The Nervous System - flashcards

Amelia Claire
Flashcards by Amelia Claire, updated more than 1 year ago
Amelia Claire
Created by Amelia Claire over 4 years ago
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the nervous system

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Question Answer
Afferent Division Carries Sensory Information from the Peripheral Nervous System sensory receptors to the Central Nervous System. "INCOMING DIVISION"
Efferent Division Carries Motor Commands from the Central Nervous System to the Peripheral Nervous System, muscles and gland. "OUTGOING DIVISION"
Somatic Nervous System The Somatic Nervous System controls: Skeletal muscle contractions (a voluntary response to stimuli) AND Reflexes (an involuntary response to stimuli)
Autonomic Nervous System The Autonomic Nervous System regulates: Smooth muscle tissue, cardiac muscle and glandular secretions (subconscious response) Sympathetic and Parasympathetic divisions
Sensory Neurons AFFERENT Neurons of the PNS Deliver information FROM Sensory Receptors TO the CNS
Somatic Sensory Neurons Monitor the external conditions
Visceral Sensory Neurons Monitor the internal conditions
Sensory Receptors Proprioceptors (position in space and movement) Exteroceptors (external/outside) Interoceptors (internal/inside)
Motor Neurons EFFERENT Neurons of the PNS Deliver information FROM the CNS to the peripheral EFFECTORS
Somatic Motor Neurons Innervate Skeletal Muscle
Visceral Motor Neurons Innervate "other" effectors (e.g. smooth muscle)
Anaxonic Neuron Anaxonic Neurons have more than two processes and they are all dendrites. They have NO axon.
Bipolar Neuron Bipolar Neurons have two processes separated by the cell body. They have only one dendrite, with dendritic branches at the distal tip. They occur in special sense organs and relay information about sight, smell, or hearing.
Unipolar Neuron (pseudounipolar neuron) Unipolar Neurons have a single elongated process with the cell body off to the side. Most sensory neurones of the Peripheral Nervous System are Unipolar Neurons. Axons can extend a metre or more (e.g.. toes to spine), ending at synapses in the Central Nervous System.
Multipolar Neurons Multipolar Neurons have more than two processes; there is a single son and multiple dendrites, They are the most common neuron in the Central Nervous System. All the motor neurons that control skeletal muscle are multipolar. Their axons can be very long (e.g. spine to toes)
Ependymal Cell (Central Nervous System) Ependymal Cells line ventricles of the brain and the central canal of the spinal cord. They assist in producing, circulating and monitoring Cerebrospinal Fluid (CSF)
Astrocyte (Central Nervous System) Astrocytes maintain the blood-brain barrier, provide structural support, regulate ion, nutrient and dissolved gas concentrations. They absorb and recycle neurotransmitters. They may form scar tissue after injury.
Ogliodendrocytes (Central Nervous System) Ogliodendrocytes myelinate the Central Nervous System axons, provide structural framework,
Microglia (Central Nervous System) Microglia remove cell debris, waste, and pathogens by phagocytosis.
Satellite Cells (Peripheral Nervous System) Satellite cells surround neuron cell bodies in ganglia, regulate O2 and CO2, nutrient and neurotransmitter levels around the neurones in the ganglia.
Schwann Cells (Peripheral Nervous System) Schwann Cells surround all axons in the Peripheral Nervous System, are responsible for the myelination of peripheral axons and participate in repair processes after injury.
Graded Potential transient, occurs in dendrites and soma. Size and Duration determined by input size and duration. Does NOT usually move into axon. Synapse closer to trigger zone may result in an action potential.
Action potential does not decay with distance like graded potential - conducted down axon unchanged all or none potential
Synapse where two neurons meet - usually axon/dendrite
Leak Channels Always open
Voltage Gated Channels Open/Close when membrane crosses a voltage value
Refractory Period difficult/impossible to trigger another potential in this part of the membrane
EPSP excitatory post synaptic potential
IPSP inhibitory post synaptic potential
temporal summation the addition of stimuli occurring in rapid succession at a single synapse that is active repeatedly.
spatial summation occurs when simultaneous stimuli applied at different locations (synapses) have a cumulative effect on the membrane potential
CNS brain and spinal cord
spinal cord passage of sensory information to the brain, passage of motor information from brain to defectors, integrates information and controls spinal reflexes
posterior - sensory PS anterior - motor AM
central canal of spinal cord (ependymal canal) CSF space, runs longitudinally, continuous with ventricular system of brain
dorsal root ganglia dorsal = sensory DRG = cell bodies of sensory neurons
dorsal root dorsal = sensory dorsal root = axons of sensory neurons
ventral roots ventral = motor ventral roots = axons of motor neurons
gray matter forms butterfly shape around central canal. dominated by cell bodies of neurons, neuroglia, unmyelinated axons. Nuclei = masses of gray matter = functional group. integrates info and initiates commands.
white matter - tracts carry info into and out of CNS superficial to grab matter, large number of myelinated and unmyelinated axons. ascending tracts carry sensory info descending tracts carry motor info LOGICAL
spinal nerves surrounded by 3 layers epineurium - outer, collagen. perineurium - forms fascicles (bundles of axons) endoneurium - surrounds individual axons
dermatone monitored by spinal nerves - specific region,
spinal reflexes rapid, automatic responses triggered by specific stimuli controlled by spinal cord alone. interconnected sensor, motor, and interneurons. producer simple and complex reflexes.
reflex arc stimulus sensed by receptor sensory neuron transmits signal from PNS to CNS integration centre decodes Motor neuron sends direction back, effector responds
stretch reflex monosynaptic stimulus - > receptor (muscle spindle) - > effector stretch and contract allows load to be added to muscle.
golgi tendon reflex skeletal muscle contraction causes agonist to lengthen and relax - inverse of stretch reflex, protects from excessively heavy loads.
withdrawal reflex ipsilateral (same side) polysynaptic moves affected part of body away - reciprocal inhibition crossed extensor similar, but crosses body.
polysynaptic reflexes pools of interneurons intersegmental distribution extend across spinal segments reciprocal inhibition reverberating circuits prolonged motor response coordinated and controlled
receptors touch - tactile / mechano pressure - mechano temperature - thermo pain - nociceptor body position - proprioceptor somatosensory cortex interprets
tonic recptors always active - slow to adapt
phasic receptors only active sometimes quick to adapt
somatosensory pathways first order neuron - delivers info to CNS 2nd order neuron 3rd order neuron spinothalamic posterior column spinocerebellar
spinothalamic pathway touch, pain crosses at spinal cord arrives at primary sensory cortex
posterior column pathway touch, vibrations, proprioception crosses at medulla oblongata arrives at sensory cortex
spinocerebellar pathway proprioception crosses at spinal cord ends at cerebellum
somatic nervous system - corticospinal pathway higher and lower nerouns medial - gross lateral - fine
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