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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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The Brain

• Cerebrum

• Diencephalon

• Cerebellum

• Brain stem

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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

• 1st and 2nd

– Right and left lateral ventricles

• 3rd

– Connected to the lateral ventricles by the interventricular foramen

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Ventricles of the Brain

• 4th

– Connected to the 3rd 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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Disorders

• Meningitis

• Encephalitis

• Epilepsy

• Cerebral palsy

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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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Headaches

• Tension

• Migraine

• Cluster