurons

Back 44

single process arising from its soma- rare in mammalian; single process arises from its soma and soon bifurcates into pair of branches- one into peripheral tissue and other entering spinal cord

Front 45

define characteristics of purkinje cell

Back 45

branch extensively in one plane but little at right angles

Front 46

what is branching like in motor neurons?

Back 46

branch symmetrically

Front 47

define nissl bodies

Back 47

neurons contain abundant RER for protein synthesis required to form and maintain cells with such complex geometry
RER packed in compact clusters called nissl bodies (stains violet)

Front 48

define chromatolysis

Back 48

disintegration of chromophil substance in body of nerve cell which may occur after exhaustion of cell or damage to peripheral process

Front 49

eg of morphologic changes in neuronal cell body due to damage

Back 49

disruption and dispersion of nissl bodies (chromatolysis) associated with rearrangement of cytoskeleton and marked accumulation of intermediate filaments

Front 50

what is the pigment in a human brain? where is it located?

Back 50

neuromelanin- naturally occuring dark pigment in substantia nigra, pars compacta, locus coeruleus, dorsal motor nucleus of vagus nerve and median raphe nucleus of pons

Front 51

believe neuromelanin aids in synthesis of what?

Back 51

neurotrasmitters- dopamine, norepinephrine and serotonin

Front 52

what is characteristic of parkinsons? how is neuromelanin related?

Back 52

parkinsons- loss of dopamine
loss of neuromelanin postmortem shows signs of parkinsons

Front 53

what percentage of cells in brain neuroglia

Back 53

90

Front 54

what is the function of neuroglia?

Back 54

maintain ionic milieu of nerve cells
modulate synaptic action (controlling uptake of NT in cleft)
provide scaffolding for some neural development
aiding in recovery from neural injury
-overall maintaining homeostasis

Front 55

what do glia differentiate from in PNS? in CNS?

Back 55

PNS- from gliobasts in neural crest
CNS- from gliobasts in ventricular zone of neural tube

Front 56

how does differentiation in neurons differ from in glia?

Back 56

in neurons terminated, in glia retain ability to proliferate under certain stimuli

Front 57

what are 4 main types of glia cells?

Back 57

astrocytes, oligodendrocytes, ependymal cells, microglia

Front 58

what is function of astrocytes

Back 58

maintain internal environment around neurons (star shaped)
most abundant

Front 59

what is function of oligodendrocytes

Back 59

myelinate axons
can myelinate multiple

Front 60

what is function of ependymal cells

Back 60

line the fluid filled ventricular spaces of brain

Front 61

what is function of microglia

Back 61

phagocytic response to microbes

Front 62

what are 2 types of astrocytes and what are their function?

Back 62

protoplasmic- stubbier processes abundant in gray matter
fibrous- long thin processes with abundant IF and abundant in white matter

Front 63

describe number of processes in astrocytes and oligodendrocytes

Back 63

many processes in asrocytes; oligodendrocytes few

Front 64

what is synonymous to oligodendroctyes in PNS

Back 64

schwann cells

Front 65

what is main function of astrocyte and how

Back 65

limit spread of electric fields from active to inactive neurons
-take up ions from ECF, spread through many glial cells via gap junctions, released to capillaries

Front 66

what pumps to astrocytes membranes have?
REVIEW pg 4,5, 6

Back 66

abundant Na+/K+ pump
-astrocytes coupled together by gap junctions through which K+ ions spread through many cells

Front 67

what is the process of myelination

Back 67

-glial cell extends plasma membrane to wrap around axon segment
-tucking of plasma membrane under other
-forms on surface and pushes old membranes out
-membranes fuse forming thinner intraperiod line

Front 68

define internode

Back 68

each segment of myelin is created by this single glial cell

Front 69

what is located between each successive myelin segment?

Back 69

node of ranvier

Front 70

list and define myelin proteins

Back 70

protein 0- integral membrane protein in schwann cells
proteolipid protein- integral membrane protein in oligos
myelin basic protein- cytoplasmic, essential for compaction
-proteins interact at extracellular domains to promote adhesion

Front 71

what is main function of myelin?

Back 71

insulator of axon membrane resulting in large inc in action potential conduction velocity
-ion channels become concentrated only at nodes of ranvier

Front 72

what is significance of nodes of ranvier?

Back 72

energy demands for restoration of ion concentration is reduced in myelinated fibers

Front 73

in myelin-related disorders, what does breakdown of myelin result in?

Back 73

slowing of action potential propagation- when large areas of axon lose myelin, propagation is stopped entired due to lack of V-gated channels in bared internodal areas

Front 74

describe inflammatory theory on aging

Back 74

-circulating cytokine levels are elevated in aged individuals
-body is less able to handle infection during aging
-inc microglial activation in aged brain

Front 75

describe role of microglia in immune response

Back 75

-in absence of injury, stay dormant
-differentiate into motile cells and migrate toward injury sites
-expess macrophage like molecules
-surround damaged cells or microbes and isolate them from other tissues

Front 76

what do microglia secrete? function? what are the factors?

Back 76

-cytokines secreted that activate astrocytes and attract peripheral macrophages to injury site
-ROS, proteases, cytokines

Front 77

what are functional consequences of inflammation/microglial activation?

Back 77

-loss of regulatory signals from neurons/neuronal damage or dysfunction
-neurons rapidly change their gene expression and stimulate nearby microglia and astrocytes

Front 78

what is the role of astrocytes in homeostasis involving uptake of ions

Back 78

maintains ionic balance of ECF in spite of neuronal activity- astrocyte membranes have abundant NA+/K+ pumps
-astrocyte depolarized when exposed to inc in extracellular K, depolarization spreads by gap junctions to neighboring cells and could activate release of K at capillaries

Front 79

what is function of end feet

Back 79

glial processes loosely surround CNS capillaries

Front 80

what is function of radial glia

Back 80

guidance for migrating neurons during development

Front 81

what type of glial cell is involved in inducing formation of tight junctions?

Back 81

astrocytes

Front 82

what are ependymal cells derivatives of? where are they located?

Back 82

highly specialized derivatives of astrocyte stem line
-form surface lining of cavities in brain- central canal of neural tube in embryo and ventricles in adult brain

Front 83

what is the shape of the ependymal cells

Back 83

single layer of cuboidal cells with motile cilia in the ventricular side
-cilia help circulate CSF

Front 84

what is the role of ependymal cells in choroid plexus?

Back 84

secrete CSF