Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
mcb163 lec exam 1
short answer
| Question | Answer |
|---|---|
| Tay-Sachs | an ailment of defective lysosomal storage and present primarily in Jewish males of middle European origin; it is progressive, involves motor retardation, and is lethal |
| Parkinsonism | an ailment that involves cell death of dopaminergic cells in the basal ganglia motor system, is progressive, and may be lethal; it features intention tremor, muscle rigidity, and poverty of movement |
| Poliomyelitis | a viral infection that destroys alpha motoneurons and leaves skeletal muscle paralyzed |
| Pacinian corpuscles | rapidly adapting deep pressure encapsulated mechanoreceptors that are vibration sensitive |
| Merkel’s discs | slowly adapting unencapsulated mechanoreceptors that are plentiful on the index finger and well suited to transduce pressure and texture information |
| Thermoreceptors | A delta of C conduction velocity receptors that transduce either burning or freezing information in the spinothalamic system. The precise receptor that corresponds to each temperature range is unknown |
| Ganglion cells | have one end that either forms or makes contact with a receptor |
| neurons | are entirely segregated from the periphery |
| peripheral ganglion cell process forms a | sensory nerve |
| Ganglion cell peripheral processes | can regenerate |
| neurons | do not regenerate |
| Ganglion cells | are independent of one another and are not connected |
| neurons | are connected to one another and interdependent and form circuits, while ganglion cells only form pathways. |
| Renshaw cells | are local circuit interneurons that project to alpha motoneurons, which they inhibit by the release of GABA |
| The principal input that activates the Renshaw cell | is the same alpha motoneuron to which it projects |
| as the alpha motoneuron fires repetitively | it activates the high-threshold Renshaw cell |
| the activated high-threshold renshaw cell | then releases GABA onto the same alpha motoneuron, creating autogenetic discharge-dependent inhibition |
| renshaw cell's release of GABA will | ensure that the discharge behavior of the alpha motoneuron is carefully regulated |
| Input to the central gray is propagated | bidirectionally, forward to the hypothalamus for autonomic and visceral responses to pain |
| in the raphespinal system and more caudally to the raphe nuclei | serotoninergic axons descend as the raphespinal tat to terminate in the superficial layers of Rexed’s dorsal horn laminae I-II |
| The enkephalinergic interneuron | makes an axo-axonal synapse on the primary afferent (which is substance P-positive if it is paleospinothalamic) thus blocking the subsequent transmission of nociceptive information to brain stem sites. |
| Schwann cells | are the source of peripheral myelin, which enables axons to send all-or-none signals over long distances rapidly and faithfully from node of Ranvier to node of Ranvier. |
| The thickness of the myelin membrane | is proportional to the conduction velocity of the axon. |
| Microglia | are phagocytic cells activated by damage, especially when the axoplasm is open to the extracellular space |
| Microglia | they are transiently activated and otherwise dormant and are responsible for eliminating neurons with pathologic firing patterns. |
| Astrocytes | serve as the interface between capillaries and neurons, ensuring that nutrients reach the neurons and removing from the neurons waste gasses and structurally unusable molecules |
| Meissner corpuscles | are tiny sensory receptors located in dermal ridges |
| Meissner corpuscles | are tiny, rapidly adapting corpuscular mechanoreceptors responsible for the sensation of stroking and fluttering stimuli on the glabrous skin and they project to the CNS by way of thick A alpha axons. |
| Merkel disks | are in the slight depressions beside the meissner corpuscles |
| Merkel Disks | are the slowly adapting and are larger encapsulated mechanoreceptors responsive to changes in pressure and texture which occur over a long time course. |
| The axons of merkel disks | are of the A alpha type |
| free nerve endings | are in all layers of the skin and end without apparent specialization |
| Larger free-nerve endings and their fibers(A delta) are | nociceptors that serve sharp, pinprick pain (RA-rapidly adapting) |
| the SA(slow adapting) subtype of free nerve endings is | polymodal and is associated with tiny dorsal root ganglion cells and C-fibers. |
| RFs(receptive fields) for fine (epicritic) touch are | small (a few mm in diameter), numerous, and nonoverlapping and have high spatiotemporal resolution on the fingertips |
| pain and temperature RFs (protopathic) are | larger, fewer in number, and have much more overlap |
| RFs (receptive fields) for A delta fibers/ganglion cells are | smaller than those for C fibers/ganglion cells, but larger than the RFs of Meissner or Merkel receptors |
| the fingertips (and all skin, muscles and joints) have | multiple layers of receptors differentiated by RF (receptive field) size, threshold, and function. |
| Complete elimination of the dorsal column system | abolishes conscious epicritic sensation for fine touch and two-point discrimination on the skin, including flutter, texture, and vibratory discrimination. |
| elimination of the dorsal column would leave | Crude touch and pain and temperature sensibility unaffected since their information travels in the spinothalamic pathways in the anterolateral system, which does not involve the dorsal columns. |
| Dorsal columns are also responsible | for body proprioception when visual guidance is unavailable. |
| The classic anterolateral system for crude touch travels | to the posterior thalamus, whose cells project to wide areas of cortex, especially the cingulate gyrus and insular cortex |
| the cingulate gyrus and the insular cortex | help mediate autonomic responses to nociception. |
| The spinoreticular subdivision | ends impulses to the medullary and pontine reticular formation, whose outflow ascends diffusely to the cerebral cortex |
| the spinoreticular subdividion of the spinothalamic pathway | serves an alerting function and has no known somatotopy. |
| The spinomesencephalic pathway ends | in the central gray |
| the spinomesencephalic pathway | contributes ascending input to the hypothalamus for autonomic responses to nociception, and to the raphe, whose descending raphespinal projection can modulate the intensity of protracted pain. |
| Feedback inhibition between Golgi type II Renshaw cells and alpha motoneurons | checks the motoneuron’s output from becoming runaway and perhaps epileptiform. |
| Feedforward inhibition from spinal afferents in the dorsal column system onto postsynaptic neurons in the dorsal column system | transforms receptive fields from pure excitatory to center-surround, thus enhancing the precision of localization on skin. |
| GABAergic spinal and cortical interneurons can | mutually or serially inhibit one another, and thus elicit excitation in a postsynaptic neuron. |
| interneurons | play many roles and are equally able to create excitation in postsynaptic neurons (using disinhibition) as to regulate discharge dynamics and thus stop seizures from propagation. |
| Inhibitory interneurons | come under direct cortical influence to control motoneuron excitability via descending pathways. |
| The spatial distribution of synapses selectively influences | the excitability of the postsynaptic cell. |
| synapses near the axon hillock are | maximally effective in controlling discharge, |
| synapses on the most distal dendritic spines | are weakest since dendrites are unmyelinated and because of the high impedance of the spine head to the flow of current. |
| Neurons thus use the spatial locus of synapses | as a filter for a synaptic hierarchy |
| synaptic hierarchy | inhibitory axosomatic synapses follow those on the axon hillock, and those on the proximal dendrites are next most powerful, though significantly weaker. |
| (a v. d)Axons | are singular (one per cell) |
| (a v. d)dendrites | are multiple and diverse in shape. |
| (a v. d)Axons are | smooth, thin, and sinuous and may project locally |
| (a v. d) dendrites are | thicker, rougher in texture, and divide only a few times |
| (a v. d)axons | may branch profusely. |
| (a v. d)Axons | are commonly presynaptic |
| (a v. d)dendrites | rarely presynaptic |
| (a v. d)Axons can propagate | all-or-none impulses over vast distances rapidly |
| (a v. d)dendrites convey | decremental and graded signals over comparatively shorter distances |
| (a v. d)Axons are capable of | rapid transport |
| (a v. d)transport in dendrites | is far slower |
| (a v. d)Axons have high levels of | putative neurotransmitters at the terminals |
| (a v. d)dendrites have low levels | of putative neurotransmitters at the terminals |
| (a v. d)Axons have a pathfinding role in choosing | which targets to innervate. |
| Renshaw cells | are Golgi type II local circuit neurons that receive input from a motoneurons and which then project recurrently onto them to regulate their global excitability with synapses on the soma near the axon initial segment. |
| in renshaw cells, the motoneuron | creates its own inhibition autogenetically, reducing the likelihood of prolonged discharge which might injure the cell through excitotoxicity, and maintaining the motoneuron in a ready-to-fire state |
| reciprocal inhibition between matched sets of flexor and extensor motoneurons | ensures that a high discharge rate in one elicits a concomitant reduction in the a motoneurons innervating muscles that are antagonistic. |
| The dorsal horn | is the route by which all ganglion cells enter the spinal cord, including those from receptors destined for the dorsal column, spinothalamic, and spinothalamic systems. |
| The ventral horn contains | the a and g motoneurons, Renshaw cells, interneurons for feedforward and feedback operations, and it is the target of the direct corticospinal system. |
| Damage to the ventral horn | renders muscle flaccidly. |
| Laminae I-VII are | sensory |
| laminae I-V are devoted to | the spinothalamic system |
| lamina VI contains parts of the | spinocerebellar pathway |
| lamina VII is part of the | interneuron-rich spinal intermediate zone. |
| Flexors and extensors | correspond to the motoneuron pools in laminae VIII and IX |
| the dorsal columns are | the first order axons from ganglion cells innervating skin, joint and muscle receptors (conscious) and for spinocerebellar (subconscious) information. |
| (a v. g)Neurons propagate | all-or-none signals regeneratively across axons for long distances |
| (a v. g)glial cells | have neither axon nor dendrites, generate no action potentials, are never pre- or postsynaptic |
| (a v. g) glial cells have a role in | myelination, in forming the blood brain barrier, and in phagocytosing damaged neurons. |
| (a v. g)Neurons | can receive nutrients only through glial cells, and glia form the blood-brain barrier. |
| After their final, terminal mitosis, neurons are | largely incapable of further subdivision |
| (a v. g) glia are capable of division | throughout life |
| (a v. g)Neurons cannot readily | buffer the pH of the extracellular space |
| (a v. g)glia can readily | buffer the pH of extracellular space |
| (a v. g)Glial cells are | secretory only and an order of magnitude more numerous. |
| Axons | are smooth, specialized processes that are present on some but not all neurons |
| all neurons have | dendrites |
| As a rule axons are | presynaptic |
| Axons have myelin which permits | them to send constant-amplitude all-or-none signals over long distances rapidly (from 1-120 meters/sec) and faithfully and with no decrement |
| neurons have | several dendrites |
| dendrites are usually ______ than axons | thicker |
| dendrites are often | spinous (which serves to increase their surface area and provide specific filtering properties because of spine impedance) |
| dendrites are typically | unmyelinated, and they are only occasionally presynaptic. |
| Impulse conduction in dendrites is | decremental except where boosted by Ca2+ amplifiers at dendritic nodes. |
| Ganglion cell receptive fields (RFs) in the somatic sensory system are | circular for the most part and only excitatory. |
| localizing a stimulus more precisely within the RF center is | impossible. |
| In the dorsal column, local feed-forward inhibitory interneuronal Golgi type II cells | provide lateral interconnections between ganglion cell afferents ascending and postsynaptic medial lemniscal neurons. |
| When impulses ascend in one dorsal column axon | postsynaptic gracile and cuneate nucleus cells lateral to it receive parallel, inhibitory input via the Golgi type II cells, creating center-surround RFs. |
| the RF with an inhibitory surround is able more exactly to | localize the stimulus within the RFs, providing a computational advantage over pure excitatory RFs. |
| Noxious impulses ascend in the paleo- and neospinothalamic systems to reach | the posterior thalamus, reticular formation and the central gray. |
| The enkephalinergic interneuron makes an axo-axonal synapse on | the primary afferent (which is substance P-positive if it is paleospinothalamic) thus blocking the subsequent transmission of nociceptive information to brain stem sites. |
Created by:
greerbaby
Popular Biology sets