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Exam II
Anatomy and physiology with Liu
214
Anatomy
Undergraduate 2
10/20/2010

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Term
What are 2 control systems in the body?
Definition
Nervous and endocrine systems
Term
Which system uses chemical and electrical signals (neurotransmitters)
Definition
nervous system
Term
This is the master control system of the body
Definition
nervous system
Term
In this major system, responses are fast and specific (also called a "wired" system)
Definition
nervous system
Term
This system communicates only by chemical signals (hormones)
Definition
endocrine
Term
This major system has slower but long-lasting responses (also considered to be "wireless"
Definition
endocrine system
Term
This system interacts with the nervous system to coordinate and integrate the activity of body cells
Definition
endocrine system
Term
what are the 3 functions of the nervous system?
Definition
sensory input, integration, and motor output
Term
The central nervous system is composed of? and the function is?
Definition
brain and spinal cord; Integration and control center of the body
Term
The peripheral nervous system is composed of? and the function is?
Definition
Composed of all nervous structures outside of the CNS
(Cranial nerves (originate from the brain)
Spinal nerves (originate from the spinal cord)
Ganglia (groups of nerve cell bodies in the PNS)
Plexuses (intermingling of nerve cell processes)
The function is: Communication lines between the CNS and rest of the body
Term
This is a collection of neuronal axons found in the PNS
Definition
A Nerve
Term
What do somatic afferent fibers do?
Definition
carry impulses from skin, skeletal muscles, and joints to the CNS
Term
What do visceral afferent fibers do?
Definition
transmit impulses from visceral organs to the CNS
Term
What does the Sensory (afferent) division of the PNS do?
Definition
conveys sensory information to the CNS
Term
What does the motor (efferent) division of the PNS do?
Definition
Transmits impulses from the CNS to effector organs (muscles and glands)
Term
What are the 2 functional divisions of the PNS?
Definition
Sensory (afferent) division and motor (efferent) division
Term
What are the 2 main parts of the motor division?
Definition
somatic and autonomic nervous system (SNS/ANS)
Term
This motor division is voluntary and is where you have conscious control of skeletal muscles
Definition
somatic nervous system
Term
this motor division is composed of visceral motor nerve fibers, regulates smooth muscle, cardiac muscle, and glands of internal organs; has 3 subdivisions (sympathetic, parasympathetic, and enteric nervous system);and this is involuntary actions
Definition
autonomic nervous system (ANS)
Term
what are 2 principle types of cells in the nervous tissue?
Definition
neurons and support cells
Term
these are the basic structural and functional units of the nervous system (makes up 10% of cells in the CNS) fully differentiated, non-dividing cells, and excitable cells that transmit electrical signals
Definition
neurons
Term
also called neurolglia or glial cells
Definition
support cells
Term
non-excitable cells, provide metabolic and physical support to neurons, make up 90% of cells but only 50% of volume, capable of cell division (brain tumors caused by uncontrolled division of these)
Definition
support cells
Term
Characteristic: high metabolic rate; totally dependent on aerobic pathway to make ATP (need O2 and glucose);fully differentiated
Definition
neurons
Term
biosynthetic center
Definition
cell body (soma)
Term
dendrites
Definition
receive info from other neurons and signal toward cell body
Term
transmit signals to other neurons or cells
Definition
axon (nerve fiber)
Term
action potentials generated here
Definition
axon hillock (or initial segment)
Term
release neurotransmitters onto other neurons or cells
Definition
axon terminals
Term
direction of signal transmission in a neuron?
Definition
dendrites->cell body->axon or dendrites-> cell body -> axon hillock -> axon terminal
Term
3 or more processes extending from the cell body (neuron)
Definition
multipolar neuron
Term
how many processes extend from a bipolar neuron's cell body
Definition
2 processes
Term
1 process extending from the cell body of a neuron
Definition
unipolar neuron
Term
What is the most abundant neuron type in the body? (unipolar, bipolar, multipolar)
Definition
multipolar (99%)
Term
where are bipolar neurons found?
Definition
retina and olfactory mucosa
Term
Where are unipolar neurons found?
Definition
PNS; dorsal root of ganglia of spinal cord; sensory ganglia of cranial nerves
Term
what are the functional classes of neurons
Definition
sensory/afferent neurons(input);interneurons(integration);motor/efferent neurons(output)
Term
what are sensory neurons? (unipolar, bipolar, multipolar)
Definition
most unipolar, all bipolar, no multipolar
Term
what is the function of an interneuron and where is it found
Definition
integration, lies between sensory and motor neurons in neural pathways (CNS)(99%)(multipolar)
Term
function of motor/efferent neurons and where they are found
Definition
transmit information from CNS to effector organs (somatic/autonomic) commonly multipolar
Term
do neurons always work alone or in large groups?
Definition
in large groups of functionally-related neurons that run in parallel
Term
what are bundles of axons called in the PNS and the CNS
Definition
nerves;tracts
Term
The membrane that surrounds the whole group of nerves is called?
Definition
epineurium
Term
the membrane that covers a group of nerves contained in the epineurium is called?
Definition
perineurium
Term
covering the axon and myelin sheath is the?
Definition
endoneurium
Term
Characteristic: mixed(contain both sensory and motor nerve fibers);purely sensory(rare, e.g. CN I % II); purely motor(rare, e.g. CN III); cranial nerves (originate from the brain); spinal nerves (originate from spinal cord)
Definition
nerves (in PNS)
Term
Characteristic: either sensory or motor; common origin & destination
Definition
tracts (in CNS)
Term
4 components in a spinal nerve
Definition
somatic afferent, visceral afferent, somatic efferent, visceral efferent
Term
also known as "support cells" or "glue", remains mitotic, and is non-excitable
Definition
Glial cells
Term
name the cell based on the function: provide physical support for neurons, provide nutrition to neurons, insulation(form myelin that wraps around axons), regulation chemical environment of neurons(composition of the ECF)
Definition
Glial cells
Term
What does excitable mean?
Definition
the ability to initiate or conduct electrical signals
Term
these cells surround neuron cell bodies in the PNS
Definition
satellite cells
Term
these cells myelinate all PNS axons-covers 1 axon
Definition
schwann cells
Term
axons can be myelinated or unmyelinated. myelin-forming cells can cover about 1mm of axon length. the gaps inbetween are called?
Definition
nodes of ranvier
Term
the most abundant neuroglia, supports the CNS, make exchanges between neurons and capillaries, and regulates the chemical environment around neurons (cleans up leaked k+ and released neurotransmitters)
Definition
astrocytes
Term
modified immune cells, monitor health and perform defense functions for neurons (in CNS)
Definition
microglial cells
Term
these cells line the central cavities of the brain and spinal cord, forms a permeable barrier between cerebrospinal fluid(CSF) and interstitial fluid of the CNS, beats the cilia to help circulate the CSF, and germinative centers of the CNS, contain neural stem cells
Definition
ependymal cells
Term
form myelin sheaths around CNS axons, each covers a portion of up to 40 axons.
Definition
oligodendrocytes
Term
definition of neurophysiology
Definition
study of nervous system function
Term
how do neurons communicate with other cells
Definition
via electrical and chemical signals
Term
what is an electric potential across a cell membrane? and what are the units?
Definition
membrane potential(Em); milivolts(mV)
Term
definition Voltage (V)
Definition
the measure of electrival potential between two points
Term
current (I)
Definition
movement of electrical charge from one point to another- flow of ions (not free electrons)
Term
resistance(R)
Definition
the hindrance to the movement of electrical charge through the material(in the body, the resisitance to current flow is provided by the cell membrane)
Term
Ohm's law
Definition
I=V/R
Term
when does membrane potential arise?
Definition
when there is a difference in electrical charge on the 2 sides of a call membrane
Term
what is the membrane potential measured at resting state called?
Definition
resting membrane potential(RMP)
Term
What is the range and average voltage of the resting membrane potential of a neuron
Definition
-40mV to -90mV;-70mV
Term
membrane potential develops due to:
Definition
differences in ionic composition(na+ and K+) of intracellular fluid(ICF) and the extracellular fluid(ECF) (K+ higher inside cell) (Na+ higher outside cell); differences in membrane permeability(K+ more permeable)
Term
where is K+ higher and Na+ higher? and how are the concentrations maintained?
Definition
K+ higher inside the cell/Na+ higher outside the cell; maintained by the Na+-K+ pump
Term
is the plasma membrane permeable to cytoplasmic proteins?
Definition
no
Term
what is responsible for resting membrane potential
Definition
The resting membrane potential depends mainly on K+ concentration gradient across the plasma membrane and a selective permeability of the plasma membrane to K+ through K+ leak channels
Term
what is the difference between K+ leak channels and voltage-gated K+ channels?
Definition
k+ channels are always open, voltage-gated K+ channels only open in response to membrane potential changes (depolarization)
Term
what are 2 forces that influence the diffusion of ions across the cell membrane and their definition?
Definition
electrical force(determined by the Em) chemical force(determined by the ion concentration gradient between the ECF and ICF) both forces act on each individual ion(may work in same or opposite direction of eachother) the total force is the "electrochemical gradient(force)"
Term
the electrochemical gradient represents the combination of 2 influences:
Definition
electrical force(or electrical gradient) across the membrane; chemical force( or concentration gradient) for that ion.
Term
when there is no net movement of K+ across a membrane, the membrane potential at which this equilibrium is reached is called the? and for Na+
Definition
K+ equilibrium potential (Ek); Na+ equilibrium potential(Ena)
Term
The Resting Membrane Potential is Close to but not Equal to K+ Equilibrium Potential. why?
Definition
Because the plasma membrane is not just permeable to K+, it is also very slight permeable to other ions (e.g. Na+)
Term
if the membrane is permeable only to k+, what is the membrane potential?
if the membrane is permeable only to Na+, membrane potential is?
what happens if the membrane is permeable to multiple ion species?
why is the membrane 75 times more permeable to K+ than Na+? what is the resting membrane potential closer to, Na+ or K+?
Definition
If the membrane is permeable only to K+, membrane potential = EK = -90 mV.
If the membrane is permeable only to Na+, membrane potential = E Na = +60 mV.
If the membrane is permeable to multiple ion species, the most permeable ion would have the greatest influence on membrane potential.
At rest, the membrane is about 75 times more permeable to K+ than Na+ because the presence of K+ leak channel. K+ has greater influence on the resting membrane potential than Na+. Thus, resting membrane potential is close to EK.
Term
how do ligand-gated ion channels open?
Definition
they open when a chemical (e.g. neurotransmitter) binds to its receptor (also known as chemically gated ion channels)
Term
how do voltage-gated ion channels open?
Definition
open and close in response to changes in membrane potential. (e.g. voltage-gated Na+ channels open in response to membrane depolarization)
Term
how do stretch-activated ion channels open?
Definition
mechanosensitive channels open in response to physical deformation of the channels
Term
How can the RMP (Em = -70 mV) be Changed
Definition
A change in Em can be produced by any stimulus that changes permeability of membrane to certain ions (due to opening or closing of ion channels).
Term
what does overshoot mean?
Definition
overshoot refers to a reversal of the membrane potential polarity
Term
what does repolarization mean?
Definition
repolarization is when the membrane potential returns to its resting value (RMP)
Term
what does RMP stand for?
Definition
Resting Membrane Potential
Term
When is a cell polarized
Definition
a cell is "polarized" because its interior is more negative than its exterior
Term
what does hyperpoarization mean?
Definition
hyperpolarization is when the membrane potential becomes more negative than the RMP
Term
what does depolarization mean?
Definition
depolarization is when the membrane potential becomes less negative than RMP
Term
in which two ways do changes in membrane potential occur? explain what they are.
Definition
graded potentials:transmit information only over short distance; action potential: transmit information over very long distance
Term
Are graded potentials signals over short or long distances?
Definition
Short
Term
what is the meaning of decremental?
Definition
the decrease in magnitude with increasing distance from the site of origin (graded potentials)
Term
True or false: Graded potentials can not be depolarization or hyperpolarization.
Definition
false. Graded potentials can be depolarization or hyperpolarization.
Term
Where do graded potentials occur?
Definition
at the receptor region of a sensory neuron (known as receptor potentials) and the dendrites and cell body of an interneuron or a motor neuron (known as synaptic potentials)
Term
what is action potential?
Definition
action potential is a brief change in membrane potential that can propagate along the surface of excitable cells.
Term
what is the difference between action potential and graded potential?
Definition
action potential involves voltage-gated ion channels; graded potentials involve chemically-gated ion channels or stretch-activated ion channels.
Term
what are cells called that generate action potentials?
Definition
excitable cells (e.g. neurons, muscles, and gland cells)
Term
what is occuring with the voltage-gated Na+ and K+ channels and the leak channels during resting state?
Definition
voltage-gated Na+ and K+ channels are closed, leak channels are open maintaining resting membrane potential.
Term
in the depolarizing phase, what happens?
Definition
initial depolarization(graded potential), which causes few voltage-gated Na+ channels to open. Na+ rushes into the cell and causes more channels to open, causing a large influx of Na+ to occur.
Term
What happens in the repolarizing phase?
Definition
with some delay, voltage-gated K+ channels begin to open(sometimes called delayed K+ channels) K+ ions flux out of the cell, which helps the membrane repolarize rapidly.
Term
what happens in hyperpolarization?
Definition
slowly the voltage-gated K+ channels close, Pk remains above resting levels, causing tansient membrane hyperpolarization (called after-hyperpolarization); voltage-gated Na+ channels being to reset back to closed states.
Term
what does the Na+/K+ pump do?
Definition
restores ionic composition of the ICF and ECF
Term
when are Action potentials produced?
Definition
they are produced when graded potentials reaching the "trigger zone" (the initial segment of the axon) depolarize the membrane to a critical level.
Term
True or false: can graded potentials be subthreshole or suprathreshold?
Definition
true. graded potentials can be subthreshold or suprathreshold
Term
what is a threshold stimulus?
Definition
when the initial stimulus is just large enough to evoke an action potential.
Term
what is a subthreshold stimuli and a subthreshold potential?
Definition
an initial stimuli that is too weak to produce an action potential; a subthreshold potential is what occurs after these weak depolarizations.
Term
What happens if the stimulus is larger than the threshold stimulus?
Definition
The action potential is the same as if it was caused by the threshold potential. (action potentials either occur maximally or not at all-allornone)
Term
what is an absolute refractory period?
Definition
during a period of action potential, a second stimulus, no matter how strong, will not produce a second action potential. (the channels cannot reopen unless closed, but the channels are already open or in the inactivated state)
Term
what is relative refractory period?
Definition
the period of time following absolute refractory period. during this time a second action potential can occur only if its a larger than threshold stimulus. some Na+ channels have returned to the closed state and can be re-opened. membrane is hyperpolarized because K+ channel is still open. larger magnitude of stimulus is needed to reach threshold.
Term
true or false? all action potential amplitudes are alike.
Definition
true, the amplitude of action potential is independent of stimulus intensity. although a strong stimuli can generate action potentials more often than weaker in a given time interval.
Term
where are action potentials generated?
Definition
at the axon hillock (junction between neuronal cell body and axon)--has a high concentration of voltage-gated Na+ channels
Term
what 2 things determine the speed at which action potential propogates along an axon?
Definition
axon diameter (larger>smaller) and axon myelination (myelinated>unmyelinated)
Term
true or false? in unmyelinated axons, action potential is not generated continuously along the axonal membrane.
Definition
false. in unmyelinated axons, action potentials are generated continuously along the axonal membrane (continuous conduction)
Term
what are the gaps called between myelin-forming cells on axons?
Definition
nodes of Ranvier
Term
is there a high density of voltage-gated Na+ channels found at the nodes of Ranvier?
Definition
yes. there is a high density
Term
what is it called when action potential jumps from node to node during propagation (nodes of Ranvier)
Definition
saltatory conduction
Term
what happens to someone with multiple sclerosis?
Definition
demyelination in the CNS. autoimmune disease.
Term
what happens when a person has Guillain Barre syndrome?
Definition
demyelination in the PNS. autoimmune disease. usually triggered by an actute infectious process.
Term
what is the purpose of type A fibers?
Definition
transmit sensory information on position, balance, and delicate touch & pressure sensation from skin. They also carry motor commands to skeletal muscle
Term
what is the purpose of type B and C fibers?
Definition
transmit sensory info on temperature, pain, general touch & pressure sensations, instructions to smooth & cardiac muscle, visceral sensation
Term
which types of fiber have myelination (A, B, C)
Definition
A, and B. type C does not have myelination.
Term
in which order of size do the fibers go (type A, B, C)
Definition
type A is the largest, then B, and type C is the smallest.
Term
what does lidocaine do?
Definition
blocks voltage-gated Na+ channels, used as a local anesthetic.
Term
what does tetrodotoxin and where is it found?
Definition
a neurotoxin found in the internal organs of puffer fish which blocks voltage-gated Na+ channels.
Term
what is a synapse?
Definition
a synapse is the junction that mediates info transfer from one neuron to the next or from a neuron to an effector cell
Term
what does a presynaptic neuron do?
Definition
a presynaptic neuron sends information toward the synapse
Term
what does a postsynaptic neuron do?
Definition
a postsynaptic neuron receives information
Term
what is the difference in function between an electrical synapse and a chemical synapse
Definition
in an electrical synapse, information is passed by electrical current (less common); in a chemical synapse, information is passed by chemicals called neurotransmitters. common in the nervous system.
Term
what are the 3 types of synapses?
Definition
axodendritic synapses, axosomatic synapses, and axoaxonal synapses
Term
where are axodendritic synapses?
Definition
between the axon and dendrite
Term
where are axosomatic synapses?
Definition
between the axon and cell body
Term
where are axoaxonal synapses?
Definition
between two axons
Term
what type of synapse corresponds to gap junctions in non-nervous tissue, is made of connexin molecules, has rapid transmission, is one-way or two-way, provides a simple means of synchronization, and is more abundant in embryotic NS than the adult
Definition
electrical synapses.
Term
what happens in a chemical synapse and what is its structure?
Definition
info is transmitted by chemical messengers called neurotransmitters (NTs) that diffuse across the synapse. the structure is
presynaptic axon terminal
synaptic cleft (~30-50nm)
postsynaptic membrane
Term
what is synaptic delay?
Definition
the time required for neurotransmitter release, diffusion across the synaptic cleft, and binding to receptors (usually lasts .3-.5ms) rate limiting step in neutral transmission because active potential much faster along axon (up to 150m/s)
Term
What chemical does a cholinergic synapse release? what breaks it down? and where is it found?
Definition
acetylcholine (ACh); acetylcholinesterase; neuromuscular junctions (NMJs) and many synapses in CNS and PNS
Term
the postsynaptic membrane responds to the release of neurotransmitters in one of two ways...
Definition
excitatory synapse, the postsynaptic membrane is depolarized, bringing the membrane potential closer to threshold; inhibitory synapse, the postsynaptic membrane is hyperpolarized, bringing the membrane potential farther away from threshold
Term
What is EPSP?
Definition
excitatory synapse and excitatory postsynaptic potential-at excitatory synapse, binding of neurotransmitters usually opens ligand-gated cation channels, Na+ influx is greater than K+ efflux through the channel, net effect is rapid depolarization. EPSP is graded potential. its function is to bring the membrane potential closer to threshold
Term
What is IPSP?
Definition
inhibitory synapse and inhibitory postsynaptic potential; at inhibitory synapses, binding of neurotransmitters opens Cl- or K+ channels, causes a flux of Cl- into, or K+ out of, the postsynaptic cell, which results in membrane hyperpolarization. graded potential. its function is to bring the membrane potential further away from threshold.
Term
These are graded potentials that spread decrementally from point of origin to axon hillock
Definition
EPSPs and IPSPs
Term
true or false: a single EPSP is sufficient to trigger action potential in a postsynaptic neuron.
Definition
false. a single EPSP is insufficient to trigger action potential in postsynaptic neurons. the magnitude becomes much smaller and cannot reach threshold at axon hillock. no ap is generated. in combination with other EPSPs at the same postsynaptic neuron, may trigger an AP
Term
what is synaptic integration?
Definition
a postsynaptic neuron receives thousands of synaptic inputs(convergence). some excitatory(EPSP) and some inhibitory(IPSP). postsynaptic neuron must integrate potentially conflicting incoming signals. temporal and spatial summation.
Term
what is temporal summation?
Definition
when two or more stimuli are applied in close succession, graded potential produced by the second stimulus sums on top of the first, producing composite potential to reach threshold. (both EPSP and IPSP can undergo temporal summation)
Term
what is spatial summation?
Definition
the two stimuli are received simultaneously at two close locations. graded potentials produced by the two separate events sum together to reach threshold. both EPSP and IPSP can undergo spatial summation
Term
what is the meaning of synaptic integration?
Definition
both EPSPs and IPSPs summate, EPSPs also summate with IPSPs. if EPSPs are dominate, membrane potential reaches threshold, and ap is generated. if IPSPs are dominate, membrane potential can't reach threshold, AP wont be generated. even if summation yields subthreshold depolarization, postsynaptic neuron is more easily excited by successive depolarizaiton-facilitation
Term
transmission of signals across synapses can be one of 2 things(modulation of synaptic transmission is the topic)
Definition
attenuated or enhanced via natural pre-wired mechanisms (presynaptic inhibition/facilitation) or via drug, toxin, poison effects
Term
what is presynaptic inhibition and what type of synapse is it?
Definition
release of neurotransmitter from one neuron is inhibited by the activity of another neuron; axoaxonic synapses;Decreases the amount of Ca2+ that enters presynaptic nerve terminal following AP
Term
what is presynaptic facilitation and what type of synapse is it?
Definition
release of neurotransmitters from one neuron is enhanced by the activity of another neuron;axoaxonic synapses; Increases the amount of Ca2+ that enters presynaptic nerve terminal following AP
Term
true or false: drug/toxin can't interfere with neurotransmitter synthesis
Definition
false. drug/toxin can interfere with NT synthesis
Term
Can drugs/toxins increase or block neurotransmitter release(not the same drug/toxin for both)
Definition
yes. increase(amphetamine) block(botulinum toxin)
Term
Can drugs/toxins prevent neurotransmitter inactivation?
Definition
yes
Term
can drugs/toxins prevent neurotransmitter reuptake?
Definition
yes
Term
can drugs/toxins both stimulate and prevent neurotransmitters from binding to the receptor?
Definition
yes. stimulate(agonist) prevent(antagonist)
Term
What classifications are neurotransmitters?
Definition
acetylcholine, biogenic amines(norepinephrine, dopamine, serotonin), amino acids(glutamate, GABA, glycine), neuropeptides(endorphine, tackykinins, substance P, etc.), purines(ATP), and dissolved gases(NO, CO, H2S)
Term
what are specific neurotransmitters of particular interest?
Definition
acetylchoine(ACh), norepinephrine(NE), glutamate, gamma aminobutyric acid (GABA), endorphine
Term
what are 2 types of acetylcholine receptors?
Definition
nicotinic and muscarinic
Term
explain nicotinic receptor for acetylcholine
Definition
NMJ in somatic NS, autonomic ganglia, CNS;excitatory
Term
explain muscarinic receptors for acetylcholine
Definition
visceral effectors and in CNS;either excitatory or inhibitory depending on receptor subtype
Term
What happens to the ACh level in CNS during alzheimer's disease?
Definition
the ACh level is significantly reduced
Term
where and by what is acetylcholine synthesized?
Definition
synthesized in presynaptic nerve terminal by choline acetyltransferase
Term
where and by what is acetylcholine degraded by?
Definition
degraded in synaptic cleft by acetylcholinesterase
Term
Where is norepinephrine (NE), what does it do, and is it excitatory or inhibitory?
Definition
Found in CNS and sympathetic NS; both excitatory and inhibitory, depending on receptor; in brain, functions in emotions and feelings of well being. decrease in NE (and dopamine) in certain brain region leads to depression; in periphery, NE stimulates heart and constricts blood vessels(cocaine blocks re-uptake of NE which leads to a "good-feeling", but also causes over stimulation of the heart (potential for lethal arrhythmias))
Term
what is Glutamate?
Definition
major excitatory neurotransmitter in CNS. often opens non-selective cation channels and produces EPSP, important in learning and memory. excessive release produces excitotoxicity and neuronal death, implicated in stroke
Term
what is GABA?
Definition
gamma aminobutyric acid; primary inhibitory neurotransmitter in CNS, opens Cl- channels and produces IPSP, anti-anxiety drugs of the bensodiazepine class (e.g. valium) works by binding to GABAa receptors and opening Cl- channels. this inhibits pathways that produce anxiety.
Term
what is glycine
Definition
primary inhibitory neurotransmitter in CNS. often opens Cl- channels and produces IPSP.
Term
what are neuropeptides?
Definition
divers groups of neurotransmitters. endorphins are natural opiates that inhibit pain, substance P mediated pain transmission.
Term
what are neurotransmitter receptors?
Definition
actions of neurotransmitters are mediated by their receptors. receptors are classified into 2 categories:channel-linked receptors; g protein-coupled receptors (GPCRs)
Term
what are channel-linked receptors?
Definition
chemically-gated ion channels, ligand-gated ion channels, or ionotropic receptors. mediate direct, fast synaptic responses(i.e. fast EPSP, fast IPSP)
Term
what are G-protein couple receptors?
Definition
linked to g proteins, cause the productin of intracellular second messengers(eg cAMP), the second messengers regulate ion channels, activate enzymes, or regulate gene function; synaptic responses mediated by GPCRs are slow (slow EPSP/IPSP); also called metabotropic receptors
Term
what is the difference between general and special senses?
Definition
general- conscious awareness of touch, pressure, vibration, proprioception, temperature, and pain; special-vision, hearing, smell, taste, equilibrium
Term
true or false: activation of any specific receptor will produce many types of sensation, no matter how it is activated.
Definition
false. activation of any specific type of receptor always produces one type of sensation, no matter how it is activated.
Term
what is the classification of sensory receptors by stimulus type?
Definition
Mechanoreceptors
sense touch, pressure, vibration, and stretch
Thermoreceptors
sense temperature change
Photoreceptors (in retina of the eye)
sense light
Chemoreceptors
respond to chemicals in solution (e.g. taste bud)
Nociceptors
respond to potential damaging stimuli that result in pain
e.g. extreme heat or cold, excessive pressure, and inflammatory chemicals
the potential damaging signals stimulate subtypes of thermo-, mechano- and chemoreceptors
Term
what is the classification of sensory receptors by location?
Definition
Exteroceptors
sensitive to stimuli arising outside the body
include receptors in the skin (e.g. touch, pressure, pain, temperature), and receptors for special senses (vision, hearing, equilibrium, smell, taste)
Interoceptors
also called visceroceptors
monitor the changes of internal environment
Include receptors that sense internal temperature, chemical changes, tissue stretch, etc.
Proprioceptors
respond to internal stimuli located at restricted regions (skeletal muscles, joints, tendons, ligaments, connective tissues coverings of bones and muscles)
monitor body movement
Term
what is the classification of sensory receptors by structural complexity?
Definition
Simple receptors
modified dendritic endings of sensory neurons
for general sensation
Complex receptors
sense organs (contain receptor cells, sensory neurons and other supporting cells)
for special sensation
Term
does stimulus energy need to be converted to action potential in order to be sent to the CNS?
Definition
yes. the stimulus energy does need to be converted to ap in order to be sent to the CNS
Term
what is transduction?
Definition
stimulus energy is converted into receptor potential(graded potential)
receptor potential triggers aps in sensory nerve fibers, which are sent to CNS for processing
Term
what is receptor potential?
Definition
a type of graded potential
Term
where are sensory neurons for general senses that are unipolar neurons are found?
Definition
dorsal root ganglia of spinal cord and sensory ganglia of cranial nerves.
Term
all APs are all or nothing, are sensory stimuli the same thing?
Definition
no, sensory stimuli vary in intensity.
Term
what is the definition of adaption?
Definition
reduction in response (number of APs) to the continuous presence of a stimulus; helps prevent sensory overload.
Term
what is the speed of phasic receptors in adaption?
Definition
fast adapting; generating burst of APs at the beginning and end of the stimulus. act to report changes in the internal or external environment. (e.g.) pacinian and meissner's corpluscles)
Term
what is the speed of tonic receptors in adaption?
Definition
slow adaption, generating APs during the stimulus. provide a sustained response. (e.g. nociceptors and most proprioceptors)
Term
what are your somatic senses?
Definition
touch, pressure, proprioception, temp, pain.
Term
where much afferent info reach to discriminate quality, intensity, and location of stimulus?
Definition
somatosensory cortex
Term
what are the locations of the 1st, 2nd, and 3rd order neurons?
Definition
1st-dorsal root ganglia/crandial ganglia; 2nd-spinal cord or brainstem/ axons across over to the opposite side of the CNS(decussation); 3rd-thalamus/conduct impulses to primary sensory cortex of the cerebral hemisphere
Term
how does somatosensory information travel to the CNS?
Definition
cranial nerves(head/some parts of neck) and spinal nerves(rest of body)
Term
what has 12 pairs, the CN1 and 2 are purely sensory and others are mixed, convey sensory info from the head and some areas of the neck
Definition
cranial nerves
Term
characteristics of spinal nerves(4)
Definition
31 pairs, all are mixed nerves, named according to which vertebra they are associated with, each supplies a specific body region.
Term
what is the definition of dermatomes?
Definition
the skin region innervated by a single spinal nerve
Term
what are the names of the 2 roots that merge to form the spinal nerve?
Definition
dorsal and ventral roots
Term
what is the function of a dorsal root in a spinal nerve?
Definition
it carries sensory info from peripheral sensory receptors to the spinal cord, cell bodies are in dorsal root ganglia
Term
what is the function of the ventral root in the spinal nerve?
Definition
motor neuron axons, cell bodys in ventral horn and lateral horn.
Term
what is gray matter in the spinal cord?
Definition
contains neuronal cell bodies; dorsal horn, ventral horn, and lateral horn
Term
what does white matter consist of?
Definition
myelinated and unmyelinated axons forming ascending and descending tracts.
Term
what are spinal roots?
Definition
dorsal and ventral roots
Term
what is contained in gray matter? (3 horns and what they contain)
Definition
dorsal horn(cell bodes of interneurons on which some afferent neurons synapse) lateral horn(cell bodies of autonomic pre-ganglionic efferent neurons) ventral horn(cell bodies of somatic efferent neurons)
Term
what are contained in white matter?
Definition
myelinated and unmyelinated axons, organized into columns or funiculi, each column consists of distinct bundles of axons called tracts, each tract composed of axons having similar origin, destination, and function
Term
what are ascending tracts composed of?
Definition
Composed of axons of 1st and/or 2nd order neurons carrying sensory info up to the primary somatosensory cortex. High degree of segregation of modalities into specific tracts!
Term
what are descending tracts composed of?
Definition
Composed of axons of motor neurons that carry signals from various parts of brain down spinal cord. Synapse on motor neurons in lateral & ventral horns of spinal cord . They are axons of “Upper motor neurons”.
Term
what is the definition of decussation?
Definition
crossing over (like somatosensory info in the brain from left to right or the opposite)
Term
what are 3 major ascending pathways on each side of the spinal cord?
Definition
Dorsal column pathway (fasciculus gracilis, fasiculus cuneatus)
Spinothalamic tracts (anterolateral pathway)
Spinocerebellar tracts (anterior and posterior)
Term
what sensations does the dorsal column pathway sense and what are the names of the tracts?
Definition
fine touch(discriminative touch), pressure, vibration, conscious proprioception; fasciculus gracilis(transmits sensation from lower limbs and inferior body trunk) and fasciculus cuneatus(transmits sensation from upper limbs, upper trunk and neck;not present in spinal cord below T6)
Term
no idea how to make a question :(
Definition
Central axons of 1st order neurons enter spinal cord and ascend in dorsal column (fasciculus cuneatus and fasciculus gracilis) on same side without synapsing.
These axons synapse with 2nd order neurons in nucleus gracilis and nucleus cuneatus in Medulla oblongata of the brain stem.
Axons of 2nd order neurons cross to opposite side (decussation), ascend in medial lemniscal tract, and synapse with 3rd order neurons in thalamus.
Thalamic neurons project to primary somatosensory cortex.
Term
where can you find the fasciculus cuneatus in the spine?
Definition
T6 and above
Term
where can you find the fasciculus gracilis in the spine?
Definition
everywhere
Term
what senses does the spinothalamic (anterolateral) pathway sense and in what tracts is it found?
Definition
anterior (ventral) spinothalamic tract(crude touch and pressure) and lateral spinothalamic tract(pain and temp)
Term
how does the lateral spinothalamic tract work?
Definition
Central axons of 1st order neurons enter spinal cord and synapse with 2nd order neurons (interneurons in dorsal horn) at the same level.
Axons of 2nd order neurons cross to opposite side (decussation), and ascend in lateral spinothalamic tract.
Axons of 2nd order neurons synapse with 3rd order neurons in thalamus.
Thalamic neurons project axons to primary somatosensory cortex
Term
how does the anterior spinothalamic tract work?
Definition
Central axons of 1st order neurons enter spinal cord and synapse with 2nd order neurons (interneurons in dorsal horn) at the same level.
Axons of 2nd order neurons cross to opposite side, and ascend in anterior spinothalamic tract
Term
what are the tracts and what is the function of the spinocerebellar pathway?
Definition
Tracts
Anterior spinocerebellar tract
Posterior spinocerebellar tract
Function:
Convey subconscious proprioceptive information about muscle or tendon to the cerebellum.
Do not contribute to conscious sensation.
Info is used to coordinate skeletal muscle activity
Remember that the conscious proprioception is mediated by the dorsal column pathway.
Transmits subconscious proprioceptive info from trunk and lower limb only
Posterior spinocerebellar pathway (does NOT decussate)
Anterior spinocerebellar pathway (decussate immediately in S.C.)
Fibers will cross back in brainstem
Send to the same side of cerebellum
No 3rd order neurons
Term
What is phantom limb pain?
Definition
pain experienced in amputated limb, may persist or recur, caused by activity in sensory neurons or interneurons in spinothalamic pathway, neurons involved once monitored conditions in the intact limb
Term
what is the convergence theory (or referred pain)?
Definition
pain felt in uninjured part of body, but actually originates in another part of the body (most commonly sensed in skin when internal organ affected) mechanism not fully understood.
Term
where do motor neurons from the CNS go?
Definition
to the somatic and autonomic nervous system.
Term
what 2 motor neurons does the somatic motor pathways involve?
Definition
upper(located in the brain, synapses on lower, facilitates or inhibits lower motor neuron) lower(located in ventral horn of spinal cord, innervates skeletal muscle, activation triggers contraction in innervated muscle, only the axon of lower extends outside CNS, damage to lower eliminates voluntary and reflex control over the innervated motor unit
Term
what are the 2 major descending pathways?
Definition
pyramidal system(direct system-ventral(anterior) tract and lateral corticospinal tract) extrapyramidal system(indirect system)
Term
what is this called?
Originate with the pyramidal neurons (upper motor neurons) in the primary motor cortex
Impulses are sent through the corticospinal tracts and synapse with lower motor neurons in ventral horn of spinal cord
Stimulation of lower motor neurons activates skeletal muscles
regulates fast and fine movements (voluntary motor control)
what decussates in pyramids of medulla?
what decussates at spinal cord?
Definition
pyramidal system (corticospinal pathway);Lateral corticospinal tracts;Ventral (Anterior) corticospinal tracts
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