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Objectives• Understand how the nervous system is organized
• Know the various cell types that are found in nervous tissue and their function
• Identify and understand the function of the various parts of the central nervous system
• Define and know what memory is
• Understand how a reflex arc works
Neurons and Glial Cells• Three functional classes of
neurons– Afferent
• sensory
– Interneurons
– Efferent• motor
• Four types of glial cells– Astrocytes
• Spatial orientation and support• Synapse formation
– Thrombospondin• Repair and barrier formation• Nourish• Degradation of neurotransmitters• K+ regulation
– Oligodendrocytes• myelination
– Microglia• Immune protection• Nerve growth factor
– Ependymal cells• Internal lining of CNS• Production of CSF• Neural stem cells
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Protection and Nourishment• Skull
• Meninges– Dura mater– Arachnoid mater– Pia mater
• Cerebral Spinal fluid– Secreted by choroid plexus– Rich in Na+
• Blood-brain barrier– Anatomical and physiological
barrier
•Oxygen– neuroglobin
•Glucose
csuchico.edu
Overview of CNS• Brain and spinal cord
• Brain organization– Forebrain
• Cerebrum– Cerebral cortex– Basal nuclei
• Diencephalon– Thalamus – Hypothalamus
– Cerebellum– Brain stem
• Midebrain• Pons • medulla
open-source-cranio.com
Cerebrum• Composed of two hemispheres divided into four lobes
– Frontal• Voluntary motor skills, speaking, though
– Parietal• Somatosensory processing
– Temporal• Auditory processing
– Occipital• Visual processing
– Hemispherical specialization• Left – logical and analytic• Right – creative and artisitic
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Motor and Sensory Humunculi
• Use-dependent competition– Modifications
based on use
• Plasticity– Ability to be
functionally remodeled
structural-communication.com
Electroencephalogram (EEG)
• Record of postsynaptic activity in cortical neurons– EPSPs or IPSPs
• Uses– Brain dysfunction– Brain death– Sleep stages
Basal Nuclei and Diencephalon• Basal Nuclei
– Regulatory inhibition of motor control
– Divided into four regions of grey matter• Caudate nucleus• Putamen• Globus pallidus• Claustrum
– Associated with Parkinson’s disease
• Diencephalon– Thalamus
• Relay station for sensory input
• Also involved in motor control
– Hypothalamus• Integrates and regulates
important homeostatic functions– Body temp– Thirst – Adenohypophysis control
The Limbic System
• Associated with learning and emotions
• Controls basic behavioral patterns– Reward and punishment centers– Motivation – ability to direct behavior to toward
specific goals
• Norepinephrine, dopamine, and seratonine
Learning and Memory
• The acquisition of knowledge or skills as a consequence of experience or instruction
• The storage of acuired knowledge for later recall
• Memory traces– Neural changes
responsible for storage of knowledge
Short-term Memory• Involve temporary modifications in the function of
preexisting synapses
• Two types– Habituation
• Decreased responsiveness to a repetitive indifferent stimulus• Ca2+ channels do not readily open
– Sensitization• Increased responsiveness to mild stimuli following a strong stimulus • Ca2+ channel open and stay open longer
– K+ influx prevented
• Long term Potentiation– Modifications due to increased use, connection gets stronger the more it is
used– Transition to long term memory
Long-Term Memory
• Involves formation of new, permanent synaptic connections
• Immediate early genes– Play a role in memory consolidation– Genes may encode for proteins that are necessary
for synapse formation, production of neurotransmitters, answer not clear yet
Memory Traces in the Brain• Hippocampus– Declarative memory
• The “what’ memories of specific people, places, objects, facts (semantic) and events (episodic)
• Cerebellum– Procedural memories
• “how to” memories involving repetitive motor skills
• Prefrontal cortex– Working memory
• Memory necessary to integrate information that is relevant now
Cerebellum
• Balance and coordination
• Three regions– Vestibulocerebellum
• Balance and controls eye movements– Spinocerebellum
• Enhances muscle tone and coordinates voluntary movements
– Cerebrocerebellum• Plans and initiates voluntary activity by providing input to
cortical motor areas– Procedural memory
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Brain Stem• Link between spinal cord and high brain
– Medulla, pons, midbrain
• 12 cranial nerves arise from brain stem
• Cardiac, respiratory, and digestive control centers
• Reticular formation (RAS)
• Regulates muscle reflexes involved with euilibrium and posture
• House the sleep center
Spinal Cord
• Slender tube that extends from the brain stem and goes through vertebral column
• Gives rise to 31 pairs of spinal nerves– Cervical, thoracic, lumbar, sacral, coccygeal
• Grey matter core, white matter on the periphery– White matter organized into tracts
• Begin and end in specific brain regions and transmit specific information
Spinal Tracts• Ascending tracts
– Carry sensory information up
• Descending tracts– Carry motor input down
• Horns of spinal cord– Dorsal
• Synapse with sensory neurons
– Ventral• Cell bodies of motor
neurons– Lateral
• Fibers supplying cardiac and smooth muscle, glands
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