Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
314 Cards in this Set
- Front
- Back
|
What makes up the central nervous system?
|
brain, brain stem (medulla, pons, midbrain), spinal cord
|
|
|
What makes up the peripheral nervous system?
|
31 pairs of spinal nn
12 pairs of cranial nn |
|
|
How many cervical spinal nn are there?
|
8
|
|
|
how many thoracic spinal nn are there?
|
12
|
|
|
how many lumbar spinal nn are there?
|
5
|
|
|
how many sacral spinal nn are there?
|
5
|
|
|
how many coccygeal nn are there?
|
1
|
|
|
What makes up the autonomic nervous system?
|
sympathetic and parasympathetic output
|
|
|
What are the 4 fundamental processes of the NS?
|
1. reception of sensory stimulation (environmental awareness)
2. analysis of info (stimuli) 3. transmission of the motor reponse to analyzed info 4. initiation of an effector response |
|
|
What are 2 types of sensory stimulation?
|
special senses
general sensation |
|
|
how do enviromental stimuli get to the CNS?
|
by PNS
|
|
|
What percentage of analyzing stimuli occurs in the CNS?
|
99%
|
|
|
What is the simplest form of analysis of info?
|
reflex activity
|
|
|
Where in the NS does transmission of the motor response occur?
|
PNS (sometimes ANS)
|
|
|
DEFINE afferent
|
info coming into CNS (always sensory)
|
|
|
DEFINE efferent
|
info going away from CNS (always motor)
|
|
|
How much of the Oxygen carried in the blood is used by the NS?
|
20-40%, therfore nuerons are sensitive to O2 deprivation
|
|
|
What specific NS cells and areas of the brain can undergo mitosis?
|
glial cells, hippocampus and olfactory complex
|
|
|
DEFINE somatic organization
|
a specific body part is controlled by a specific location in the brain
|
|
|
what are the 2 divisions of the somatic organization?
|
somatosensory strip (post central gyrus)
motor strip (pre central gyrus) |
|
|
What other body systems work with the NS in order for it to work properly?
|
cardiovascular, endocrine, metabolic, digestive, and immune systems.
|
|
|
What are nonneuroglial cells?
|
non impulse transmitting, non supporting cells, collectively called the ependyma (choroid plexi), located at the roof of the ventricles
|
|
|
FUNCTION nonneuroglial cells
|
produce cerebrospinal fluid (CSF)
|
|
|
What are neuroglia cells
|
non impulse transmitting, occur in CNS and PNS, located in spaces not occupied by blood cells and neurons
|
|
|
how much more abundant are neuroglia cells compared to neurons?
|
5-50x
|
|
|
FUNCTION neuroglia cells
|
1. acts as "connective tissue" for the brain
2. involved with synapse formation 3. helps form Blood Brain Barrier (BBB) 4. use phagocytosis to clean up cellular debris to jdecrease infection 5. able to mitose 6. provides chemicals/molecules for neurons (chem. influence neurons during neurodev. and move neurons to specific part of brain) 7. have an inhibitory effect on NS mitosis |
|
|
What are the 4 types of glial cells?
|
astrocytes
oligodendrocytes schwann cells microglia |
|
|
What are the 2 types of astrocytes?
|
fibrous astrocytes
protoplasmic astrocytes |
|
|
Where are fibrous astrocytes found?
|
in white matter
|
|
|
FUNCTION fibrous astrocytes
|
*form blood brain barrier (BBB) by forming links between capillaries and the neurons of the brain
*limited involvement in phagocytosis *metabolically active: provide metabolic support to neurons by regulating the ionic concentration of the neuronal environment *inhibit or promote the outgrowth of neuronal cellular processes during development by synthesizing and releasing trophic and adhesion molecules. these also tell neurons when underused and die off during childhood *provide transient scaffolding to developing neurons during gestation (neurons migrate) *form gliomas |
|
|
What is the blood brain barrier?
|
specialized barrier formed by endothelial cells and fibrous astrocytes which prevents large proteins and charged molecules from entering the CNS
|
|
|
how do endothelial cells form a BBB?
|
cells that line the capillaries and mediate diffusion of substances from blood directly into interstitial fluid
|
|
|
how do fibrous astrocytes form the BBB?
|
these cells have processes with "end-feet" which cover most of the capillary surfaces that influence passage of substances between capillaries and neurons of the brain
|
|
|
what can go through the BBB?
|
glucose, O2, electrolytes, insulin, thyroxin
|
|
|
what CANNOT go through the BBB?
|
*molecules that are too big
*serum proteins (ie-albumin) because these cause brain swelling *penicillin (therefore cannot us to rx brain infection) |
|
|
where are protoplasmic astroctyes found?
|
grey matter
|
|
|
FUNCTION protoplasmic astrocytes
|
isolate receptive surfaces of neurons by separating/insulating neurons and reduce random flow of neuronal activity
|
|
|
Where are oligodendrocytes located?
|
white matter of CNS
|
|
|
FUNCTION oligodendrocytes
|
myelinate neurons by producing myelin (phospholipid) that forms concentric circle around an axon to make a sheath.
can myelinate more than one axon. |
|
|
Where are schwann cells located?
|
white matter of PNS
|
|
|
FUNCTION schwann cells
|
myelinate cellular processes of neurons in PNS
*function like oligodendrocytes to laminate neurons for insulation |
|
|
What does the absence of either oligodendrocytes or schwann cells cause?
|
increase chance of neurons shorting out/over interaction (ie-MS)
|
|
|
where are microglial cells found?
|
normally in CNS
|
|
|
FUNCTION microglial cells
|
NONPATHOLOGICAL
*maintain integrity of synapses (provide nutrients) *maintain structural support PATHOLOGICAL *become active under inflammatory condition phagocytose bacteria via enzematic digestion (antibodies) |
|
|
What diseases have been linked to malfunction and decrease amount of microglial cells?
|
general dementia
alzheimers Parkinsons schizophrenia |
|
|
What are the only cells in the NS that can produce an action potential
|
neurons
|
|
|
Where is the nucleus of a neuron found?
|
in the middle of the cell body
|
|
|
What surrounds the nucleus?
|
double layer nuclear membrane which contains nuclear pores and the outer membrane is continuous with the ER
|
|
|
What is contained within the nucleus?
|
46 chromosomes and DNA
nucleolus |
|
|
FUNCTION nucleolus
|
ribosomal RNA is sythesized and produced
|
|
|
FUNCTION mitochondria
|
energy production
|
|
|
What is the only nutrient that neurons will use for energy? can neurons store it?
|
glucose or glucose products;
no |
|
|
FUNCTION lysosomes
|
difest substances that originated in and out of the cell
|
|
|
what are lysosomes?
|
double membrane bound vesicles that contain hydrolytic enzymes
|
|
|
What are 2 ways for cells to die?
|
necrosis
apoptosis |
|
|
DEFINE necrotic cell death
|
lysosomes rupture and digest the contents of the cell
|
|
|
DEFINE apoptotic cell death
|
preprogrammed cell breakdown. this is a natural process in which some cells are programmed to die off, but when it occurs to early it can cause senile dementia, also responsible for "pruning" of neurons during childhood
|
|
|
Where are the rough ERs located in a neuron?
|
cell body and dendrites
NOT in axon or axon hillock |
|
|
What is the rough ER?
|
a flattened, double-layered membrane structure lined with ribosomes
|
|
|
FUNCTION rough ER
|
translation and synthesis of general proteins occurs in rough ER (enzymes, actin, myacin, neurofilaments, microfilaments, plasma membrane proteins)
|
|
|
FUNCTION smooth ER
|
channel proteins produced in the rough ER to the Golgi apparatus
|
|
|
FUNCTION golgi apparatus
|
receive protein molecules from smooth ER that are then processed through the golgi apparatus where proteins are modified, sorted, and packaged into specific membrane-enclosed vesicles
|
|
|
Where to the vesicles go after being packaged by the golgi apparatus?
|
cell membrane (cell growth)
neurotubules (further transported from there) |
|
|
FUNCTION cytoskeleton/fibrillar protein
|
gives shape and support to neuron through fibrillar proteins
|
|
|
What are the 3 types of fibrillar proteins?
|
microfilaments
microtubules neurofilaments |
|
|
What are microfilaments primarily made up of?
|
actin
|
|
|
Where are actin molucules located within the neuron?
|
close to cell membrane and are in constant flux
|
|
|
DEFINE growth cone production
|
the use of actin to allow dendrites and axons to grow, forming a cone at the end dendrite/axon throughout development, so neuron can bet from pt a-->b
|
|
|
DEFINE microtubules
|
long tubular structures that form tracts to transport metabolites, vesicles and ions
|
|
|
which is the largest of the 3 fibrillar proteins?
|
tubulin
|
|
|
Where are microtubules located?
|
in the cytoplasm, axon and dendrites
|
|
|
FUNCTION microtubules
|
axonal transport mechanism
|
|
|
Where are neurofilaments located?
|
in the cytoplasm oriented along the axis of the axon
|
|
|
FUNCTION neurofilament
|
add strength and diameter to axon
|
|
|
how are neurofilaments defective in Alzheimer's patients?
|
microscopically, these are seen as clumps in the cells of the frontal lobe and hippocampus
|
|
|
DEFINE axonal transport mechanism
|
transport of substances from cell body to the cellular processes and conversely utilizing microtubules
|
|
|
What are the 2 directions in the transport mech. of cells
|
anterograde: away from cell (efferent)
retrograde: from cellular process towards cell body (afferent) |
|
|
What are the 2 rates of transport in the axonal transport mech?
|
fast: 200-400mm per day
slow: 1-5mm jper day |
|
|
What are the 3 movement direction/speed combinations that occur in the axonal transport mech?
|
fast anterograde
fast retrograde slow anterograde |
|
|
What is transported in fast anterograde transport?
|
*plasma membrane componenet
*smooth ER *synaptic vesicles (contain neurotransmitters *mitochondria |
|
|
what is transported in slow anterograde transport?
|
*soluble enzymes
*proteins to renew the cytoskeleton and plasma membrane *proteins involved with regeneration |
|
|
what is transported in fast retrograde transport?
|
*mitochondria
*degenerated structures *vesicles with molecules (ie-Nerve Growth Factor (NGF) and other ligands) |
|
|
What are the 2 force-generating motor proteins?
|
kinesin and dynein
|
|
|
DEFINE kinesin
|
protein molecule for anterograde movement
|
|
|
DEFINE dynein
|
protein molecure for retrograde movement
|
|
|
How do force generating motor proteins work to transport objects into and out of the cell?
|
energy for motion comes from ATP; molecules bind to microtubule and vesicle and work their way through tubules
|
|
|
What are the 3 options for movement when transporting objects into/out of cell?
|
*can pass another vesicle moving in the same direction
*2 vesicles can move in opposite directions *vesicles can shift between neurotubules |
|
|
DEFINE axon
|
*ALWAYS EFFERENT
*one axon for cell body *smaller and longer than dendrites *smooth *may branch but only once |
|
|
DEFINE telodendria
|
specialized structures that facilitate transmission of AP to adjacent neurons
|
|
|
DEFINE buton
|
small rounded swelling on the ends of telodendria
|
|
|
DEFINE synapse
|
the point at which 2 neurons communicate. they have presynaptic and postsynaptic membranes
|
|
|
What organelles are contained within dendrites?
|
all cellular organelles EXCEPT nissle bodies (ribosomes)
|
|
|
What are the 4 types of post synaptic membranes?
|
axodendritic
axoaxonic axosomatic dendodendritic |
|
|
DEFINE axodendritic
|
axon of one neuron and the dendrites of another
|
|
|
DEFINE axoaxonic
|
axon of one neuron and the axon of another
|
|
|
DEFINE axosomatic
|
axon of one neuron and the cell body of another
|
|
|
DEFINE dendodendritic
|
dendrite of one neuron and the dendrite of another
|
|
|
what part of a neuron is NEVER myelinated?
|
dendrites
|
|
|
when does the myelination of neurons begin during gestation?
|
4th month
|
|
|
What type of cells myelinate neurons in the CNS?
|
oligodedrocytes that can myelinate more than one axon
myelin is continuous |
|
|
What type of cells myelinate neurons in the PNS?
|
schwann cells that wrap around internodes
|
|
|
DEFINE internodes?
|
insulated segments of myelination that are difficult to depolarize
|
|
|
DEFINE nodes of ranvier
|
non myelinated spaces on axons
|
|
|
DEFINE saltatory conduction
|
when AP comes down the axon, the AP can "leap-frog" from node to node, speeding up the AP
|
|
|
Are all axons in the PNS myelinated?
|
NO
|
|
|
DEFINE dendrites
|
*ALWAYS AFFERENT
*short, numerous, branched, non myelinated |
|
|
what is contained within dendrites?
|
*dendritic spines that increase surface area and potential for synapse
*contain microtubules, microfilaments and neurofilaments *contian ribosomes, so protein synthesis does occur *contain elongated mitochondria |
|
|
DEFINE dorsal root ganglion
|
location of cell body in a sensory neuron
|
|
|
What cellular processes are not a part of sensory neurons
|
axons or dendrites
|
|
|
What is the plasma membrane composed of?
|
phosphates and lipids
|
|
|
what does the plasma membrane surround?
|
the soma and all the processes (flexible)
|
|
|
What other molecules are imbedded randomly throughout the plasma membrane?
|
proteins and CHO
|
|
|
What do the proteins in the plasma membrane do?
|
function as pores/channels/receptors to allow larger molecules to be recognized by the cell
*can also act as ion pumps |
|
|
what are the 3 main embryonic classifications of the brain?
|
prosencephalon (forebrain)
mesencephalon (midbrain) rhombensephalon (hindbrain) |
|
|
What does the prosencephalon further divide into?
|
telencephalon
diencephalon |
|
|
What does the rhombencephalon further divide into?
|
metencephalon
myelencephalon |
|
|
What part of the brain come from the telencephalon?
|
cerebral cortex
basal ganglia rhinencephalon semioval center |
|
|
what parts of the brain come from the diencephalon?
|
thalamus
hypothalamus epithalamus subthalamus |
|
|
What parts of the brain come from the metencephalon?
|
pons
cerebellum |
|
|
what parts of the brain come from the myelencephalon?
|
medulla oblongata
|
|
|
DEFINE zygote
|
fertilized,undivided cell
|
|
|
DEFINE cleavage
|
zygote divides into 2-->4-->8 cells via mitosis
|
|
|
DEFINE morula
|
solid ball of cells formed after cleavage
|
|
|
DEFINE blastula
|
hollow ball of cells
|
|
|
DEFINE gastrula
|
layers of cells begin to invaginate and form 3 basic germ layers
|
|
|
What are the 3 basic germ layers?
|
ectoderm
mesoderm endoderm |
|
|
what does the ectoderm become during development?
|
nervous system
skin |
|
|
What does the mesoderm become during development
|
blood, mm, bones, tendons, ligs, fascia
|
|
|
what does the endoderm become during development
|
lining of vessels in CV system, lymphatic system
|
|
|
DEFINE primitive streak
|
human being at 2 weeks gestation
|
|
|
What does the primitive streak include?
|
an ectodermal layer, a neuroectoderm, and a notochord
|
|
|
What has occured by 18 days gestation?
|
ectoderm thickens just above the notochord and forms a neural plate. The neural plate invaginates along the central axis forming the neural groove and neural folds
|
|
|
when is the neural tube fully formed?
|
23 days gestation
|
|
|
in what order does the neural tube close?
|
1. middle
2. superiorly 3. inferiorly |
|
|
what does the neural tube become?
|
CNS
|
|
|
What does the neural crest become?
|
PNS
|
|
|
What is spina bifida?
|
failure of the neural tube to close inferiorly
|
|
|
What is aencephaly
|
failure of the neural tube to close superiorly
|
|
|
What does the neural tube become?
|
Lateral wall thicken to form central cannal, running the length of SC (becomes ventricular system)
middle becomes sulcus limitans |
|
|
What does the sulcus limitans divide?
|
divides SC into dorsal and ventral halves
|
|
|
DEFINE alar plate
|
lateral walls of the dorsal half; develop into sensory structure/function (ie dorsal horn)
|
|
|
DEFINE basal plate
|
lateral walls of the ventral half; develop into motor structure/function (ie ventral horn)
|
|
|
What are the 3 embryonic layer of the CNS
|
ventricular/ependymal layer
marginal layer mantle |
|
|
FUNCTION ventricular/ependymal layer of the embryonic CNS
|
first layer to form, innermost
surrounds central canal produces neurons (motor or sensory), glial cells |
|
|
FUNCTION marginal layer of embryo CNS
|
outermost of 3 layers
outer portion differentiate to form cellular processes that diesplace laterally into the marginal layer. generally always white matter acellular, contains axdons and dendrites of cell w/in ventricular layer (not neurons) |
|
|
FUNCTION mantle
|
middle of 3, last to form
product of neuroblasts that develop in the ventricular layer then migrate laterally into the mantle. produces neurons -motor -interneurons -projection neurons forms ventral and dorsal horns of SC |
|
|
DEFINE interneurons
|
short pieces of neurons that connect short distances (ie simple reflex arc)
|
|
|
DEFINE projection neurons
|
projecting from the dorsal horn to somewher else (the brain) part of the sensory pathway
|
|
|
what are the 3 meningeal layers
|
dura mater
arachnoid mater pia mater |
|
|
What produces the dura mater?
|
mesoderm
|
|
|
what produces the arachnoid mater?
|
neural crest/ ectoderm
|
|
|
What produces the pia mater
|
neural crest/ectoderm
|
|
|
when does myelination begin to occur? for how long does it take?
|
4.5 mo gestation through 1st post natal year
**however, brain not completely myelinated until puberty** |
|
|
DEFINE fiber tracts
|
CNS becomes functional when myelination is complete
|
|
|
What do schwann cells originate from?
|
neural crest
|
|
|
Where do oligodendrites originate from?
|
ventricular layer of neural tube
|
|
|
by when is the brain divided into its 3 vesicles?
|
28 days
|
|
|
how are the flexures of the midbrain, pontine, and cervical portions of the brain form?
|
the neural tube bends ventrally
|
|
|
what has formed in the brain by 35 days gestations
|
*5 vesicles (prosencephalon and rhombensephalon divide)
*central canal continues up into the brain and enlarges to form the ventricular system |
|
|
where do sensory neurons of the PNS originate from?
|
neural crest
|
|
|
where do the cranial nerves originate from?
|
cell bodies are located in ganglia of the head and neck
**exception for CN I, II that are out growths of the brain (phombencephalon, diencephalon** |
|
|
Where do autonomic ganglia originate from?
|
neural crest and further subdivide into sympathetic and parasympathetic
|
|
|
DEFINE preganglionic
|
products come from the neural tube
|
|
|
DEFINE postganglionic
|
products come from the neural crest
|
|
|
Where do the motor neurons of the PNS originate
|
neural tube
|
|
|
how many neurons are produced every minute during gestation?
|
2500
|
|
|
How many neurons does an individual have before "pruning" takes place?
|
1,263,600,000,000
|
|
|
How many neurons does an average individual have after "pruning" takes place?
|
1 million
|
|
|
Why does the NS overproduce neurons during development?
|
ensure NS has the potential to do all that it needs to do
|
|
|
How do neurons differentiate into various types of cells?
|
*begin as neuroblasts
*differentialtion depends on a series of signals that control gene transcription |
|
|
What regulates the signals that cotrol differentiation on neurons?
|
genotype/phenotype and chemical signals in the local embryonic environment
|
|
|
DEFINE genotype
|
factors inherited by cells
|
|
|
DEFINE phenotype
|
how genotype is expressed
|
|
|
What are some of the chemical signals produced by the local environment that regulate signals that control differentiation of neurons?
|
cell to cell interaction (ie mesodermal cells influence ectodermal cells)
presence of hormones and growth factors also influence differentiation |
|
|
How do neurons reach target organs?
|
differentiated cell projects axons in order to form complex and precise connections with other neurons or target cells through certain mechanisms for guidance
|
|
|
what are the 2 main mechanisms for guidance in the NS?
|
radial glial cells
guidance cues |
|
|
DEFINE radial glial cells
|
act like scaffolding to guide a migrating axon to its target
|
|
|
What are the 2 categories of guidance cues?
|
Neural cell adhesion molecules (NCAMs) and Neurotrophic factors (neurotrophins)
|
|
|
How do guidance cues work?
|
*distal end of axon forms filopodia (terminal ends) that contain receptor proteins in plasma membrane
*these proteins (aka butons) bind to cues from fibroblasts and extracellular matrix. |
|
|
Where are NCAMs found?
|
glycoprotein molecules found on surface of neighboring cells and extracellular matrix
|
|
|
what are the 3 generic families of NCAMs?
|
immunogloblins, cadherins and integrins
|
|
|
what do NCAMs do?
|
stabilize axon as it grows so that past position is not lost
|
|
|
What do neurotrophic factors do?
|
they are released by the target structure to attract, repel, turn, rotate the growth cone.
|
|
|
What are the 3 types of neurotrophic factors?
|
Nerve growth factor (NGF)
Brain derived neurotrophic factor (BDNF) neurotrophin-3 (NT-3) |
|
|
DEFINE apoptosis
|
programmed cell death (of multiple types of cells) with no inflammatory process as with cell death due to trauma.
|
|
|
how does apoptosis occur?
|
1. the whole cell rapidly decomposes
2. orderly decompose bit by bit 3. small vesicles of debris are formed in the process |
|
|
What determines whether a cell dies through apoptosis?
|
Nuerons must reach their target to survive-->neurotrohic factors produced by the target cells must be in sufficient quantityto ensure continued maturation-->however, there is competition for neurotrophic factors at target site-->the quatity of available neurotrophic factors is a means of matching the appropriate # of neurons to the physiological needs of target-->neurons not receiving enough neurotrophic factors will die via the apoptosis process-->the lack of neurotrophic factors triggers the DNA of the neuron to set in action the genetic basis of cellular death
|
|
|
What is the clinical relevance of the NS development?
|
*there is a genetic predisposition of the NS to be "hardwired" due to the evolutionary process
*in order for "hardwired" pathways to be working right, adequate stimulation must take place during embryonic and postnatal development. "use it or lose it" |
|
|
What are some of the genetic predisposition components of the NS to be "hardwired"?
|
est. motor/sensory pathways
est funcional areas in cortex est. functional association areas in the cortex create somatotypical organization of about 40 areas in cortex form billions of synapses |
|
|
What are the most critical years for developing pathways?
|
first 3 years
|
|
|
When is myelination of SC neurons completed?
|
12 years
|
|
|
when is myelination of the cerebral cortex neurons completed?
|
25 years
|
|
|
What will lack of exposure to auditory language during development cause?
|
children cannot develop significant language skills after age 12 (as in no first language, can still learn foreign language but harder after this time)
|
|
|
What will lack of visual stimulation at birth cause?
|
will cause neurons in the occipital love of cortex to dies or be diverted to other function causing blindness. (helped save sight of 1,000s with conginital cataracts)
|
|
|
What can aid in making premature infants more mentally alert and physically stonger?
|
stimulation of sensory systems through being held and cuddled as opposed to being isolated in the incubator.
|
|
|
What can cause profound behavioral problems?
|
if normal synaptic patterns are not established early in life
|
|
|
how can you retard development?
|
if child is understimulated
**however, cannot enhance development through overstimulation** |
|
|
how can people maintain synaptic activity as they age?
|
read, participate in activities, talk, and exercise
|
|
|
DEFINE neuroplasticity
|
potential for major compensatory activities in the NS bc the architecture of the brain is constantly changing through synaptic contacts. (if you lose fx in part of your brain, another part of the brain can take over)
|
|
|
What can pass directly through the plasma membrane?
|
glucose and its deirvatives
growth hormone/other hormones gases insulin |
|
|
DEFINE simple diffusion
|
passive transport where the movement of ions goes from high concentration to low concentration, est a RMP and AP
|
|
|
DEFINE concentration gradient
|
passive movement of ions that go where there is less energy to reach equilibrium (high-->low)
|
|
|
What are the 3 types of channels that simple diffusion can occur?
|
non-gated channels
voltage-gated channels ligand-gated channels |
|
|
DEFINE non-gated channels
|
these channels are always open and are composed of proteins imbedded in the plasma membrane with chemical nature that controls what ion can pass through
|
|
|
DEFINE voltage gated channels
|
closed during RMP and open by a conformational change in response to change in voltage (AP)
|
|
|
DEFINE ligand gated channels
|
normally closed but undergo conformation change by interacting with a ligand that contains chemicals (NTMs) that attach to a receptor site on the protein pore.
|
|
|
DEFINE facilitated diffusion
|
utilization of carrier molecules that move bidirectionally to move ions from high-->low concentration
|
|
|
DEFINE active transport
|
use of ATP to move ions against their gradient through transporter molecules
|
|
|
when is exocytosis used within a neuron?
|
whent Ca++ influx in, a vesicle filled with NTMs press through presynaptic membrane and release NTMs into synaptic cleft
|
|
|
which ions are found in abundance in the extracellular space of an ion?
|
Na+ and Cl-
|
|
|
which ions are found in abundance in the intracellular space?
|
K+
|
|
|
What ion is primarily responsible for the RMP?
|
K+
|
|
|
What ion is primarily responsible for the AP?
|
Na+, except when at presynaptic portion of axon then Ca++
|
|
|
What is the RMP of a human neuron?
|
-70mHz
|
|
|
which ions are found in abundance in the extracellular space of an ion?
|
Na+ and Cl-
|
|
|
What is the threshold of a human neuron that needs to be reached to trigger an AP?
|
-60mHz
|
|
|
which ions are found in abundance in the intracellular space?
|
K+
|
|
|
DEFINE action potential
|
an electrical signal based on depolarization of a neuron, which travels its full length
|
|
|
What ion is primarily responsible for the RMP?
|
K+
|
|
|
Where does the AP begin in a sensory neuron?
|
1st node of ranvier
|
|
|
What ion is primarily responsible for the AP?
|
Na+, except when at presynaptic portion of axon then Ca++
|
|
|
Where does the AP begin in a motor, projection, or commissural neuron?
|
axon hillock
|
|
|
What is the RMP of a human neuron?
|
-70mHz
|
|
|
What is the key component to an AP?
|
influx of Na+ due to stimulation using voltage gated channels
|
|
|
What is the threshold of a human neuron that needs to be reached to trigger an AP?
|
-60mHz
|
|
|
DEFINE action potential
|
an electrical signal based on depolarization of a neuron, which travels its full length
|
|
|
Where does the AP begin in a sensory neuron?
|
1st node of ranvier
|
|
|
Where does the AP begin in a motor, projection, or commissural neuron?
|
axon hillock
|
|
|
What is the key component to an AP?
|
influx of Na+ due to stimulation using voltage gated channels
|
|
|
what occurs during depolarization?
|
K+ gated channels open and let K+ out of cell
|
|
|
What is a local current?
|
occurs during depolarization, goes from + potential to - potential. Therefore, bringing the membrane potential ahead of the depol region occurs bringing it to threshold
|
|
|
What consequence lead to local currents?
|
difference in potentials
|
|
|
What is saltatory conduction?
|
involves myelinated neurons where AP travels from one node of ranvier to another
|
|
|
What is continuous conduction?
|
involves non-myelinated neurons
|
|
|
DEFINE hyperpolarization
|
during repolarization of the neuron the K+ gates close milliseconds after RMP is reached causing a "dip" to about -80mHz
|
|
|
DEFINE absolute refractory period?
|
immediately follows AP and no AP can be created
|
|
|
DEFINE relative refractory period
|
follows absolute refractory phase.
AP possible but stimulation must be stronger than normal |
|
|
DEFINE graded potentials
|
transition between RMP and AP; does not travel the distance of the neuron and has no threshold or refractory period
|
|
|
What are the 3 different forms of graded potential?
|
receptor, generator, synaptic
|
|
|
Where are receptor portentials found?
|
in cochlea and semicircular canal in ear--conduct hearing
|
|
|
DEFINE receptor potential
|
cells are modified neurons located on the distal end of a sensory neuron that relase NTM onto neuron
|
|
|
DEFINE generator potential
|
involves the receptor organ of sensory neuron and responds to all types of sensation through mechanical or chemical stimulation
|
|
|
DEFINE synaptic potential
|
occurs where one neuron approximates another neuron via synapse
|
|
|
What occurs at the presynaptic membrane during an AP?
|
AP triggers Ca++ channels to open and Ca++ rushes into the cell and depolarizes it.
the fursion pore complex is formed and NTM is released via exocytosis NTM diffuses across synaptic cleft and binds to ligand gated channels on postsynaptic membrane |
|
|
What occurs at the postsynaptic membrane during an AP?
|
1 of 2 things:
1. if excitatory (EPSP), will open ligand gated Na+ channels OR 2. if inhibitory (IPSP), will open ligand gated Cl- channels |
|
|
How does a neuron know if it is excited (AP) or inhibitted (no AP) if receiving signals for both?
|
if summation of ESPS> summation of ISPS, then AP
if summation of ISPS> summation of ESPS, then NO AP!! |
|
|
DEFINE spatial summation
|
the adding together of the effects of many presynaptic neurons neurons acting on the postsynaptic cell
|
|
|
DEFINE temporal summation
|
the process by which consecutive synapses at the same site are added together in the postsynaptic cell
|
|
|
DEFINE neuromuscular junction
|
occurs at the distal end of motor neuron, within the muscles where a lower motor neuron (LMN) inn. a skeletal muscle
|
|
|
DEFINE motor unit
|
one neuron can innervate many skeletal mm
|
|
|
What is the difference between a lower ration and a higher ration motor unit?
|
lower ratio causes incr dexterity, fine moter (1 neuron to 5 mm)
higher ratio causes decrease dexterity, gross motor (1 N to 500 MM) |
|
|
where are the MEPs located?
|
on postsynaptic membrane of sarcolemma
|
|
|
DEFINE sarcolemma
|
specialized area that contains ligand-gated channels, containing 2 types of receptors for ACh
|
|
|
What are the 2 types of muscle receptors?
|
nicotinic
muscarinic |
|
|
DEFINE nicotinic receptor
|
produce sympathitic respond to ACh
are ligand gated Na+ channels. |
|
|
What does activating a nicotinic receptor cause in the MEP?
|
binding causes influx of Na+ causing end plate potential (EPP)
|
|
|
What is the ONLY thing an EPP can generate?
|
AP, no graded potential
|
|
|
how does the influx of Na+ and EPP cause mm to contract?
|
incr of Na+ changes voltage of sarcolemma that changes the sarcoplasmic reticulum that causes a massive release of internal Ca++ that activates actual contraction of mm cells (myosin and actin)
|
|
|
Where are muscarinic receptors located?
|
located on parasympathetic postganglionic neurons
|
|
|
How does the body avoid rigidity or cont depol at one site (mm spasm)?
|
AChase enzyme present in synaptic cleft to break down ACh into A and Ch which is then reabsorbed by presynapse and recycled for next time
|
|
|
DEFINE hyperkalemia
|
incr K+ in blood caused by renal failure. incr K+ casues concentration gradient so ion diffuses into interstitial space which decreases RMP (-65mHz) so it is easier to generate AP and causes excessive contractions of smooth mm (intestines/cardiac)
|
|
|
DEFINE hypokalemia
|
decreased level of K+ due to dehydration/vomiting. causes migration of K+ into intravascular space causing RMP to decrease (-80mHz) making it harder for AP to be generated. decrease of skeletal/smooth mm activity
|
|
|
DEFINE lidocaine
|
a local anesthetic that binds to receptor organ (voltage gated) and axons of passage and closes Na+ channels so depol cannot occur
|
|
|
DEFINE curare
|
naturally occuring plant compound that binds to nicotinic receptor sites (pancurium is a synthetic version used in anesthesai)
competes w/ ACh for receptor site causing paralysis |
|
|
DEFINE succinylcholine
|
similar to curare. blocks nicotinic receptor site causing paralysis
|
|
|
DEFINE anticholinesterase drugs
|
prevent the action of AChase causing a build up of ACh in synaptic cleft causing prolonged mm contractions. leads to convulsions and respiratory distress (eventually suffocation) used to treat myasthenia gravis
|
|
|
DEFINE myasthenia gravis
|
a neuromuscular disorder characterized by variable weakness of voluntary muscles, which often improves w/ rest and worsens w/ activity (weakness and fatigue of frequently used mm ie-extrinsic eye mm, soft palate, pharynx, mastication, shoulders, respiratory) due to destruction of nicotinic receptrots on postsynaptic membrane at MEP. progressive, autoimmune disease
|
|
|
DEFINE botulinum toxin
|
aka food poisoning produced by the clostridium botulinum bacteria. prevents release of ACh by blocking Ca++ channel on presynaptic membrane. if affects diaphragm can lead to suffocation bc no mm contraction.
**diluted form used in botox |
|
|
DEFINE nerve gases
|
act as inhibitors of AChase causing an incr in ACh in synaptic spase resulting in activity of effector organs (ie-lacrimal glands, salivary glands, cardiac mm, skeletal mm)
|
|
|
What is a common antidote to nerve gases?
|
atropine (an ACh antagonist)
|
|
|
DEFINE prozac/antideppresants
|
blocks reuptake of serotonin by presynaptic neuron, leaving serotonin in synaptic cleft--incr AP duration
**may cause side effects elsewhere** |
|
|
DEFINE aspirin
|
comes from willow trees and is used in pain reduction through the breakdown of prostaglandin (cannot stimulate neurons to convey pain to NS)
|
|
|
DEFINE transmitter substances
|
general term which implies that they are involved with transmission of AP from one neuron to the next or to mm cell or gland (neurotransmitter, neuromodulator)
|
|
|
DEFINE neurotransmitters
|
substance which is released ftom presynaptic neuron and affects the postsynaptic membrane (neuron, mm cell, gland cell) in a specific manner in milliseconds
|
|
|
What kind of effects can neurotransmitters cause? what determines what effect a NT has?
|
excitatory or inhibitory
*chemical nature of RECEPTOR determines effect |
|
|
What are the criteria to be a NT?
|
*must be synthesized in neuron and become localized in presynaptic membrane
*must be released into synaptic cleft *need to bind to receptors of postsynaptic membrane *need to be removed from receptor by specific mech (ie reuptake) |
|
|
What are common NT?`
|
ACh
Dopamine Serotonin GABA (gamma amino butyric acid) glutamate Glycine |
|
|
DEFINE ACh (NT)
|
binds to nicotinic or muscarinic (excitatory/inhibitory) receptors that are found in:
NMJ all PRE and POST ganglionic PARASYMPATHETIC neurons all PREGANGLIONIC SYMPATHETIC neurons |
|
|
DEFINE dopamine (NT)
|
INHIBITORY only
produced in substantia nigra of midbrain and ends up in basal ganglia to inhibit muscle activity |
|
|
What disease is associated to a lack of dopamine?
|
parkinsons: substantia nigra degenerates, dopamine not released, resulting in overactivity of mm
|
|
|
DEFINE serotonin (NT)
|
Excitatory/Inhibitory
involved in a variety of CNS systems (Prozac prevents reuptake, resulting in higher levels) |
|
|
DEFINE GABA (NT)
|
major inhibitory NT of NS with lots of subtypes
|
|
|
DEFINE glutamate (NT)
|
Major Excitatory amino acid of NS used to form GABA.
During stroke, when neurons die, glutamate is released, increased, and becomes cytotoxic to brain |
|
|
DEFINE glycine (NT)
|
inhibitory amino acid found in SC
|
|
|
DEFINE neuromodulators
|
chemicals that interact w/ pre/post synaptic membranes which are usually linked to G-protein and second messenger systems. Slow compared to NT
|
|
|
What process does a neuromodulator cause in a receptor neuron?
|
*bind w/ receptor proteins
*receptor contacts and activates G-proteins G-proteins begin cAMP cycle (2nd messenger system) * 2nd messenge3r molecules cuase cascade of metabolic activity *increased activity results in changes in the biochemical nature of the neuron |
|
|
What are 3 examples of 2nd messenger activity neuron response?
|
* produce change in molecular nature of the protein receptor resulting in opening or closing the channels
*alteration of gene expression *permanent change in cell membrane (w/ long term effects assoc w/ memory and learning) |
|
|
What are the common NM molecules?
|
dopamine
norepinephrine/epinephrine serotonin Neuroactive peptides -substance P -endorphins -vasoactive intestinal polypeptides (VIP) adenosine nitric oxide |
|
|
Since many NTs can be NMs as well, what decides which one they act like?
|
intrinsic nature of receptros that determines if a substance will behave as NT/NM
|
|
|
DEFINE binding component of a receptor
|
active site, specific for different TS
|
|
|
DEFINE ionophore component of a receptor
|
pore component (which ions flow through)
|
|
|
DEFINE ionotrophic receptors
|
bonding to NT
|
|
|
DEFINE metabotrophic receptors
|
binding to NM
|
|
|
What are the 4 main properties of amino acid/ligand gated channels?
|
pharmacology of binding site (channels/receptors)
kinetics (binding process) selectivity (which ions flow through) conductance (magnitude) |
|
|
DEFINE coding
|
how neurons understand what other neurons are telling it (EPSP/IPSP)
|
|
|
Where are 1st order sensory neurons found?
|
in PNS (though enter CNS and synapse w/ 2nd order neuron in SC/brainstem)
|
|
|
Where are 2nd order sensory neurons found?
|
CNS in SC/brainstem
|
|
|
Where does coding begin?
|
2nd order sensory n goes to thalamus
|
|
|
what must take place to make a neuron a 2nd order sensory neuron?
|
temporal/spatial summation
|
|
|
Where are 3rd order sensory neurons found?
|
begin in thalamus and end up at post central gyrus (primary sensory cortex)
|
|
|
What are the 4 types of synapses and do they tend to cause inhibitory/excitatory responses?
|
axosomatic-->inhibitory
axodendritic--.excitatory axoaxonic--inhibitory dendodendritic--excitatory |
|
|
DEFINE inhibition
|
brains ability to choose between competing alternatives by selecting on and suppressing the others.
(ie-do not constantly feel clothing to allow for other tough sensations) |
|
|
What would you not be able to do if there was no inhibition?
|
*no mm activity (body inhibits wrist flexors when doing wrist ext.)
*could not makesense out of special sensory input *inhibits emotions |
|
|
DEFINE disinhibition
|
mechanisms that prevent inhibition
|
|
|
what are some examples where disinhibition is helpful?
|
maximize movement
incr awareness of special senses |
|
|
What is a clinical example of disinhibition?
|
Parkinson's: basal gangli inhibits activity by producing dopamine. If no dopamine, disinhibition of mm activity (tremors)
|
|
|
What are 5 mechanisms of inhibition?
|
neg feedback inhibition
presynaptic inhibition lateral/recurrent feedback inhibition feedforward inhibition descending supraspinal inhibitory mechanisms |
|
|
What cells are used in neg feedback inhibition?
|
renshaw cells (type of interneuron)
|
|
|
DEFINE renshaw cells
|
an interneuron that can allow a neuron to regulate itself
|
|
|
DEFINE neural processing
|
mechanism by which CNS channels/focuses and sorts info
|
|
|
DEFINE convergense
|
many neurons synapse on a single neuron (focused input)
|
|
|
DEFINE divergence
|
means by which one neuron is spread to others
enhance spread of info |
|
|
DEFINE serial
|
neurons are arranged sequentially (1st, 2nd, 3rd orders)
|
|
|
DEFINE parallel
|
info is conveyed in parallel sequences (more than one pathway)
involved w/ rehab |
