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135 Cards in this Set

  • Front
  • Back
What is the function of the nervous system?
It works w/ the endocrine system to control integrated activities of the organs and maintain homeostasis
What are the two main divisions of the Nervous system?
Central Nervous System; Peripheral Nervous sytem
What makes up the Central Nervous sytem?
The brain (hypothalamus, brain stem) and the spinal cord
What are the 2 parts of the Peripheral nervous system?
somatic and Viceral/autonomic
What are the 2 main parts of the autonomic (visceral) nervous system? What is the third part?
sympathetic and parasympathetic;
Enteric-nerves lining the walls of the gastrointestinal track
where is the somatic located?
muscles and joints
Where is the autonomic located
smooth muscle-lining hollow tubes and organs
What are the 4 subdivisions of the brain?
cerebellum, brainstem, forebrain, spinal cord
What makes up the forebrain?
cerebrum and diencephalon
what makes up the brain stem?
midbrain, pons, medulla oblongata
What makes up the diencaphalon
thalamus and hypothalamus
What makes up the cerebral hemisphere?
cortex, subcortical nulcei, neuronal pathways
What are the cerebral hemispheres
the right and left side of the brain
What is the cortex
outer most layer of the cerebral hemispheres, where the nerve cell somas are
What is the subcortical nuclei? an example?
collection of neve cell soma that connect different areas w/ in a hemisphere; basal ganglia
What is the fxn of the thalamus?
an important relay station for sensory info and motor commands
What is the hypothalamus?
the chief integrative center for the ANS and homeostasis. It regulates water intake, eating behavior, reproduction, body termp. It secretes hormones that effect the pituitary gland
What is the limbic system?
It connects different nuclei/structures in the brain. Imortant for memory/learning/emotions.
What is the cerebellum?
coordination fo motor movement. Recieves constant feedback from periphere. Balances sensory feedback w/ on going motor command-keeps things smooth
what is the function of the brain stem?
sensory info must travel through axons in the brain stem, site for nerve cell bodies for all cranial nerves, connects the hemispheres w/ the spinal cord
What are 2 important parts of the brain stem?
Reticular formation and the Medula
What is reticular formation?
nerve cell bodies bundles w/ axons, the only part that is essential for life
What is the function of the medula
integrating centers for cardiovascular and respiratory reflexes
what is the spinal cord important for?
nerve cell bodies run up and down it
What are the 4 major parts of neurons?
soma, dendrites, axon, axon termina
What is the soma?
nerve cell body which contains nucleus an other major cell organelles
What are dendrites?
branching extensions from the nerve cell soma
What is the axon?
Single process that externds from the nerve cell soma and tavels to target cell. Substances made in the soma are tansported by the axons, which can be mylenated or unmylenated
what is the function of the axon terminal? What are its 2 forms?
stores and secrets neural transmitters. Discrete synaptic areas ( alpha motor neuron at motor end plate) or varicrose swelling in zones of transmission (autonomic postganglionic neurons)
What is a glia?
A type 2 neuron that can undergo mitosis
What are the 4 glia cells of the nervous system?
oligodendrocytes, astrocytes, microglia, ependymal cells
What do oligodendrocytes do?
synthesize myelin, like schwann cells in the peripheral nervous sytem
What do astrocytes do? 4
1. Regulate the composition of Extracellular fluid (waste, chemical messengers/neurotransmitters, potassium levels)
2. Maintain blood brain barrier, keeping things from leaking into the brain
3. development of neural system
4. can generate weak electrical signals
function of Microglia?
Clean up areas where thereis damage
What is the function of Ependymal cells
line fluid filled cavaties
regulate the flow/production of cerebral spinal cord
what are the 3 classes of neurons
Afferent, efferent, interneurons
What is the fxn of interneurons
To connect neurons w/ the CNS, By far the most numeros
What is the function of efferent neurons
transmit action potentials OUT of the CNS to effector cells, soma, in the periphery ( muscle cells, glands)
Nuerons make up _% of brains weight and _% of brains space
10, 50
what are neurons specialized for?
initiation and conduction of action potentials
What is the reproduction of Type 1 neurons? of glia?
fixed post mitotic; can undergo mitosis
What has happend to people who have MS? what is the physiological cause?
degenerative disease that destorys plasma membrane and myelin
what is the function of afferent neurons
transmit seonsory info from periphert INTO the CNS, special sensory receptors
What 4 qualities need do sensory nuerons need to be able to encode?
modality, intensity, duration, location
what type of sensation it is (pain, pressure, ect.)
how strong is the stimulus (increase intensity= increase in action potential)
What do somatic recepotrs do?
they act on local reflexes and relay impusles to the brain
what does muscle spindle do
detects the length of the muscle and the rates of change in the length of the muscle
what does the golgi tendon organ do
reads the aount of tension/strength of a contraction
What do i need to know about example reflexes
wHo KnOwS?!?
What does it mean that they plasma membrane is an excitatory membrane?
It can initiate and conduct and action potential
what is the Resting Membrane Potential (RPM)?
the negative potential difference between the inside of the neuron w/ respect to the ECF
what 2 differences cause the magnitude of the RPM?
1. differences in Ion concentrations across the membrane
2.differences in Ion permeability across the membrane
What is a typical value of RPM?
-70 mV
What is the equlilbriumpotential of Na+ in ECF?
60 mV
What is the equilibrium potential of K+ in ECF?
-90 mV
What predicts the equilibrium potential of a particularl cell?
the nernst equation
membrane potential increases, becoming less negative and farther from RPM
What 4 things largely determine the magnitude of the RPM?
1. Eflux of postasium through the resting channels, which are more permeable to calcium when @ rest
2. Leakiness of the neuron to Na+ or Calcium
3. presences of nonpenetrating substances w/ in the neuron that have a negative charge (anions)
4. Sodium/Potassium ATPAse
what is Sodium/Potassium ATPase?
an electrogenic pump that contributes to the separation of charge across the membrane
when it over shoots, pringing it back downto RPM
going lower than the RPM, more negative
Define action potential
A brief, all or none reversal of polarity that has thresholds and exhibits a period of refractoriness
What determines the shape/ionic basis of an action potential?
types of ion channel foulnd in the neuron
ionic basis
change in ionic permeability that occur in the squid giant axon
Who did the original research on the giant squid axon? when
Hodgkin and Huxley; 1952
threshold potential?
membrane potential at which axon potential is initiated
Describe the depolarization pase
Due to the opening of voltage regulated sodium channnels;
Go to inactive state long before it reaches action potential
Describe the Repolarization Phase
due to the opening of voltage-regulated potassium channels (slower/open longer); sodium channels inactivated
Sodium channels inactivated
What happens after hyperpolarization?
some potassium channels remain open
What causes refractoriness
sodium inactivation nates
Absolute refractory period?
time interval following an AP when no AP can be initiated
Relative refractory period
time interval when a suprathreshold stimulus can elicit anAP
What percentage of excitable membranes are refractory?
What is threshold
cirtical point where voltage-gated channels are activated and produce an all-or-none AP due to opening of sodium channels
What does the positive sodium feedbacck cycle cause at threshold
rapid depolarization
describe the positive feedback reaction cycle
open Na+ channels→ increase Na+ permeability→ Increased flow of Na+ in cell→ Decreased membrane potential (depolarization)→starts all over
what can affect action potential duration/amplitude
changes in ionic concentrations in the area of the excitable membrane
What is propogation of an action potential due to?
the flow of current and subsequent depolarization of adjacent membrane areas
What is saltatory conduction?
AP propagation on a myelinated neuron
What determines the direction of action potentials?
the refractory period, insures it will be away from the site of stimulus
What are graded potentials?
changes in local membrane potential that occur in a small area of limited distance
What 3 types of current can a graded potential be
depolarizing or hyperpolarizing
What changes the amplitude of graded potnetial changes?
stimulus strength
Are graded potentials conducted w/ decrement?
How can graded potentials be summated
temporal or spatial summation
Give 4 examples of graded potentials
IPSP, EPSP, EPP, receptor potentials
When do graded potentials stimulate an AP
if th effect the magnitude of the potential change brings the excitable membrane to threshold
What effect do inhibitory graded potentials have on the excitable membrane
they hyperpolarize the membrane and make it less excitable
What is always summating axon potential
the nervous system
What are pacemaker potentials?
spontaneous polarizations that can occur in some excitable membranes due to changes in permeability to ions
give examples of pacemaker potentials 3
1. increase in conductance to calcium/sodium
2. Decrease in conductance to potassium
3. slow the pump down
Where are pacemaker potentials very important
cardiac muscle and smooth muscle
do pacemakers potentials occur in the neurons?
yes; 5 CN-nuclues associated w/ hypothalamus
what are synapes?
Specialized area of contact between neuron and its effectors
where are 3 places synapses can exist?
1. between 2 neurons
2. Between a neuro and a gland
3. between a neuron and a muscle cell
what are the 2 types of synapes?
electrical and chemical
Which synapse type is most prevalent?
Describe electrical synapes
-Bidirectional flow b/c of gap junction that allows currents resulting from arriving action potentials to flow directly across the junction connecting the channels
-Spontaneous large area activated (go for hypothalamus-bursting secretion of hormones)
What is a neurotransmitter?
Specialized chemical messengers secreted from neurons
where are the 2 places neurotransmitters can be synthesized?
1. in the soma
2. ???
3 key characteristics of nuerotransmitters?
1. Substance must be present in presynaptic neuron
2.Substance must be released in response to presynaptic depolarization and is dependent on calcium influx
3. Receptors that specifically bind the neurotransmitter must be present on postsynaptic membrane
What process releases neurotransmitters?
What is proportion to the amount of NT released?
calcium concentration
what goes in to release the NT?
What modifies the activity of presynaptic terminals?
metabotropic glutamene receptors
What is an ionotropic receptor
liggand gated channel found n most post synaptic membranes
what are glutamate receptors?
ionotropic and metabotropic
location of synaptic vessicles?fxn of synaptic vessicles?
nerve terminal; Synthesize and stores neurotransmitter
Name the parts of the presynaptic membrane and nerve terminal
1.synaptic vessicles
2. calcium channels
3. docking sites
fxn of the synaptic vessicle
synthesize and store neurotransmitters
what happens to calcium channels when nerve terminal is depolarized?
They are gated open
fxn of docking sites
Calcium influx allows for docking of synaptic vesicles at docking sites and release of neurotransmitter in to the synaptic cleft ECF
what is the main part of the postsynaptic neuron
Name 3 things that binding the receptor w/ the neurotransmitter can stimulate?
1. ion influx
2. a second messenger
3. altered transcription and translation
What is the synaptic cleft?
A Narrow 20cm space that separates pre and post synaptic membranes at all synapses except transmission zone
Where do synaptic clefts not exist?
transmission zone found @ visceral sites innervated by the ANS
What is an Atypical synapes
zone of transmission @ visceral sites and are found at the terminal branched ends of autonomic neurons
What is the most common typical synapes?
What is on the membrane of vesicle, postsynaptic terminal, and presynaptic membrane
what are the 4 fxns of the proteins on the membrane vessicle, postsynaptic terminal, and presynaptic membane?
2. Fuse
3.Release neurotransmitter
4.Recycle vesicles
Steps of Neurotransmission?
1. action potential reaches terminal, then depolarizes the nerve channel
2. Voltage-gated calcium channels open
3. Calcium enters the axon terminal
4. Neurotransmitter is released (amount based on the amount of calcium) and diffuses
5. Neurotransmitter binds to postsynaptic receptors, get a cellular response
6. Neurotransmitter is removed from the synaptic cleft
What is the 2nd for of Myasthenia Gravis?
-Receptors and destroyed
-Leads to weakness and paralysis
Describe Lamber Eaton Myasthenia Gravis
-Disease associated with cancer and chemo
-Build up of antibodies that attack calcium, inhibiting the release of neurotransmitters
What determines the direction the of the transmisson
the refractoriness of neurons
what is an excitatory synapse?
-receptor transmited excited neuron toallow more sodium in and a little potassium out
-postsynaptic response of depolarization
-brought closer to threshold
What is an inhibiotry synames
-neurotransmitter secreted opens chloride and potassium channels
-chloride out and potassium causes hyper polarization (or stabillization in cells that don't actively transport chloride)
-membrane potential gets further away from threshold
what determines the excitability of a neuron
The sum of the IPSPs and EPSPs
What 3 things can effect synaptic effectivness?
1. presynaptic events
2. drugs
3. residual calcium, disease, and autoreceptors
What is Botolumin toxin (Botox)?
-inhibits vesicle fusion/release of neurotransmitter
-good for headaches, but you can become immune to it
what is curare?
plant extract that blocks Ach receptors
What is Myasthenia Gravis?
autoimmune destruction of Ach receptors
what are 3 ways to stop the transmission of a neurotransmitter message?
1. Chemical degredation (ACHEsterase)
2. Inactivation by enzymes found in the ECF, neurons, or other tissues
3. Reuptake into the presynaptic nerve terminal
What are 2 enzymes good for ceasing a chemical messenger?
1. MAO (monoamine oxidase)
2. CO MT (catechol-O-methyltransferase)
What are 5 major classes of neurotransmitters?
achetocholine, biological ammines, amino acids, neuropetides, nitrous oxide