Chapter 8
Central Nervous System
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CNS Functions
• Communication and coordination system in the body
• Seat of intellect and reasoning
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The Nerve Cell
• Called the neuron
• Nucleus, cytoplasm, and cell membrane
• Dendrites
• Axons (only one per cell)
– Neurilemma or myelin sheath
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Nervous Tissue/Cells
• Neuroglia
• Neurons
– Sensory or afferent
– Motor or efferent
– Associative or interneurons
• Membrane excitability
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Synapse
• When messages go from one cell to the next cell
• Synaptic cleft
• Neurotransmitters
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Animation – Firing of
Neurotransmitters
Click Here to play Firing of
Neurotransmitters animation
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Divisions of the Nervous System
• Central nervous system
– Brain
– Spinal cord
• Peripheral nervous system
– 12 pairs of cranial nerves
– 31 pairs of spinal nerves
– Autonomic nervous system
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Effects of Aging
• Slowing nerve conduction
• Loss of brain size
• Slowing of reaction time
• Changes in sleep patterns
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The Brain
• Weighs about 1400 grams or 3 pounds
• 100 billion neurons
• Meninges and cerebrospinal fluid
• Without oxygen, brain damage occurs within
4-8 minutes
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• Cerebrum
• Diencephalon
• Cerebellum
• Brain stem
The Brain
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The Brain
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Memory
• Storage of old and new information
• Role of the hippocampus
• Short or long term memory
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Coverings of the Brain
• Dura mater
• Arachnoid mater
• Pia mater
• Cerebrospinal fluid
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Ventricles of the Brain
• Four lined cavities filled with cerebrospinal fluid
• 1 st and 2 nd
– Right and left lateral ventricles
• 3 rd
– Connected to the lateral ventricles by the interventricular foramen
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Ventricles of the Brain
• 4 th
– Connected to the 3 rd by the cerebral aqueduct
• Choroid plexus
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CSF
• Formed inside the four ventricles
• Formation and flow of CSF (cerebrospinal fluid)
• Blood-brain barrier
• Lumbar puncture
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Cerebrum
• Largest part of the brain
• Weighs about 2 pounds
• Cerebral cortex
• Two hemispheres and longitudinal fissure
• Fissures and sulci
• Gyri or convulutions
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Five Major Fissures
• Longitudinal fissure
• Transverse fissure
• Central fissure
• Lateral fissure
• Parieto-occipital fissure
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Cerebral Functions
• Frontal lobe
• Parietal lobe
• Occipital lobe
• Temporal lobe
• Limbic lobe or system
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Diencephalon
• Located between the cerebrum and the midbrain
• Thalamus
• Hypothalamus
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Hypothalamus
• Autonomic nervous control
• Cardiovascular control
• Temperature control
• Appetite control
• Water balance
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Hypothalamus
• Manufacture of oxytocin
• Gastrointestinal control
• Emotional state
• Sleep control
• Mind-over-body experiences
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Cerebellum
• Located behind the pons and below the cerebrum
• Right and left cerebellar hemispheres connected by vermis
• Communicates with the rest of the CNS by three pairs of tracts called peduncles
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Cerebellar Function
• Maintenance of balance
• Maintenance of muscle tone
• Coordination of muscle movements
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Brain Stem
• Midbrain
• Pons
• Medulla oblongata
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Spinal Cord
• Begins at foramen magnum of the occipital bone
• Ends at the second lumbar vertebrae
• 31 pairs of spinal nerves
• Protected by meninges and other tissues
• White and gray matter
• Functions
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• Meningitis
• Encephalitis
• Epilepsy
• Cerebral palsy
Disorders
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Disorders
• Poliomyelitis
• Hydrocephalus
• Parkinson’s disease
• Essential tremor
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Disorders
• Multiple sclerosis
• West Nile virus
• Dementia
• Alzheimer’s disease
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Disorders
• Brain tumors
• Hematoma
• Spinal cord injuries
– Quadriplegia
– Paraplegia
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• Tension
• Migraine
• Cluster
Headaches
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