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173 Cards in this Set
- Front
- Back
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Broca's area
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speech production
- inferior frontal gyrus |
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Wernicke's area
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language comprehension
- left posterior temporal lobe |
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3 different tissues in the nervous system
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nervous tissue
glia blood vessels |
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chromatolysis
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disintegration of chromafil substance in cell body of neuron after exhaustion or damage to peripheral process
--> dispersal of Nissl bodies --> cell edema --> nucleus moved to periphery |
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Wallerian degeneration
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degeneration of N. fiber DISTAL to cut
--> lysis of myelin sheath |
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transsynaptic degradation
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atrophy of N. cells following damage to axons that make synaptic contacts with them
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denervation hypersensitivity
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denervated structures become extremely sensitive to chemical stimuli
ex. in muscles, increased response to Ach = repetitive contractions |
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regeneration tube of Schwann cells
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- secretes NGF
- guides axon sprouts to their destination |
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neurotrophins
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proteins necessary for survival and growth of neurons
--> produced by mm., neurons and glial cells --> retrograde transport to cell body |
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neurotrophin R.
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- receptor tyrosine kinases
- TrkA = NGF - TrkB = BDNF |
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kinesin
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- anterograde transport (toward +)
- fast - requires ATP/Ca/glucose - carries: glycoproteins, vesicles |
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dynein
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- retrograde transport (toward - )
- slow - actin, neurofilaments, MTs |
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4 types of glial cells
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- astrocytes
- ependymal cells - microglial cells - oligodendrocytes |
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fibrous astrocyte
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many IFs
white matter |
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protoplasmic astrocyte
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gray matter
granular cytoplasm |
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function of astrocytes
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support for neurons
blood brain barrier scar formation K+ uptake from cerebral fluid release of Ca2+ uptake of neurotransmitters |
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oligodendrocytes
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myelin formation in CNS
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ependymal cells
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present in cerebral ventricles
produce CSF (ciliated, simple cuboidal epi.) |
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microglial cells
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macrophages located in vicinity of blood cells --> chemotaxis and phagocytosis
- produce ILs and neutrophins - increased in inflammation |
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electrolytes conc.
CSF = plasma (4) |
Na+
Cl- HCO3- osmolarity |
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electrolyte conc.
CSF < blood |
K+
Ca2+ glucose cholesterol protein - negligible |
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electrolyte conc.
CSF > blood |
Mg2+
creatinine |
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Blood Brain Barrier
- made of (1) - permeable to (2) - impermeable to (3) |
1 = astrocytes, basal mb, endothelium
2 = O2/CO2, ethanol, steroids, lipophilic substances 3 = proteins, hmw substances |
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ventral horn
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cells bodies of somatic efferent N.
- motor area - contains a-MN and y-MN |
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dorsal horn
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cell bodies of interneurons where afferent N. terminate
- sensory area |
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intermediate horn
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centres of ANS esp. SNS
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Bell-Magendie law
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impulses enter the spinal cord via dorsal roots and leave the spinal cord via ventral roots
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Reflex Arc (5)
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1. sensory receptor
2. afferent neuron 3. centre 4. efferent neuron 5. effector |
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muscle spindle detects changes in (1) and therefore, mediates (2)
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1 = muscle length (stretch)
2 = proprioception |
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intrafusal fiber
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8-10 fibers in parallel with muscle
middle of muscle spindle attached to sides of extrafusal mm. fibers or tendons contractive ends |
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two types of intrafusal fibers
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nuclear bag fibers
nuclear chain fibers |
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group Ia and II sensory fibers provide info about (1)
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static response
--> info about steady state length of muscle |
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dynamic stretch reflex
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primary endings on nuclear bag fibers, with rapid discharge and rapid muscle contraction
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static response reflex
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primary endings on nuclear chain fibers, with slow stretching and maintenance of muscle tone
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coactivation
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signals from motor cortex are sent to both alpha and gamma MNs
--> contracts both intrafusal and extrafusal fibers at same time --> keeps muscle spindles from opposing mm. contraction |
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Functions of Stretch Reflex
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maintains muscle tone (static)
adaptation of muscle tone to increased load prevention of oscillation and jerkiness of muscle |
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Golgi tendon organ detects (1).
Sends (2) fibers to inhibitory interneurons. Effect = contracts (3), relaxes (4) |
1 = muscle tension
2 = Ib fibers 3 = contracts antagonist 4 = relaxes agonist |
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function of inverse stretch reflex
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prevents muscle damage
maintains muscle tone |
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Clasp-knife reflex
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resistance to passive stretch followed by relaxation
- response of spastic muscle to lengthening |
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Withdrawl Reflex
- receptor (1) - afferent neuron (2) - centre (3) - efferent neuron (4) - effectors (5) |
1 = naked nerve endings (C fibers)
2 = II, III nerve fibers 3 = polysynaptic (inhibitory interneurons, motor neurons) 4 = motor axons 5 = flexors contract, extensors relax |
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afterdischarge
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prolonged repeated firing of motor neurons
ex. strong pain stimulus activates reverberating interneuron circuits |
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Lower Motor Neuron
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alpha motor neuron in ventral horn
brain stem for mm's of head and neck |
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LMN lesion (5)
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1. loss of voluntary control of movement
2. flaccid paralysis 3. loss of spinal reflexes 4. muscle atrophy 5. oscillations of mm. fibers |
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spinal shock - symptoms
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- fall of arterial BP
- loss of: heat reg. reflexes, sacral reflexes, spinal reflexes, voluntary movement and sensation - decreased muscle tone |
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2-5 weeks following spinal shock
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- neurovegetative reflexes return
- muscle tone is spastic - spinal reflex hyperactive - sacral reflexes returned |
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Renshaw cells
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- lateral inhibition
- stimulation of each motor neuron tends to inhibit adjacent motor neurons |
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pyramidal system
- what type of movement? |
voluntary movement
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supplementary motor area
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programs motor cortex when performing complex, sequential movements
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posterior parietal cortex
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body image
- appreciation of sensory input from contralateral side of body |
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motor homunculus
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medial = leg, trunk, arm, fingers, face = lateral
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lesion of motor cortex
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weakness and spasticity, with increased muscle tone and increased resistance to passive stretch
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pyramidal tract
- (1) percent of fibers cross midline at medulla forming the (2) - (3) percent cross midline at spinal cord forming the (4) |
1 = 80%
2 = lateral pyramidal tract 3 = 20% 4 = medial pyramidal tract |
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lesion in lateral pyramidal tract
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- disrupts fine motor control
- lateral tract innervates DISTAL mm. |
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lesion in ventral corticospinal tract
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- disrupts walking, balance etc.
- ventral tract innervates PROXIMAL mm. (axial mm) |
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pyramidal tract fibers terminate on:
70 % (1) 15 % (2) 15 (3) |
1 = inter neurons
2 = alpha motor neurons 3 = dorsal horn of spinal cord |
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Upper Motor Neuron Lesion
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loss of voluntary activity
increased muscle tone (spastic) spinal reflexes hyperactive positive Babinski sign |
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Babinski sign
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dorsiflexion of big toe
plantar flexion (fanning) of little toes |
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Structures making up the basal ganglia
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putamen
globus pallidus caudate nucleus substantia nigra subthalamic nucleus |
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Parkinson's disease
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degeneration of dopaminergic neurons in substantia nigra (pars compacta
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Features of Parkinson's disease
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rigidity
resting tremor akinesia bradykinesia shuffling gait dementia |
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Huntington's Disease
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loss of GABA and cholinergic neurons in basal ganglia
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Features of Huntington's
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hyperkinesis
decreased muscle tone |
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vestibulocerebellum
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control of posture and equilibrium
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spinocerebellum
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control of fine movement of limbs
proprioception |
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corticocerebellum
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planning and sequencing of movements
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Role of Cerebellum
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control of muscle tone
postural control control of voluntary mm. contraction planning and sequencing of movement |
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cerebellar lesion
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disturbance of equilibrium
dysmetria ataxia adiadokinesis (inability to perform rapidly alternating movements) dysarthria intention tremor nystagmus |
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dentate cerebellar nucleus
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info concerning actual position and tone of muscles
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fastigial cerebellar nucleus
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control of posture
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cuboiformus/globus nucleus
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control of agonist and antagonist muscles of peripheral limbs
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decerebrate rigidity
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transection of brainstem between superior and inferior colliculi
--> reticulospinal tracts remain intact --> hyperactivity in all 4 extremities |
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where is the reticular formation located?
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midventral part of the medulla and midbrain
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gigantocellular nucleus
- secretes what nt? (1) - function? (2) |
1 = Ach
2 = awake and excited nervous system |
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locus ceruleus
- secretes what nt? (1) - function? (2) |
1 = NE
2 = excites brain, REM sleep |
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nuclei raphe
- secretes what nt? (1) - function? (2) |
1 = 5HT
2 = suppresses pain, NREM sleep |
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substantia nigra
- secretes what nt? (1) - function? (2) |
1 = DA
2 = inhibitory in basal ganglia, excitatory elsewhere |
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Functions of reticular formation
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- heart rate, blood pressure, respiration, swallowing, sneezing, vomiting
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Upper Reticular Formation
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controls state of brain activity
- RAS = consciousness, alertness - thalamus = sleep |
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Lower Reticular Formation
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regulation of muscle tone and spinal reflexes
- has a facilitatory area and an inhibitory area (for REM sleep) |
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Which motor neurons does the lower reticular formation project to?
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gamma motor neurons
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What kind of feedback does the cortex send to RAS?
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positive feedback --> leads to further arousal and activation
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effect of general anesthesia on RAS
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blocks RAS = loss of consciousness
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evoked cortical potentials
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seen in anesthesized individuals -- otherwise blocked by normal brain activity
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primary evoked cortical potential
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highly specific localization
observed where the path of a particular sensory receptor ends |
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secondary evoked potential
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involves the whole cortex, series of waves throughout --> responsible for excitatory state of cortex
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What does an EEG record?
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summation of cortical post-synaptic potentials in neurons on neocortex (NOT due to currents associated with AP)
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synchronization (on EEG)
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due to simultaneous firing of large groups of neurons
low frequency, high amplitude a-waves 8-12 hZ non-REM sleep |
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desynchronization (on EEG)
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due to firing of small groups of neurons in sequential order
high frequency, low amplitude B-waves 13-30 Hz mental arithmetic, eyes open |
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alpha waves (EEG)
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8-12 Hz
at rest, with eyes closed parietoocciptal area |
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beta waves (EEG)
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13-30Hz
when attention is focused on something i.e. math frontoparietal area |
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theta waves (EEG)
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4-7 Hz
hippocampus, parietotemporal region studying/creation of memory in children adults --> emotional distress, degenerative brain states |
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delta waves (EEG)
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1-4 Hz
occur in deep sleep, infancy, serious organic disease located in whole cortex |
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NREM sleep
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deep
restful 4 stages absence of desynchrony sleep spindles, delta waves no dreams no eye movements some activity of skeletal mm. |
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REM sleep
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irregular EEG waves, PGO spikes
dreaming increased HR, respiration consolidation of memory EEG resembles awake stage |
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Stage 1 Sleep
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low voltage, mixed frequency pattern, theta waves
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Stage 2 Sleep
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sinusoidal "sleep spindles"
occasional biphasic K complexes |
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Stage 3 Sleep
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high amplitude
delta rhythm body repair (body temp decreases) |
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Stage 4 Sleep
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max slowing with large waves
deep sleeps shows synchronization (REM) |
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REM sleep shows increased brain activity in (1) and decreased brain activity in (2)
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1 = pontine area, amygdala, cingulate gyrus
2 = decreased activity in prefrontal/parietal cortex |
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PGO spikes aka. (1)
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1 = pontogeniculooccipital spikes
--> large phasic potentials that originate in cholinergic neurons of pons and pass rapidly to LGB and occiptal lobe |
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What are the 2 roles of the suprachiasmatic nucleus?
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- sleep wake cycle
- secretion of melatonin from pineal gland |
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Effect of 'x' on sleep?
- serotonin ? (1) - caffeine ? (2) - PgD2 ? (3) |
1 = 5HT - suppresses sleep
2 = adenosine antagonist 3 = NREM sleep |
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adequate stimulus of sensory receptor
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each receptor is highly sensitive to one type of stimuli and the threshold for other stimuli is much higher
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Doctrine of Specific Nerve Energies aka. MULLER LAW
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sensation evoked is dependent on the kind of receptor stimulated, NOT on the ligand
--> quality of stimulus is encoded by pathway of transmission |
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Law of Projection
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conscious sensation produced is referred to the location of receptor, no matter where the pathway is stimulated ex. phantom limb
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pacinian receptor
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pressure
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meissners corpuscle
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touch
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GTO/muscle spindle
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kinesthetic
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free nerve endings
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pain, warmth, cold
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sensory receptor potential
i.e. LINE code |
amplitude is directly proportional to the intensity of stimulus
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Phasic Receptors
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adapt rapidly, signal rate of touch i.e. no frequency code (only at beginning and end)
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Tonic Receptors
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adapt slowly
signal amplitude of skin indentation have frequency code |
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Ex. of Phasic Receptors (2)
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Pacinian corpuscle
Meissners |
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Ex. of Tonic Receptors (4)
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merkel cells
ruffini endings mm. spindles nociceptors |
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two point discrimination test
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min. distance that can be felt between 2 caliper points that is perceived as different
--> measure of tactile acuity --> tests integrity of dorsal column medial lemniscal pathway |
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Anterolateral Pathway
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pain
thermal sensations crude touch pressure tickle/itch sexual sensations crude localization |
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Dorsal Column Pathway
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fine touch
vibration proprioception |
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Ablation of Somatic Sensory Area 1
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deficits in positional sense
inability to discriminate size and shape deficits in sensory processing in SII |
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2 Kinds of Pain receptors
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free nerve endings
vanilloid receptors |
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What activates VR-1?
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capsaicin
high temperature protons |
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What activates VRL-1 receptors?
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only temperatures above 50 C
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Slow pain is mediated by (1) fibers and (2)
Slow pain has (3) localization and projects to (4) |
1 = unmyelinated C fibers
2 = substance P 3 = poor localization 4 = RAS |
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Fast pain is mediated by (1) fibers and (2)
Fast pain has (3) localization and projects to (4) |
1 = alpha delta fibers
2 = glutamate 3 = exact localization 4 = thalamus and SI/SII |
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Gate Control Hypothesis
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can inhibit pain pathways in dorsal horn gate by stimulation of large diameter touch-pressure afferents
--> pain gate is located in spinal cord and is mediated by enkephalins |
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endogenous opioids system
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enkephalins
binds mi, kappa and delta opioid receptors |
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Visceral Pain is an example of (1) pain that is (2) localized.
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1 = slow pain
2 = poorly localized (diffuse, referred) |
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Parietal pain is an example of (1) pain that is (2) localized
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1 = rapid pain
2 = well localized (sharp, strong) |
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convergence projection theory of referred pain
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- convergence of somatic/visceral pain fibers on same 2ndary neurons that project to thalamus and then dorsal horn
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What structures make up the limbic system?
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cingulate gyrus
septum pellucidum olfactory bulb amygdala hippocampus thalamus |
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Role of Limbic System?
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creation of emotions
motivation and addiction role in memory sexual behavior also controls vegetative structures |
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After removal of which structures does a person show an abnormal rage response?
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neocortex
VMH septal nuclei |
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reward area of brain is mediated by (1) neurons located in the (2), (3), (4), (5)
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1 = dopaminergic neurons
2 = medial forebrain bundle 3 = ventral tegmentum 4 = nucleus accumbens 5 = dorsal brain stem |
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punishment area of brain is mediated by (1) neurons located in (2), (3) and (4)
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1 = cholinergic neurons
2 = posterior hypothalamus 3 = dorsal midbrain 4 = entorhinal cortex |
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What is the rational brain? and what is its role?
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rational brain = prefrontal cortex
--> modulates and inhibits emotional reactions of limbic system |
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What brain area is responsible for addiction?
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nucleus accumbens (dopaminergic neurons)
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Which dopamine receptor plays a role in schizophrenia?
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D2
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Which dopamine receptor plays a role in addiction?
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D3
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Which receptors do hallucinogens activate?
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5HT
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Role of serotonin
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inhibition of pain
NREM sleep wakefullness |
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Medial hypothalamus contains which nuclei?
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ventromedial nucleus (satiety)
arcuate nucleus (endocrine control) |
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anterior hypothalamus contains which nuclei?
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paraventricular and supraoptic nuclei (ADH, OT)
suprachiasmatic nucleus |
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Role of Hypothalamus
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modulation of ANS
control of endocrine functions regulation of circadian rhythms main centres of homeostatic regulation |
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the anterior hypothalamus affects (1) nervous system and causes (2)
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1 = parasympathetic
2 = urinary bladder contraction |
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the lateral hypothalamus affects the (1) nervous system and causes (2)
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1 = sympathetic
2 = increased heart rate, BP etc. |
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which area of hypothalamus is responsible for decrease of body temperature?
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ANTERIOR hypothalamus
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which area of hypothalamus is responsible for increase of body temperature?
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POSTERIOR hypothalamus
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which brain area responsible for control of body temperature?
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preoptic area
--> releases PGs responsible for change in temp. set point during fever |
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Where is the feeding centre located?
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lateral hypothalamus
--> bilateral lesion = lethal starvation |
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where is the satiety centre located?
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ventromedial hypothalamus
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3 satiety signals?
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increased temperature
increased leptin increased glucose |
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Where is leptin synthesized?
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white adipocytes from ob gene
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function of leptin?
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inhibits food intake
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what are the magnocellular neurons?
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paraventricular - OT
supraoptic - ADH |
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which are of hypothalamus is osmolarity regulated?
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anterior hypothalamus
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non-declarative memory is considered (1) and involves (2), (3), (4) and (5).
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1 = implicit
2 = skills/habits 3 = conditioning 4 =nonassociative learning 5 = priming |
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declarative memory involves (1) and is memory for (2) and (3)
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1 = awareness/concsiousness
2 = semantics (words) 3 = episodic (events) |
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what are the 2 forms of implicit memory?
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nonassociative --> habituation, sensitization
associative --> skills/habits, conditioning, priming |
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habituation
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single stimulus, repeated many times --> organism eventually ignores the stimulus and shows a decrement in response
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sensitization
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enhancement of a behavioral response to a stimulus when it is coupled with a novel stimulus to the animal
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Mechanism of habituation
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decrease release of nt because of decreased Ca2+ influx at PRE terminal (gradual inactivation)
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mechanism of sensitization
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increase in synaptic transmission due to increased Ca2+ influx at PRE
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long term potentiation is mediated by which receptors? and which neurotransmitter?
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1 = NMDA receptors on POST neuron
2 = glutamate |
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retrograde amnesia
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inability to recall former events
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anterograde amnesia
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inability to form new long term memory
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Role of Prefrontal Association Area
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planning voluntary movement
making plans for future moral laws |
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Left Hemisphere
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- dominant hemisphere
- categorical - math - analysis - conclusions - language |
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lesions of LH result in ?
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language disorders
depression |
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Right Hemisphere
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- representational
- spatio-temporal relation - creativity - facial recognition - non verbal communication |
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lesion of RH results in ?
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feeling of euphoria
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fluent aphasia
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Wernickes area
--> normal words, but speech makes no sense |
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nonfluent aphasia
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brocas area
--> know what to say, but cannot articulate |
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anomic aphasia
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angular gyrus
--> difficulty understanding written word |
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conduction aphasia
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arcuate fasciculus
--> speak well and comprehend but cant form words together |
