Shared Flashcard Set

Details

Physiology
VMB 913 - 2nd exam
106
Veterinary Medicine
Professional
09/28/2010

Additional Veterinary Medicine Flashcards

 


 

Cards

Term

Prosencephalon

(forebrain)

Definition
  • Embryonic
  • develops into the telencephalon (cerebrum), and diencephalon (subcortical nuclei).
  • high-order information processing and executive function
Term
Mesencephalon
Definition
  • embryonic
  • gives rise to midbrain nuclei
Term

Rhombencephalon

(hindbrain)

Definition
  • Gives rise to the metencephalon and myelencephalon
  • metencephalon develops into the pons and cerebellum
  • myelencephalon (aka medulla oblongata)
  • part of the brain stem
Term
Brain Stem
Definition
  • diencephalon, midbrain, pons and myelencephalon
Term
Spinal Intumescences
Definition
  • enlargements
  • Cervical intumescence: C6-T2 - brachial plexus
  • Lumbosacral intumescence: L4-S3 (S5 in large animals) - lumbosacral plexus
Term
Gray matter of spinal cord
Definition
  • Dorsal horn - sensory function (develops from alar plate)
  • Ventral horns - motor function (basal plate)
  • Lateral horns (only T1-L3) - autonomic neurons located in the CNS (basal plate)
Term
Gray matter of brain stem, cerebrum, cerebellum
Definition
  • functionally related clusters of nerve cell bodies = nuclei
  • cerebral cortex and cerebrum - neruron cell bodies form layers (lamina) - also deep seated basal nuclei (cerebrum).
Term

White Matter of

Spinal Cord

Definition
  • FUNICULUS
  • dorsal funiculus - b/w dorsal horns - sensory only (ascending tracts)
  • lateral funiculus - b/w dorsal and lateral horns - motor and sensory function
  • descending tracts are motor tracts.
  • ventral funiculus - b/w ventral horns - sensory and motor.
Term

White matter in

brain stem, cerebellum,

and cerebrum

Definition
  • diffuse in brain stem - may for fasciculi, tracts, lemnisci, and stria.
  • peduncles - b/w cerebrum and pons
  • internal capsule - b/w cerebrum and brain stem
Term
Dorsal Root
Definition
  • joins 2 segments of cord at dorsolateral sulcus
  • dorsal root contains afferent sensory fibers entering the spinal cord.
  • may then synapse w/in spinal cord or ascend to the brain
  • dorsal root ganglion - in PNS - nerve cell bodies of sensory fibers.
Term
Ventral Root
Definition
  • Joins 2 segments of SC at ventrolateral sulcus
  • contains efferent motor fibers
  • neuronal cell bodies are within the ventral horn or lateral horn of some segments.
  • no associated ganglia
  • nerves divide into spinal dorsal and ventral branch
  • T1-L3 - ramus communicans - lead to autonomic ganglia.
Term
Meninges
Definition
  • under skull
  • dura mater - most external
  • arachnoid and pia - leptomeninges
  • subarachnoid space continuous with ventricles filled with CSF
  • outside of the CNS
Term

Glial Cells

PNS

Definition
  • satellite cells - surround nerve bodies
  • neurolemmocytes (schwann cells) - myelinate axons
  • myelin - high lipid content
  • one schwann cell to one fiber
  • if it doesn't myelinate - cradles in several processes.
Term
CNS glial cells
Definition
  • oligodendrocytes - myelinating cells of CNS - one oligo to many fibers.
  • astrocytes - cover surface of CNS capillaries --> BBB
  • microglia - macrophages
  • ependymal - line ventricles/central canal - filter CSF
Term
Neuron shape
Definition
  • unipolar - one process (functionally an axon and a dendrite) - splits into 2 away from cell body - dendritic zone and an axon. EX - sensory neurons
  • bipolar - one dendrite, one axon - retina, inner ear, olfactory epithelium
  • multipolar - several dendrites - one axon - most common - striated muscle
Term
Network Approach
Definition
  • organization based on functionality and elecrophysiological networks.
  • involves intensity and timing of neuronal firing
  • uses sensory networks, motor networks, higher order networks
  • high-order networks poorly understood
  • high order: emotions, memory, endocrine
Term
Sensory Networks
Definition
  • chemical receptors
  • mechanical receptors
  • specialized receptors (retina, temp)
Term
Motor Network
Definition
  • lower motor neurons - connect CNS to muscle
  • upper motor neurons - connect brain to lower motor neurons.
  • Most neurons are associative - involved in interconnections w/in brain
Term
NMJ
Definition
  • nerve to muscle
  • skeletal muscle - motor neuron axon branches to contact multiple fibers
  • sarcolemma folded with receptors
  • motor unit: neuron and associated muscle fibers.
  • smooth muscle: axons have a series of swellings along length - varicosities - fuse with axolemma
  • no modification of sarcolemma of smooth muscle
Term
Ion Channel Selectivity
Definition
  • pore size - determines which ions can pass: large ions (K+, Cl-), small ions (Na+, Ca2+)
  • ion filters - within the pore of the channel (intrapore) - highly selective for binding of ions - may be specific targets of drugs - anesthetics and K+ channels
  • channel gates - inactivation gate - if nongated, flow determined by concentration gradient, size, ion filter.
Term
Ion Channel Kinetics
Definition
  • fluctuations b/w open and close depends on:
  • kinetics of voltage dependent channels - how fast/slow the gate opens/closes
  • conc grad
  • current running through a channel determines how quickly ions can pass - influenced by Vm
  • conc of ligand for gated channel
Term
Resting Membrane Potential
Definition
  • neuron equilibrium - determined by conc grad and relative permeability of membrane to ions
  • -70mV
  • at rest - K+ and Cl- channels are open, Na+, Ca++ are closed.
  • Na+ - more conc outside
  • K+ - more conc inside
Term
Nernst Equation
Definition
  • RT/zF = 61
  • E=61log (conc. out/ conc. in)
  • K+ = -96mV
  • Na+ = +59 mV
  • changes in conc grad inside and outside cell alter the equilibrium potential
  • larger gradient - larger equilib potential
Term
Na+/K+ pump
Definition
  • to maintain conc gradients - keep Na+ out of cell - keep channels closed at rest
  • membrane is slightly leaky to Na+
  • 3 Na+ out, 2 Na+ in
Term
Graded Potentials
Definition
  • subthreshold (-40mV) stimuli - depolarizing or hyperpolarizing.
  • summation: spatial (2+ applied at diff locations at same time), temporal (2 of same stimulus at diff times)
  • local currents, short lived (temporally and in distance)
Term
Ca2+ conc and AP
Definition
  • EC Ca2+ conc
  • can potentially block Na+ and K+ channels - changes in membrane potential more difficult
  • increases in Ca2+ EC will increase threshold
  • decreases in Ca2+ will decrease threshold
Term
Hodgkin and Huxley
Definition
  • giant squid axon
  • showed the propagation and recovery of an action potential
Term
APs sequence
Definition
  1. summated GPs reach -40mV threshold - large # of voltage Na+ channels open - Na+ enters cell - depolarization
  2. influx of Na+ -> +59mV - voltage-gated K+ channels activated slowly, flow of Na+ slows b/w reach equilib potential, K+ flows out - efflux of +ve charge- repolarization
  3. secondary gating of Na+ channels - block Na+ influx - refractory period.
Term
unmyelinated nerves
Definition
  • stimulus -> local current flow -> depolarization of adjacent membrane
  • Na+ out and K+ in occurs along entire length of the axon
  • AP prop via ionic conductance
  • unidirectional b/w of refractory period
Term
Myelinated nerves
Definition
  • largest and fastes
  • b/w schwann cells - interfiber nodes of Ranvier
  • myelin insulated preventing ion leakage or diffusion except at nodes - high conc of Na+- conduction of AP at this point.
  • Saltatory conduction
Term
Myeline Disorders
Definition
  • MS - genetic - myelin degradation - progressive nerve paralysis
  • canine shaking pups - genetic myelin disease in dogs - reduced size at birth - usually survive for 2 years.
  • visna/ canine distemper - inflammatory myelin diseases - sheep and dogs - ataxia, paresis, depression.
Term
Calcium deficiency
Definition
  • stabilizes membranes - keeps Na+ channels closed
  • when Ca2+ deficient - nerves have increased permeability to Na+, spontaneously excitable
  • muscle spasms and rigidity
Term
Toxins decrease in Vm
Definition
  • hypoxia, toxins
  • local anesthetics - 'caines' - block voltage-gated Na+ channels - no pain transmission to brain
  • preferential action on small unmyelinated nerves (pain nerve fibers)
  • Tetrodotoxin - TTX - fish and some bacteria - block voltage Na+ channels -> paralysis
  • Saxitoxin (STX) - marine dinoflagellates, cyanobacterium - blocks many Na+ channels - paralysis, loss of excitability.
Term
NT production
Definition
  • large - peptides - synthesized in cell body, vesicles transported down axons to terminasl
  • small - glutamate, GABA, ACh, NE - synthesized and packaged at nerve terminal - enzymatic production
Term
Synaptic life cycle
Definition
  1. vesicle associate proteins synthesized
  2. transport to packaging sites in axon terminal - motor protein, cytoskeleton
  3. maturation of vesicles - active packaging of NTs
  4. reserve pool of vesicles
  5. APs depolarize terminal - Ca2+ enters via voltage gated channel
  6. vesicles mobilized - active zone on pre-syn membr.
  7. vesicles docked and exocytosed
  8. NT release - recycled into buton or enzymatically degraded
Term
Vesicle mobilization
Definition
  • require ATP for activity of ca/calmodulin kinase II (CaMKII) and myosin light chain kinase (MLCK)
  • both phosphorylate proteins that are substrates for mobilization of synapsin I and myosin II - prime vesicle for movement to active pool
Term
Vesicle fusion/exocytosis
Definition
  • calcium sensing protiens -
  • synaptotagmin - only binds SNARE complex of proteins once bound by Ca2+
  • SNARE components
  • VAMP-2 (synaptobrevin) syntaxin I, SNAP-25 - important for vesicle fusion.
Term
Synaptic Delay
Definition
  • time b/w pre-synaptic release of NT and post-syn response
  • time take for NT discharge, NT diffusion across synapse
  • binding of NT post
  • response of post-syn membrane
Term
NMJ end plate potential
Definition
  • ACh release onto NMJ - binds ACh-gated Na+/K+ channels - open - Na+ influx - depolarization
  • generates an end-plate potential (graded potential)
  • AP generated in both directions along sarcolemma
  • ACh metabolised by AChE
  • all input to NMJ is excitatory
Term
Curare
Definition
  • ACh antagonist
  • binds ACh receptors - no activity - competitive inhibition of ACh
  • not susceptible to AChE
  • flaccid paralysis, death by asphyxiation
Term
Organophosphates
Definition
  • AChE inhibitor
  • neostigmine, physostigmine
  • ACh not metabolized
  • muscles repeatedly stimulated - spasms
  • laryngeal spasms - suffocation - death.
Term
Metacholine, Carbachol
Definition
  • ACh agonist - muscle spasms
  • not susceptible to AChE but still active
Term
Botulinum Toxin
Definition
  • clostridium botulinum
  • prevents release of ACh from nerve
  • targets SNAP-25
  • prevents docking and secretion of ACh
Term
Myasthenia Gravis
Definition
  • decreased numbers of ACh receptors at NMJ
  • autoimmune disease
  • muscle paralysis
  • ACh still released
  • AChE blockers - (neostigmine) - transient relief of symptoms.
Term
Milk Fever
Definition
  • pariparturient muscle weakness
  • low blood calcium at onset of lactation
  • failure to transmit nerve signals across NMJ
Term
Monoamine NTs
Definition
  • catecholamines (Da, NE)
  • serotonin
  • histamine
Term
AA NTs
Definition
  • glycine
  • glutamate
  • aspartate
  • GABA
Term
Peptide NTs
Definition
  • Substance P
  • enkephalins, endorphin, bradykinin, bombesin, somatostatin, VIP, cholecystokinin-like peptide, neurotensin, insulin, gastrin, glucagons, TRH, GnRH, ACTH, angiotensin II, ADH, ocytocin, Prolactin, etc.
Term
Major CNS NTs
Definition
  • glutamate - excitation usually - neurons are long-distance projection neurons - across different modules of brain.
  • GABA - inhibitory - mostly local networks, inhibition of "circuits"
Term
2 general receptor types
Definition
  • Ionotropic - ligand-gated ion channels - more rapid transmission
  • metabotropic - intracellular signalling - ex - GPCR - takes longer b/w of cell signalling.
  • receptors can be recycled
Term

Glutamate Receptors

Ionotropic

Definition
  • NMDA - most common - can pass Na+, Ca2+, K+ depending on state - mostly Ca2+
  • AMPA- same - except gated mostly for Na+ and K+
  • Kainate receptor - selectively activated by kainite - conduct Na+ and K+ ions
Term

Glutamate Receptor

Metabotropic

Definition
  • GPCR
  • 3 classes
  • 1) mGlu1 mGlu5 - trigger Phospholipase C and Ca2+ signalling
  • 2 and 3) mGlu 2-4; 6-8 - coupled to adenylyl cyclase - makes cAMP - negatively coupled
  • expressed by glial cells (astrocytes) - regulate availability of glutamate to environment
  • control excitotoxicity to glutamate signalling
Term

GABA receptors

Ionotropic

Definition
  • GABA-A
  • related to alpha-adrenergic and glycine receptors
  • ligand gated Cl- channels - Cl- enters cell, hyperpolarized.
  • inhibits generation of APs
Term

GABA receptors

metabotropic

Definition
  • GABA-B
  • GPCR
  • influence K+ and Ca2+ conductance in post membr.
Term
Inhibitory Surround
Definition
  • lateral inhibition - focuses transmission of neural signals
  • neighbouring GABA neurons "damped" glutamate released
Term
Long Term Potentiation
Definition
  • long-lasting increase in responsiveness of post neuron to specific pre input given in trains
  • neuronal learning - in hippocampus
  • dependent on NMDA and AMPA glutamate receptors
  • blocking NMDA - prevent LTP - activated by glu. - increase IC Ca2+ activates CaMKII - activation of AMPA, increase in AMPA receptor on post
  • increased gene expression required
  • retrograde messages from post neuron to pre important
Term
Modulation of Neurotransmission
Definition
  • inhibit synthesis (DON and MSO - inhibit glutamate synth)
  • block reuptake (resperine - 5HT, Da, NE reuptake)
  • mimic NT (nicotine - ACh, LSD - 5HT, tranquilizers - GABA)
  • inhibit release of NT (botulism)
  • block degradation of NTs in cleft (amphetamines block DA and NE degradation)
  • Synaptic fatigue - exhaustion of NT stores - need to make more - ex seizure
Term
Primary Somatic Sensations
Definition
  • tactile information - touch, pressure, vibration
  • proprioception - limb, muscle, joint
  • pain
  • temp
Term
Somatosensory receptors
Definition
  • free nerve endings - mechanical, thermal, noxious
  • Merkel's discs - expanded tip - sustained response to vibrations 5-15Hz
  • Meissner's corpuscles - dermis of glabrous (hairless) skin - low frequency - 20-40 Hz
  • Pacinian Corpuscles - deep layer of dermis - 150-300 Hz
  • Hair follicle endings - hair displacement
  • Krause's corpuscles - dermal layer of lips, tongue genitals - pressure detection
  • Ruffini's end-organ - dermis of hairy and glabrous skin - pressure
Term
Pacinian Corpuscle
Definition
  • axon with unmyelinated tip - encapsulated by concentric layers of CT capsule - each layer separated by viscous fluid.
  • conversion of mechanical to electrical
  • pressure -> deformation of capsule - fluid compressed, axon tip deformed - mechanically-gated Na+ channels open - graded potential -> AP generated at 1st interfibral node -> CNS via dorsal root
  • respond to intensity, receptor potential magnitude, AP frequency
  • greater pressure, larger graded potentials, more AP generated in neuron.
Term

Pacinian Corpuscle

Adaptation

Definition
  • most somatosensory receptors - attenuated response to constant stimulus.
  • 1) physical property - fluid eventually redistributes with constant pressure - equalizes pressure on both sides of axon - axon regains shape - diminished capacity for stimulus to generate graded potential
  • 2)nerve fiber accommodation - slow recovery of ion gradients after multiple stimuli. Decrease in number of ions available
Term
Rapidly Adapting Receptors
Definition
  • Pacinian
  • hair receptors
  • semi-circular canal receptors
  • adaptation allows for detection of changes in rate of stimulus
Term
Slow Adapting Receptors
Definition
  • detecting general status of incoming stimuli
  • muscle spindles
  • golgi tendon organ
  • pain receptors
  • baroreceptors/chemoreceptors
  • provide constant information about stimuli status to CNS
Term

Relay of somatosensory

to CNS

CIRCUIT!

Definition
  • DORSAL SPINAL BRANCHES
  • cell bodies - in dorsal root ganglia
  • axons travel via dorsal funiculus (dorsal lemniscal track)- no synapsing
  • synapse in nuclei of myelencephalon (gracile and medial cuneate nuclei)
  • Second order neurons project across to contralateral side of myelencephalon - enter medial lemniscus to ventrobasal thalamus (diencephalon)
  • tertiary neurons - in thalamus - send sensory info to somatosensory cortex - somesthetic interpretation of info (unknown mechanism)
Term
Proprioception
Definition
  • vestibular input
  • muscle spindles (stretch)
  • golgi tendon organ
  • Ruffini's endings
  • Pacinian corpuscles (joints)
Term
Muscle Spindels
Definition
  • extrafusal fibers - contraction
  • intrafusal - in the middle - wrapped by nerves
  • spindle is paralell to extrafusal
  • muscle stretch - mechanically gated Na+ channels on nerve endings open -> graded potential -> AP-> CNS
  • CNS response via gamma motor neurons - axons innervate small contractile muscles at 2 ends of each muscle spindle
  • alpha motor neurons signal motor contraction in extrafusal
Term
Golgi Tendon Organ
Definition
  • primary sensory neurons - dendrites intertwined with collagen fibers in tendons
  • depolarized when muscles contract (opp of spindle)
  • contraction - increased tension in tendon - stimulation of mechanically gated ion channels on dendrites of neurons
Term

Unconscious proprioception

transmission to CNS

Definition
  • DO NOT CROSS MIDLINE
  • if from pelvic limb - synapse in nucleus thoracicus
  • if from thoracic limb - enter dorsal funiculus w/o synapse - travel ipsilaterally and synapse in lateral cuneate nucleus in myelencephalon
  • dorsal spinocerebellar track/cuneocerebellar track - axons terminate in cerebellum
Term
Pain Receptors
Definition
  • A-delta - extreme pressure/heat - myelinated, fast fibers
  • C-delta - slowest conductivity of all fibers - unmyelinated - stimulated by noxious stimuli - pressure, temp, chemicals
  • Peptidergic fibers - secrete substance P in spinal cord
  • Nonpeptidergic - glutamate and other transmitters
Term

Transmissin of Pain Info

to CNS

Definition
  • spinothalamic track
  • axons from pain neurons synapse in dorsal horn
  • some fibers cross contralaterally, others stay ipsi
  • opiate influence - interneurons and projections from periaqueductal gray of brain stem
  • multisynaptic
  • ultimately synapses on ventrocaudolateral nucleus of thalamus - may also involve perception of pain
Term
Somatosensory Cortex
Definition
  • caudal to post-cruciate gyrus in parietal lobe
  • primates - face, hands, and figers have a high number of sensory receptors - larger representation in homunculus.
  • mice - whiskers and nose important - altered representation.
  • right side of body on left side of brain and vice versa
  • b/c of crossing of sensory fibers prior to thalamix synapse.
Term
Ciliary Muscles
Definition
  • close object - ciliary muscles contract, zonular fibers relax - lense bulges into sphere
  • far object - ciliary muscles relac, zonular contract - flattens the lens.
  • accomodation
Term
Layers of Retina
Definition
  1. photoreceptor layer - contains rods and cones - very back of retina
  2. bipolar cells - also interneurons and amacrine cells
  3. ganglion cells - at surface, in contact with vitreous humour.
  • Centre of the retina - fovea
  • cones mostly central, more rods peripherally
Term

photoreceptor activity

in dark

Definition
  • outer segment as opsins and ligand gated (in response to intracellular molecules) Na+ and Ca2+ channels
  • binding of cGMP opens channels - activation
  • in dark, IC conc of cGMP high, cells are "active" - tonic depolarization - release of glutamate.
Term

Photoreceptor Activity

in light

Definition
  1. photos of light isomerize vitamin-A portion of opsin
  2. free opsin activates G-protein tansducin
  3. GPT activates phosphdiesterase
  4. PDE hydrolyzes cGMP molecules - decrease in cGMP - closing of Na+, Ca2+ channels - decreased activity of photoreceptors - less glutamate released from the cell.
Term
Retinal Transmission
Definition
  1. light decreases glutamate release by photoreceptors (glutamate is inhibitory on bipolar cells)
  2. inhibition removed and bipolar cells activated
  3. bipolar cells activate ganglionic cells
  4. ganglionic cells send axons through optic nerve to lateral geniculate nucleus (metathalamus)
  5. LGN relays infor to primary visual cortex - occipital lobe
  6. REMEMBER - ganglion cells on medial cross at optic chiasm - on lateral - stay ipsilateral (left goes through right LGN, right goes through left LGN)
Term
Rods vs. Cones
Definition
  • Rods - high convergence, high sensitivity to light, night vision, low acuity, black and white
  • Cones - low convergence, low sensitivity to light, day vision, high acuity, 'see' colour
Term
Photoreceptor Adaptation
Definition
  • light adaptation - prolonged exposure to light - breakdown of rhodopsin faster than it reforms, less sensitive to light
  • dark adaptation - vitamin A mobilized for synthesis of rhodopsin - not being broken down in absence of light - rhodopsin levels increase - increased sensitivity to light.
Term
Suprachiasmatic Nucleus
Definition
  • optic tract projects here too
  • detection of day and night
  • involvement with circadian rhythm
  • axons also go to brain stem nuclei involved in eye movement and those involved with turning the head.
Term
High order visual processing
Definition
  • 2 streams in cortical information
  • dorsal stream - movement and spatial information - where
  • vental stream - object info - what
Term
Choclea
Definition
  • 2 flexible membranes - vestibular and choclear window
  • 2 chambers filled with perilymph - scala vestibuli and scala tympani - separated by basilar membrane
  • hole in basilar membrane - helicotrema - allows flow of perilymph
  • hair cells embedded in basilar membrane
Term
Choclear Duct
Definition
  • Organ of Corti
  • tectorial membrane that lies on top of organ - contacts stereocilia projections of hair cells
  • tectorial membrane relatviely inflexible - movement relative to the tectorial membrane causes deflection of cilia
Term
Sound Wave Transduction
Definition
  • vibration in perilymph - vibration of basilar membrane
  • cilia deflected as tect. mem. doesn't move
  • Na+ channels open in hair cell - mech gated - depolarization
  • deflection toward thickest cilium - depolarization
  • opposite direction - hyperpolarization
  • seen as waves of depolarization/hyperpolarization
Term
Hair Cell Depolarization
Definition
  • hair cell depolarized
  • release of glutamate and activate ligand-gated glutamate receptors on afferent auditory gibers
  • auditory nerve - bodies in spiral ganglion of CN 8
Term
Place Principle
Definition
  • Pitch detection
  • higher frequency detecting cells - basal end
  • low-frequency - at apical end of choclea
  • also - louder sound, larger vibration, higher frequency of AP -> loudness of sound
Term
Auditory CNS
Definition
  • from inner ear -> medial geniculate nucleus of metathalamus
  • MGN -> auditory complex
Term

Semicircular Ducts

Anatomy

Definition
  • 3- contain vest. sensory receptors - detect rotational motion of head and body.
  • 3 canals - rostral - angular motion in saggital plane, horizontal - horizontal angular motion, caudal - angular motion in transverse plane
Term

Utricle and Saccule

Anat

Definition
  • detection of linera movement
  • motion due to gravity (vertical acceleration)
  • horizontal acceleration
  • maculae - sensory organs - contains hair cells that protrude into gelatinous mass
  • otoliths - CaCO3 crystals - in gel - movement of otoliths in response to movement activates vest. hair cells.
Term
Vestibular receptors
Definition
  1. deflection of vest. hair cells b/c of movment of otoliths - depolarization OR hyperpolarization
  2. movement towards larest cilium (depolarization), movement away (hyperpolarization)
  3. activation - release of glutamate
  4. hair cells of SSDs - single tuft at base of SSD (cupula of Ampulla) - same mechanism
Term
Vestibulo-Occular reflex
Definition
  • keep eye focused while head moves
  • vestibular nerve synapses in vestibular nucleus - project to contralateral abducens nucleus (CN 6) - then to the right lateral rectus muscle of the eye
  • also to the ipsilateral oculomotor nucleus (CN 3) - stimulates ipsilateral medial rectus muscle
  • ultimately, eye will rotate opposite to direction of head movement in horizontal plane.
Term

Motor Function

Brain Stem Nuclei

Definition
  1. control of postural support of muscles - extrapyramidal pathways (ventra tracts of brain stem) - reticulo-spinal, vestibulo-spinal, rubro-spinal (red nucleus from cerebellum), tecto-spinal tract (visual) 
  2. control of unconsious, stereotyped movement - modulation of tone in extensor muscles - control of gait - red nucleus - influences CPGs - in non-primate animals - most importnat centre for control of gait (more control over forelimbs/shoulders? - analagous to humans?)
Term
Cerebellum
Definition
  • damage to - ataxia
  • function in coordination of motor function
  • execution of rapid movements
  • receives a copy of output from motor cortex (red nucleus), provides error correction, then back to nuclei/cortex.
Term
Subcortical Motor Control
Definition
  • basal nuclei - striatum (caudate/putamen), globus pallidus (GPe, GPi) - input from all cortical areas and substantia nigra (DA production)
  • process and send info to same areas via thalamus (Subthalamic nuclei) - sent to cortex as motor plan
  • basal nuclei may be important in initiation of movement once plan in reached
  • maintenance of inhibitory function
  • more important in animals for conscious control of movement.
Term

Cerebral Cortex

Motor Cortex

Definition
  • over-representation of areas of body associated with finely controlled movement.
  • right side of body in left cortex
  • corticospinal pathway/ pyramidal tract - conscious motor output - from motor cortex - fibers pass directly into spinal cord after crossing at level of myelencephalon
  • for learned, skilled, fine, voluntary movement of flexors
Term
CNS ACh neurons
Definition
  • ACh release as neuromodulator in brain
  • in nucleus basalis - diencephalon - wide-spread ACh input to cortex
  • ACh releasing neurons also to pedunculopontine area of the pons - project to the thalamus
  • receptors: nicotinic - ligand-gated Na+/K+ channels (fast) muscarinic - GPCR(slower response)
Term
CNS NE neurons
Definition
  • in locus coeruleus of brain stem
  • important in limbic system - emotion, endocrine function
  • receptors: alpha and beta - all are GPCR
Term
CNS serotonin neurons
Definition
  • in raphe nuclei - project to entire cortex and subcortical nuclei
  • receptors: at least 13 different ones - most are GPCR
  • 5HT3 - ligand gated Na+/K+ channel
Term
CNS DA neurons
Definition
  • substantia nigra (midbrain)
  • strong projections to frontal cortex
  • pathways:
  • 1) mesocortical - DA to frontal cortex,
  • 2) mesolimbic - DA to limbic (ventral) striatum of basal nuclei
Term
DA Receptors CNS
Definition
  • 5 subtypes
  • most GPCR -
  • D1 and D5 - increase Vm
  • D2,3,4 - decrease Vm
  • D1,D2 - in striatum - unconsious motor control
  • D1,D5 - cortex - cognitive and executive CNS fxn
  • D3,D5 - hypothalamus: endocrine and autonomic fxn
Term
Neuromodulation influence by
Definition
  • binding kinetics of receptor: influences which receptor activated and at what strength (diff receptors for one NM have different affinities)
  • influence of receptor activation on post-synaptic cell : hyperpolarization or depolarization?
Term
Functions of NMs
Definition
  • NE - arousal/reward
  • DA - motor/reward/cognition/CNS endocrine, nausea
  • 5HT - sleep/mood/satiety/body temp
  • ACh - arousal/short term memory(attention)/learning
  • effects modulated by location and amount of specific receptors throughout the CNS
Term
OCD
Definition
  • abnormal 5HT pathway
  • may be a genetic mutation in 5HT transporter gene
  • malfunction of communication b/w frontal cortex and basal nuclei
  • orbital and medial frontal cortical areas (OMFC) - send signal to thalamus to get more info about stimulus
  • then back to OMFC -> motor response to caudate nucleus - malfunction leads to constant stimulation of caudate nucelus -> motor responce
Term
NMDA Receptor
Definition
  • glutamate - ionotrophic - Na+, K+, Ca2+
  • ligand and voltage gated
  • Mg2+ block channel - voltage dependent
  • Zn2+ block non competitively and voltage indep - both need to be removed
  • antagonists - detromethorphan, dextorphan, ehtanol, ketamine, NO, methadone
Term

Tapetum Lucidum

Diseases

Definition
  • some animals naturally lack tapetum - white coats, small dogs.
  • tapetal degeneration - nutrition-induced (Zn2+ def)
  • chemical-induced (Zn-pyrithione in shampoo
  • hereditary - autosomal recessive - beagles
Supporting users have an ad free experience!