Term
| lipid portion of the cell membrane |
|
Definition
phospholipid, cholesterol, and glycolipid
these make the membrane highly permeable to lipid soluble substances (gases, O2, CO2) |
|
|
Term
| protein portion of the cell membrane |
|
Definition
| structural proteins, transporters, enzymes, hormone receptors, antigens, and ion/water channels |
|
|
Term
| movement in the lipid bilayer |
|
Definition
phospholipid molecule rotate and the fatty acid chains bend
rapid lateral diffusion occurs, but phospholipids rarely cross to the other half of the bilayer |
|
|
Term
| can the lipid composition of the 2 halves of the membrane be different? |
|
Definition
|
|
Term
| intrinsic membrane proteins |
|
Definition
ion/water channels, transporters, hormone receptors, cell surface antigens
usually span the bilayer completely (alpha helices with hydrophilic AA sidechains with the helix) |
|
|
Term
| extrinsic membrane proteins |
|
Definition
don't penetrate bilayer (can be located on either the cytosolic or extracellular side)
attachment occurs via weak ionic interactions to membrane phospholipids or regions of intrinsic membrane proteins |
|
|
Term
| carbohydrates on the extracellular surface |
|
Definition
| glycolipids (10% of lipids), glycoproteins (extrinsic), monosaccharides (help determine receptor specificity) |
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Term
|
Definition
substance is transported down an electrochemical gradient & doesn't not require energy
simple diffusion and facilitated diffusion |
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Term
|
Definition
substance is transported against an electrochemical gradient and requires the use of metabolic energy (ATP)
primary active transport and secondary active transport |
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Term
|
Definition
| difference between 2 quantities/distance (length) separating them |
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|
Term
|
Definition
binding sites of the carrier proteins are all occupied with solute and no new solute can be transported
simple diffusion cannot saturate |
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|
Term
|
Definition
binding of solute to its transporter or carrier molecule is highly stereospecific (D-glucose but not L-glucose gets transported across the intestine wall)
simple diffusion doesn't distinguish among isomers |
|
|
Term
|
Definition
| structurally similar solutes can compete for the same transporter by binding to the same site (D-galactose vs. D-glucose) |
|
|
Term
|
Definition
rate of net diffusion of solute molecules
depends on concentration, thickness of membrane, lipid solubility, diffusion coefficient, permeability of solute |
|
|
Term
|
Definition
| concentration difference across a membrane (bigger the [] gradient, the larger the flux) |
|
|
Term
| facilitated diffusion differs from simple diffusion because... |
|
Definition
allows higher rates of solute transport than simple diffusion at the typically low solute concentrations
it's saturable
it's solute specific
it can be inhibited by substances that compete with the solute for a carrier or channel |
|
|
Term
| ion channels differ from facilitated diffusion because... |
|
Definition
driven by an electrochemical gradient
regulated - ion movement only occurs when channels are open
much faster - 100 million ions/sec
involved in electrical signaling/secretory processes |
|
|
Term
|
Definition
directly coupled to an energy producing reaction
one of the most studied is the Na+/K+ ATPase/sodium pump |
|
|
Term
| Na+/K+ ATPase/sodium pump |
|
Definition
| exchanges 3 Na+ for 2 K+ ions (electrogenic) |
|
|
Term
| inhibitors of the Na+/K+ ATPase/sodium pump |
|
Definition
| cardiac glycosides: ouabain and digoxin |
|
|
Term
|
Definition
found in membranes of the sarcoplasmic reticulum, mitochondria, and some plasmalemma membranes
it removes calcium from the cytoplasm |
|
|
Term
|
Definition
| found in gastric parietal cells of stomach and cells of the tubule of the kidney |
|
|
Term
| secondary active transport |
|
Definition
| movement of solute against the gradient is driven by the energy stored in the electrochemical gradient that exists for Na+ ions, so it depends on primary active transport |
|
|
Term
|
Definition
| all solutes move in the same direction across the cell membrane |
|
|
Term
| antiport/countertransport |
|
Definition
| solute moves in opposite direction to sodium across the cell membrane, against it's own [] gradient |
|
|
Term
|
Definition
water moves rapidly across membranes through channels called aquaporins
occurs due to a difference in [] of particles of solute that is unable to cross the membrane |
|
|
Term
|
Definition
| expresses the number of solute particles present in solution |
|
|
Term
| resting membrane potential |
|
Definition
| electrical potential difference across a membrane (the inside of a cell is 65-75 mV negative to the outside under resting conditions |
|
|
Term
|
Definition
a membrane that maintains separation of charges
hyperpolarized: more negative than RMP
depolarizzed: less negative than RMP |
|
|
Term
|
Definition
electrical potential at which there is no longer any net movement of K+ down its [] gradient
Ek = (RTln/zF)([K]o/[K]i) |
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|
Term
|
Definition
| critical value of the membrane potential or the level of depolarization at which an impulse is initiated |
|
|
Term
|
Definition
| rapid depolarization (reduction) in membrane potential from resting values towards zero |
|
|
Term
|
Definition
| reversal of the membrane potential during the peak of the AP |
|
|
Term
|
Definition
| reduction of membrane potential from resting value towards zero |
|
|
Term
|
Definition
| return of the AP towards RMP |
|
|
Term
|
Definition
| increase in membrane potential from RMP |
|
|
Term
| absolute refractory period |
|
Definition
| time following an AP during which a stimulus cannot elicit a second AP |
|
|
Term
| relative refractory period |
|
Definition
| time during which only an extra strong stimulus (much larger than normally required) can trigger an AP |
|
|
Term
|
Definition
| conduction velocity increases with the diameter of the axon |
|
|
Term
| action potentials depend on... |
|
Definition
voltage-gated, Na+/K+ selective transmembrane ion channels
assymetric chemical gradients for Na+/K+ ions across the nerve membrane (established by Na+/K+ ATPase)
negative RMP which provides a huge electrical gradient for Na+ movement |
|
|
Term
| AP velocity in unmyelinated fibers |
|
Definition
| velocity is proportional to the square root of the axon diameter in unmyelinated fibers |
|
|
Term
|
Definition
| transmitter is stored within these vesicles, located in the terminal bouton |
|
|
Term
| calcium ions are removed from the cell by... |
|
Definition
sodium/calcium exchange
active transport across the plasma membrane or into the SR
uptake by the mitochondria or calcium-binding proteins |
|
|
Term
|
Definition
receptors that respond to their nerve's own transmitters
when activated they reduce the amount of transmitter released in response to APs
work by reducing the amount of Ca2+ that enters the nerve terminal in response to depolarization |
|
|
Term
|
Definition
transmitter released from one nerve terminal acts on its own receptors located on a target terminal to increase/decrease Ca2+ entry through voltage-gated ion channels
widely used in CNS to modify the evoked release of transmitter from targeted nerves |
|
|
Term
|
Definition
| where all receptors are located |
|
|
Term
|
Definition
| hundreds of vesicles attached to cytoskeleton and some to the membrane that overlays the innervated post-synaptic membrane |
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|
Term
|
Definition
| blocks the release of transmitter at the skeletal neuromuscular junction and causes muscle paralysis |
|
|
Term
|
Definition
| blocks the release of transmitter from inhibitory neurons in the CNS, leading to over excitation of muscles or "tetanus" |
|
|
Term
|
Definition
| alpha latrotoxin - causes a massive fusion of vesicles with the nerve terminal and release of transmitter. the pool of vesicles is depleted and nerve terminal becomes enlarged |
|
|
Term
|
Definition
| major excitatory transmitter in CNS |
|
|
Term
|
Definition
| major inhibitory transmitter in CNS |
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|
Term
|
Definition
| inhibitory transmitter in spinal cord & brainstem |
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|
Term
|
Definition
| CNS & PNS (skeletal NMJ & autonomic NS) |
|
|
Term
|
Definition
| CNS & PNS (sympathetic neuroeffector junction) |
|
|
Term
|
Definition
| CNS & PNS (enteric nervous system) |
|
|
Term
|
Definition
|
|
Term
|
Definition
| stored in large dense cored vesicles (LDCV) usually occur along with small synpatic vesicles that store low molecular weight transmitters |
|
|
Term
| metabolic breakdown of transmitter |
|
Definition
| transmitter is inactivated and removed from the synaptic cleft by metabolic breakdown with acetylcholine and peptides |
|
|
Term
| macromolecules involved with transmitters |
|
Definition
| macromolecules are moved down the axon to the nerve terminal by fast axonal transport that requires ATP |
|
|
Term
|
Definition
| synthesized in precursor form in the cell body and transferred by fast axonal transport to the terminal in the LDCV |
|
|
Term
| fast chemical signaling (ionotropic) |
|
Definition
| transmitter interacts with receptors that are part of a trans membrane ion channel (ionotropic signaling) |
|
|
Term
|
Definition
| transmitter interacts with G-protein coupled receptors (metabotropic signaling) |
|
|
Term
|
Definition
| presynaptic terminal lies immediately above the postsynaptic density of the postsynaptic neuron where receptors are clustered together. Signaling is fast, precise, and reliable. Such synapses use ionotropic signaling and convey info from one part of the nervous system to another |
|
|
Term
| diffuse ("en passant") synapses |
|
Definition
| consist of highly branched networks of beaded fibers which pass by the postsynaptic neurons at a variable distance. Such synapses typically use G-protein coupled signaling mechanisms. Signaling is slow and modulates fast isotropic signaling |
|
|
Term
|
Definition
| bind chemical signaling molecules with high specificity and high affinity (ligands) |
|
|
Term
|
Definition
| ligand that produces a response in the target cell when it binds to the receptor |
|
|
Term
|
Definition
| ligand that binds with high affinity to the receptor but doesn't produce a response |
|
|
Term
|
Definition
all receptors are transducers
they convert a chemical signal into a cellular response |
|
|
Term
| postsynaptic potential (PSP) |
|
Definition
| a trans-membrane voltage change that is brought about by an ionic current that flows through the opened channels |
|
|
Term
|
Definition
| acetylcholine and L-glutamate |
|
|
Term
|
Definition
|
|
Term
|
Definition
excitatory post synaptic potential
produced by an inward positive ionic current (sodium) |
|
|
Term
|
Definition
inhibitory postsynaptic potential
produced by an inward movement of negatively charged ions (chloride) driving the membrane toward hyperpolarization
make a neuron more difficult to excite |
|
|
Term
|
Definition
| the ionic current that flows through a single ion channel per unit time |
|
|
Term
|
Definition
| sum of all single channel currents flowing through the membrane in response to the released transmitter |
|
|
Term
| unitary postsynaptic potential |
|
Definition
| change in membrane potential produced by the synaptic current that flows when transmitter is released from a single synaptic vesicle. When multiple packets are released, they add up and produce either a EPSP or IPSP (depending on the transmitter) |
|
|
Term
|
Definition
L-glutamate acts at AMPA receptors found throughout the CNS, which allow Na+ and K+ ions to pass and set up fast EPSPs in response to released L-glutamate
Mediate fast ionotropic signaling, conveying info from one part of the CNS to the other |
|
|
Term
|
Definition
| occur together with AMPA receptors and have a special role in synaptic transmission. Blocked by Mg ions at RMP, but are opened by the combined action of L-glutamate binding to the receptors and the ongoing depolarization of the presynaptic neuron by high frequency activation of adj AMPA receptors |
|
|
Term
|
Definition
at many central synapses, prolonged neuronal depolarization produces only a brief burst of APs and AP firing stops even though depolarization persists
this arises b/c prolonged depolarization of neurons also opens certain classes of K+ channels which prevent AP firing |
|
|
Term
|
Definition
| transmitters that allows AP firing to continue for as long as the neuron is depolarized. It blocks the depolarization-induced changes in the postsynaptic neuron responsible for accommodation |
|
|
Term
|
Definition
| when G-protein coupled signaling changes the effectiveness of fast ionotropic signaling |
|
|
Term
|
Definition
binds ligand-gated ion channels
binds nicotinic cholinergic receptors, usually at the skeletal NMJ
causes mm. paralysis |
|
|
Term
|
Definition
binds ligand-gated ion channels
blocks the action of the CNS inhibitory transmitter glycine
causes convulsions |
|
|
Term
| G-protein coupled receptor signaling involves 4 things... |
|
Definition
1. extracellular signal/first messenger
2. a receptor in the target cell plasma membrane that binds the first messenger
3. heterotrimetric GTP-binding protein
4. an effector mechanism that produces an intracellular signal/second messenger |
|
|
Term
|
Definition
heterodimeric complexes made of alpha, beta, and gamma subunits
bind guanine nucleotides and serve as a link between G-protein coupled receptors and their target effectors |
|
|
Term
| removal of Ca2+ from the cell |
|
Definition
-active transport (Ca2+ ATPase)
-Na+/Ca2+ exchange (antiport)
-storage in the ER
-mitochondrial uptake
-Ca2+ binding proteins in the cytosol |
|
|
Term
| transmitters and their G-protein coupled receptors |
|
Definition
acetylcholine - muscarinic (autonomic NS; CNS)
norepinephrine - alpha & beta (autonomic NS; CNS)
dopamine - D1 and D2 (striatum)
serotonin (5-HT) - 5HT1, 5HT2, 5HT4-7 (pain, GI, and CNS function) |
|
|
Term
|
Definition
| when receptors are exposed to a high concentration of agonist (transmitter) for an extended period of time and they very quickly become unresponsive |
|
|
Term
| desensitization of ligand-gated ion channels |
|
Definition
| conformational change occurs to the receptor ionophore that makes it unresponsive to the agonist |
|
|
Term
| desensitization of G-protein coupled receptors |
|
Definition
| receptors are internalized so that the number present in the plasma membrane is reduced or down regulated |
|
|
Term
| long term potentiation (LTP) |
|
Definition
| when central synapses are activated strongly, the number of receptors expressed in the postsynaptic membrane may be increased or up regulated and hence transmission strengthened (and it lasts for hours/days) |
|
|
Term
| long term depression (LTD) |
|
Definition
| weakly activated central synapses may show a reduced expression or down regulation of receptors that also persists for hours or days |
|
|
Term
|
Definition
| specialized structures that respond to specific changes in the environment |
|
|
Term
|
Definition
| convey info about the external environment |
|
|
Term
|
Definition
| convey info about the internal environment |
|
|
Term
|
Definition
differentiates one type of sensation (hearing) from others
there are qualitative and quantitative differences in different modalities |
|
|
Term
|
Definition
| a single sensory nerve and the receptor or receptors to which it responds |
|
|
Term
|
Definition
| the area of response for the receptor in each separate sensory unit |
|
|
Term
|
Definition
| how receptors function by converting energy of the stimulus into electrical signals in the nervous system |
|
|
Term
|
Definition
the specific stimulus that normally activates a particular type of sensory receptor
produces a graded electrical potential in the receptor |
|
|
Term
|
Definition
| when the graded potential of the adequate stimulus is the sensory nerve ending itself |
|
|
Term
|
Definition
| when the graded potential of the adequate stimulus is non-neural |
|
|
Term
|
Definition
a somatic sensory receptor that responds to touch and pressure and consists of a free nerve surrounded by layers of connective tissue
it is a phasic receptor (if compression is maintained, the nerve terminals eventually return to their original state) |
|
|
Term
|
Definition
| fire for as long as the stimulus is applied, or show only very slow adaptation (pain receptors) |
|
|
Term
| intensity of a stimulus is encoded by... |
|
Definition
the frequency of firing of nerve APs in individual sensory nerves
(frequency code of stimulus intensity) |
|
|
Term
| population code of stimulus intensity |
|
Definition
| how a stronger stimulus will produce compression of a larger area (i.e. more pacinian corpuscles will respond and more sensory fibers will be activated) |
|
|
Term
| labeled-line code of stimulus |
|
Definition
| the mechanism for coding the type of stimulus that a receptor detects |
|
|
Term
|
Definition
how well different stimuli can be discriminated
depends on the size and placement of receptive fields relative to one another |
|
|
Term
| at the first order neuron... |
|
Definition
| the receptive field is the area on the skin where applied pressure excites the neuron |
|
|
Term
| at the second order neuron... |
|
Definition
| the receptive field changes shape, it now has an excitatory center and an inhibitory surround (produced by activation of adj receptors) |
|
|
Term
| at the third order neuron... |
|
Definition
| a similar receptive field is obtained. It persists at the first cortical synapse , but after further processing it leads to summation of annular receptive fields and generation of bars of excitation and inhibition |
|
|
Term
|
Definition
| very sensitive to light touch; nerve ending wrapped around follicle activated when hair bends |
|
|
Term
|
Definition
| sensitive to light touch; located in the dermis; a single fiber innervates many discs |
|
|
Term
|
Definition
| occurs in hairless skin such as soles of feet, palms, lips, etc |
|
|
Term
| radidly adapting receptors |
|
Definition
hair follicle receptor
Merkels disk
Pacinian corpuscle
Meissner's corpuscle |
|
|
Term
|
Definition
responds to stretch of skin
slowly adapting receptor |
|
|
Term
|
Definition
| sense mechanical stimulation of the body's surface, involved in sensing touch, pressure, and vibration |
|
|
Term
|
Definition
sense changes in temperature of the body's surface
(below and above 30 degrees C) |
|
|
Term
|
Definition
pain receptors
high threshold receptors activated by noxious stimuli; most numerous in the skin, but found elsewhere in body as well |
|
|
Term
|
Definition
| detect limb movements and position |
|
|
Term
|
Definition
| respond to high intensity mechanical, thermal, or chemical stimuli |
|
|
Term
| dorsal column-medial lemniscus pathway |
|
Definition
convey sensory info to the brain that provides very precise sensations concerning pressure, vibration, and proprioception
crosses over to the contralateral side in the medulla |
|
|
Term
|
Definition
convey info on temperature, touch, and itch
crosses over in the spinal cord |
|
|
Term
|
Definition
due to direct activation of receptors sensitive to noxious stimuli in the skin or soft tissue
usually arises from damaged tissue and inflammation |
|
|
Term
|
Definition
due to direct injury to peripheral or central nerves
burning sensation
may occur after a bout of shingles or after severing sensory nerves |
|
|
Term
| classes of peripheral nociceptors |
|
Definition
| thermal, mechanical, polymodal, visceral |
|
|
Term
|
Definition
| occurs within about 0.1s and is transmitted through Ad fibers and is generally produced by mechanical or thermal stimuli |
|
|
Term
|
Definition
occurs after a second or more
due to activation of polymodal nociceptors and their slowly conducting, small diameter, unmyelinated C fibers |
|
|
Term
| non-noxious afferent nerves |
|
Definition
their activation significantly reduces pain
large diameter, low threshold sensory fibers |
|
|
Term
|
Definition
normal stimuli are painful (stroking a sunburn with a feather)
pain only occurs with a stimulus |
|
|
Term
|
Definition
tremendous hypersensitivity to painful stimuli
mediated via peripheral or central mechanisms
involves tissue injury |
|
|
Term
|
Definition
1. second order projection neurons in spinal cord are activated by both nociceptive and non-nociceptive afferents
2. afferent inputs also influence firing of inhibitory interneuron which innervates the second order projection neuron (noci afferents = inhibit non-noci = excite)
3. intensity of pain depends on balance of activity btw noci and non-noci afferents
4. TENS |
|
|
Term
| transcutaneous electrical stimulation (TENS) |
|
Definition
| direct electrical stimulation of large diameter afferent fibers that overlap an area of injury and pain is used to relieve intractable pain |
|
|
Term
| Enkephalin-containing interneurons |
|
Definition
inhibit the release of substance P from nociceptor afferents
Enkephalin released from the interneuron acts at presynaptic receptors on the terminals of nociceptor afferents to inhibit release of substance P (presynaptic inhibition) |
|
|
Term
|
Definition
| consists of sudden severe pains, usually on one side of the face in the jaw region |
|
|
Term
|
Definition
| determines the diameter of the pupil and hence the amount of light that falls on the retina |
|
|
Term
|
Definition
| bend light rays and focus them on a retina to give an inverted image, they form a compound convex lens |
|
|
Term
|
Definition
| the way the focal length of the lens can be adjusted for near or distant vision |
|
|
Term
|
Definition
loss of elasticity of the lens with age
increases the distance for the near point of accommodation |
|
|
Term
|
Definition
responds to light intensity
it contains photoreceptors that absorb photons
fovea only contains cones (color vision)
peripheral vision is mediated by both rods and cones (rods = night vision) |
|
|
Term
|
Definition
fluid in the anterior chamber of the eye
turns over rapidly
provides nutrients for the lens and cornea |
|
|
Term
|
Definition
| gel that provides structure to the eyeball |
|
|
Term
|
Definition
| improper drainage of the aqueous humor that raises pressure throughout the eyeball and can damage the optic nerve |
|
|
Term
|
Definition
lie on the innermost layer of the retina, so light has to pass through the layers of nerve cells to reach the retina
have an outer segment where the signal transduction takes place and an inner segment which synthesizes the photopigments required for the detection of light |
|
|
Term
|
Definition
cylindrical in shape
found in the entire retina except the fovea
absorb a broad range of wavelengths with very high sensitivity
converge onto many bipolar cells which then converge on many ganglion cells producing a large receptive field |
|
|
Term
|
Definition
conical in shape
concentrated in the fovea; occur at very low density outside the fovea
sensitive to color
foveal cones synapse on single bipolar cells which then synapse on single ganglion cells (small receptive field, but images with a high resolution) |
|
|
Term
|
Definition
a depolarizing current carried by photoreceptor cells in the absence of any light
produced by the inward movement of Na+ ions through cation selective channels located in the membrane of the outer segment of the photoreceptor |
|
|
Term
|
Definition
absorbs a photon and changes its conformation; transducin becomes activated and activates phosphodiesterase (causes a decrease in cGMP levels that closes cation selective channels in rod cell membrane)
photoreceptor cell becomes hyperpolarized and transmitter release is reduced |
|
|
Term
| T/F photoreceptors are always hyperpolarized by light |
|
Definition
TRUE
this reduces their neurotransmitter output |
|
|
Term
|
Definition
two types exist:
1. responds to the decrease in photoreceptor transmitter release with a depolarization and release of transmitter
2. responds with a hyperpolarization and reduced transmitter release |
|
|
Term
| organization of cells in the retina |
|
Definition
| photoreceptors are connected to bipolar cells which in turn project to ganglion cells. Axons of ganglion cells form the optic nerve which conveys visual stimuli to the brain |
|
|
Term
|
Definition
fire tonically; their firing rate is altered by bipolar cell input
(depolarizing cells = increase in firing, hyperpolarizing cells = decrease in firing)
horizontal and amacrine cells also effect the firing rate of ganglion cells |
|
|
Term
|
Definition
areas of retina that excite or inhibit a retinal ganglion cell = receptive field for that ganglion
sometimes the center is inhibitory and the outside is excitatory or vice versa |
|
|
Term
|
Definition
|
|
Term
|
Definition
| made up of ganglion cell axons and projects through the "blind spot" of the retina and goes to the lateral geniculate nucleus of the thalamus |
|
|
Term
|
Definition
| arrangements of cells in the visual cortex that respond to light from the right or left eye |
|
|
Term
|
Definition
| three types of cones all have different visual pigments that absorb blue, red, or green light |
|
|
Term
|
Definition
| respond to color and convey inputs to parvocellular neurons within the lateral geniculate |
|
|
Term
| large retinal ganglion cells |
|
Definition
| process info from cones that is not selective for color but for shape and movement. They convey inputs to magnocellular neurons in the lateral geniculate |
|
|
Term
| 3 receptive fields for color |
|
Definition
broad band
single opponent cells
double opponent cells |
|
|
Term
|
Definition
| loss of near vision due to hardening of the lens with age (loss of accommodation) |
|
|
Term
|
Definition
nearsightedness
light falls in front of the retina b/c the eyeball is longer than normal or due to defects in the cornea/lens |
|
|
Term
|
Definition
| image falls behind the retina due to a shorter than normal eyeball |
|
|
Term
|
Definition
| unit of sound intensity measured as pressure |
|
|
Term
|
Definition
| funnels sound to middle ear |
|
|
Term
|
Definition
tympanic membrane vibrates due to sound waves
ossicles transmit vibrations to the oval window
oval window vibrates with movement of ossicles and transmits sound to the cochlear fluid |
|
|
Term
|
Definition
| contains cochlea, basilar membrane, audio receptor hair cells, stereocilia, and the round window |
|
|
Term
|
Definition
| fluid filled spiral tube wound up into a cone shape |
|
|
Term
|
Definition
| flexible structure extending the length of the cochlea that vibrates with oochlear fluid in response to sound |
|
|
Term
|
Definition
| auditory receptor cells that are attached to the tectorial membrane via stereocilia |
|
|
Term
|
Definition
attach hair cells to the tectorial membrane and sit on the basilar membrane
bend as basilar membrane vibrates which causes ion channels to open |
|
|
Term
|
Definition
| dissipates the power of the vibration thereby preventing any residual effect from interfering with incoming signals |
|
|
Term
|
Definition
| depends on the specific part of the basilar membrane that vibrates in response to incoming sound stimulus |
|
|
Term
|
Definition
| auditory nerve fibers innervating hair cells near the base of the cochlea respond to high frequencies and those supplying hair cells at the apex respond to low frequencies |
|
|
Term
|
Definition
| what auditory nerve cells will respond to most readily (the lowest intensity frequency that they will respond to |
|
|
Term
| sound is localized by the CNS by: |
|
Definition
1. the delay btw sound arriving in one ear versus the other (interaural time delay)
2. differences in intensity of sound from a single source perceived by the left and right ears due to greater attenuation of sound on one side of the head than the other
3. map in the brain for interaural time differences |
|
|
Term
|
Definition
| arises from inadequate transmission of sound from the outer and middle ear to the inner ear. Causes are many and include damage to tympanic membrane, inflammation of the middle ear and damage to the ossicles |
|
|
Term
| sensorineural hearing loss |
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Definition
| produced by damage to the organs of the inner ear to the cochlear nerve fibers or the hair cells. Can be caused by infectious agents, bone disease, or trauma (loud noise) |
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Term
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Definition
| damage to or defects in the auditory pathways can produce profound loss of hearing |
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Term
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Definition
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Term
| ampullae of semicircular canals |
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Definition
superior, inferior, horizontal
detect angular acceleration in one of the three planes due to bending of stereocilia |
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Term
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Definition
| largest of the stereocilia |
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Term
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Definition
| calcium carbonate crystals within a membrane of the utricle and saccule where stereocilia are found |
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Term
| vestibular-ocular reflexes |
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Definition
| allow the eyes to fix on a point when the head rotates. |
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Term
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Definition
| The eyes move slowly in opposite direction to the head and when they have moved as far as possible they move rapidly in the direction of head rotation to fix on a new point of reference |
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Term
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Definition
1. first order sensory neurons of cranial nerves project to the gustatory nucleus in the brain stem . Second order neurons convey taste signals to the VPM nucleus of thalamus while 3rd order neurons relay taste info to the cerebral cortex
2. taste also conveyed via the limbic system to the hypothalamus (gives emotional qualities to taste) |
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Term
| seven general odors humans detect |
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Definition
| camphor, musk, floral, peppermint, ethereal, pungent, and putrid |
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Term
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Definition
| errors are detected and corrected during execution of the movement; useful for slowly executed movements |
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Term
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Definition
| movements or entire sequences of movements are preprogrammed by extensive practice and can be mentally rehearsed; they can be re-enacted flawlessly with appropriate visual, proprioceptive and vestibular inputs that must anticipate the movement |
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Term
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Definition
| comprise most of a muscle and generate mm movement. They are large, and have a large range in length. Stimulated to contract by the wide diameter alpha motor neurons |
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Term
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Definition
| small and arranged in parallel to the extrafusal fibers. They are sensory organs designed to detect static mm length and changes in mm length. They are stimulated to contract by gamma motor neurons |
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Term
| fast skeletal mm. characteristics |
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Definition
fast twitch - rapid contraction
white - little myoglobulin
anaerobic
fatigues rapidly
physical activity - intense, brief, precise contractions |
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Term
| slow skeletal mm. characteristics |
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Definition
slow twitch - slow, sustained contraction
red - lots of myoglobin
aerobic
resistant to fatigue
posture - slow, tonic contractions |
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Term
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Definition
consists of a single motor neuron and the mm fibers it innervates
the basic functional unit that produces contraction of individual mm fibers |
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Term
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Definition
| number of mm fibers innervated by a single motor neuron varies markedly depending on the mm |
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Term
| topographical organization of motor neurons |
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Definition
neurons innervating axial mm are located medially while neurons innervating distal mm are located laterally
neurons supplying flexor mm lie dorsal to those supplying extensors |
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Term
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Definition
| the group of motor neurons that innervate a single mm |
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Term
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Definition
| convey info about mm length, force, and speed of contraction in order to have coordinated movement |
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Term
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Definition
lie in parallel to the extrafusal fibers (stretch receptors) signal existing muscle length (static receptors) and changes in mm length (dynamic receptors)
found throughout mm, but are most concentrated in mm that execute fine movements
consist of intrafusal mm fibers wrapped in connective tissue |
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Term
| two types of intrafusal fibers found in muscle spindles |
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Definition
nuclear chain fibers
nuclear bag fibers |
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Term
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Definition
contain large numbers of nuclei clustered around a central region
very sensitive to stretch and provide info about rate of change of mm length (dynamic) |
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Term
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Definition
have their nuclei arranged one after another like a chain
provide info about mm length (static) |
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Term
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Definition
| are in series with extrafusal fibers and signal mm tension or force |
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Term
| feedback control of muscle length |
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Definition
muscle spindles oppose changes in mm length over a spinal reflex
alpha motor neurons in spinal cord cause muscle to contract |
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Term
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Definition
the resistance of a muscle to passive movement
tonic firing of static muscle spindles at a particular muscle length produces a reflex activation of the motor neuron pool producing normal tension |
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Term
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Definition
| innervate the contractile regions at either end of the muscle spindle and, when activated, cause the intrafusal fiber to shorten and stretch the spindle |
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Term
| stretch (myotatic) reflex |
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Definition
simplest reflex, only uses 2 neurons (knee jerk)
muscle spindles of the quads stretch and the muscle contracts while hamstrings are inhibited |
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Term
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Definition
| when the antagonist mm during a reflex are inhibited (quads contract, hamstrings are inhibited) |
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Term
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Definition
mediated by the golgi tendon organ and involves 2 synapses
activated when the tendon organ detects excessive force on a mm and activates antagonistic mm so that the mm in question will relax |
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Term
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Definition
| occurs in response to stimulation of nociceptors in the skin (experiencing a painful stimulus on one foot results in a rapid withdrawal of that foot away from the stimulus - activation of flexors and inhibition of extensors) |
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Term
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Definition
| when a flexor withdrawal reflex occurs (with the foot), the foot on the opposite side of the body must balance the body while the other foot is moved away from a painful stimulus (extensors are activated and flexors inhibited in the unaffected limb) |
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Term
| locomotor generators in spinal cord |
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Definition
control walking by producing alternating contractions and relaxation of the flexor /extensor mm of legs
under the control of the brainstem |
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Term
| vestibular nuclei and vestibulospinal tracts (medial and lateral) |
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Definition
involved in the control of balance and posture
provide excitatory inputs to motor neurons of extensor mm to support balance |
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Term
| pontine and medullary reticulospinal tracts |
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Definition
| maintain posture against gravity by activation axial mm and proximal extensors and inhibiting flexors (automatic posture and gait related movements) |
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Term
| tectum (superior colliculus) and tectospinal tract |
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Definition
| coordinate head movements in response to visual, auditory or somatosensory stimuli |
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Term
| lateral corticospinal tract |
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Definition
| controls skilled movements of contralateral distal limbs |
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Term
| anterior/medial corticospinal tract |
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Definition
| target neurons project bilaterally to control axial and proximal mm |
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Term
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Definition
| supplies cranial motor neurons to head (has lateral and medial components) |
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Term
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Definition
a plan developed by the supplementary motor and premotor areas of the cortex that determines which mm must be contracted, as well as strength and the sequencing of the contractions
executed over the primary motor cortex as well as the supplementary and premotor areas |
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Term
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Definition
needed to monitor and make needed corrections to the motor plan
comes to the primary motor cortex over the thalamus and sensory areas of the cortex |
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Term
| stimulation of the primary motor cortex vs. the premotor/supplementary motor cortex |
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Definition
primary - produces discrete movements
supplementary - complex movements |
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Term
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Definition
| allows for some recovery of function after damage to the motor cortex (repeated long-term practice is essential) |
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Term
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Definition
learning, planning, rehersal and execution of rapid, coordinated, complex movements
control of posture and balance |
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Term
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Definition
| spinocerebellar tracts provide info from mm and joint proprioceptors and other somatosensory info as well as info from spinal interneurons about descending motor commands to these neurons. Info provides cerebellum with different aspects of the state of the organism |
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Term
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Definition
inputs arise from the vestibular system and outputs project to lateral and medial vestibulospinal tracts over the vestibular nuclei
controls posture and balance |
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Term
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Definition
cortical inputs occur over the pontine nuclei; outputs are conveyed over the dentate nuclei.
Regulates of cortical motor programs, plans movements and learning new movements |
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Term
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Definition
| provide an inhibitory input to the output nuclei of the cerebellum , the deep cerebellar nuclei and vestibular nuclei |
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Term
| climbing and mossy fiber systems |
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Definition
supply the input to the cerebellum
provide info relevant to movement that comes from both sensory and motor systems
main excitatory cerebellar circuit which produces firing of the neurons in the deep cerebellar nuclei |
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Term
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Definition
| consist of 4 nuclei (striatum, globus pallidus, substantia nigra, and subthalamic nucleus) that have a major role in normal voluntary movement and they influence cognition, mood and behavior |
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Term
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Definition
| receives widespread inputs from the cortex related to plans for intended movements (putamen = movements of body, caudate = eye movements) |
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Term
| direct pathway of basal ganglia |
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Definition
goes through the basal ganglia to the motor areas of the cortex in order to facilitate movement
runs from cortex to striatum to globus pallidus to thalamus to cortex |
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Term
| indirect pathway of basal ganglia |
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Definition
reduces activity in the thalamo-cortical pathway to the motor areas of the cortex and hence inhibit movement
runs from cortex to striatum to the external segment of the globus pallidus to the subthalamic nucleus to the internal segment of the globus pallidus to the thalamus to cortex |
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Term
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Definition
| a modulatory transmitter that is required for the normal functioning of the basal ganglia circuitry |
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Term
| upper motor neuron lesion |
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Definition
if it occurs before the corticospinal tracts cross = mm paralysis on the contralateral side
if it occurs after the fibers cross = mm paralysis on the ipsilateral side |
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Term
| lower motor neuron lesion |
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Definition
ipsilateral hypoactive reflexes
paralysis limited to specific groups of mm innervated by the affected motor neurons |
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Term
| lesions to the cerebellum |
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Definition
symptoms occur ipsilateral to the lesion
ataxia (loss of motor coordination) |
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Term
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Definition
loss of dopamine containing neurons in the substantia nigra with loss of dopamine projections to putamen and caudate
bradykinesia (slow movements)
tremors
slow speech |
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Term
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Definition
inherited neruological disorder involving depression and dementia and progressive loss of motor control
loss of GABAergic neurons in the striatum that project to the globus pallidus |
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Term
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Definition
| abnormal synchronous discharges of neurons due to abnormally increased excitability |
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Term
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Definition
originate with the activation of a small group of neurons
begin with auras and are followed by postictal periods |
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Term
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Definition
start without any warning signs and involve both hemispheres
classified into convulsive (tonic/clonic movements) or nonconvulsive (abrupt onset) types |
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