Term
Neuroglia
(definition and types) |
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Definition
Supporting cells of the NS- 6 types
CNS- Astrocytes, Microglia, ependymal, oligodendrocytes
PNS- satellite cells, Schwann cells |
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Term
| What makes up the Central Nervous System? |
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Definition
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Term
| 2 Components of the Sensory Division of the NS |
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Definition
Somatic Afferents- info sent to brain from receptors that tell you what you "feel"
Visceral Afferents- info sent to reflex centers- subconscious for visceral organs |
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Term
| 2 Divisions of Motor Division |
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Definition
Somatic NS (somatic efferents)- signals to control voluntary skeletal muscles
Autonomic NS (visceral efferents)- composed of the sympathetic NS and Parasympathetic NS:signals sent from autonomic centers in the brain to visceral organs for control (smooth and cardiac muscle, glands, adipose tissue) |
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Definition
largest and most abundant type
wraps around neurons and blood vessels
contribute to Blood brain barrier
guide neuron development |
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Definition
| monitor neuron health and can become phagocytic |
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Definition
| have cilia and help circulate CSF |
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Definition
| wraps around axon to form myelin sheath |
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Definition
| surround and insulate cell bodies within a ganglia |
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Definition
| wrap around axon to form myelin sheath (one cell wraps around one internode of a neuron and creates neurilemma) |
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| What cellular organelle do neurons lack |
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Definition
| centrioles - amitotic so they are not needed because the cells don't replicate |
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Definition
| neurofilaments that form the cytoskeleton |
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Term
| Terminal branches / telodendria |
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Definition
| end opposite the cell body where NT are released |
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Definition
| motor proteins involved in fast axonal transport |
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Definition
| motor proteins involved in fast axonal transport |
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| segement on an axon between myelin sheath |
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Term
| Interneurons (association neurons) |
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Definition
Most in CNS in autonomic ganglia
Mostly comprised of multipolar neurons
Involved in higher level processing and planning.
Simples type involved one interneuron between a sensory and motor neuron |
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Definition
| in the form of separation of charges across a membrane |
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Definition
| the unit used to measure potential energy (in volts of milivolts) |
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Definition
| kinetic energy in the form of current when separate charges are allowed to move through channels |
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Definition
flow of charges between two points
Ohms law - I=V/R
Depends on Voltage and resistance to flow |
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Term
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Definition
always open (non-gated)
used to generate Resting membrane potential |
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Definition
chemical binding causes the channel to change (conformational change)
Used to generate graded potentials |
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Definition
change in voltage triggers channel to open or close
Used to generate AP |
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Term
| Mechanically gated channels (mechanoreceptors) |
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Definition
respond to deformation in the membrane
Used by some sensory receptors to generate a graded potential (meissner's corpuscles) |
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Term
| What factors create and maintain the Resting Membrane Potential |
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Definition
1. Leak channels (K>>>>Na)
2. Na-K pump maintains the concentration of Na and K across the membrane |
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Term
| Equilibrium potential for Na and K |
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Definition
*the membrane potential resulting in an electrical gradient that is equal and opposite to the concentration gradient- no net ion movement
Na +65mV
K -94mV |
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Term
| why is the RMP closer to the resting membrane potential for K? |
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Definition
| because the membrane in more permiable to K. -94 vs -70 |
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Term
| What is a graded potential called at the cell body or dendrites |
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Definition
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| Why does a graded potential decay over distances? |
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Definition
| resistance of the cytosol and ions leaking back across the membrane |
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Term
| How strong does the graded potential need to be when it reaches the axon hillock to generate an AP? |
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Definition
| 15mV- if the resting membrane potential is -70 and the threshold for a cell is -55 you would need 15mV to raise the -70 to threshold for an AP |
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Term
| Activation and Inactivation Gates |
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Definition
| Activation gates for Na open at threshold (both are "triggered" but only one opens first) and then 1ms later the inactivation gate closes. To reactivate the channel, the activation gate must be closed and the inactivation gate must be open. |
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Term
| Repolarization (30 to -70 mV) |
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Definition
| voltage gated K channels are also triggered at threshold but have a 1ms delay (they open when Na inactivation gates close) |
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Term
| Absolute refractory period |
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Definition
Opening of V-gates NA channels to closure of inactivation gate until enough of the channels have reset
*cannot generate an AP at this time |
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| Relative refractory period |
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Definition
Some v-gates Na channels are still resetting. Voltage gated K channels still open
*Can generate an AP at this time but need suprathreshold stimulus |
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Definition
along an unmyelinated axon
Requires a lot of voltage gated Na channels along the entire length of the axon. More energy used to pump Na back out of the cell. Speed= 2 mph |
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Term
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Definition
along myelinated axon
Voltage gated Na channels only along Nodes of Ranvier
Less Na moved into the cell so less energy used to pump the ions back out
speed= 40-300 mph
Disease- demelinating disease |
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Definition
large diameter and myelinated
150 meters per second
somatic sensory- vision, proprioception, balance, touch and pressure
somatic motor |
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Definition
medium diameter and myelinated
speed- 15 meters per second
visceral and somatic sensory- temperature, pain, touch and pressure
Autonomic motor- smooth and cardiac muscle and glands |
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Definition
small Diameter and unmyelinated
1 meter per second
same information carried as type B neurons |
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Definition
| Axosomatic, axodendritic, axoaxonic, electrical synapse, chemical synapse |
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Definition
| rare- direct transfer of AP across gap junctions |
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Definition
| same as the Ach synapse at the NMJ (cholinergic synapse) |
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Definition
same time at different location
additive and increase the strength of the depolarization current spreading toward the axon hillock |
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Definition
| same location at different times |
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| Mechanism of NT action- Direct Action |
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Definition
| protein that binds receptor is also the channel (nicotinic) faster but only 1:1 reaction- smaller |
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| Mechanism of Action- Indirect Action |
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Definition
binding of protein to receptor does not directly cause an action (may activate a pathway that creates a second messanger- second messenger pathway)
slower but much larger effect because one NT can generate MANY second messangers |
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Definition
direct action, excitatory NT
Found at telodendria of somatic and middle neurons of the PNS and SNS |
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Definition
indirect action and can be excitatory or inhibitory
Found at PNS effectors- parasympathetic (for heart cells) |
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indirect action
widely used in CNS and SNS (sympathetic NS)
catecholaminues, serotonin and histamines (adrenergic synapse)- Norepinephrine |
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Definition
Glutamate- excitatory NT in the brain (direct)
GABA- inhibitory NT in the CNS (direct)0 |
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Definition
| endorphins and enkephalins |
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Definition
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Definition
| chain of neurons leading to a specific, predictable response (spinal reflex, somatic sensory input from receptor in somatosensory cortex of the bain) |
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Definition
| inputs are divided into multiple pathways, with different destinations and more complex responses |
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Definition
"amplifying circuits"
one input from the upper motor neuron --> many outputs |
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"concentrating" circuit
many inputs (different sensory stimuli)--> one output (single memory) |
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Definition
"oscillating" circuit
branches in the pathway provide feedback to previous neurons in the chain
Involved in repetitive motor activities (breathing, locomotion, sleep wake cycle) |
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Definition
| Blocks Ach release directly |
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Definition
| Decreased rate of Ach release |
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Definition
| reduces membrane permiability to Na by blocking the voltage gated Na channels |
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Term
Tetrodotoxin (TTX)
Saxitoxin(STX)
Ciguatoxin (CTX) |
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Definition
| blocks sodium ion channels by blocking the fast voltage gated Na Channels |
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Definition
Prevents Ach inactiviation by cholinestrase
used to treat myasthenia gravis |
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Definition
Anti-cholinesterate inhibitor
used to treat alzheimer's disease along with rivastigmine and galantamine |
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Definition
| prevents Ach inactiviation by cholinestrase |
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Term
| d-tubocurarine (curare- plant based) |
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Definition
| prevents Ach binding to postsynaptic receptor |
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Definition
| Binds to Ach receptor site (high doses cause paralysis) |
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Definition
Reduces sensitivity to Ach
(used for muscle relaxation during surgery) |
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Definition
competes with Ach for binding sites on the postsynaptic membrane
producted by nightshade plant (reduces heart rate, smooth muscle activity, salivation, dilates pupils, skeletal muscle weakness |
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Term
| 4 phases where compounds interfere with synaptic activity |
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Definition
1. NT synthesis (hemicholinium)
2. rate of NT release (botox and barbitarates)
3. preventing NT inactivation (Neostigme)
4. preventing NT binding to receptors (chorare) |
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Definition
| stimulates massive release and exocytosis of Ach (sustained contraction) |
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Term
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Definition
| Antibodies destroy and reduce the number of Ach receptors on the MEP (auto-immune disease. Use black widow venom as treatment |
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Term
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Definition
| neuromuscular Ach-R antagonist- antagonist binds to and hogs Ach receptor. Cannot contract. (**An agonist would bind to the receptor and excite the cell just like Ach would) |
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