BSC 2085 Exam 4 Study Guide Lesson 16 Cont starts with question 3 according to class today 1 Describe the difference between the gray and white matter found in the spinal cord a White matter Is superficial i ii Contains myelinated axons b Gray matter i Surrounds central canal of spinal cord ii Contains neuron cell bodies neuroglia unmyelinated axons iii Has projections gray horns 2 Explain the function of the gray horns of the spinal cord a Posterior gray horns contain somatic and visceral sensory nuclei b Anterior gray horns contain somatic motor nuclei c Lateral gray horns are in thoracic and lumbar segments contain visceral motor nuclei d Gray commissures i Axons that cross from one side of cord to the other before reaching gray matter 3 Explain the function of the white columns of the spinal cord a Posterior white columns lie between posterior gray horns and b Anterior white columns lie between anterior gray horns and posterior median sulcus anterior median fissure i Anterior white commissure area where axons cross from one side of spinal cord to the other c Lateral white columns located on each side of spinal cord between anterior and posterior columns d Tracts or fasciculi are bundles of axons in the white columns i Relay same information in same direction ii Ascending tracts Carry information to brain iii Descending tracts Carry motor commands to spinal cord 4 Describe the connective tissue layers covering the spinal nerves a Epineurium Outer layer i Dense network of collagen fibers b Perineurium Middle layer i Divides nerve into fascicles axon bundles c Endoneurium Inner layer i Surrounds individual axons 5 Describe the locations and function of the major nerve plexuses a Spinal nerves i Form lateral to the intervertebral foramen at the foramen the dorsal and ventral roots unite then branch and form pathways to destination b Motor nerves i Dorsal and ventral rami 1 Dorsal ramus a Contains somatic and visceral motor fibers b Innervates the back ii Ventral ramus 1 Larger branch 2 Innervates ventrolateral structures and limbs i In addition to motor impulses dorsal and ventral rami also carry sensory information c Sensory nerves d Dermatomes a Divergence b Convergence i Bilateral region of skin ii Monitored by specific pair of spinal nerves 6 Describe the five different patterns of neural circuits found in neuronal pools i Spreads stimulation to many neurons or neuronal pools in CNS visual info goes to visual cortex and postural balance areas i Brings input from many sources to single neuron subconscious and conscious control of breathing i Moves information in single line relay of pain info c Serial processing d Parallel processing i Moves same information along several paths simultaneously step onto nail you withdraw foot shift weight feel pain and scream e Reverberation i Positive feedback mechanism ii Functions until inhibited iii May help maintain consciousness muscle coordination and A mechanism for spreading stimulation to multiple neurons or neuronal pools in the CNS normal breathing A mechanism for providing A mechanism in which neurons input to a single neuron from multiple sources or pools work sequentially A mechanism in which A positive feedback mechanism neurons or pools process the same information simultaneously Lesson 17 a Reflex 7 Explain what is a reflex and the components of the reflex arc i Automatic responses coordinated within spinal cord through interconnected sensory neurons motor neurons and interneurons 1 Produces both simple and complex reflexes 2 Preserves homeostasis by making rapid adjustments in organs organ systems function 3 Each time a particular reflex is activated produces the same motor response ii Neural Reflexes 1 Rapid automatic responses to specific stimuli 2 Basic building blocks of neural function 3 One neural reflex produces one motor response b Reflex Arc i The wiring of a single reflex ii Beginning at receptor iii Ending at peripheral effector iv Generally opposes original stimulus negative feedback 8 Describe the five steps in a neural reflex a Step 1 Arrival of stimulus activation of receptor i Physical or chemical changes b Step 2 Activation of sensory neuron i Graded depolarization leads to action potential generation c Step 3 Information processing by postsynaptic cell i Triggered by neurotransmitters d Step 4 Activation of motor neuron i Action potential generated in motor neurons e Step 5 Response of peripheral effector i Triggered by neurotransmitters cause skeletal muscle contraction 9 Describe how reflexes are categorized a By early development i Innate reflexes Formed before birth 1 Basic neural reflexes 2 Ex Withdrawal from pain chewing suckling tracking objects with eyes ii Acquired reflexes Learned motor patterns 1 Rapid automatic 2 Ex Riding a bike pressing on brakes b By type of motor response i Nature of resulting motor response ii Somatic reflexes Involuntary control of muscular system Includes 1 Superficial reflexes of skin mucous membranes 2 Stretch or deep tendon reflexes e g patellar or knee jerk reflex ex Plantar reflex iii Visceral reflexes autonomic reflexes Control systems other than muscular system ex Consensual light reflex c By complexity of neural circuit i Monosynaptic reflex only 1 synapse in reflex arc 1 Sensory neuron synapses directly onto motor neuron ii Polysynaptic reflex more than 1 synapse in reflex arc 1 At least one interneuron between sensory neuron and motor neuron 2 Five General Characteristics of Polysynaptic Reflexes a 1 Involve pools of interneurons may be excitatory flexor cross extensor refllex or inhibitory tendon reflex b 2 Are intersegmental in distribution c 3 Involve reciprocal inhibition d 4 Have reverberating circuits i Which prolong reflexive motor response e 5 Several reflexes cooperate i To produce coordinated controlled d By site of information processing i Spinal reflexes response 1 Occur in spinal cord 2 Range in increasing order of complexity a From simplest to most complex b Monosynaptic reflexes c Polysynaptic reflexes d Intersegmental reflex arcs i Many segments interact ii Produce highly variable coordinated motor response iii Remember the more synapses the slower the reaction synaptic delay ii Cranial reflexes 1 Occur in brain Acquired Reflexes 10 Explain the difference between monosynaptic and polysynaptic reflexes a Monosynaptic Reflexes i One synapse ii A stretch reflex iii Have the least delay between sensory input and motor output 1 For example stretch
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