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Exam 3 Chapter 12
Terms in this set (270)
The nervous system includes all ______ in the body.
What are the two kinds of cells in the neural tissue?
What are neurons?
nerve cells capable of generating and transmitting electrical signals
What are neuroglia cells aka glial cells?
cells that support and protect neurons
What are the organs of the nervous system?
brain and spinal cord, sensory receptors of senses, nerves
Receptors are _______ which can ________.
proteins, change shape
What are the functions of nerves
connect nervous system with other systems
What is the central nervous system divided into?
brain and spinal cord
What are the functions of the CNS?
process and coordinate: sensory data, motor commands, higher functions of brain such as intelligence
What does the peripheral nervous system consist of?
neural tissue outside the CNS
What are the functions of the PNS?
carries sensory info to CNS, carry motor commands to peripheral tissues and systems
What are ganglia?
areas of communication where electrical activity occurs
Know where the cervical nerves, thoracic nerves, lumbar nerves, and sacral are located. CH. 12 Slide 7
The sympathetic nervous system is important in ________ response.
fight or flight response
The parasympathetic nervous system is important in ______ and ______.
resting and digestion
The afferent and efferent divisions are apart of which nervous system?
What is afferent division?
carries sensory information from PNS' sensory receptors to CNS
What is the function of receptors of afferent division?
detect changes or respond to stimuli
What are the receptors of afferent division?
neurons and specialized cells like merkel cells, complex sensory organs
What is the function of effectors of afferent division?
respond to efferent signals
What are the effectors of afferent division?
What is efferent division?
carries motor commands from CNS to PNS' muscle glands
What is the PNS divided into?
somatic nervous system, autonomic nervous system
What is the function of the somatic nervous system?
controls skeletal muscle contractions
Is the somatic nervous system voluntary or involuntary?
What is the function of autonomic nervous system?
controls subconscious action
What is the autonomic nervous system divided into?
sympathetic nervous system, parasympathetic nervous system
The sympathetic nervous system has a _____ effect.
The parasympathetic nervous system has a ______ effect.
_______ are the basic functional units of the nervous system.
What are the types of neurons?
anaxonic, bipolar, unipolar, multipolar
Where are anaxonic neurons found?
brain, sense organs
In anaxonic neurons, the _____ and _____ look alike.
Where are bipolar neurons found?
special sensory organs
What does a bipolar neuron look like?
one dendrite and one axon with a cell body in-between
Where are unipolar neurons found?
sensory neurons of PNS
What does a unipolar neuron look like?
cell body is off to one side
Where are the mutlipolar neurons found?
The mutlipolar neurons include ________ in the body.
all skeletal muscle motor neurons
What does a multipolar neuron look like?
multiple dendrites, one axon
What are the 3 functional classifications of neurons?
sensory, motor, intraneuron
What are sensory neurons?
afferent neurons of PNS
What are motor neurons?
efferent neurons of PNS
What are interneurons?
from connection between other neurons
What are interneurons also called?
What are the three types of sensory receptors?
interoceptors, exteroceptors, proprioceptors
What is the function of interoceptors?
monitor internal systems such as digestive, respiratory, cardiovascular, urinary, reproductive
What are exteroceptors? What is their function?
external senses, sense things like touch, temperature, pressure
What are proprioceptors. What is their function?
skeletal muscles and joints, monitor position and movements
What is the function of sensory neurons?
monitor internal environment and effects of external environment
What are some examples of sensory neurons?
pacinian, nociceptor, meissner, merkel cells
What is the function of pacinian sensory neuron?
sensitive to vibration and pressure in skin
What is the function of nociceptor sensory neuron?
What is the function of the meissner corpuscle sensory neuron?
senses light touch in skin
What is the function of merkel cell sensory neurons?
sense light touch
Where are meissner corpuscles found?
surface of skin
Where are merkel cells found?
superficial skin layers
What is the function of motor neurons?
using efferent fibers to carry instructions from CNS to peripheral effectors
What are the two major efferent systems?
somatic nervous system, autonomic nervous system
What does the somatic nervous system include?
all somatic motor neurons that innervate (supply with nerves) skeletal muscles
What is the functions of the autonomic nervous system?
controls subconscious action
What is the autonomic nervous system also called?
visceral nervous system
What does the autonomic nervous system include?
smooth muscle, cardiac muscle, glands
Where are interneurons located?
brain, spinal cord, autonomic ganglia between sensory and motor neurons
What are interneurons involved in?
higher functions such as memory, planning, learning
What is the function of the neuroglia?
preserve physical and biochemical structure of neural tissue
_______ is essential to the survival and function of neurons.
What are the four types of neuroglia in the central nervous system?
ependymal, astrocytes, oligodendrocytes, microglia
What is the function of the ependymal cells?
line central canal of spinal cord and ventricles of brain, secrete cerebrospinal fluid, circulates CSF with its cilia and microvilli, contain stem cells for repair
What is the function of astrocytes?
maintain blood brain barrier, repair damaged neural tissue, guide neuron development
What is the function of oligodendrocytes?
wrap around axons to form myelin sheaths
What is the function of microglia?
migrate through neural tissue to clean up cellular debris, waste products and pathogens
What are the two types of neuroglia in the peripheral nervous system?
satellite cells, schwann cells
What is the function of satellite cells
surround ganglia, regulate environment and neuron
What is the function of schwann cells?
from myelin sheath around peripheral axons
What is the function of myelin?
increases speed of action potentials, insulates myelinated axons, makes nerves appear white
What color is the region of the CNS with many myelinated nerves?
What color are the unmyelinated areas of CNS?
What is happening in figure 1 and 2 of slide 29?
Na+ moves across axon/neuron depolarizing it-(making it more positive) which then opens ion channels and more sodium rushes in creating electrical signal. Electrical signals= change in ion concentrations
The change in ion concentration create ________.
What does hyperpolarization do to axon/neuron?
makes it more negative by Cl- leaking in or K+ leaking out. Although this changes charge of cell it does not lead to electrical signal
What happens in 1 that's different from figure 2 on slide 29
In order for electrical signal to occur the 10 Na+ ions (example number) need to move across cell. However, this membrane has constant leakage of Na+ due to no myelin, so you have to have ion channels very close together to have a constant flow of sodium ions inside cell in order to get 10 Na+ across cell.
The electrical signal moves slower due to constant leakage of Na+. Prof explanation- electrical signal jumping close together, jump.jump.jump,jump
What happens in figure 2 on slide 29 that's different from figure 1
In order for electrical signal to occur the 10 Na+ ions need to move across cell. This membrane has myelin sheath which prevents leakage of Na+ ions, so ion channels only have to be between myelin sheaths to still have a flow of Na+ ions in cell.
Electrical signal moves faster due to myelin sheaths preventing leakage of Na+. Prof explanation: electrical signals jump far apart, jump....jump....jump....jump
What are the major organelles of the neuron structure in the cell body?
nucleus, nucleolus, perikaryon, mitochondria, RER, cytoskeleton
What is the perikaryon found in cell body of neuron structure?
What is the function of the mitochondria?
What is the function of the RER? What do
What is located on RER that produces protein?
What can ribosomes produce? Give reasoning.
neurotransmitters because they are chemical messengers which can be proteins
What makes up the cytoskeleton?
neurofilaments (intermediate filaments in neuron), neurotubules (microtubules in neuron), neurofibrils
What are the functions of neurofibrils?
bundles of neurofilaments that provide support for dendrites and axon
What are intermediate filaments made of?
What are microfilaments made of?
What are microtubules made of?
What are nissl bodies?
dense ares of RER and ribosomes
What do dendrites look like?
_____ makes up 80-90% of neuron surface area.
What is the function of dendrites?
receive information from other neurons
What is the axon hillock?
thick section of cell body
What is the function of axon hillock?
involved in signal integration which is the translation of change of ion concentration and type
_______ will determine if a signal will pass down axon.
What is the function of an axon?
pathway that carries electrical signal aka action potential to target
What is the axoplasm?
cytoplasm of axon
What does the axoplasm contain?
neurotubules, neurofibrils, enzymes, organelles
What is the axolemma?
specialized cell membranes
What is the function of the axolemma?
What is the synapse?
site of communication area between two neurons or between a neuron and another effector
What is an effector? Give examples.
junction that permits a neuron to pass an electrical or chemical signal to another cell; muscle, gland, neuron, organ, tissue
What is the function of a presynaptic cell?
neuron that sends message
What is the function of a postsynaptic cell?
cell that receives messages such as neurons, muscles, and endocrine glands and translates the messages in to receptors/proteins. This changes the shape and may cause stuff to happen
What is the synaptic cleft?
small gap that separates the presynaptic membrane and postsynaptic membrane
What is a neuromuscular junction?
synapse between a motor neuron and a muscle
What are the steps that occur at the neuromuscular junction?
Action potential arrives at axon terminal, opens voltage gated calcium channel, calcium enters cell, calcium binds to vesicles, vesicles move and fuse to membrane at docking protein, docked vesicles release neurotransmitter ACH by exocytosis, neurotransmitter ACH diffuses across synaptic cleft and binds to receptors on motor end plats
What is the function of the synaptic knob?
contain synaptic vesicles consisting of neurotransmitters
What are the characteristics of neurotransmitters?
chemical messengers, released at presynaptic membrane, affect receptors of post synaptic membrane, broken down by enzymes, reassembled at synaptic knob
What are the types of synapses between neurons?
axodenderitic, axosomatic, dendrodendritic, axoaxonic
Where is the axodendritic located?
between axon terminal of one neuron and the dendrite of another
Where is the axiomatic located?
between axon terminal of one neuron and cell body of another
Where is the dendrodendritic locate?
between dendrites of neurons
Where is the axoaxonic located?
between an axon terminal of a presynaptic neuron and axon of postsynaptic neuron
What happens after ACH binds to receptors at motor end plate? (Steps leading to muscle contraction)
bound ACH activates receptors, opens sodium ion channels, sodium flows into sarcoplasm of muscle depolarizing it, triggers second muscle action potential, ACH activity is terminated
What happens after ACH activity is terminated? (steps leading to muscle contraction)
muscle action potential propagates to SR, SR releases calcium ions into muscle cell
What happens after SR releases calcium ions into muscle cell? (steps leading to muscle contraction)
calcium ion binds to troponin, troponin pulls tropomyosin away from myosin-actin binding site, cross bridge forms, ATP binds to myosin detaching myosin head from actin, ATP hydrolyzes, binds myosin head to new actin, phosphate and ADP is released from myosin, power stroke occurs (sliding of filament), ATP binds to myosin head releasing it, calcium pumped back into SR
The axoplamsic transport within the axon transports substances by using _________ (like a rail).
Th neurotubules within the axoplasmic transport, transports ________ between ______ and _______.
vesicles, cell body, synaptic knob
What are kinesin and dynein powered by?
mitochondria and the dephospho rylation of ATP
What are kinesin and dynein?
motor proteins that actively move along microtubule cables
Kinesin moves in the ____ direction.
Dynein moves in the ____ direction.
What is the difference between kinesin and dynein?
Dynein is larger and moves 5-times faster
What are the types of synapses?
chemical synapse, electrical synapse
What are the characteristics of an electrical synapse?
fast, bi-directional, excitatory
What makes an electrical synapse fast?
gap junctions give direct contact
What does it mean by electrical synapse are excitatory?
always result in depolarization
What are the characteristics of a chemical synapse?
slow, unidirectional, excitatory or inhibitory
Chemical synapses are unidirectional so stuff always travels from _____ to _____.
Depending on ______ a chemical synapse can be excitatory or inhibitory
receptors which are proteins that allow different ions in/out
Neurons are electrically excitable due to what?
voltage difference across their membrane
What are the 2 types of electrical signals?
action potentials, graded potentials
What is the significance of action potentials?
can travel long distances
What are graded potentials?
local membrane charges due to different ions entering or leaving
______ potentials lead to _______ potentials
Where are ion channels present?
plasma membrane of all cells
A very important component to have in the nervous system is what?
What are ion channels?
proteins that change shape when stimulated by voltage, physical stimulus or chemical stimulus
In a living cell a flow of ion occurs though _____ in the cell membrane
How does the plasma cell membrane produce electrical signals?
by movement of ions
What are the 3 types of potentials?
resting potential, graded potential, action potential
What is the resting potential?
potential of a resting cell
What is graded potential?
temporary, localized change in resting potential due to changes in ion movement (ions moving in/out)
What is an action potential?
What produces an action potential?
Where does the action potential propagate?
from surface of axon to synapse
The greatest number of ____ ions are found in cell while the greatest number of ___ ions are found outside cell
What is stuck inside of the cell?
proteins and phosphates
What ion leaks out of the cell through leak channels?
What restores the cell to resting potential?
How does the NKA pump restore a cell to resting potential?
removes 3 Na+ and brings in 2K+
How does a cell change its charge?
by opening or closing different ion channels which creates electrical signal
What are the types of channels?
leakage channels, chemically gated channels, voltage gated channels, mechanically gated channels
____ channels are always open.
Why is the nerve cell membrane more permeable to K+ than to Na+?
the nerve cells have more K+ than Na+ leakage cells
_____ channels are open in the presence of specific chemicals at a binding site.
chemically gated channels
Where are chemically gated channels found?
neuron cell body and dendrites
____ channels respond to changes in transmembrane potential i.e. they need a voltage or certain charge of a certain strength to open them
What kind of gates do voltage gated channels have?
activation gates which are open, inactivation gates which are closed
Where are voltage gated channels found?
neural acons, skeletal muscle sarcolemma, cardiac muscle
______ channels respond to membrane distortion
Where are mechanically gated channels found?
What is hyperpolarization?
membrane becomes more negative due to Cl- entering or more K+ leaving
What is depolarization?
membrane becomes more positive due to Na+ entering, Ca2+ entering, or keeping K+ inside by closing K+ leak channels
Why is it called graded potentials?
signals are graded
What does it mean by the signals are graded in graded potentials?
vary in amplitude (size) and are localized
The signals of graded potentials vary in amplitude depending on what?
strength of the stimulus
Where do graded potentials most often occur?
dendrites, cell body of neuron
Graded potentials decay with _____.
Graded potentials decay with distance due to what?
leakage of charged ions across membrane, electrical resistance of cytoplasm
What substances are hydrophobic?
What substances are hydrophilic?
glucose, charged substances
_____ substances enter by facilitated diffusion.
____ substances enter by simple diffusion.
Describe what is happening in this picture.
Green neurons fire due to lots of positive charged ions entering or keeping K+ inside. Their graded potentials are below threshold alone but once graded potentials are all at trigger zone they sum up to create a super threshold signal which generates action potential
Describe what is happening in this picture.
Green neurons fire due to lots of positive charged ions entering or keeping K+ inside but red neuron allow Cl- to enter or more K+ to leak out. Their graded potentials are below threshold so no action potential created.
Can many graded potentials be generated simultaneously? yes/no
Describe what this image means.
different stimuli strengths result in different strength changes in charge
(different strength changes in charge=graded potential)
What does hyperpolarizing graded potentials do to the cell?
make cell more negative depending on how many Cl- ions enter or how many K+ ions lead out
What does depolarizing graded potentials do to the cell?
make the cell more positive depending on how many Na+/Ca2+ ions enter or how many K+ ions kept
Explain how action potentials are generated.
if depolarizing graded potential is strong enough and reaches a threshold (voltage strong enough to open the protein) then voltage-gated Na+ channels open and an action potential is created (by large change in positive charge due to opening of sodium channels)
How are action potentials different from graded potentials?
travel long distance, magnitude of depolarization is same to trigger action potential (all or none)
How are graded potentials different from action potentials?
local, don't travel far, magnitude of potential is determined by magnitude of stimulus
What are the three phases of an action potential?
depolarization, depolarization, hyperpolarization
Briefly describe, in order the 4 steps in the generation of action potentials.
depolarization to threshold, activation of Na+ channels, Inactivation of Na+ channels and activation of K+ channels, return to normal permeability
Explain the first step in the generation of action potentials.
depolarizing graded potential has a strong enough voltage to reach threshold
Explain the second step in the generation of action potentials
threshold reached and the Na+ channels are opened, causing Na+ to rush in cytoplasm and rapid depolarization, positive feedback process happens
What is the positive feedback process during the generation of action potentials when Na+ channels are activated?
more Na+ channels oped due to charge change from having other Na+ channels opening
Explain the third step in the generation of action potentials?
inactivation gates close so Na+ inflow stops (this automatically happens and is time dependent), voltage gated K+ channels open (they started opening when threshold reached in step 1 but opened slowly and effect seen after Na+ channels became inactivated), depolarization begins due to K+ rushing out
Explain the fourth step in the generation of action potentials
K+ channels start to close but slowly so membrane is briefly hyper polarized, membrane returns to resting and action potential is over
What are the two refractory periods of an action potential?
absolute refractory period, relative refractory period
What happens in the absolute refractory period of an action potential?
sodium channels are open to sodium channels are inactivated where no action potential is possible
What happens in the relative refractory period of an action potential?
Sodium channels close and a very large stimulus can initiate an action potential
What are the 3 states that voltage gated Na+ channels have?
Closed, open, inactive
How do voltage gated Na+ channels go from being closed to open?
membrane has to depolarize to open channel and positive feedback process occurs
How do voltage gated Na+ channels go from being open open to inactive?
depolarization causes channels to become inactive meaning that channel cannot be opened again at this time and no action potential can occur
How do voltage gated Na+ channels go from being inactive to closed?
membrane has to depolarize before channel switches to closed state and once at closed state the channel can be reopened
What are the 2 states that voltage gated K+ channels have?
How do voltage gated K+ channels go from being closed to open?
depolarization needed to open the channel (channel opens slowly) which hyper polarizes cell
How do voltage gated K+ channels go from being open to closed?
close when membrane becomes hyperpolarized
What are the two ways of propagating action potentials?
continuous propagation with unmyelinated axons, saltatory propagation with myelinated axon
How are action potentials propagated along axons that are unmyelinated?
passive conduction of the depolarizing current depolarizes the surrounding area which opens nearby Na+ channels which generates another action potential (there are many voltage gated Na+ channels close to each other
How are action potentials propagated along axons that are myelinated?
myelin around axons prevents current leakage, so the passive current spreads further down axon until it reaches nodes of ranvier which contain Na+ channels where action potential is generated due to passive current. Basically, the action potentials hum from node to node
What is saltatory conduction?
jumping of action potentials from node to node
What are nodes of ranvier?
gaps between myelin sheaths that contain Na+ channels
What is unidirectional conduction of an action potential due to?
transient inactivation of voltage gated Na+ channels
Ion movement depends on what?
cytoplasm concentration, axon diameter, membrane properties
Axon diameter affects action potential speed, so the _____ the diameter the _____ the resistance.
Ion movement depends on membrane properties, so in a(n) _____ membrane ions will move slower and in a(n) ______ membrane ions will move faster.
What are the types of fibers?
Type A, B, Cfibers
What are the characteristics of type A fibers?
myelinated, large diameter, high speed
What is the function of type A fibers?
carry rapid information to/from CNS
Give examples of type A fibers.
position, balance, touch and motor impulses
What are the characteristics of type B fibers?
myelinated, medium diameter, medium speed
What is the function of type B fibers?
carry intermediated signals
Give examples of type B fibers?
sensory information, peripheral effector
What are characteristics of type C fibers?
unmyelinated, small diameter, slow speed
Give examples of type C fibers.
involuntary muscle, gland controls
What are the two classes of neurotransmitters?
excitatory neurotransmitters, inhibitory transmitters
What does the excitatory neurotransmitter do to the postsynaptic membrane?
causes depolarization which promotes action potential
What does the inhibitory neurotransmitter do to the postsynaptic membrane?
causes hyperpolarization of postsynaptic membrane which suppresses/inhibits action potential
The effect of a neurotransmitter on a postsynaptic membrane depends on the ______, not on the ______.
Name the neurotransmitters studied in class.
norepinephrine, dopamine, serotonin, gamma aminobutyric acid
What is norepinephrine released by?
Is norepinephrine excitatory or inhibitory?
What are the neurotransmitters in the CNS?
dopamine, serotonin, gamma aminobutryic acid
Is dopamine excitatory or inhibitory?
can be excitatory or inhibitory depending on receptor
What does serotonin affect?
attention and emotional states
Is Gamma aminobutyric acid (GABA) excitatory or inhibitory?
What are neuromodulators?
other chemicals released by synaptic knobs and similar in function to neurotransmitters because they also bind to receptors
Name the neuromodulators studied in class.
What are neuropeptides?
neuromodulators that bind to receptors and activate enzymes
What are opioids?
neuromodulators in the CNS that bind to the same receptors as opium or morphine
What can opioids do?
What are the four classes of opiods?
endorphins, enkephalins, endomorphins, dynorphins
What produces endorphins and when are they produced?
pituitary gland and hypothalamus during strenuous exercise, excitement, pain, and orgasm
What are enkephalins involved in?
regulating nociception in the body
What are endomorph ins involved in?
regulating sedative and arousal behaviors
What are dynorphins involved in?
controlling appetite, regulating body temperature
What are the two effects neurotransmitters and neuromodulators can have on a neuron?
have direct or indirect effects
Explain the direct effect of neurotransmitters and neuromodulators.
open and close voltage gated ion channels
Neurotransmitters and neuromodulators carry out indirect effects through _____ or ______.
G proteins, intracellular enzymes
Explain the indirect effect of neurotransmitters and neuromodulators through G proteins.
neurotransmitters which is the first messenger binds to the receptors, the 3D shape of the receptor changes, this changes the shape of the G protein which activates the G protein, G protein activates the enzyme adenylate cyclase which produces a second messenger, cyclic AMP
Explain the indirect effect of neurotransmitters and neuromodulators through intracellular receptors.
Neurotransmitters or neuromodulators must be hydrophobic to bind to a receptor inside of cell
What are postsynaptic potentials?
graded potentials developed in postsynaptic cell in response to neurotransmitters
What are the two types of postsynaptic potentials?
excitatory postsynaptic potential, inhibitory postsynaptic potential
What is an excitatory postsynaptic potential?
graded depolarization of postsynaptic membrane
What is an inhibitory postsynaptic potential?
graded hyper polarization of postsynaptic membrane
Excitatory postsynaptic potential and inhibitory postsynaptic potential combine through what is called ________.
What is temporal summation of excitatory postsynaptic potential and inhibitory postsynaptic potential?
rapid repeated stimuli at one synapse
What is spatial summation of excitatory postsynaptic potential and inhibitory postsynaptic potential?
many stimuli arrive at multiple synapses
What is presynaptic inhibition? Example on pg. 20 of notes
action of an axoaxonic synapse at a synaptic knob that decreases the neurotransmitter release by presynaptic membrane
What is presynaptic facilitation? Example on pg. 10 of notes
action of an axoaxonic synapse at a synaptic knob that increases the neurotransmitter release by the presynaptic membrane
What is glutamate?
What is the most common excitatory neurotransmitters in the CNS?
How many ligand gated ion channel receptors are there for glutamate?
at least 3 different ones
What is the major cellular mechanism that forms the basis of learning and memory?
long term potentiation
Explain how long term potentiation works.
In late phase of LTP, calcium enter cell, triggers ca-calmodulin, this activates adenylyl cyclase and cAMP kinase, cAMP kinase translates to nucleus of cell and helps start protein synthesis and structural changes such as forming new synapses
What according to scientists forms long term memory and learning?
formation of new synapses
Axon and dendrites may be repaired if...
neuron cell body stays intact, schwann cells stay active and form a tube, scar tissue doesn't form too rapidly
What is wallerian degeneration?
process that results when a nerve fiber is cut or crushed
What is neurogenisis?
formation of new neurons from stem cells
What are factors preventing neurogenesis in CNS?
inhibition by neurogilal cells, absence of growth stimulating factors, lack of neurolemmas, rapid formation of scar tissue
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