BMS 300 Exam 2 combined
Somatic Nervous System
Consists of motor neurons that activate the skeletal muscles. One portion of the motor division of the PNS
Central Nervous System
Consists of the brain and the spinal cord
Ventral/Anterior Horn
Contain a collection of neuronal cell bodies that send processes out of the PNS through a structure known as the ventral root.
Ventral Roots
Contain myelinated axons of motor neurons that innervate both somatic and visceral muscles. The ventral roots carry information away from the central nervous system (efferent).
Dorsal Roots
Contain the process of sensory neurons carrying information toward (afferent) the central nervous system.
Cell body/soma
Contains a nucleus
What does potassium want to do
Follow it's concentration gradient
What holds myelin layers together
Myelin basic protein
Dendrites
Input Region
Does acetylcholine esterase have selectivity to which acetylcholines it will reputable?
No
Dendrite and cell body combine to form the _______ of the neuron where it functions to integrate info.
Input Region (Analytic Region)
Gray matter
Input region of the neurons.
The pia mater
Latin for gentle mother Lies directly on the spinal cord
The dura mater
Latin for hard mother Lies above the arachnoid and is a tough layer surrounding the spinal cord.
Lateral
Means toward the edge.
Dorsal Root
PNS
Sensory afferents are in the
PNS
nerves are only in the
PNS
Peripheral Nervous System
PNS. Anything that comes off the spinal cord (nerves and ganglia).
Ventral Root
PNS. Joins with the dorsal root to make the spinal cord.
What does the dorsal column medial lemiscus provide senses for
Proprioception and fine touch
If the spinal cord is severed, what do you lose
Proprioception and fine touch of the same side and crude touch, temperature, and pain of the opposite side
______ is confined to the cell body.
Protein Synthesis (on the ribosomes)
Neuron Doctrine
States that the neuron is the fundamental structural and functional unit of the nervous system.
Dendrites and cell bodies contain ________, which are basically out-put regions of other neurons.
Synapses
What kind of information does he spinothalamic tract carry
Temperature, pain, and crude touch
Concept of ion permeability
The membrane potential seeks the equilibrium potential of the ion whose permeability is dominate.
Threshold
The membrane potential when sodium influx exceeds potassium efflux.
What did Otto loevi do?
Took frog hearts and made them beat with acetyl choline neurotransmitter
Mechanical Energy
Touch, Hearing (audition)
anatomical neuron
dndrites, cell body soma, axon and axon terminal, sxynapse
name the nuclei in order for proprioception and fine touch
dorsal column, thalamic
t-tubulues do what in a muscle cell?
draw electrical activity into the muscle cell
EPSP
excitatory post synaptic potential ligand gated Na+
EPSP
excitatory postsynaptic potential, inititated in the input region of a postsynaptic cell
what is the dorsal route ganglion?
collection of cell bodies of primary sensory afferents
ganglian
collection of neuronal cell processes in the PNS
Nucleus in CNS
collection of neuronal input regions
Visceral Afferents
comes from intestines
visceral affarents
coming from organs such as the intestines
anterograde transport
fast axoplasmic transport
visceral efferents
fibers innervate the smooth muscle of the viscera, intraocular muscles, heart, salivary glands, etc.
activation NT in CNS
glutamate
inhibitory transmitters
glycerine (spinal cord), GABA( brain)
EPSP
graded with the number of ligand gated ionotropic channels that are open
A neuron is at its resting membrane potential. What is the state of each of its main channels? Please check all that apply.
k+ leak open v gate Na + close v gate K+ close
oxidative molecules are
hydrogen peroxide, bleach, free electrons
protiens
hydrophobic. in vesicvles. kinesin and microtubules
diensephalon
hypothallamus and thallamus
hydrophilic cythoplasmic
katonic, kinesin microtubules cytoskeletal
somatic affarent
info coming from the body such as skin, skeletal muscle and joints
Three box model- computers
information in, analysis, information out
allow for repolarization if Na+ influx isn't enough for membrane potential to reach threshold responsible for depolarization and creating an action potential responsible for rapid repolarization once Na+ Voltage Gated Channels inactivate
k+ leak Na+ v gate K+ v gate
Muscle fibers are also known as?
muscle cells
Each lower motor neuron may innervate several _______, but each muscle fiber can only be innervated by one lower motor neuron.
muscle fibers
ogliodendrocyte function
myelin wraps around nueronal conductile regions→provides insulation around acons
action propagation channel in myelinated axons
myelin wraps laid down by ogliodendrocytes in CNS and Schwan cells in PNS repeated every 1-2 mm along axon. Clustered Na⁺ and K⁺ channels at nodes of ranvier. The myelination increases membrane resistance so less current escapes speeding up the action potential propagation
schwann cells
myelinate axons in PNS
axon potentials will pass much more rapidly along a
myelinated axon
what is white matter
myelinated axons (by oligodendrocytes). ventral tracts, lateral tracts
In the CNS, clusters of ________________ are called ______, and the _______ of these neurons run in _______
neuronal cell bodies, nuclei, axons, tracts
hypothallamus
neuronal cell body of the neuron posterior pituitary
where are astrocytes found
neuronal synapses
In the CNS, clusters of neuron cell bodies are called _______________, and the axons of these neurons run in ______________________
nuclei, tracts
what is the current constant in Ohm's law?
number of ions that flow at a synapse
What does the input region DO
receives signals from neighboring neurons
PNS glial cells
schwan cells
Glia
"Glue." Supporting cells.
Astrocytes
"Star-like" shape. Function is to maintain the extracellular environment for proper neuronal function.
TSR junction
* on sarcolemma: voltage gated Na+ channels and voltage gated K+ channels -then sarcolemma dips down into transverse tubules which contain: Dihydropyradine receptors (DHP)--> voltage sensitive, changes shape with arrival of + charge as Na+ (little foot moves in and leaves RYR channel- unblocks it) allows Ca2+ to run down its concentration gradient and into the cytoplasm -sarcoplasmic reticulum on inside of cell with a narrow gap between it and the tubules: contains ryanodine receptors (Ca2+ channel in sarcoplasmic reticulum) RYR
Seperation of ions to form a biological battery
*Inside of the cell: -large, impermeant anions (cant cross bilayer-stuck inside cell) -charge is negative, has a negative voltage with respect to the outside -100 micromol concentration of K+ (leaves throught K+ leak channels) *Outside of the cell -plasma membrane forms a barrier -10 micromol concentration of K+ -K+ will flow down concentration gradient until equilibrium is reached
Actin Thin Filament Structure
*Monomeric actin arranged like this: 00000 00000 -tropomyosin ribbon covers about 6 actins --troponin C binds to tropomyosin ribbons -myosin binding sites in the actin *when calcium binds to troponin C, it causes the tropomyosin ribbon to change position and go into the middle of the monomeric actin, which exposes the myosin binding sites on the actin -the myosin head comes in (carrying ADP and Pi at its binding site, which can stay stable here until the actin binding site is used) and binds to the actin, which causes the ADP and Pi to leave the binding site -myosin head then rotates and folds over, but remains attached to the actin thin filament -ATP then binds and causes myosin head to let go and start the process over again to continue contracting the muscle
Thin Filaments
*actin filament -tropomyosin attached to actin filament --troponin attached to tropomyosin ---3 components of troponin: ----troponin I ----troponin T ----troponin C (Ca2+ binding protein)
Cytoskeletal proteins of skeletal muscles that produce muscle contraction
*actin thin filament: composed of filamentous actin, tropomyosin (actin binding), troponin c (calcium binding) *alpha actinin (actin binding protein) forms Z line to which actin filaments bind *myosin thick filament
Frequency Coding
*an action potential is an all or none signal -long distance signaling impulse -once membrane reaches potential, it can fire as many action potentials as it wants -threshold ~55millivolts. (balance between influx of Na+ and leaving of K+)
Action potential propagation in MYELINATED neurons
*bundles of myelin rings on membrane with little breaks between them (Nodes of Ranvier) -voltage gated channels cluster in the Nodes of Ranvier -voltage gated Na+ channels allow + charge of Na into the cell, which that sends an electromagnetic field on each ion to open all of the other voltage gated Na+ channels (takes nanoseconds) -voltage gated K+ channels -K+ leak channels -capacitor with reduced number of charges because not much needs neutralized (--- on inside of membrane, +++ along myelin rings on outside) -internodal region: area of membrane directly underneath myelin rings (on inside of cell)
Delivering somatosensory info to somatosensory cortex of cerebrum (postcentral gyrus)
*dorsal column medial lemiscal pathway (DCML) -proprioception = fine touch, where you are in space, fine touch= finding keys and lock in the dark *anterolateral system -spinothalamic tract (bundle of conductile processes) in the CNS: carries info about pain, crude touch, and temperature *both the DCML and the anterolateral system are part of a 3 neuron chain. 2nd neuron in chain crosses midline of body and synapses in the thalamic relay nucleus
Action Potential
*higher concentration of K+ inside cell. once threshold is reached Na+ flows in. Higher concentration of Na+ outside cell **charges flow in and out but concentrations dont change** -voltage gated Na+ ball and chain opens when Na+ can come back into the cell -K+ cant reach equilibrium because of large anions -action potential will reach (+) 40 mv -threshold is -55 mv - (-) 70 mv is membrane potential *On a graph: -up = depolarizing (+) -down = repolarizing (-) -hyperpolarizing: below -70millivolts, vgated K+ channels shut
Three Box Model of Nervous System
*input--> analysis-->output *sensory input --> integration--> motor output
Membrane Potential that approaches the equilibrium potential
*inside the cell: 100micromol K+ 10micromol Na+ large negative anions *outside the cell 10micromol K+ 100micromol Na+ *on the cell potassium leak channels sodium channels: 10x as much sodium on outside as on inside. gated channel (gates closed at rest, dont let Na+ in) when gates open, positive influx of Na+ into cell. when channel is closed, dominant permeability to K+, when open dominant permeability to Na+ **if theres voltage gates K+ channels= charge sensitive, positive charge opens gate (delayed rectifier)
Neurotransmitter release and fate at the neuromuscular synapse
*large muscle cell -plasma membrane = sarcolemma -voltage gated Na+ channels -area of sarcolemma that dips in = place for lower motor neuron to synapse *output region of lower motor neuron -vesicles filled with acetylcholine (some docked in the active zone) -voltage gated Ca2+ channels around vesicles (allow Ca2+ into cell) --extracellular protein between output and postsynaptic membrane. acetylcholine molecules attached to these-- *postsynaptic membrane -ligand gated ionotropic channels -voltage gated Na+ channels *acetylcholine released into gap and binds to ligand gated channels (nicotinic acetylcholine receptors), allows for influz of sodium to generate an EPSP, begins depolarization of the membrane -2 molecules of acetylcholine must bind in order to open channels
Membrane Resistance
*low: -more K+ leak channels, more IPSP (Cl- coming in) *high: -fewer leak channels -less IPSP, more EPSP (better chance of firing action potentials)
Visceral Afferents and Visceral Efferents
*part of autonomic nervous system *usually come through brain stem *visceral efferents-->autonomic nervous system-->sympathetic (fight or flight) OR parasympathetic (rest and digest)
Muscle Relaxation
*reduce cytoplasmic Ca2+ concentrations by pumping the Ca2+ from the sarcoplasm back into the sarcoplasmic reticulum which causes Ca2+ concentrations to fall
Components of the Nervous System
*sensory --(afferent)-->central nervous system (brain and spinal cord)--(efferent)-->output (muscles and glands) *afferent: to carry toward *efferent: to carry away --affect (to bring about)
Afferents Carrying Info Toward CNS
*somatic afferents: carry info about info in body *"soma" means body *somatic afferents-->CNS-->somatic efferents (skeletal, voluntary muscle)
Visceral Afferents
*visceral: anything in abdominal thoracic cavity (lung, heart, etc) *visceral condition --visceral afferents-->CNS (brain stem)-->visceral efferents (smooth muscle, cardiac muscle, glands)
The equilibrium potential for Na+ is about ___mv.
+40
what is the voltage of the peak of an action potential?
+40 mV
Pre-central and post-central gyrus
-post-central gyrus is part of somatosensory cortex -pre-central gyrus is where the motor cortex is
how many pairs of cranial nerves in the brain
12
DCML
-1st degree afferent enters the dorsal horn, cell body in DRG -2nd order neuron crosses over and synapse in the thalamus -3rd order neurons deliver message to somatosensory cortex -1st synapse in brain stem -2nd neuron in brain stem -2nd neuron crosses in brain stem *fine touch and proprioception -synapses in brain stem
Trigger zone
- clustered voltage gated Na+ channels -charge comes from stretch activated channels because Na+ comes in through these channels
ALS
-1st degree afferent enters the dorsal horn, cell body in DRG -2nd order neuron crosses over and synapse in the thalamus -3rd order neurons deliver message to somatosensory cortex -1st synapse in spinal cord -2nd neuron located in spinal cord -2nd neuron crosses in spinal cord *pain, temperature, crude touch, pressure -synapses RIGHT AWAY
Action Potential Generation
-2 ion selective channels are responsible for initiating and terminating action potential -for long distance communication
Glial Cells "glue"
-3 types of glial cells in CNS -astrocytes: cells that regulate the extracellular environment. regulate ion concentrations and concentrations of neurotransmitters (maintain favorable environment for neurons to do their jobs). located in CNS. make sure you arent constantly receiving a neurotransmitter -oligodendrocytes: regulate electrical impulse propagation in the CNS. form myelin wraps around axons/conductile regions (myelinated axons/conductile regions = white matter. concentric rings of phospholipid bilayers. Cant remyelinate (multiple sclerosis: immune system attacks myelin sheath, slows down signal) --schwann: PNS, can remyelinate -microglia: not true glia, actuallly macrophages (nonspecific branch of immunity. release oxidative molecules. only immune system in CNS) <--can often be damaging (sometimes eat cells that arent foreign) -Glial cells in PNS= schwann cells
Spinal nerve
-31 pairs -carries motor and sensory neurons -dorsal root ganglion and ventral root combined
What happens after myosin and actin bind
-ADP and Pi leaves myosin head -myosin performs power stroke and is now at a new angle -ATP then binds to myosin head, and the myosin then lets go of actin -ATP then turns into ADP and Pi and myosin head returns to upright position and looks for a new actin to bind to
Cytoskeletal components
-Actin thin filaments -Z line -Myosin thick filaments
Types of Glia
-Astrocytes (CNS) -Oligodendrocytes (CNS) -Microglia -Schwann Cells (PNS)
Spatial summation
-EPSPs from spatially separate synaptic sites are summating
Forms of energy
-Electromagnetic: changing form of energy to movement of Ions across a membrane -Mechanical: touch -Chemical: bind to receptor and opens channel allowing ions to move
Brown Sequard Syndrom
-Hemisection of the spinal cord -severed the spinal cord to the midline -think of when proprioception/pain afferents can/can't go through
Three Box Model
-Input: sensory in (PNS) -Analysis: integration-goes to brain and spinal cord a decision is made(CNS) -Output: Motor out (PNS)
(3 box model) as it relates to sensory neurons, association neurons, interneurons, and motor neurons.
-Sensory neurons carry information into the central nervous system. -The dorsal horn contains the cell bodies and dendrites of interneurons that are important for processing sensory (afferent) information coming from the periphery and going into the central nervous system.
TSR Junction
-T-tubule and sarcoplasmic reticulum -dihydropyridine receptor -ryanodine receptor
SNARE Hypothesis
-Target snares -Vesicle snares 1. Calcium enters the pre-synaptic element 2. Synaptotagmin binds to calcium 3. when synaptotagmin binds to calcium, 3 alpha helical transmembrane proteins bind together and pull the vesicle to the membrane and allow it to fuse and release N.T.
3rd order neuron in DCML
-Thalamic Relay nucleus -located in thalamus -goes to somatosensory cortex
Distinguish between the central nervous system and the peripheral nervous system.
-The central nervous system consists of the brain and spinal cord. -Much of the peripheral nervous system consists of nerves that carry both sensory and motor information
When is Threshold reached?
-Threshold is reached when influx of Na+ > efflux of K+ -once threshold is exceeded, Na+ continues to enter cell
Components of the Spinal Cord
-Towards back (sensory) - dorsal, posterior -Towards belly (motor) - ventral, interior -all parts outside of cord located in PNS -inside spinal cord is CNS -grey matter on inside -white matter surrounds grey matter -symmetrical (right and left sides are same)
Sensory Transduction
-a change in the form of energy --electromagnetic: ions moving across membranes --mechanical: ions moving across membranes --chemical energy transduction: using shapes of molecules to generate the movement of ions across membranes
Refractory period
-a part after the action potential that makes it hard for another action potential to fire -Na+ channels close during this time
Capitance
-ability to store charge -separation of charge across a non-conducting medium
Functional Description of Output Region of Neuron
-action potential reaches output region - positive charge increases in intracellular space because of arrival of action potential -opens voltage gated Ca2+ channels to admit Ca2+ from extracellular space -Ca2+ influx causes exocytosis of synaptic vesicles and release of neurotransmitters -PNS
How does myosin and actin bind
-after calcium is released by sarcoplasmic reticulum, calcium binds to troponin -troponin then makes tropomyosin smaller so myosin binding sites are exposed -the actin binding site on myosin then binds to myosin binding site on actin
Tetanus Toxin
-all muscles contract -bacterium gets into open wound (lives in horse intestines) -stops neurotransmitter release (inhibitory release) -death by suffocation -lack of inhibition
Input region of neuron
-all protein synthesis happens here -responsible for synaptic potentials (transmembrane proteins are ligand-gated channels)
Primary Afferent Neurons
-ascend the spinal cord in the dorsal columns -primary afferents of the anterolateral system synapse on 2nd order neurons in the spinal cord
Spinal cord
-bilaterally symmetrical -split into L/R and anterior/posterior
Myosin Thick Filament
-bundle of myosin molecules -myosin is an ATPase (converts ATP to ADP and Pi)
Myosin thick filaments
-bundle of myosin molecules (motors) -actin binding site
Myelin Wrapping
-can re-myelinate PNS better than CNS -clustered voltage gated channels generate action potential to hop from nerve to nerve
Otto Lewi
-cardiac physiology -placed frog heart into solution in a beaker and stimulated the Vegus nerve (which caused heart to slow down). Then placed 2 frog hearts into seperate containers connected by a tube that allowed the fluid to flow freely from one heart to another and stimulated the Vegus nerve of the 1st heart. 2nd heart also responded. -acetylcholine
Axoplasmic Transport
-cellular process responsible for the movement of synaptic vesicles, proteins, and other organelles from the cell body through the membrane of the axon -ribosomes on cell body and dendrites ONLY -very discontinuous movement (hitchhiker)
White matter
-characterized by myelinated axons -conductile regions of neurons in CNS (tracts)
Gray matter
-characterized by neuronal cell bodies -input regions and output regions of neurons (synaptic sites)
High capitance
-charges interact more since they are closer together (nothing in between) -charge is stored near the membrane -a lot more negative charges get through -decreased velocity
Role of Astrocytes
-clear out synapses so communication can occur -limit NT receptors -use sodium K+ pumps to control concentration of K+ -if it is too high neurons cannot signal properly -must maintain good environment for electric signaling cells *after a stroke astrocytes lack oxygen->damaged neurons->defficiency in ability of astrocytes to clear NT
Functional Description of Trigger Zone on Neuron
-clusters of charge gated channels -decision point
Ventral Root
-connects with dorsal root -motor efferents send messages through here
Dorsal Root Ganglion
-connects with ventral root -primary sensory afferents bring messages in through here -collection of primary sensory afferent neuronal cell bodies
Cerebrum
-contains cerebral cortex (gray matter) -gray matter is composed of 6 neuronal cell body layers (where analysis happens) 3mm thick at most -white matter: contains conductile regions (axons) ensheathed in myelin
Capacitor
-created from separation of charges across the lipid bilayer -must discharge capacitor before opening next v. gated Na+ channel -node of Ranvier has large amounts of capacitors and transmembrane proteins
Patterns of Cutting Spinal Cord
-cut halfway through cord -left side lost sensation of fine touch -pain and touch are not affected -right side pain temperature is blocked to go to left side -right side fine touch can get through
Brown Sequared Syndrome
-cut spinal cord to midline -severed pathways and processes that crossover are spared on cut side, but processes like dorsal column system are intercepted
Henry Dale
-discovered that the vagus stuff is known as acetyl choline -NT released from neuron affected the nerve
Summation
-each synaptic site produces a potential that is then added to the overall potential to get up to threshold -adding together of EPSP drives membrane potential towards threshold -more leak channels= more positive charge leaks out= smaller potential at trigger zone
Penfield
-excise tiny portion of brain to cure epilepsy -started to perform surgery on conscious patients -literally poked at brains to see where parts lead to in the body --"somatotopy" body map: the map of the body plan on cortical regions (homonculus) -somtosensory system is located on post central gyrus
Ohm's Law high resistance
-few leak channels -voltage increases
Oligodendrocytes
-form myelin sheaths around axons -myelin forms around neurons so action potentials can conduct more rapidly -form white matter in CNS -when wrapping, leading edge lays down 2 plasma membrane layers and squeezes out other cytoplasm
Otto Loewi story
-frog heart with vagus nerve (transferred this water to the heart without nerve) -the heart rate slowed down even without the vagus nerve
Bodian Classification
-functional classification -input region (dendrites): receives synapses from other neurons. enriched for ligand gated -conductile region (axon): contains voltage gated ion channels responsible for action potential -cytoplasmic raft: moves at fast axoplasmic transport rates (200-400 mm per day) but then chills for a few days (moves in fits and starts) i.e. hitchhiking: you get rides to different cities on the way to santa fe, but vesicular proteins get a direct ride to santa fe
Na+ Channels
-gated and generally closed -gate is opened by an increase in + charge -open and close so quickly that the electrical potential changes -concentration of ions across membrane doesnt change all that much
Schwann Cells
-glia cell of PNS -maintains neurons/neuronal activity
Primary sensory afferent in Dorsal Column Medial Lemniscus
-goes in spinal nerve -enters dorsal column -heads toward 2nd order neuron
Potassium Leak Channel
-graph starts with Ek dominant K+ permeability. A + charge is added which causes Na+ channels to open (voltage/charge sensitive). The graph goes up the Y axis until an Ek (equilibrium potential) of +58mmol is reached -graph begins to go back down, sodium channels begin to close/ inactivate. potassium becomes dominant permeability (channels open-delayed rectifiers) *Voltage gated channels: -gate opens by an increase of + charge -ball and chain on voltage gates Na+ channel: moves into open channel to close it up which is inactivation of this channel
Brown Segard Syndrome
-hemisection of spinal cord (cut through cord half way) -can feel pain on one side and fine touch on the other (basically)
Propagating Potentials in Unmyelinated Axons
-high concentration of Na+ on outside of cell -high concentration of K+ on inside of cell -Na+ moves into cell, local positive charge triggers other voltage gated Na+ channels to open = influx of Na+ (Depolarization, increased action potential) -Na+ channels inactivate shortly after opening which causes opening of K+ channels -these K+ channels move positive charge out of the cell creating an equilibrium resting state (Repolarization, decreased action potential)
Inhibitory Post Synaptic Potential
-hyperpolarization due to Cl- influx -membrane potential more negative and away from threshold -causes dip in graph
Diencephalon
-hypothalamus: hypo=beneath, lots of info about autonomics -thalamus: sensory relay site (all sensory info except smell comes in through this site
Dominant permeable
-if K+ channels are open, K+ channels are dominant permeable (leads to equilibrium of potassium)
Propagating Potentials in Myelinated Axons
-in conductile region of myelinated neurons, internodal regions are wrapped in myelin -voltage gated Na+ channels and K+ channels are clusters in the plasma membrane of the nodes -charge carried by Na+ ions entering the neuron at a node is rapidly delivered to the neuronal membrane at next node where the positive charge depolarizes the nodal membrane and causes v. gated Na+ channels at this site to open -this influx pattern of Na+ is repeated along length of conductile region so that action potential jumps from node to node -this hoping is called saltatory conduction which is very fast and speeds up rate of action potential conduction along axon
Effect of Open Cl- channels on Rm
-increase # of open Cl- channels, decrease Rm -this affects amplitude of EPSP arriving at trigger zone -increasing inhibition, lowering Rm, amplitudes are smaller so need more EPSP
Postsynaptic element (input)
-influx on Cl- into cell (chloride) -ligand gated ionotropic channels (bind neurotransmitter GABA, when neurotransmitter binds, it opens the channel) *on graph -hyperpolarization (when graph dips down into a U shape) inhibitory postsynaptic potential IPSP -EPSP (when graph hills up into an upside down U shape right over the U shape of the hyperpolarization) cancels out IPSP = inhibition offsetting effects of exhibition
Functional nomenclature of neuron
-input region: dendrite and cell body -conductile region:axon -output region: axon terminal
Grey Matter
-input regions of neurons -synaptic integration -cell body and dendrites
Langley
-interested in nicotine -placed drops of nicotine onto single muscle fiber. about 1/3 of the way down the muscle contracted= nicotine receptor -acetylcholine released by lower motor neuron
Stretch Activated Channels
-let Na+ in -amplitude of depolarization is proportional to amplitude of stretch -cell body in DRG and process into spinal cord -nerve ending in finger, signal travels down nerve to voltage gated Na+ trigger site, which is opened by stretch channels and then travels to spinal cord
Myelin Basic Protein
-located on wrapped oligodendrocytes -suppress immune system if signal for attack occurs -breakdown in BBB->tight junctions prevent large molecules from crossing -cells go through->go to CNS->recognize MBP and attack astrocytes
Lots of K+ leak channels
-low resistance membrane -number of ions at excitatory synapse is almost always the same- resistance is what changes things -low resistance = low voltage loss of K+ is the same thing as allowing an anion in (Cl-) -Ohm's Law: voltage = resistance x current (ions moving per second)----V=IR -voltage driving a current across a resistor -T=RmCm --T=time it takes for potential to decay --Rm=membrane resistance (if it is low, T is short) --Cm=capacitance
Lower Motor Neuron (somatic efferents) Interbation of Muscle (skeletal or voluntary)
-lower motor neuron cell bodies in ventral horn -each muscle fiber receives input from ONE motor neuron -each motor neuron interbates MULTIPLE muscle fibers -motor unit= lower motor neuron and the group of muscle fibers it interbates
Microglia
-macrophases -part of immune system
Actin thin filaments (filamentous actin)
-made up of Globular (G) Actin -Tropomyosin: connects 6-7 actin monomers -myosin binding sites -Troponin: Calcium binding protein
Sarcomere
-made up of actin and myosin -Z lines are the boundary
Ohm's Law low resistance
-many leak channels -voltage decreases
Upper Motor Neurons Synapse onto Lower Motor Neurons
-message on upper motor neuron until lateral corticospinal tract then synapses onto lower motor neurons -found almost entirely in primates and racoons because we dedicate a lot of lower motor neurons to our hands ALL MOTOR NEURONS ARE EFFERENTS
Pre-central Gyrus
-motor cortex determining how we move -region on frontal lobe dedication to movement
Descending Pathways and the Motor Cortex (Precentral Gyrus)
-motor cortex of precentral gyrus is located in the frontal lobe -a neuronal cell body of an upper motor neuron sits inside the precentral gyrus and extends a process into the internal capsule (contains axons of upper motor neurons) and then extends a process into the brain stem immediately above the spinal cord (decussation of the pyramids) which crosses the midline and enters the lateral corticospinal tract (cell body is here, forms synapses in the gray matter of spinal cord) in the spinal cord and extends a process into the ventral horn and synapses onto a lower motor neuron
How to regenerate action potentials?
-must occur at very close regions along the membrane -Na+ comes in, makes inside positively charged, replaces capacitors -only place where plasma membrane opens is the node of ranvier -myelinated axons have stretch activated channels which make action potential signal travel faster down the neuron
Capacitor Strength
-myelinated axons makes membrane a weak capacitor because the charges are more greatly separated by the myelin -in absence of other channels, strength of stimulants is proportional to amount of depolarization
White Matter
-myelinated conductile regions -action potential propagation
Low Capitance
-myelination separates charges -less interaction (less charge) -depolarizes cell faster -increased velocity
Anions
-negatively charged -trapped inside cells -movement of K+ down gradient is held in check by anions -nucleic acids and proteins
Ventral horn
-neuronal cell bodies of lower motor neurons are found here
Input Region cont
-neurotransmitter will be glutamate -excitatory synapses located on dendrites -inhibitory synapses located just below dendrites (axon terminals, output regions, presynaptic element of inhibitory neuron) -trigger zone at base of cell head: voltage gated Na+ and K+ channels -ligand gated = input region -voltage gated = conductile region
Neurotransmitter receptor on post-synaptic neurons
-neurotransmitter-operated channels (ligand-gated, Ionotropic channels) -binding of N.T. opens gates and allows ions to flow through (Na+)
Cations
-positively charged -freely travels membrane through K+ leak channels
Integration
-occurs in CNS when electrical signals are transferred among neurons at sites called synapses -sensory info enters CNS via dorsal root
Sensory Input
-occurs in PNS
Spatial Summation
-occurs when potentials originating in different regions of the dendritic tree or the cell body summate -like using many shovels to fill up a hole all at once
Temporal Summation
-occurs when the potentials arrive within a narrow enough time window when the potentials can add together -any process that affects the time course of the potential will affect temporal summation -like using a single shovel to fill up a hole over time
Myelination
-oligodendrocyte wraps around the plasma membrane of the axon (keeps wrapping and squeezes out cytoplasm--spiral), transmembrane proteins stick the two plasma membranes together. -each layer is a plasma membrane of oligodendrocytes -creates concentric layers of plasma membrane -Nodes of Ranvier: contains clusters of voltage gated ion channels (space between concentric rings of myelin) about 100 micrometers wide
Dihydropyridine receptor
-on T-tubule membrane -plugs ryanodine receptor (like foot in hole) -Voltage sensor -When positive charge from sodium enters muscle fiber, the DHR pulls out of RDR and then calcium pours out of sacroplasmic reticulum
Potassium leak channels
-only allows K+ ions to pass -always open -large anions (A-) keep all the potassium from leaking out
Oligodendrocytes
-only in CNS -ensheates axons and forms an insulating layer -regulates extracellular potassium concentrations
Astrocytes
-only in CNS -regulate extracellular potassium ion and neurotransmitter concentrations (uptakes if too much)
Repolarization
-open v. gated K+ channels -these channels move K+ out of cell, removing positive charge in the cell which returns the membrane potential to its resting state -K+ channels close a membrane potential becomes more negative (closing is voltage sensitive)
Structure of Striated (skeletal or cardiac) muscle
-organizing the cytoskeletal proteins into a series of repeating structures called SARCOMERES (1-2 micrometers in length) *ON A MUSCLE CELL: -z lines composed of alpha actinin along length of cell -actin thin filaments are horizontally anchored to the alpha actinin of the Z lines -between the actin thin filaments are myosin thick filaments -shortening distance between the z lines contracts the muscle *thick and thin filaments are horizontally packed (6 thin around 1 thick)
Anterolateral System (pain sensory afferent)
-pain afferents directly synapse with 2nd order neuron -does not go through dorsal columns -goes through spinothalamic tract
Dorsal Column
-part of white matter -contain extensions, processes of the primary sensory afferent
Langley
-pharmacologist interested in Nictoine -developed idea of receptive substance on muscle fiber which causes contraction muscle contracts = some type of chemical reaction Experiment: Got muscle fiber from mouse, motor neuron comes close to fiber, so he made a bath of nicotine and dunked 1 fiber into solution, he walked along muscle fiber, when he got close to motor neuron a contraction occured
Structure of skeletal muscle fiber/cell
-plasma membrane=sarcolemma -multi-nucleated -t-tubules: extensions of sarcolemma -Sarcoplasmic reticulum: Calcium storage organelle
What are the two forces that pull sodium ions into the cell?
-positive charged Na+ ions are being pulled down since there is a negative charge in the cell -Sodium diffuses down its concentration gradient
Gyri
-postcentral gyrus = motor cortex -precentral gyrus = somatosensory cortex -the two are seperated by the central fissure (central sulcus) -think of the gyri as plateaus and the sulcus as valleys
100s of leak channels
-potential will be around .1mm -need many more potentials to reach threshold
Conductile region
-predominately has voltage gated Ion channels (responsible for action potentials) -vesicle from cell body is loaded onto kinesin and walks along axon
Input Region
-presynaptic element of another neuron along dendrites -K+ leak channels (EPSP) -trigger zone at base of cell head (voltage gated K+ and Na+ channels cluster here) -input region lacks voltage gated channels but is enriched for ligand gated channels -ligand gated channels on input region open (when 2 molecules of transmitter bind), Na+ comes in and generated postsynaptic depolarization (excitatory posysynaptic potential)
Spinothalamic Tract
-primary sensory afferent goes into spinal cord via dorsal horn -creates synapse with primary sensory afferent onto 2nd order neuron -2nd order neuron crosses over midline *ALWAYS* -enters spinothalamic tract -goes up to brainstem, then goes to thalamic relay nucleus -creates 3rd order synapse which goes to cerebrel cortex
Dorsal Column Medial Lemiscal Pathway
-primary sensory afferent in DRG leads to input of stretch receptor -cell body in dorsal horn -dorsal column = ascending pathway carrying somatosensory info -neuronal cell body = input region *lets say were talking about your RIGHT leg -neuron comes in from DRG into right side of spinal cord and synapses in brain stem (dorsal column nucleus, cluster of neuronal cell bodies in CNS). then 2nd order neuron crosses the midline (enters the anterolateral system: spinothalamic tract= bundle of conductile processes in CNS) and synapses and then the 3rd order neuron synapses in the thalamic relay nucleus -3rd order neuron forms synapses in the primary sensory cortex of cerebrum OR -pain, crude touch, and temperature neuron comes in and synapses immediately, then 2nd order neuron crosses midline and travels up spinal cord to thalamic relay nucleus, synapses, and 3rd order neuron travels up to left somatosensory cortex and synapses -6 layers in primary sensory cortex= cell bodies of sensory cortex -right side of body = right side of cord for proprioception and fine touch
Action potential propagation in unmyelinated neurons
-propagates action potentials at 1-2 m/sec -channels are spread out equally -voltage stays the same
SNARE Hypothesis
-proteins on vesicle and proteins on plasma membrane interaction lead to vesicle exocytosis
Katanins (katana samurai sword)
-proteins that cut/sever cytoplasmic, cytoskeletal matrix --cut out a raft of cytoplasm attached via kinesins
2nd order neuron in DCML
-reaches dorsal column nucleus -crosses over midline and heads toward 3rd order neuron
Astrocytes
-regulate movement of substances between CNS and BBB -regulate ion concentration of K+ by pumping ions -regulate concentration of neurotransmitters in extracellular space
Otto Loewii
-relationship between nervous system and target -wanted to know how nervous system was affecting heart Experiment: took heart out of frog and put it in a bath, vagus nerve connected to heart was stimulated with electrodes which caused heart to slow down, stimulating nerve releases substance into bath, so when new heart was put into old bath, new heart began to beat slower -this tells us that something is being released by vagus nerve which affects heart
Myotatic Reflex (stretch receptor reflex)
-requires: primary sensory afferent and lower motor neuron -patellar tendon and quads are directly connected -strike patellar tendon and stretch quad muscle -neuromuscular synapse in quad: causes muscle to contract -quad muscle has input region for sensory afferent (stretch receptors) which generates potentials -lower motor neuron in bottom of butterfly in spinal cord, goes to DRG, then to sensory afferent then ends in quad muscle -EPSP= glutamate (released by action potentials in lower motor neuron) -myotatic reflex arc is confined to spinal cord
Membrane Systems of Skeletal Muscle Cells
-sarcolemma: muscle cell plasma membrane -transverse tubules: extentions of sarcolemma, think of it as a well, its the same as the extracellular environment -sarcoplasmic reticulum: intracellular membrane bound bag containing Ca2+, calcium storage and release. located between transverse tubules--very narrow gap between this and tubules -TSR junction: transverse tubule becomes connected to sarcoplasmic reticulum by protein bridges -muscle cells are multinucleic: 2 myoblasts fuse to become one cell with 2 nuclei and continues multiple times
Post Central Gyrus
-sensory -somatosensory cortex
Somatic Afferents
-sensory neuron, dorsal root ganglion -input is peripheral
Functional Description of Input Region of Neuron
-sensory signals recieved from neighboring cells -synaptic signals generated -ligand gated channels -CNS **THE GREATER THE STIMULUS STRENGTH, THE LARGER THE AMPLITUDE OF DEPOLARIZATION
Central Sulcus
-seperates frontal and parietal lobes -precentral gyrus sits immediately in front of this -postcentral gyrus sits immediately behind this and contains somatosensory cortex
Synapse
-site of chemical communication between neurons and between neurons and muscle (glands) -means to clasp or hold
Switching the membrane potential
-starts as potassium as dominant -after action potential is fired, sodium becomes dominant -once the dominant permeability is sodium, then the membrane potential seeks end
Schwann Cells
-supporting cells of the PNS -myelin producing cells which wrap around axon in many layers -clean up debris after peripheral nerve damage and support regeneration of peripheral nerve
Temporal summation
-synaptic potentials must over lap in time
Anatomy/ structure of output region (presynaptic element)
-synaptic vesicles float about freely -docked synaptic vesicles attached to membrane -voltage gated Na+ channels: causes calcium channels to open because of the influx of + charge -voltage gated Ca2+ channels allow Ca2+ into cell (on membrane surrounding docked vesicles) cause vesicles to release contents into outside world (neurotransmitter release by exocytosis) -transmitter release sites = active zones -----transmitter released into synaptic cleft---- -binding to receptors on postsynaptic element which causes ligand gated ionotropic channels to open (generated depolarization because Na+ delivers a + charge)
T-SNARES
-syntaxin: found in plasma membrane of axon terminal -SNAP 25
Summation
-temporal: amount of time between each charge coming in -spatial: comes in from dendrites
Threshold
-the influx of sodium through sodium channels is balanced by the efflux of potassium through potassium channels -sodium has to come in faster than it is leaving
Ek membrane potential approaches Ek when only K+ channels are open
-the membrane potential seeks equilibrium potential for the ion with dominant permeability -on a graph: open Na+ channel starts at -58mmol, this causes the membrane to depolarize, once it has reached +58mmol, the dominant permeability is to Na+. After that, the graph goes back down as the membrane repolarizes in order to increase membrane permeability for K+. the Na+ gate closes and the dominant permeability is to K+
How much sodium enters through stretch activated channels?
-the number of sodium ions that enter the input region through stretch-activated channels is proportional to the amount stretch -the harder we stretch plasma membrane the more the Na+ channels open, the more sodium comes in
Action potential frequency
-the stronger the stimulus, the more frequent the action potential
Neuromuscular synapse
-there are extracellular proteins in the synapse -enzymes replace astrocytes -enzymes eat extra N.T. or break it down -enzymes are called acetyl cholesterase (break N.T. into acetate and choline...these two then open receptor on dendrites)
Camillo Golgi
-thought all neurons were connected by cytoplasmic bridges
Santiago Ramon y Cajal
-thought each neuron was a separate unit -figured out information flow (dendrite to cell body to axon to axon terminal to next cell)
Sherrington
-thought there must be a site where neurons clasp on to each other based off of neuron doctrine -some form of chemical communication
Slow Axonal Transport
-tubulin, actin, intermediate filament -moves proteins made on free ribosomes (cytoplasmic proteins) -0.5-2 mm/day
Dynamic Polarization
-unidirectional flow of information -dendrite-->cell body-->axon
What happens after Astrocyte uptake neurotransmitters?
-uptake of neurotransmitters -converts N.T. to an inactive form -the inactive neurotransmitter goes out of astrocyte and into the cytoplasm -axon receptor picks it up again
Nernst Potential
-used to calculate the equilibrium potential (Veq.) of an ion -It is the membrane potential at which no net movement of the ion in question occurs across the membrane -Ek is proportional to concentration of K+
Action potential propagation in myelinated axons
-v-gated Na+ and K+ channels are clustered at Nodes of Ravier -100-115 m/sec
Fast Axonal Transport
-vesicle and kinesin -moving proteins that have been made on the rough ER (secreted proteins) -200-400 mm/day
Movement of info along Axon
-vesicles move along microtubules -vesicles along actin use myosin to travel across neuron
Mechanisms for releasing neurotransmitters
-voltage calcium channels allow Ca+ to enter the pre-synaptic element (axon terminal) -the intake of calcium triggers for N.T. to release into synpatic cleft -the Na+ then enters post-synaptic element and depolarizes the cell (excitatory post-synaptic potential)
Propagating an action potential in membrane containing voltage gated channels along its entire length
-voltage gated Na+ channels allowing Na+ into the cell -K+ leak channels allowing K+ out of the cell -voltage gated K+ channels -the cell membrane is a capacitor: on the outside is +++ charges lined up and on the inside is --- charges lined up. THIS MUST BE NEUTRALIZED BY Na+ IONS -influx of Na from one channel gives rise to the sequential opening of voltage gated channels (permits regeneration of action potential- which is what allows it to travel all the way down the membrane) -new action potentials (propagation)--in UNMYELINATED neurons
Initiation of Action Potential
-voltage gated Na+ channels open -causes Na+ to flood into cells in response to local increase in positive charge on cytoplasmic side of plasma membrane -influx of Na+ causes depolarization which opens more Na+ channels
propagation of potentials in membranes that lack v-gated channels (hose story)
-voltage gated channels do not span across the membrane -positive charge is leaving the cell through the potassium leak channels -this makes it hard for the action potential to fire because voltage is decreasing
Functional Description of Conductile Region of Neruon
-voltage gated channels propagates and transfers electrical signals down the neuron signal = action potential -charge sensitive and located in CNS
Na+ selective channels
-voltage-gated (charge sensitive) -doors open by charge
How is the membrane potential produced?
-when K+ exits the cell it creates a separation of charge across the membrane creating a battery -this makes the inside of the cell negatively charged
When do these voltage gated Na+ channels close?
-when membrane potential reaches +40mV -Na+ channel remains in this state until repolarization occurs (opening of voltage gated K+ channels)
Stretch Activated Channels
-when open they cause depolarization -located in dendrite region, when open Na+ goes into sensory neuron -this graded depolarization opens voltage gated Na+ channels and initiate all or nothing action potentials
When is an equilibrium reached for potassium?
-when the tendency for potassium to leave is balanced by the electrical gradient
Phineas Gage
-worked on railroad building team in 1800's -went to blow something up but messed up and had a steel rod shoot through cheek and head (took out most of frontal lobe) -he survived but was never quite the same again -he died 20 years later of epilepsy (seizures because of neural rewiring) -the philosophical transition: who we are is derived by what our brain tells us (not our soul)
In Slow Axoplasmic Transport, movement of tubulin, actin, and neurofilament protein are moved at a rate of _______.
.2 - 5 mm/day
Slow Axoplasmic Transport
0.5-2 mm/day. These were the cytoplasmic proteins. Similar to taking flights with layovers to a destination.
slow component of axoplasmic transport
0.5-2mm/day. cytoplasmic protein. Attach briefly to vesicles on kinesin. (like riding a bus a little ways, then getting off and waiting for another)
Unmyelinated axon conduction velosity is ~ __ meter/sec. This is way too slow
1
about how long is an axon
1 meter
What does deccasation mean
Crossing over
How can you release a Neurotransmitter from a neuron?
1. Depolarization ( positive charge comes in cell by v. gated Na+ channels) 2. Extracellular Calcium (voltage gated Ca2+ channels) -positive charge inside cell opens up Ca2+ channel to let Ca2+ into the cell -Ca2+ triggered fusion of vesicle with plasma membrane which leads to exocytosis
3 Types of sensory transducers
1. Electromagnetic (light) - animals sense warm blooded animals through infrared rays 2. Mechanical (move tip of cell--> open channel --> ions flood in) 3. Chemical (taste and smell)
What do myosin heads do
Bind ATP to make ADP and Pi It is an ATPase
Types of Axoplasmic Transport
1. Retrograde transport- moves membrane bound vesicles towards cell body 2. Fast anterograde transport- moves vesicles from cell body towards terminal -actin, tubulin, and glycoenzymes synthesized on free ribosomes -all fast are membrane bound proteins -movement along microtubule from cell body to terminal powered by kinesin which cleaves ATP tp ADP
DCML neurons
1. dorsal root ganglian 2. dorsal column nucleus in brainstem 3. thalamic relay nuclius
spinothalamic neurons
1. dorsal root ganglian 2. dorsal horn spinal cord(crosses over) 3. thalamic relay in nuclues
Cranial nerves contain ____ pairs.
12
steps of action potential
1. resting membrane potential k+ leak channels and flickering net channels cloe to Ek 2. EPSP, temporal and Spatial Summation 3. depolarization, v-gated Na+ channels open, fast, Seek +70 4. peak A.P. v-gate Na+ inactivate. v-gate K+ activate slow delayed. 5. repolarize. become more negative all v-gate K+ channels o0pen membrane seeks equlibrium -80 6. hyper polarization, more negative then resting membrane. aprach Ek.
Periphral Nervous System PNS
1. sensory affrents 2. visceral affrents 3. Effrents -somatic -visceral
central nervous system CNS
1. spinal cord 2. brain
taste
1. sweet- simple sugar 2. salty- Na selective channel 3. bitter- 2nd messenger 4. sour- H+ channel 5. unami - glutamate + sodium ( monosodium/ glutamate
Intracellular Na+ is always in the neighborhood of about ______, while Extracellular Na+ is always in the neighborhood of about 130 mm.
10 mm, 130 mm
Intracellular K+ is always in the neighborhood of around ______, while Extracellular K+ is always in the neighborhood of _______.
140 mm, 4-5 mm
Axoplasmic Transport
2 types, fast and slow.
Extracellular calcium (Ca2+) is in the neighborhood of ~___mm. While Intracellular calcium is in the neighborhood of ~___nm.
2-3, 10
What is needed for calcium reputable in a muscle cell
Calcium pumps in the SR
Synaptotagmin
Calcium sensor.
In Fast Axoplasmic Transport, proteins are moved throughout the neuron at a rate of _____ mm/day. (Long-distance communication of proteins)
200-400
fast transport
200-400 mm a day, transmembrane, lysosomal, secreted proteins
Fast Axoplasmic Transport
200-400 mm/day. Were membrane bound proteins. Similar to taking a direct flight to a destination.
fast component of axoplasmic transport
200-400 mm/day. transmembrane and packaged proteins synthesized on rough ER and packed onto vesicles. transported by kinesin in + direction and dyenein in - direction
How many pairs of spinal nerves?
31.
Spinal nerves contain ____ pairs.
31
____ pairs of spinal nerves
31
how many pairs of spinal nerves in the spinal cord
31
What wavelength can people see
375 nm to 750 nm
How many layers of upper motor neurons make up the cerebral cortex thick-wise
6
The cerebral cortex is composed of ___ layers of neuronal cell bodies.
6
Rapid depolarization
A build up of positive charge. It is the influx of Na+ carrying the membrane potential to +40mv. This demonstrates the firing of an action potential.
Nerve
A bundle of neuronal processes in the PNS
Gray matter
A collection of cell bodies and unmyelinated processes. The gray matter on each side of the cord is divided into a dorsal horn and a ventral horn.
Ganglion
A collection of neuronal cell bodies in the PNS that are all sensory afferents (such as the dorsal root gangion). One process goes out of the PNS, one process goes into the CNS.
Ganglion
A collection of neurons in the peripheral nervous system.
What does an increase in IPSP mean
A decrease in EPSP duration
Node of Ranvier
A gap in the myelin sheath of a nerve, the open site where the plasma membrane of the axon is open to the outside world. Characterized by the clustering of V-gated Na+ channels.
What is inside the conductive region that is able to translocation vesicles?
A network of microtubules
Amyotrophic Lateral Sclerosis (Lou Gehrig's Disease)
A progressive, selective degeneration of the motor neurons of the CNS, leading to wasting of the muscles and paralysis.
Katanin
A protein that severs microtubules and uses slow axoplasmic transport to move cytoplasmic sections.
What follows an action potential directly
A refractory membrane which causes an action potential to be more difficult to set up immediately after the first action potential
Thalamus
A relay site for information going to the cerebral cortex
What is a sarcomere
A repeating unit of cytoskeleton organization in skeletal muscle
The arachnoid layer
A separate layer that is connected to the pia by spider-like processes.
What is a synapse
A site of chemical communication between two neurons and between neurons and muscles or glands
Neuronal processes of the white matter carrying info toward the brain?
Ascending Pathways
Do action potential amplitudes change
No
Dorsal Root Ganglion
All of the neurons with processes entering the central nervous system through the dorsal horn have their cell bodies in the dorsal root ganglion. The dorsal root ganglion is located in the periphery.
Amplitude
Depends on the membrane resistance.
What is the most common excitatory neurotransmitter in the PNS
Acetylcholine
What type of ligand-gated ionotropic channels are in the PNS
Acetylcholine
_______ are sent along the ________ region stimulating long distance communication.
Action Potentials, Conductile
________ causes sarcoplasmic reticulum to release Ca2+
Action potential
The docked vesicles docked adjacent to the v-gated Ca2+ channel is known as the _______.
Active Zone
What is a characteristic of an action potential
All the sodium channels open at once
What do voltage gated calcium channels do?
Allow for the executors is of neurotransmitters into the synaptic cleft
What does the shape of a stretch sensitive neuron do
Allows a change in chapel of the membrane to cause stretch channels to open, letting sodium in
Where does the secondary nerve cross over in the Spinothalamic tract pathway
Almost immediately after synapsids with the primary neuron
What are z lines made of
Alpha actinin
Multiple sclerosis
An autoimmune and degenerative disease that targets proteins in oligodendrocytes, and destroys it. This disrupts the flow of action potentials and information.
Brain stem
An extension of the spinal cord that is responsible for skin and muscles of the head. The cranial nerves originate in this region.
________ moves vesicles from the cell body toward the terminal. ________ moves membrane bound vesicles toward the cell body.
Anterograde Transport, Retrograde Transport
Resting Membrane Potential
Approximates the equilibrium potential for K+ (Esablishes a K+ battery). ~ -80mv
K+ Leak Channels
Are always open. They determine the resting membrane potential.
Cells that maintain the extracellular environment in the central nervous system by pumping sodium and potassium ions and mopping up excess neurotransmitter are:
Astrocytes
What cleans up the extra neurotransmitters to prohibit random firing of action potentials.
Astrocytes
Glia Cells in CNS
Astrocytes and Oligodendrocytes
What path does the primary neuron take in the DCML pathway
Dorsal root into the white matter, and up the spinal cord
Why can't potassium follow it's concentration gradient
Because of its electrical gradient
Why is the resting membrane potential slightly higher than the Ek
Because potassium channels flicker on and off, allowing a more positive charge to reside in the cell
Sarcomeres are the
Basic building block of muscle
what does nucleus mean
a collection of cell bodies
cells in the motor cortex
Botz cells
CNS
Brain & Spinal cord
Tracts
Bundles of axons in the central nervous system.
Tracts
Bundles of neuronal processes in the CNS
How is the number of stretch channels opened determined
By the strength of the stimulus so the more the stretch, the more depolarizer the membrane gets
Dorsal Horn
CNS
where are ogliodendrocytes located
CNS
where are associative neurons found
CNS (associative nerons)
where are afferent neurons found?
CNS and PNS
where are efferent neurons found?
CNS and PNS
What are oligodentrocytes
CNS glial cells
COPS
CNS oligodendrocytes( mylinate many), PNS Shwan( mylinate 1)
oligodendrocytes in ______, schwaan cells in _________
CNS, PNS
Central Nervous System
CNS. Brain/spinal cord
Sarcoplasm lacks ______
Ca2+
Which of the following molecules plays the largest role in exocytosis of neurotransmitter into the synaptic cleft?
Ca2+
the Sarcoplasmic reticulum holds all of the ______ in a muscle cell
Ca2+
troponin
Ca2+ binding protein
sarcoplasmic reticulum is a membrane bound compartment that contains the following
Ca2+, Ryanidine receptor, Ca2+ ATPase
How do inhibitory synapses work
Calcium causes vesicles to release GABA and glycine GABA and glycine bind to ligand gated ionotropic channels to then allow chloride into the cell causing an IPSP
Ryanodine
Calcium channel on sarcoplasmic reticulum membrane
What happens if sodium no longer enters the muscle cell
Calcium is taken back up by the SR allowing the muscle to relax
_______ refers to the ability to separate charge across the membrane
Capacitance
Internal Capsule
Carrier of upper motor neuron axons. Heavily myelinated since it has to travel such a long way.
What does binding of neurotransmitter in a postsynaptic cell do?
Causes conformational change in sodium channels to allow sodium into the cell causing an EPSP
describe troponin
Ca²⁺ binding site
SNARE hypothesis
Ca²⁺ binds to a binding protein on the vesicle called the VSNARE triggering the VSNARE to wind to the target protein called the TSNARE allowing the charged heads of the vesicle to fuze with the charged heads of the membrane
describe how a muscle fiber contracts
Ca²⁺ binds to troponin causing the tropomysin to rotate and expose the myosin binding sites in the actin filament. The actin then binds to the myosin which releases the ADP + Pi from the myosin. This causes the myosin to bend forward, bringing the actin with it and causes a muscle contraction
Ventral Horn
Cell body of the lower motor neurons
Cellularist and Cajal
Cellularist- say we have individual cells Santiago Ramony Cajal- developed Golgi stain to tweak it -could recognize individual neurons -info flowed in 1 direction
Santiago Ramon y Cajal
Cellularist. Anatomist in Spain. Converted images of neurons through use of telescope into detailed drawings that he recalled from memory. Concluded that the neuron is the fundamental structural unit, and developed the concept of Dynamic Polarization.
Sensory Transduction
Change in energy (electromagnetic, mechanical, chemical) of environmental stimuli to movement of ions across a membrane.
Mechanical energy change
Change in the shape of a neuron.
Chemical energy change
Change in the shape of a receptor.
What can IPSPs do
Change the amplitude of the EPSPs arriving to the trigger zone so more EPSPs must occur
Intercellular communication in the nervous system occurs at __________.
Chemical synapses.
Gray Matter
Composed of neuronal cell bodies and dendrites (analytic region of the neurons)
Axon
Conductile Region
What is the internal capsule
Conductive regions of upper motor neurons
What is the prefectural gyrus in control of
Conscious movement
Peripheral Nervous System
Consisting of the portion of the nervous system located outside of the central nervous system. Consists of nerves that carry both sensory and motor information. The nerves are bundles of nerve cell processes in the peripheral nervous system. There are two major subdivisions of the peripheral nervous system, sensory and motor
Dorsal Horn of the spinal cord
Contains the cell bodies and dendrites of interneurons that are important for processing sensory (afferent) information coming from the periphery and going into the central nervous system.
Ventral Horn of the spinal cord
Contains the cell bodies and dendrites of lower motor neurons.
Dorsal Column
Contains the conductile region of the primary sensory afferent. White matter.
Parietal Lobe
Contains the post central gyrus.
What does the movement of z lines do
Contracts the muscle
Hypothalamus
Controls various autonomic, endocrine, and visceral functions.
Hypothalamus
Controls various autonomic, endocrine, and visceral functions. The neurons of the posterior pituitary (neurons that secrete releasing hormone) have their cell bodies here.
What does the second order nucleus do?
Crosses over the midline.
Three Box Model
Data In, Data Analysis, Data Out
What is the name for crossing over of upper motor neurons
Deccasation of the pyramids
How does information fellow in a neuron?
Dendrite to cell body to axon to axon terminal to the next cell
Parts of the neuron
Dendrite, cell body, axon, axon terminal
Neuronal processes of the white matter carrying info away from the brain?
Descending Pathways
Dynamic Polarization
Developed by Cajal. States a unidirectional flow of info within neurons from the dendrites, through the cell body to the axon, and to the axon terminal where it is transferred to the next neuron or cell.
What is found in the t tubule that blocks calcium release
Dihydropyridine receptors (DHP receptors)
Cerebrum
Divided into four lobes, frontal, parietal, occipital, and temporal. Some regions are primarily motor, some are primarily sensory, and some are primarily associative.
Dorsal Horn
Dorsal root gangion neuronal processes enter this CNS structure where they synapse onto second order neuronal cell bodies residing in the dorsal horn.
Frequency Coding
Duration of the bout of action potential. Within the bout, we have the frequency of action potentials in the bout.
Movement along the microtubule from the axon terminal to the cell body is powered by the molecular motor _______.
Dynein (- end directed)
what opens v-gated Na+ channels?
EPSP
Spatial
EPSP arrive at trigger zone at same space
temporal
EPSP arrive at trigger zone at same time
Motor output
Effects a change. After info is processesed, the nervous system elicits a response by activating an effector organ (either muscles or glands). This response originates in the CNS but is caused by actions in the periphery.
Nernst Potential
Ek = equilibrium potential= RT/ZF (ln)[concentration outside]/[concentration inside]
Dorsal Root Ganglion
Enlargement of the periphery on both sides of spinal cord (located b/w each vertebrae of the spinal cord) . Eminates from dorsal horn region. Contains neurons that carry info about light touch, joint position, and muscle stretch from receptors, extend processes toward the brain. Also contain primary sensory neurons (afferents) that carry pain and temp info.
What allows the membrane to reach threshold
Enough positive charge will accumulate due to potassium leak channels and voltage gated sodium channels open
PNS
Everything outside the brain and spinal cord (contain spinal nerves)
What does EPSP stand for
Excitatory post synaptic potential
Summation
Excitatory postsynaptic potentials that add together at the trigger zone.
Dorsal Root
Extension in between the dorsal horn and dorsal root ganglion.
How is excess neurotransmitter take up by in the PNS
Extracellular proteins or acetylcholine esterase
What does ADP and Pi leaving cause the myosin head do?
Fall over, therefore pulling the z lines together
What are the two axoplasmic transfer rates
Fast Slow
What makes up mechanical energy?
Feeling and sound
What does sodium do when the gates open
Flow toward its electrical and chemical gradient into the cell
Generator Potential
G.P. Amplitude is proportional to stimulus strength.
IPSP
GABA glycine
What are inhibitory neurotransmitters
GABA and glycine
what are the inhibitory neurotransmitters?
GABA and glycine
Steps of the reflex arc
Generator potential Action potential Neurotransmitter release Synaptic potential Action potential Neurotransmitter release Synaptic potential in muscle Action potential in muscle
Schwann Cells
Glia of the PNS. Supportive of the neuronal regrowth.
Oligodendrocyte
Glial cell in the CNS that produces the white matter in the brain and spinal cord. Form the myelin sheaths around axons. They are inhibitory to neuronal regrowth (do NOT regrow). Constitutes the cells that are destroyed in Multiple Sclerosis.
Astrocyte
Glial cell that regulates the extracellular environment of the CNS (lots of times at the synapses).
What are astrocytes
Glial cells in the central nervous system
What is the most common excitatory neurotransmitter in the CNS
Glutamate
What are examples of ligand gated ionotropic channels
Glutamate receptors Nicotine acetylcholine receptors
In EPSPs, _______ is the most commonly released neurotransmitter. Whereas in IPSPs ,_______ is the most commonly released neurotransmitter.
Glutamate, GABA
what inhibitory transmitter is in the spinal cord
Glycine
These are important components coming from the extracellular environment and transporting back to the nucleus. W/o them the neuron will die.
Growth Factors
What did Santiago Ramon y cajal discover? I
He saw that neurons were not continuous or in a synsitiam by using the golgi dye
What did Camillo golgi discover?
He was able to see neuronal structure using nitrate and chromium nitrate salts sometimes (at least 2% of them usually)
Where does all inhibition occur
I'm the CNS
Where are voltage gated channels in the axon located
I'm the nodes of ranvier
How do EPSPs interact
If there are two or more that overlap in time
Where are ligand gated ionotropic channels found
In the dendrites
What does an increase in membrane resistance mean
Increase in EPSP duration
What is in the post central gyrus
Information for what parts of the body feel the most things
What does ipsp stand for
Inhibitory post synaptic potential
At the trigger zone of a neuron, right at the junction of the axon and the cell body, incoming signals may be temporally and spatially summated. The sum of the signals will either generate or prevent an action potential. What is/are these signals called?
Inhibitory post-synaptic potentials (IPSPs) Excitatory post-synaptic potentials (EPSPs)
What does synaptotagmin do (2 things)
Inhibits the winding of V SNARE and T SNARE or Promotes T and V SNARE intertwinning
Data Analysis
Integration
What is the myelinated area of the axon called
Intermodal region
visceral afferents
Internal organs of the circulatory, respiratory, alimentary, excretory, & reproductive system ~ monitors BP, breathing, Temp
Integration
Interprets and processes sensory info and selects an appropriate response to the stimulus (decision). Occurs in the CNS. Also results when electrical signals are transferred among neurons at the synapses.
What does troponin c do
It binds calcium in the actin thin filaments
How does calcium help to release neurotransmitter
It binds to sunaptotagmin which cause a conformational change where v snare and t snare intertwine, allowing the pull of the vesicles to the plasma membrane
What is unique about the 2nd order neuron?
It crosses the midline
What happens to the secondary neuron in the spinal thalamus tract pathway
It crosses the midline, through the central root, and into the white space in the spinothalamic tract up the spinal cord
What happens to the voltage when voltage gated potassium channels are open
It decreases almost to the point of Ek because both the leak channels and the v gated potassium channels are open
What happens to potassium permeability when sodium channels close
It increases
How does acetylcholine reach its receptor
It is allowed out in multiple bouts so the first out is deactivated by esterase and the second bout is allowed to get to the receiving cell to create and action potential
How does myelination help an action potential propogate
It provides a way for leak channels to be covered so that electromagnetic waves of sodium can activate channels at a faster rate It decreases capacitance therefore increasing membrane resistance
What does ADP and Pi do when myosin sees the myosin binding site
It runs away and then the myosin head binds to the actin
What does capacitance do to the voltage change or depolarization
It slows it down because each positive charge that enters must cancel out a positive charge on the inside of the cell before opening another channel
How does MS cause damage
It violates the blood brain barrier and immune cells, such as Tcells, attack the myelin basic protein resulting in the demyelination of the axons
What is the main difference between voltage gated Na+ channels and voltage gated K+ channels?
K+ channels do not have ball and chain to activate and inactive the channel
What is an important part of slow transport
Katanins
Movement along the microtubule from the cell body to the axon terminal is powered by the molecular motor _______.
Kinesin (+ end directed)
A neuron has K+ leak channels that are always open. If this is the case, why is there much more K+ inside of the cell (~100 mM) versus outside of the cell (~10 mM)?
Large anions create an electrical gradient that pulls on K+ in the cell, working opposite the chemical concentration gradient
Cerebrum
Large region that is divided into four lobes inside the skull. Divided into regions that contain different functions (motor, sensory, or associative).
Diencephalon
Lies near the midbrain and contains the thalamus and hypothalamus.
Diencephalon
Lies rostral (forehead) of the midbrain and contains the thalamus and hypothalamus.
What type of membrane channels is in the input region?
Ligand gated channels in which neurotransmitters are the ligands
What makes up electromagnetic energy?
Light
Cerebral cortex
Lines the cerebrum (folded outer layer)
Central Canal
Located at the center of the spinal cord and extends up into the ventricles of the brain.
Spinal Nerves
Located in between vertebrae. Carry both sensory afferents and motor efferents
LONG* Explain the entire process of how a muscle fiber contracts from a signal from the lower motor neuron
Lower motor neuron forms a syapse with muscle cell. Ca²⁺ enters LMN due to channels opening from the action potential. A vesicle of acetyl choline is released. The acetyl choline binds to the nicotine acetyl choline receptors, opening the channels and allowing Na⁺ to flow into the muscle cell. This positive charge triggers an action potential along the v-gated Na⁺ channels all along the sarcolemma. This positive charge makes its way to DHP receptors in the T-tubules which sense the positive charge and unplug the RyR channels in the sarcoplasmic reticulum. This then releases Ca²⁺. This Ca²⁺ binds with troponin and causes the tropomyesin to rotate and expose the myosin binding sites on the actin filament. The actin then binds to the myosin which releases ADP + Pi from its active site which causes it to have a conformational change and bends forward bringing the actin with it. This contracts the sarcomere thus contracting the muscle
Microglia
Macrophages that are cells of the innate immune system. They don't make antibodies, they are nonspecific reactors to bacterial or viral invasion of the CNS. They release oxidative molecules creating a nasty environment.
How many muscle fibers can a nerve innervate
Many
How many nuclei does a muscle cell have
Many
What is a muscle cell made of
Many myoblasts fused together
Voltage-gated K+ Channels
Membrane proteins that open and close to allow influx of K+ ions into the cell. Tend to be clustered at the edges of the nodes and underneath the myelin.
What is ohms law
Membrane voltage = current times membrane resistance
Vesicles full of neurotransmitter must travel to the axon terminal before being exocytosed. Which two structures are required for this fast, anterograde axoplasmic transport?
Microtubules and kinesin
Sensory Input
Monitors what goes on in the external environment and within the body. Begins in sensory receptors (outside the CNS) and transduces some form of energy that originates inside or outside of the body. Sensory neurons carry this information INTO the CNS.
If you need to lift something heavy, what happens to the motor units
More are activated to engage more muscle fibers at once.
What is the result if there are too many leak channels
More ligand gated channels need to be activated because the membrane resistance and membrane voltage will be too low
What type of ligand-gated ionotropic channels are in the CNS
Mostly Glutamate
What does the motor output consist of
Motor efferents
What does the spinothalamic tract provide
Motor function
Data Out
Motor out to effect change. Part of the PNS.
Efferent
Motor portion of the PNS From the Latin meaning to bring out Another way to remember this term is that this division of the peripheral nervous system effects (brings about or causes to happen) a response.
Ventral/Anterior
Motor. Away from/not close to the brain.
All three types of energy change do this:
Movement of ions across a membrane.
White matter
Myelinated axons comprise the white matter. The white matter is white because myelin contains large amounts of lipid that acts as an electrical insulating layer for the axon.
White matter
Myelinated conductile regions.
Oligodendrocytes
Myelinating cell. Concentric layers of oligodendrocytes plasma membranes wrapped around an axon.
Thick filaments contain?
Myosin polymer and Arranged tail
conduct electrical signal down axon by moving _________ down cell
Na and K
Which of the following is correct when describing ion distributions in neurons?
Na+ higher in Extracellular space then cytoplasm
How do the sodium ions that enter at the nodes of ravier open the channels at the next nodes of ravier?
Na+ ions carry electromagnetic fields which opens the next Na+ channels at the next Nodes of Ravier since the electromagnetic field creates a positive charge
In EPSPs, ___ rushes in, adding positive charge and _______ the environment. Wheras in IPSPs, ___ comes in, adding negative charge and _______ the environment.
Na+... Depolarizing, Cl-... Hyperpolarizing
consider what happens if v-gated Na⁺ channels are localized to one spot
Na⁺ will come in and increase the charge at that spot. However, the neuron is like a leaky garden hose and the charge carried by sodium dissipates with distance
Impermeant Anions (A-)
Negatively charged anions (large organic acids) that are trapped inside the cell. They cannot cross the plasma membrane. Facilitates equilibrium by balancing its negatively charged force with the tendency of K+ to leave the cell through the leak channels.
Cranial Nerves
Nerves eminating from the brain stem.
White Matter
Neuronal processes (axons/conductile regions) in the cerebrum. Contains hundreds of billions of individual processes of neurons extending out of the cerebral cortex and into different parts of the brain. Long distance communication.
What do astrocytes gobble up
Neurotransmitters and potassium in the synaptic cleft
What happens to neurotransmitters once they are released from vesicles in output region?
Neurotransmitters bind to ligand gated channels in neighboring cells to initiate synaptic potentials which cause action potentials
What are the receptors in the muscles that respond to neurotransmitter
Nicotine acetyl choline receptors
What type of receptors do muscle cells have for neurotransmitters
Nicotine acetylcholine receptors
In the CENTRAL nervous system, clusters of neuron cell bodies are called _______________, and the axons of these neurons run in ______________________. In the PERIPHERAL nervous system, clusters of neuron cell bodies are located in _________________, and their axons run in ________________________.
Nuclei, tracts, ganglia, nerves
Input region of the neuron
Nucleus.
Compare and Contrast Oligodendrocytes to Schwann Cells
Oligodendrocytes -can wrap around many axons -CNS -produce myelin Schwann Cells -can only wrap around 1 axon -PNS (neurons can regenerate) -produce myelin
Motor Output
Once the information is processed, the nervous system elicits a response by activating an effector organ, which may be either muscles or glands. Motor output originates in the central nervous system, but the response is elicited by actions in the periphery.
3. motor output (3 box model)
Once the information is processed, the nervous system elicits a response by activating an effector organ, which may be either muscles or glands. This response is called motor output. Motor output originates in the central nervous system, but the response is elicited by actions in the periphery.
How many nerves can be on one muscle fiber
One
What is a large motor neuron indicative of
One motor neuron innervates a vast amount of muscle fibers
Path an upper motor neuron takes
Out the motor cortex, through the internal capsule, through the thalamus, crosses over at the brainstem, goin to the lateral corticospinal tract where it exits the white matter and enters the gray matter to synapse with the lower motor neuron in the central horn
Axon Terminal
Output Region
What does the conductive region do?
Passes the message on to the output region
Electromagnetic energy change
Perceived as light.
The membrane potential seeks the equilibrium potential for the ion whose _______ is dominant.
Permeability
Threshold
Point in which there is a balance b/w Na+ coming in and K+ going out of the cell.
What are actin thin filaments made of
Polymerized actin Tropomyocin Troponin C
What do you need in order to set up an action potential
Potassium leak Channels
Synaptic Integration
Processing of sensory information and the selection of a response that occurs in the CNS. Results when electrical signals are transferred among neurons at sites called synapses.
What does a DHP receptor do when a muscle is relaxed
Puts its foot in RYR so no calcium is released
Action potentials will pass much more _________ along a myelinated axon, as opposed to an unmyelinated axon. This is because myelin ______________ membrane resistance.
Rapidly, increases
Corpus Collosum
Region found within the Cerebrum. Contains bundles of hundreds of millions of axons that link the right and left hemispheres. Facilitates bilateral symmetry and equal communication b/w hemispheres.
Brain Stem
Region of the Spinal cord that extends (continuation) up inside the skull
Cell Body
Region where translation occurs
What do inhibitory synapses do
Regulate membrane resistance
Camillo Golgi
Reticularist. Pathologist in Italy. Developed a series of stains. Only saw 1-2%, but labelled the entire structure. Concluded that all individual cells are connected by nerve processes. There are no real individual cells. His theory was wrong.
Reticularists and Camillo Golgi
Reticularists- cytoplasmic, all neurons connected Golgi filled nervous system with stains (AgNO3 and CrNO3NACL) -precipitates showed entire neuron but only 2% were labeled
explain the DHP and RYR receptors at the T-Sr Junction
Right next to the T-tubule lies the sarcoplasmic reticulum. The T-tubule contains the DHP receptor which is pluggin up the RyR receptor in the adjacent sarcoplasmic reticulum. When the positive charge comes in from the Na⁺ channels, the DHP unplugs wht RYR and Ca²⁺ flows out of the sarcoplasmic reticulum
What does the binding of calcium to troponin C do?
Rotates the tropomysin to display the myosin binding sites
What is the receptor in the SR that release calcium
Ryan prime receptor (RYR)
What is part of the T SNARE
SNAP 25 Syntaxin
Reticularists
Said all neurons are interconnected by cytoplasmic bridges.
The _______ in the PNS support neuronal regrowth, whereas the _______ inhibit neuronal regeneration in the CNS.
Schwann Cells, Oligodendrocytes
What type of glial cell is present only in the peripheral nervous system?
Schwann cells
Data In
Sensory Input. Part of the PNS.
SAME DAVE
Sensory aferent, motor efferent. Dorsal Afferent, Ventral Efferent.
What does the sensory input consist of
Sensory afferents
3 bow model for the nervous system
Sensory input-> integration-> motor out
Afferent
Sensory portion of the PNS From the Latin meaning to bring toward
Pathway from sensory input to motor output from the periphery to the brain and back to the muscles
Sensory receptors initiate a response in the sensory neuron that conducts toward the central nervous system in a spinal nerve. The sensory information enters the central nervous system through the dorsal root and the central process of the dorsal root ganglion neuron extends into the dorsal horn of the spinal cord. For one form of sensory information (light touch or joint position) the sensory neuron travels rostrally in the spinal cord and forms a synapse in the brain stem where it communicates with an interneuron that sends a process to the thalamus. In the thalamus, this neuron synapses onto nerve cells that extend process to the cerebral cortex. Specifically, these thalamic neurons send processes to the primary somatosensory cortex, which is located in the rostral portion of the parietal lobe, just caudal to the central sulcus. Association neurons (also known as interneurons) send processes from the sensory cortex to association areas in the cerebral cortex of the frontal lobe. The association areas interpret the sensory information and send information to the motor and premotor areas. Upper motor neurons are located in the primary motor cortex and receive information from the association regions. Upper motor neurons extend descending processes carrying efferent information down the corticospinal tracts to synapse on the lower motor neurons. Activation of the lower motor neurons leads to the contraction of muscles and the initiation of movement.
Thalamus
Sensory relay site for info going into the cerebral cortex. The only sense that is able to bypass this region is olfaction (smell).
Dorsal/Posterior
Sensory. Close to the brain.
Central suculus
Seperates the frontal lobe and the parietal lobe
Name the three types of muscle.
Skeletal, smooth, cardiac
What size motor units are found in the hand
Small
______ in a muscle cell is called the sarcoplasmic reticulum
Smooth ER
What controls the release of calcium from the SR
Sodium ions
How do astrocytes control extra cellular potassium
Sodium potassium pumps
What is post central gyrus synonymous with
Somatosensory cortex
What is a synsitiam
Something that has continuity and is connected
Nernst Potential
Sometimes known as the reversal potential of an ion, and is the membrane potential at which there is no net (overall) flow of that particular ion from one side to the other.
In __________, EPSPs arrive from different locations to summate at the trigger zone, and in ___________, EPSPs must be synchronized in time to bring the membrane potential at the trigger zone to threshold.
Spatial Summation, Temporal summation
Sensory Neurons
Specialized cells located outside the central nervous system in the periphery that transduce some form of energy (e.g., mechanical, electromagnetic, or chemical) that originates inside or outside the body. They carry information to the CNS.
________ channels are opened by mechanical pull, instead of by charge.
Stretch activated
What are the components of exocytosis
Synaptic vesicles VAMP synaptotagmin Calcium channel SNAP25 Syntaxin
Syntaxin
Target SNARE
T-SNARE
Target SNARE. Proteins on the plasma membrane.
What makes up chemical energy?
Taste and smell
Chemical Energy
Taste, Smell
The Parasympathetic System
Tends to decrease activity of an organ
The Sympathetic System
Tends to increase the activity of an organ
Second order nucleus
Thalamic relay nucleus.
What did cellularists believe
That neurons were individual cells
What does the law of dynamic polarization say
That the information flow of the neuron has a unidirectional flow.
What did she inform say about neurons
That there is a synapse where neurons speak through chemicals
Proprioception
The ability to know where we are in space at all times. Makes it so we don't fall down when we are in a dark room.
What happens when an axon is not myelinated
The action potential is not propagated because potassium leak channels let the electric charge out more so.
What do the areas of the motor and somatosensory cortex directly indicate
The amount of movement and senses associated with that certain body part
How is the strength of a contraction controlled
The amount of upper motor neurons fired with correlates to the number of lower motor neurons fired
Characteristics of Schwann cells
The are in the PNS Their neurons can regenerate from their cell bodies and regrow their targets They are very good at remyelinating
What is the T-SR Junction
The area between the t-tubule and the sarcoplasmic reticulum
What does the conductive region consist of in the CNS?
The axon
What is the conductive region of the primary sensory afferent
The axon and the cell body
What is the output region of the primary sensory afferent neuron
The axon terminal
What structure makes up the output region of a neuron?
The axon terminal
What is the unique structure of the sodium channel
The ball and chain structure that acts as the gate
What happens in rigor mortis
The body stiffens because ATP is no longer made and calcium pumps no longer reputable the calcium in the cells so the lack of ATP and the presence of calcium causes the myosin never to release the actin.
How are motor neurons regulated
The brain
Where does the secondary nerve cross over in the DCML pathway
The brainstem
Where does integration take place
The central nervous system
Where does the thurd neuron synapse for the dorsal column medial lamiscus pathway
The cerebral cortex
Osmium is a heavy metal used in tissue staining. It binds to lipids and turns black. Which of the following would expect to be stained the LEAST?
The cerebral cortex The dorsal root ganglion
What is sensory transduction
The changing of energy form for example-- the changing of electrical to chemical signals along a membrane to make a movement
What is the input region of a primary sensory afferent
The dendrite
What does the input region consist of in the central nervous system?
The dendrites and the cell body
Where does the first neuron synapse with the second neuron for the dorsal column medial lamiscus pathway
The dorsal column nucleus
Where does the neuron enter for the reflex arc
The dorsal horn
Where is the cell body for the reflex arc of the first and second neurons respectively
The dorsal root ganglion The central root ganglion
Autonomic Nervous System
The efferent nerves in the autonomic nervous system regulate activity in the organs such as the heart, lung, gut, bladder, and genitalia. The autonomic nervous system is subdivided into two systems, the sympathetic system and the parasympathetic system. One portion of the motor division of the PNS
Axon Terminal
The end of the neuron.
Where does membrane potential tend toward
The equilibrium potential for the ion whose permeability is dominant
SNAP-25
The fatty acid that attaches the V.A.M.P. and the syntaxin.
Post Central Gyrus
The final synapse location for the third order neuron.
What is the butterfly structure of the spinal cord
The gray matter
Where are input regions in the spinal cord
The gray matter
Where do neurons synapse in the spinal cord
The gray matter
What is muscle fatigue caused by
The inability of motor units to rotate quick enough
Axon
The large area between the cell body and the end of neuron.
What keeps all the potassium in a cell
The large, impermeable anions inside the cell
The right side of the brain controls
The left side of the body
Motor Unit
The lower motor neuron and the group of muscle cells/fibers it innervates.
Motor unit
The lower motor neurons and the group of muscle fibers or cells that it innervates
Spinal cord
The most caudal (toward the tail) part of the central nervous system. It controls movement of the limb and trunk and receives sensory information from the skin, joints, and muscles of the limb and trunk. The cord is surrounded by three meningeal layers. The pia mater, the arachnoid layer, and the dura mater. The two most easily distinguished regions in the spinal cord are the gray matter and the white matter.
What is the price trap gyrus synonymous with
The motor cortex
efferent
The motor division is also called the efferent (Carrying away from) division. Another way to remember this term is that this division of the peripheral nervous system effects (brings about or causes to happen) a response.
Schwann Cells
The myelinating cells (of the axons) in the PNS. They also support neuronal regeneration (regrowth).
What is capacitance
The negative charge found just inside the membrane of a cell and the positive charge always found just outside of the cell
What did reticularists believe
The nervous system is a synsitiam of neurons
Neuron Doctrine
The neuron as the fundamental structural and functional unit of the nervous system.
What does the neuron doctoring say
The neuron is the fundamental structural and functional unit of the nervous system
Lower Motor Neurons
The neurons that synapse on muscle fibers and cause them to contract. Some of these lower motor neurons innervate somatic muscles and some innervate visceral muscles. Exit the central nervous system through the ventral roots.
Frequency coding
The number of action potentials in a bout and the frequency of the action potential
Visceral Afferents
The other source of afferents is from organs such as the intestines. Think about signals from intestines to nerves.
Where do the motor outputs act
The peripheral nervous system
Where is the sensory input located
The peripheral nervous system
What happens in the motor output?
The plan is acted out
What is a sarcoplasma
The plasma membrane of a muscle cell
What does somatosensory information travel theough
The post central gyrus
What happens during the spinal thalamus tract pathway to the first neuron
The primary sensory neuron synapses almost immediately in the dorsal root to the secondary neuron
What is the physiologic basis of threshold?
The rate of Na+ influx is equal to the rate of K+ efflux The membrane potential may repolarize toward the K+ equilibrium potential OR depolarize toward the Na+ equilibirum potential
What part of the body is effected when the spinal cord is injured on the right side
The right side proprioception The left side motor
What happens during integration?
The sensory information is made into meaningful information and then made into a plan
Somatic Afferents
The sensory neurons that originate in the body bring information to the central nervous system about the skin, skeletal muscles and joints. The information is coming from the body. Remember that soma means body. Basically, think pain signals coming from the skin to the nerves.
The Action Potential
The sequential opening and closing of voltage gated channels.
Dendrite
The spiky end part of the neuron.
Where does the second neuron synapse to the third neuron in the spinothalamic tract
The thalamic relay nucleus
Where does the second neuron synapse with the third neuron for the dorsal column medial lamiscus pathway
The thalamus relay nucleus of the oposite side of the injury
Where are voltage gated sodium channels in a stretch neuron located
The trigger zone
At chemical synapses, _________ primarily dictates the postsynaptic response.
The type of receptor that binds the neurotransmitter
lower motor neurons
The ventral horn contains the cell bodies and dendrites of lower motor neurons.
What is part of the V SNARE
The vesicles VAMP synaptotropin
What is a generator potential
The voltage needed, in stretch neurons, to reach threshold
What is threshold
The voltage where sodium influx is balanced by potassium leak channels The point at which all sodium channels open because of the huge positive charge within a cell where potassium leak channels cannot keep it in check anymore
What part of the spinal cord has myelinated conductive regions
The white matter
afferent
There are two major subdivisions of the peripheral nervous system, sensory and motor. The sensory portion which is also referred to as the afferent (bring toward) division carries information toward the central nervous system
What did Langley say
There is a receptor in muscles for the chemicals released by neurons to allow for a response
What do inhibitory neurotransmitters used for
They allow chloride to enter the postsynaptic cell to achieve the same result as if a bunch of potassium leak channels were present
Characteristics of oligodentrocytes
They are in the CNS The have transmembrane proteins to inhibit regrow the The are not good at remyelinating
What happens to the action potential with a larger depolarization?
They are sent more closely together at a more rapid speed
What happens to membrane voltage resistance when there are less leak channels
They both are high
What do katanins do?
They cut out pieces of the cytoplasm so transport moves quickly between katanins sections
What do astrocytes do
They regulate the extra cellular environment in the CNS to allow for favorable conditions for electrical signals to be sent in neurons
What does efferent mean?
To carry away from
Efferent Direction
To carry away from/out (motor)
Efferent
To carry away. Shows up as motor out.
What does afferent mean
To carry toward
Afferent
To carry toward integration.
Afferent Direction
To carry toward/into (senses)
What does synapse mean
To clasp or hold
What is the function of oligodentrocytes
To form myelin layers around axons
2. integration (3 box model)
To interpret the sensory information and select an appropriate response to the stimulus, the information must be processed. The processing of sensory information and the selection of a response is called integration and occurs entirely in the central nervous system.
What is the function of the sarcoplasmic reticulum
To store and release calcium
What is considered fast axoplasmic transfer
Transfer of anything synthesized in the rough ER therefore executives and transmembrane proteins
What is considered slow axoplasmic transfer
Transfer of anything synthesized on free ribosomes therefore cytoplasmic proteins
What separates the input and conductile regions and functions to make a decision? And contains the clustering of v-gated Na+ and v-gated K+ channels?
Trigger Zone
What is the treatment for MS
Try to prolong the time between attacks in the brain so that the resheathing process may occur
Law of Dynamic Polarization
Unidirectional movement in the neurons.
A protease, which is an enzyme that destroys peptide bonds, is added to the axoplasm. Its effect is to remove the inactivation gates on VG sodium channels. Without the ball and chain, what would the effect be on the membrane potential?
Upon stimulation, the membrane would deploarize but would take much longer to repolarize back to resting potential.
Upper motor neurons
Upper motor neurons are located in the primary motor cortex and receive information from the association regions. Upper motor neurons extend descending processes carrying efferent information down the corticospinal tracts to synapse on the lower motor neurons. Activation of the lower motor neurons leads to the contraction of muscles and the initiation of movement.
V-SNARES
V.A.M.P.: found in membrane of vesicle
Ohm's Law
V=IR (voltage=current x resistance) -I is a fixed number
How much does an EPSP raise a mombrane potential
Very little
At rest, the membrane potential is maintained near -70 mV. In order to fire an action potential, enough positive charge has to enter the cell to reach threshold ( around -55mV). What is true regarding the amount and form of that positive charge?
Very little Na+ has to enter the cell in order to achieve threshold and therefore an action potential.
V.A.M.P.
Vesicle associated membrane protein that has an alpha helix structure attached to it. Part of the V-SNARE.
V-SNARE
Vesicular protein. Protein on the vesicle.
Electromagnetic Energy
Vision, Visible light
What allows repolarization to occur quick enough for the next wave of depolarization
Voltage gated Potassium channels
Rectifiers
Voltage gated potassium channels.
What type of channel is important in muscle cell activation
Voltage gated sodium channels
What kinds of channels are in the output region of a neuron?
Voltage gates calcium channels
What types of channels are found in the conductive region?
Voltage-gated channels
Input regions of a neuron lacks __________.
Voltage-gated channels.
Bilateral symmetry
Whatever you see on one side of the spinal cord, you see on the other.
The SNARE Hypothesis
When Ca2+ enters, it binds the Ca2+ sensor. Then the 3 proteins wind together, reducing the space b/w the synaptic vesicle and the plasma membrane. This allows exocytosis to begin.
Spacial Summation
When the postsynaptic potentials arrived from different synapses.
Dorsal Column Nucleus
Where the collection of input regions is.
what is a ganglion?
a collection of neuronal cell bodies in the PNS
Can CNS reensheath its axons
Yes but only for a while and never as securely
What is a sarcomere made of
Z lines Myosin thick filaments Actin thin filaments
nerve
a bundle of conductile regions in the PNS (Schwann cells)
sensory transduction
a change in energy into the movement of ions across a membrane
What is ganglion
a cluster of neuronal cell bodies in the PNS
motor unit
a lower motor neuron and the specific group of muscle fibers it innervates. drives voluntary muscles
Somatosensory afferents in spinal nerves... a. may have receptors on input regions embedded in the dermis b. keep their cell bodies in the dorsal horn of the spinal cord c. always synapse directly onto lower motor neurons in the ventral horn d. propagate information away from the CNS e. are myelinated by oligodendrocytes
a. may have receptors on input regions embedded in the dermis
activation NT in PNS
acetyl choline
EPSP
acetylcholine
excitatory neurotransmitters
acetylcholine acc(PNS), glutamate (CNS)
what are the excitatory neurotransmitters?
acetylcholine, glutamate, anything that's NOT GABA or glycine
Alpha Actinin
actin binding protein that forms Z lines
what are the thin filaments in a muscle made up of
actin filaments, troponin, and tropomycin
law of dynamic polarization
action potential always goes to axon terminal
dorsal = ________, ventral = _________
afferent, efferent
_____________ nerves carry information ___________ the brain.
afferent- toweard. efferent away.
Camillo Golgi
all neurons connected by cytoplasmic bridges
What happens at threshold?
all v-gated Na+ channels open
K+ Leak Channels
always open
kinesin carries vesicle in
anterograde transport
spinothalamic tract
assending. sensory. pain. temp. crude touch.
Association Areas
association neurons send processes to association areas which interpret sensory info and send to motor areas
CNS glial cells
astrocyte and oligodendrocyte
Cells that maintain the extracellular environment in the CNS by pumping sodium and potassium ions and mopping up excess neurotransmitter are:
astrocytes
what are the three types of glia cells?
astrocytes, oligodendrocytes, and scwan cells
types of glial cells
astrocytes, oligodendrocytes, microglia
MS
attacks oligodendrocytes autoimune disease
visceral efferents and the visceral afferents are part of the
autonomic nervous system
efferent
autonomic nervous system to carry away - to cause or bring about an effect -somatic - voluntary movement 1. skeletal voluntary muscle visceral - not under concouis control 1. smooth muscle 2. car dial muscle 3. glands
efferent
away cns
cytoskeleton organized along______ of muscle fiber
axis
region where translation occurs
axon
output region =
axon terminal
white matter
axons and conductive region, long distance, sensory from spinal cord to brain
5. In high school I chucked a medium-sized pumpkin at my friend Little Mike, making hilariously sharp contact with his left precentral gyrus. Had I known about neuroanatomy at the time, I would have expected to observe which perceived loss in which of the following body regions: a. Fine touch from the right side of the body b. Motor commands to the right side of the body c. Pain from the right side of the body d. Motor commands to the left side of the body e. Temperature sensation from the left side of the body
b. Motor commands to the right side of the body
2. Your patient has bouts of sharp, painful contraction, simultaneously in both flexor muscles and extensor muscles. Which of the following explanations is/are sound? a. The patient's upper motor neurons in the anterolateral system are damaged b. Some kind of a toxin is blocking ligand-gated ionotropic receptors and decreasing their permeability to chloride c. Extracellular sodium is too low (Hyponatremia) d. Calcium channels in all lower motor neuron output regions are experiencing decreased voltage sensitivity e. Both b and c could work
b. Some kind of a toxin is blocking ligand-gated ionotropic receptors and decreasing their permeability to chloride
Lower motor neurons keep their cell bodies in the ____________ and extend axons through the ____________. a. Dorsal root ganglia; dorsal horn b. Ventral horn; ventral root c. Cerebral cortex; spinal nerve d. Dorsal root ganglia; spinal nerve e. Ventral root; thalamus
b. Ventral horn; ventral root
How do sodium voltage gates inactivate?
ball and chain
where does a synapse occur?
between the axon terminal and the dendrite of another neuron
caudal region
bottom of spinal cord
ventral horn
bottom region of the grey matter, contains cell bodies of lower motor neurons
Z-Lines
boundaries of the sarcomere made up of alpha actinin
Central Nervous System (CNS)
brain and spinal cord
what makes up the CNS
brain and spinal cord
internal capsul
bundle of conductile neuronal processes. the upper motor neuron passes through this after leaving the motor cortex
spinal nerve
bundle of conductile processes in the perpherary. The lower motor neuron passes through this
tract
bundle of conductile regions in CNS (oligodendrocytes)
Internal Capsule
bundle of heavily myelinated neurons
Nerve
bundle of neuronal processes in the PNS
Lower motor neurons are referred to collectively as ______________ and receive input from upper motor neurons whose cell bodies are in the ________________. a. Efferent pathways; ventral horn b. Afferent pathway; cerebral cortex c. Efferent pathways; cerebral cortex d. Afferent pathways; ventral horn
c. Efferent pathways; cerebral cortex
3. You stick an electrode in an axon and artificially depolarize the membrane from rest to about +40 mV. After an hour, what will be the state of the channels? a. VG sodium are open, VG potassium are inactivated b. VG sodium are closed, VG potassium are closed c. VG sodium are inactivated, VG potassium are open d. VG sodium are open, VG potassium are open e. VG sodium are inactivated, VG potassium are closed
c. VG sodium are inactivated, VG potassium are open
synaptotagmin
calcium sensor
how do motor units give you more strength?
can simultaneously activate more lower motor neurons in groups that will alternate so we don't tire as easily
spinal nerve
carries sensory afferents and motor efferents
Sensory Afferents
carry info towards
what is grey matter
cell bodies and input regions of neurons (dendrites). dorsal horn, ventral horn
proteins made in
cell body
soma
cell body of a neuron
multiple sclerosis
cells of immune system generate antibodies that attack oligondendrocytes, sees self proteins as non self and destroy myelin wrapping
Microglia Cells
cells that are thought to be modified macrophages that are derived from a white blood cell called a monocyte
Ohm's Law
change in voltage = current X membrane resistance deltaV = IRm current= # of Na+ ions that enter cell at synapse membrane resistance = # of leak channels lots of leak channels = smaller resistance high Rm = high voltage Rm determines amplitude of EPSP when it arrives at trigger zone
Sensory Transduction
changing 1 form of energy to movement of ions across a membrane
Ganglion
cluster of neuronal cell bodies in the periphery
Z-line
composed of alpha actin (alpha actin is an actin binding protein)
conductile region =
conductive region
axon
conductive region of neuron
muscle is connected to bone by continuous layers of ______
connective tissue
ventral root
contains axons of lower motor neurons which extend into the spinal nerve
When contractile apparatus________so does the muscle fiber
contracts
transduction
converting one enery to another
slow transport
cytoplasmic proteins, free ribsosomes
Imagine we create a mutant mouse that lacks voltage-gated potassium channels. Which of the following would occur? a. Depolarization would occur more quickly b. Repolarization would occur more quickly c. Depolarization would occur less quickly d. Repolarization would occur less quickly e. The mutant mouse would fly and shoot laser beams from its eye sockets
d. Repolarization would occur less quickly
Mechanisms for removing neurotransmitter from the synaptic cleft include
degradation of enzymes, slowly moves out of area, diffusion. absorbed by astrocytes
astrocytes are associated with diseases like ____________
dementia, parkinson's
input region =
dendrite
anatomy of neuron
dendrite, cell body, axon, axon terminal
lateral and ventral corticospinal tracts
descending tracts whose cell bodies are located in the motor cortex, axons synapse directly onto lower motor neurons in the ventral horn
fast axoplasmic
direct flight
Limitation: when v-gated channels open, letting in Na+, it has to _______________until it can activate the next v-gated channel.
discharge the capacitance
axoplasmic transport of proteins in - direction requires
dyenien
In neurons, which of the following occurs when many voltage-gated sodium channels open? a. The membrane potential moves toward the equilibrium potential for sodium b. The inactivation gate begins to open c. Sodium efflux d. The neuron membrane depolarizes e. Both (a) and (d) are correct
e. Both (a) and (d) are correct
4. Your prize-winning llama is experiencing flaccid (non-contracted) paralysis. Which of the following explanations could work? a. The affinity of the nicotinic receptor for acetylcholine is increased, and the receptor has inactivated. b. DHP has lost sensitivity to positive charge c. The ATP supply at the sarcomere has dropped d. Calcium is not being returned to the sarcoplasmic reticulum e. Both a and b could work
e. Both a and b could work
1. Your landlord got smashed by a semitruck full of lead-filled grand pianos. He presents himself at the emergency room with a loss of crude touch sensation in his right hand and a loss of fine touch sensation in his left. An MRI shows damage to only one side of his spinal cord. Where is his lesion? a. Lower back, left side b. Neck, right side c. Neck, dorsal side d. Lower back, right side e. Neck, left side
e. Neck, left side
Oligodendrocytes... a. Comprise grey matter in the CNS b. Myelinate nerves c. Typically only myelinate a single axon d. Comprise white matter in the PNS e. None of the above
e. None of the above
6. 6. Tetrodotoxin is a drug that acts on neruons and keeps the membrane near the equilibrium potential for sodium. What happens when you get stung by a blue octopus and receive a big dose of TTX? a. Sodium channels are forced closed b. Delayed rectifier channels are forced open c. Myelin is destroyed all along the conductile region, thereby increasing capacitance d. Potassium leak channels are opened wider, thereby decreasing resistance e. Sodium channels are prevented from inactivating
e. Sodium channels are prevented from inactivating
Santiago Ramon y Cajal
each neuron serperate and distinct
motor neurons are ______ while sensory neurons are _______
efferent, afferent
main thing neurotransmitters do in a synapse
either excite the cell by admitting cations or to inhibit the cell by admitting Cl⁻
types of energy
electromagnetic(light), mechanical(hearing), chemical (taste,smell)
Energy transduced by:
electromagnetic, mechanical, chemical
3 types of energy
electromagnetic-light, mechanical-touch/hearing, chemical-taste/smell
conductive region
enriched for voltage gated channels
Fate of Neurotransmitter in PNS
enzyme called acetylcholine esterase breaks down neurotransmitter into its components (acetyl and choline)
The extracellular concentration of potassium is greater outside the cell than inside the cell.
false
describe tropomycin
flat, ribbon-like, covers myosin binding sites
slow axoplasmix
flight with layovers
Law of dynamic polarization
flow from dendrite to axon terminal to next cell
somatic
from the body
describe the pathway of the upper motor neuron from the motor cortex to initiate movement
from the motor cortex, the upper motor neuron goes down through the internal capsul and crosses the midline in the medulla obligata in what's called a decussation pyramid. it then goes down the lateral cortico spinal tract in the white matter (bottom) and synapses directly onto a lower motor neuron in the ventral horn. The lower motor neuron then passes through the spinal nerve and operates its motor unit
schwan cells
glial cells of the peripheral nervous system→supportive of neuronal regrowth while ogliodendrocytes inhibit it
what does glia mean in latin?
glue
F-actin is a?
g-actin polymer
In the PNS clusters of neuron cell bodies are located in _________________, and their axons run in ________________________.
ganglia, nerves
graded potentials are also called...
generator potentials
Fate of Neurotransmitter in CNS
glia cells (astrocytes) take up glutamate and convert it to glutamine
oligodendrocyte
glial cells in CNS that produces the white matter in brain and spinal cord
grey matter
neuronal cell bodies, input region
synaptic potential
happens at the synapse
K in cell is ____ and outside is _____
high, low
how can potentials summate
if they fall within the same duration of time they will add together. if we increase their duration it is easier to build potential (by increasing membrane resistance)
afferent
in
electrical forces:
in balance with each other chemical-ion conditions. electrical- large negative impermeable anions
when does the neuron cross over for proprioception and fine touch
in the 2° after the dorsal column nucleus in the brain stem
In the knee jerk reflex (patellar tendon)arc described in lecture, where do we find a graded generator potential?
in the stretch receptor on the primary sensory afferent
where are the cell bodies of lower motor neurons found
in the ventral horn
IPSP
inhibitory post synaptic potential ligand gate CL- channels
IPSP
inhibitory postsynaptic potential, reduces EPSP amplitude, decreases membrane resistance
three box model
input afferent towards cns, analysis, brain and spinal cord, output efferent away fromcns
functional organization of neuron
input region, synapse, conducton region, output region
repolarize
inside of the cell is returning to baseline membrane voltage
the myelin sheath _______ the axon and allows ______________ to go straight down the axon
insulates, transfer of information
astrocytes have _____ and _____ to move things out of cellular space
ion pumps and channels
Which of the following is not true about the reflex arc?
it requires input fromupper motor neurons from precentral gyrus
axoplasmic transport of proteins in + direction requires
kinesin
Rigormortis
lack of ATP prevents myosin head from moving away (keeps muscles contracted)
input region
lack of voltage gated channels
fast muscle fibers
large, anerobic, lots of tension, sprinting
what tracts are descending and contain upper motor neurons
lateral cortico spinal tracts
explain sultatory conduction
latin for "to hop". when Na⁺ goes in the first channel it carries with it an electromagnetic field. The cytoplasm is a salt solution which is electricity conductive. This positive field passes and charges the next node activating it and so on
Proprioception from Right side of body goes to which cerebrum
left cerebrum
neuron functional
ligand gated and stretch activated channels, conductile- v gated k and Na channels and action potential. output- v gated Ca channels and neurotransmitter realese
Post-synaptic membranes are enriched with _________ channels. In the spinal cord, the neurotransmitter glycine may bind to these channels, causing an ______ due to __________ influx.
ligand gated- IPSP anion
multiple sclerosis
loss of ogliodendrocytes in CNS
Na in cell is _____ and outside is _____
low, high
Each _______ may innervate several muscle fibers, but each muscle fiber can only be innervated by one lower motor neuron
lower motor neuron
microglia
macrophages, destroy bacteria, release chemicals
asterocyte
maintain extracellular nearotransmitter and ion concentration
Glia
maintains the environment for neuronal function
glial cells
majority of cells in nerous system
voltage
measure of electrical potential difference
transverse tubules are the
membrane enclosed indents in the sarcolemma that contain the DHP receptor
Mantra
membrane potential seeks equilibrium potential for the ion whos permeability is dominant
Membrane potential
membrane potential seeks the equilibrium potential for the ion whose permeability is dominant (say 400 Na+ channels are open, compared to 2 K+channels, Na+ has the dominant permeability)
main concept of ion permeability
membrane potential seeks the equilibrium potential of the ion whose permeability is dominant
Potentials propogating away from the central nervous system carry:
motor information
Transduction
movement of energy
oligodendrocytes are the __________ cells of the CNS
myelinating
oligodendrocyte
mylinate axon in CNS
Groups of sarcomeres make up _______
myofibrils
contractile apparatus is arranged in long packets known as _______
myofibrils
Sarcomeres contain _______ which are what?
myosin heads are constantly trying to attach to the binding sites on actin
dyenine
negative end directed motor
Involuntary Nervous System
nerves in the autonomic nervous system regulate activity in organs like heart, lungs, gut, bladder
An antibody that labels the plasma membrane of Schwann cells would be found in:
nerves of PNS
Peripheral Nervous System
nervous system outside of the brain and spinal cord
In the PNS, clusters of _____________ are located in _______, and their ______ run in _______
neuron cell bodies, ganglia, axons, nerves
astrocytes remove _____
neurotransmitter
output releases ____________ in extracellular space
neurotransmitter
Ligand-gated channels
neurotransmitter operated channels
serotonin
neurotransmitter, it it gets stuck in synapse keep getting happier, how antidepressants work
motor output
once info is processed, nervous system elicits a response in the perpherary by activating an effector organ
amitotic
once neurons mature they never again divide
what do inhibitory transmitters do?
open Cl⁻ channels
efferent
out
Battery
outside more negative than inside
Peripheral Nervous System (PNS)
outside the CNS, information carried towards CNS
macrophages release
oxidative molecules
two branches of the autonomic nervous system
parasympathetic-rest and digestive sympathetic- flight or fight
No leak channels
perfect 0.5mm potential delivered to trigger zone
sensory affarent
peripheral nervous system sensory input, carries info toward CNS
motor efferent
peripheral nervous system, motor info to muscles and glands
sensory input
peripheral nervous system: input begins in sensory receptors and transduce some form of energy (mechanical, electromagnetic or chemical) that originates inside or outside the body
describe the Z-lines
perpendicular lines containing actin binding protein and alpha actinin
Sarcoelmma is the
plasma membrane of a muscle cell
Membrane Potential Generation
plasma membrane separates ions which permits generation of an electrical potential = battery -this electrical potential is the basis of electrical signaling
kinesin
positive directed motor, capture vesicles, attach to microtubules , exoplasmic transport
astrocytes eat up
potassium and neurtransmitters
what is the resting membrane potential of a neuron?
potential for K⁺, about -70 mV
Cell bodies of efferent neurons are found in the:
precentral gyrus ventral horn of spinal cord
what types of sensory are communicated in the anterolateral system?
pressure, temperature, pain, crude touch
Anterior region of spinal cord
primarily motor -somatic efferent
Posterior region of spinal cord
primarily sensory -point of input from the periphery into the CNS (primary sensory afferents)
lateral corticospinal neuron
primary motor cortex/ precentral gyrus. 2. lower motor neuron ventral horn
describe the process of communicating proprioception and descrimanitive touch to the brain
primary neuron sends a signal that passes through the dorsal route ganglia into the dorsal column. it then synapses with the secondary neuron at the DORSAL COLUMN NUCLEUS. Next it goes up the dorsal column, crosses over the midline and forms a synapse with the 3° nerve in the thalamus at the THALAMIC RELAY NUCLEUS. This then synapses into a layer of neurons in the sematosensory cortex of the brain.
integration
processing of sensory information, occurs entirely in CNS
ketanins
proteins in cytoplasm cut out section of microtubule, attach it to kinesin
Myelinating glial cells
provide insulation, physically surround neurons
Inhibition
reduces amplitude and duration of EPSP's -results from opening Cl- channels and reducing membrane resistance -looks like a dip between mountains on a graph except second mountain in much smaller
glia
regulate environment in which neurons function
astrocyte function
regulate extracellular neurotransmitter concentration in cells→regulates extracellular K⁺ concentration
astrocytes
responsible for regulating extracellular environment in the CNS
dyenine carries vesicle in
retrograde transport
tropomyosin is a?
ribbon like protein
Where does protein synthesis occur on a neuron?
ribosomes
red muscle fibers
rich in mitochondria and mitogloblin, aerobic, meant for long distances
Proprioception from Left side of body goes to which cerebrum
right cerebrum
In _______ conduction, the action potential is reignited at each node along the length of the myelinated axon, with the sequential opening of v-gated channels, and can approach conduction velocities of ___ m/sec.
saltatory, 110
Cell membrane in a muscle cell is called what?
sarcolemma
what is the membrane of a muscle cell called
sarcoma
Groups of _______ make up myofibrils
sarcomeres
Muscle fiber cytoplasm is called what?
sarcoplasm
Smooth ER in a muscle cell is called the _________
sarcoplasmic reticulum
what is the structure that is essentially a Ca²⁺ bag
sarcoplasmic reticulum
lou gehrig's disease
selective destruction of motor neurons
neuronal cell bodies in ganglia are _________, enter spinal nerve and go to CNS
sensory afferent
path of sensory afferent
sensory afferent, dorsal root ganglia, root, dorsal horn
three box model- nervous system
sensory information (input), integration, motor
Somatic Afferents
sensory neurons that originate in the body
DCML
sensory proprioception, fine touch assending
thallamus
sensory relay site
sense -> movement
sensory, sensory afferent, integration, motor efferent, movement
no myolin wraps means
signal cannot get to next node
retrograde transport
slow axoplasmic transport
what kind of motor unit would you have more control with? such as with smaller movements in the fingers?
smaller motor unit
what if the same amount of EPSP and IPSP enters a cell?
they cancel each other out
somatic nervous system versus autonomic
somatic is motor neurons that activate voluntary things such as skeletal muscles and autonomic is automatic
Voluntary Nervous System
somatic nervous system with motor neurons that activate skeletal muscles
Nodes of Ravier
space between myelinated sections
dendrite
spiky part coming from the cell body of a neuron, never myelinated, do not conduct action potentials, conduct graded potentials
anterolateral system tract
spinothelamic tract
Generator Potential
stationary depolarization of a receptor that occurs in response to a stimulus and is graded according to its intensity and that results in an action potential when the appropriate threshold is reached
Action potentials are said to be ________, because they always look the same and have a consistent duration of ___ ms.
stereotype, 1-2
Stretch Activated Channels
stretch activated input region: changing the shape of the plasma membrane in the input region opens stretch activated channels
describe the patellar tendon tap reflex
stretch sensitive channels are the input region of the primary sensory afferent. when hit, triggers action potential that goes down the 1° neuron through the dorsal route ganglion, through the dorsal route, and into the grey matter of the spinal cord. there it branches and synapses with both the lower motor neuron and the inhibitory interneuron. The lower motor neuron sends a signal to the quadricep extensor muscle to contract simultaneous to contraction of the hamstring flexor being inhibited
generator potential
stretch-activated channels let Na⁺ in. The more stretch-activated channels opened, the greater the generator potential. This depolarization can open v-gated Na⁺ channels and initiate an all or nothing action potential. As long as the charge remains above threshold action potentials keep fireing.
Glia Cells
supporting cells in the Nervous System which glue all cells together
The chemical connection between the output and input regions of two neurons is called a __________.
synapse
Sherrington
synapse = to clasp or hold
Where did transmembrane channels in the axon terminal come from?
synthesized on bound ribosomes and carried via fast axoplasmic transport
Sarcolemma tubes are known as?
t-tubules
chemical energy
taste and smell
capacitance
the ability to store a charge. a mylinated area will have lower capacitance then a node area.
in which direction does the action potential propagate?
the action potential propagates towards the CNS as sensory afferents
what part of the neuron is the output region?
the axon terminal, releases neurotransmitter to open neurotransmitter operated channels in the next cell
what is the conductile region of a neuron?
the axon, enriched with voltage-gated channels
axon terminal
the butt of the axon shaft
where is protein synthesis confined to in a neuron
the cell body
what is the input region of a neuron?
the dendrite and cell body, neurotransmitter operated and ligand-gated channels
the membrane seeks the
the equilibrium potential for the ion that is most dominant, most channels open
what is the purpose of the large impermeant anions inside the cell
the force exerted by the anions balances the tendency of K⁺ to leave the cell through leak channels and equilibrium is reached when these forces balance
describe the neuromuscular synaps and the initiation of muscle fiber action potential
the output region of the lower motor neuron synapses with the muscle cell. The positive charge from the action potential opens up the v-gated Ca²⁺ channels allowing calcium to flow into the lower motor neuron. This triggers the SNARE hypothesis and acetyl choline is released by the vesicles. This opens up the nicotine acetyl choline receptors allowing Na⁺ to flow in. This positive charge triggers other Na⁺ channels along the sarcoma to open up
hyperpolarize
the inside of the cell is becoming more negative
depolarize
the inside of the cell is becoming more positive
axon
the long shaft of the axon
Motor Output
the motor division is in PNS and has both voluntary and involuntary nervous systems
1. sensory input (3 box model)
the nervous system gathers sensory information called sensory input. This input begins in sensory receptors which are specialized cells located outside the central nervous system in the periphery that transduce some form of energy (e.g., mechanical, electromagnetic, or chemical) that originates inside or outside the body. Sensory neurons carry this information into the central nervous system.
The Neuron Doctrine
the neuron as the fundamental structure and functional unit of the nervous system
the neuron doctrine
the neuron is the fundamental, structural, and functional unit of the nervous system
what chemically happens at the synapse?
the positive charge from the Na⁺ opens Ca²⁺ channels allowing Ca²⁺ to come into the presynaptic cell trigering ecocytosis of a synaptic vesicle carrying neurotransmitters such as glutamate. These NTs operate ligand-gated ionotropic channels and open them so Na⁺ flows in. This produces synaptic potential
describe the anterolateral system and how signals for pressure, temperature, pain, and crude touch make it to the brain
the signal goes up the 1° neuron, through the dorsal route ganglia, and synapses with the second order neuron in the dorsal horn. The 2° neuron crosses the midline into the anterolateral system spinothalamic tract. It synapses with the 3rd order nueron at the thelamic relay nucleus in the thalamus. The 3° neuron then takes the signal to the sematosensory cortex
generator potential if there are no voltage gated channels in the neighborhood
the size of the generator potential becomes smaller and smaller the farther it spreads from the site of initiation due to leaking out of the membrane
sensory transduction
the transformation of ambient (nearby) energy to the movement of ions across a biological membrane.
what does the conductile region permit?
the uni-directional propagation of electrical signals (action potentials)
where are the axons of the lower motor neurons found
the ventral root
How do potassium voltage gates inactivate?
they do not inactivate, they go through delayed rectifier
what elements make up a sarcomere?
thin filaments (actin filament, troponin, and tropomycin), myosin thick filament, and Z-lines (actin binding protein and actinin)
affrent
to carry toward -sensory info somatic -conscious - visceral- from the gut
mechanical energy
touch and sound
dorsal (posterior)
toward the back
ventral (anterior)
toward the belly
afferent
towards cns
what are bundles of axons in the CNS called?
tracts
what types of sensory are communicated through the dorsal columns and where do they come from
tracts that carry info about light touch and proprioception from the periphery toward the brain
summation at the
trigger zone
sarcolemma forms_______ of muscle membrane within the muscle fiber
tubes
cytoplasmic proteins in cell bodies
tubulin, actin, move proteins
visceral
unconscious
Law of Dynamic Polarization
unidirectional flow of information Dendrite->Cell body->axon->axon terminal->neighboring cell
neuron
units of nervous system
How to get muscles move?
upper motor neurons synapse onto lower motor neurons
Action potential arrives at the axon terminal and open
v-gated Ca2+ chanels open
Oxytocin and vasopressin, which are peptide hormones synthesized in the hypothalamus and released from the posterior pituitary, must be transported to the site where they are released into the blood in _________ on _________ by _______.
vesicles, microtubulkes, kinesisn
electromagnetic energy and sensory transduction
visible light
consider what happens when propagating potentials in unmyelinated axons
voltage-gated Na⁺ channels located all along the membrane. The membrane is very thin and separates + from - making it a capacitor. Another channel can't be opened until the capacitor is discharged which takes up a lot of energy which is why the action potential propagates slower
Output region
voltage-gated calcium channels, responsible for neurotransmitter release
lateral corticospinal tract
voluntary muscle movement, not reflex
how does a muscle ultimately relax
when action potentials stop, Ca²⁺ no longer is pumped out and is pumped back into the sarcoplasmic reticulum. When Ca²⁺ levels decrease tropomyesin returns to its original conformation blocking the myosin binding sites and releases the actin from the myosin
describe the basic processes of action potential propagation and the role of Na⁺ and K⁺ v-gated channels
when exposed to a local environment of increased positive charge, Na⁺ channels open causing an influx of Na⁺ into the cell. This causes the inside of the cell to become more positive leading to more Na⁺ channels opening. Within a millisecond or two of Na⁺ channels opening, the ball and chain inactivates them and K⁺ channels open to return the balance of the charge explaining why the signal moves in one direction
what is the stable form of myosin?
when it has ADP + Pi attached
when can v-gated Na⁺ channels be opened again?
when membrane returns to equilibrium
threshold
when reached action potential fires all or none effort
Decussation of the pyramids
when the neuron crosses over the midline in the brain stem then travels to lateral cortico spinal tract
Stretch Receptor
when you stretch a muscle, Na+ flows into channels which opens voltage gated channels which causes action potential. signal travels down to cell body and back to hand to cause motion
dorsal roots
where primary afferents enter the spinal cord
decussation pyramid
where upper motor neuron crosses midline in medulla
Trigger zone is a morphological site
wherever the v-gated channels are clustered, this is where the trigger zone is
