 | Term | Definition |
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What is the functional unit in the nervous system? |
neuron or nerve cell |
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How do nerouns comminicate with each other? |
Releasing chemical nurotransmitters at spaces known as synapses, (or directly via gap junctions) |
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How is the CNS orgnaized? |
Brain, spinal and motor (efferent) and sensory (afferent) |
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How is the PNS organized? |
Somatic nervous system to the perophery and autonamic nervous system (parasympathetic, sympathetic, enteric) |
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What is enteric Nervous system? |
Still able to function without parasympathetic and sympathetic n.s. (i.e. gut) |
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What are some charactertistics of a motor neuron? |
A soma or cell body, dentrites on soma for incoming signals, integrating center, axon for outgoing signals, axon terminal for passing of signals or releasing neurotransmitters |
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What are the characteristics of a senory neuron? |
input area integrating centerm axon, cell body and axon terminal is arranged diferently., CELL BODY IN CENTER, INTEGRATING CENTER ON ENDS |
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What are the functions of a motor neuron? |
cell body on one end, may have an axon over a meter long |
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What are the functions of a sensory neuron? |
Have a cell body in the middle |
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What are the functions of an interneuron? |
Most neurons are in this category, 99% in the CNS |
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How does axonal transport work? |
Soma is the site of protein synthesis and lysomal breakdown/recycling, its also where the cells functions are controlled. Sensitive to damage, need to transport vesicals back and forth to the axon terminals. Slow and fast anterograde and retrograde transport microtublues for the fast |
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What is dynein? |
A "motor" or a microtuble used to transport from distal to soma (nonmyosin) |
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What is Kinesin? |
A "motor" microtubule used to transport from soma to distal. (nonmyosin) |
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What is Glia? |
Cellthat provide support and protection to neurons. |
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What are CNS glia? |
Astrocytes, oligodendrocytes, microglia, ependymal cells |
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What are astrocytes? |
Connect nerons adn blood vessels, in the BBB |
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What are oligodendrocytes? |
insulate axons |
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What are microglia? |
immune function, phagocytosis |
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What are ependymal cells? |
form BBB, produce CSF (ULTRAFILTER FOR PLASMA) |
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What are PNS glia? |
Schwann cells, satellite cells |
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What are schwann cells? |
insulate axons |
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What are satellite cells? |
suport cekks within ganglia not skeltal muscles |
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What two glia insulate axons? |
Schwann cells and oligodentrites, they wrap around the axon and they push out the cytoplasm, leaving layers of membrane behind |
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What are two peripheral myelin dieases? |
Guilliain Barre, Charcot-Matie Tooth (CMT) |
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What is CMT? |
Peroneal nerve trophy, heretitary motor and sensory neuropathy, (hereditary hypertrophic neuopathy) |
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What are the two types of CMT? |
One has wrapping of schwann cell problems (missing 1 aa), other has nerve conduction problems, usually autosomal recessive |
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What muscles are affected by CMT? |
Fibulr muscles is where atrophy starts, is a muscle weakening, wasting below the knees and often in hands. Also looses sensory component |
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What are the symptoms of CMT? |
Difficulty walking, higher arched feet at erly age, weakness in hands and legsm numbness of feet and hands, numbness (affects ages 5-15, and look out ofr impoper fitting shoes) |
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What is a node of ranvier? |
2-3 mm ther eis patch of naked axon, needs to be so Action potential can regenerate centrally and peripherally |
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What is the difference between schwann cells and oligodendrocytes? |
Nuerons in CNS cannot be repaired once damaged (oligo), Shwann can help clean up debris after damage and secrete neurotopic factors (helps nerve to grow) |
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What is the difference between depolarizing and hyperpolarizing the soma/ dentrite? |
Depolarizing is that the neron is postiviley excitable, and hyperpolarization is that it is neg. excitable but they can both repolarize to neutral |
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What kind of channel is in the integrated center? |
Voltage gated |
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What type of channel is in the soma? |
ligand gated, Local currents, which can decrease in distance over time, located in input, can be added up for integration center to send an electrial signal |
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What happens when threshold amounf of depolarization is reached? |
An action potential is generated |
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What is a graded potential? |
Small, local changes in the membrane potential that decrease over time and distance, can be positive or negativem varible large or small, can be summated |
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What does the action potential characteristics? |
Always the smae shape and size, all-or-none, can be proprated unchanged over long distances, due to voltage channels |
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What is subthershold vs suprathreshold? |
Sub is not enough electrical potential to get an action potential in the integrating center, and supra is enough to trigger ation potential |
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What is propagation? |
The reason the AP is always the same sizem even over long distances, as membrane depolarizes it opens VG channels adjacent to it. Na rushes in and the slower K channels open up to repolarize |
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Explain Action Potential and VG sodium channels |
pg 9 of your packet....you should know this, Na opens/closes fast and K opens/closes slow to reploarize |
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When does the VG reset? |
When K is open to let the postive charge out of the cell |
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What is ligand gated channel? |
When a ligand has to bind to the recepor and open the channel, it closes when the ligand is off of the chnnel. (GABA, and others. Second class messengers open chnne from the inside like Ca |
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What are refractory periods? |
Absolute or relative |
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What is an absolute refractory period? |
Time between when the VG Na+ channels firt open and inactivation gate is reset, Absolutlety nothtin will reopen these channels |
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What is the Relative refractory period? |
A greter stimulu might trigger an action potential (about 1msec) |
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How is intensity of an action potential determined? |
Greter the inital stimulus, the larger depolarizing graded potentils created in the soma and dentrite, keep the intgrating center above threshold for longer time, thus can result in more action potentials being generated on the axon ( higher frequency= level of intensity due to more neurotransmitters being released) |
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What is the Quanta? |
Refers to the fact that each vesicle of nuerotransmitter stored at the axon terminal contains the same number of chemical molecules, the frequency of action potentials arriving at the axon terminal determines how many vesicles are exocytosed (more calcium gets into the axon terminal, more vessicles transfused) |
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What is the order if action potential? |
message stimulus -> vesicals fused ->transmitter relaeased-> bind and depolarize-> integrating center suprthreshold -> AP generated |
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What is intensity? |
How intense the stimulus is, passed on to the next nerve target cell. The more vesicles that fuse the more transmitter is released. The more transmitter released the more it can bind and depolarize the next nerve cell, the longer the integrating center is suprthreshold the more action potential is released |
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What is the conduction of AP? |
frequency determines intensity, will conduct same membrane potential each time |
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What is the integrating center? |
VG sodium and potassium channels to generate AP, then eac oiece if membrane depolarizes through ECF and axonplams to nxt peice of membrne, threshold is reahed and proces begins again |
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Why doesn't AP conduction travel backwards? |
No VG channels past the in intergrating center and membrane isn't capable of depolarizing again yet. |
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What is the velocity of AP propagation? |
Larger the axon, the faster the AP can propegate due to less resistance and more movement. There is a limit to how big axons can get, so the other stratagey is to leave nodes of raniver so the VG channels at the nodes only have to open and the jumping over the mylein can occur |
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What is AP jumping over the mylein, and not have the AP regenerated called? |
Saltatory conduction |
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What happens when mylein is not there? |
The conduction leakes out, and is known as a Conduction Block |
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What are demyleinating dieases of the CNS? |
Multiple sclerosis, no cure, myelin is destoryed |
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What is the dmyelinating dieases of the PNS? |
Guillain- Barre (acute idiopatis peripheral polyneuropathy), and saturday night palsy (Wallerian degernaration) caused by over streched nerves |
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