The Nervous System Part II

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The Nervous System Part II

• The Central Nervous System

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There are four parts of the brain

• Cerebrum
• Cerebellum
• Diencephalon
• Brain stem

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The Cerebrum

• Has four types of lobes
• Frontal
• Two parietal
• Two temporal
• Occipital

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Physical characteristics of the cerebrum

• Cerebral cortex outer covering of brain
• Gyre ridges
• Sulci indentions
• Fissures deep indentions creating lobes
• Corpus callosum
• Left and right hemispheres

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The cerebral cortex

• The executive suite of the nervous system
• Outer covering of the brain
• Conscious mind,
• Consists of neurons, cell body dendrites and
  unmyelinated axons

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Functions of the cerebrum

• Center of conscious thought
• Personality
• Center of memory
• Consciousness
• Emotions
• Sleeping and dreaming

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Sleeping and dreaming

• EEG
• Dreams we all do it
• Storage and dream organization
• Four levels of brain activity
• Beta fast and busy
• Alpha relaxed, awake but eyes closed
• Theta drowsy
• Delta deep sleep

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Which are you?

• Left Brain

• Right Brain

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The cerebellum

• Center for motor coordination, movement, balance,
  walking, physical skills and speaking
• Vermis sits atop the two hemispheres holding them
  together

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The diencephalon

• Sits atop the brain stem
• Has three areas of importance
• Thalamus
• Hypothalamus
• Epithalamus

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Thalamus

• A relay station for sensory impulses passing to
  cerebral cortex
• Receives messages saying you have touched
  something hot and tells frontal lobe to initiate
  movement of hand

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Hypothalamus

• Plays a role in metabolism, water balance and
  body temperature
• Center for drives and emotions such as thirst,
  pain, appetite, sex, and pleasure centers
• The link between your psyche (mind) and soma
  (body)
• Regulates pituitary gland

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Epithalamus

• Contains choroids plexus where cerebral spinal
  fluid is formed
• Open chambers in the brain with fluid for
  insulation, absorption of shock and lubrication

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Brain stem

• Mid brain
• Pons
• Respiratory center
• Lies just above medulla
• Medulla oblongata
• Attaches to spinal cord

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Medulla oblongata

• Heart rate, respiration, blood pressure and
  swallowing
• Passes through foramen magnum
• About one inch in length

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Protections of the nervous system

• A. Bony Protection
• Skull
• Vertebral column

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B. Membranous protection

• Meninges protects the brain and spinal cord.
  Continuous with the brain
• Pia mater innnermost layer against brain and
  spinal cord
• Arachnoid layer spider web
• Dura mater outermost layer
• Cerebrospinal layer

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C. A watery cushion

• Cerebrospinal fluid

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D. Blood brain barrier

• Capillaries which keep bacteria and viruses from
  the brain
• Some things that can happen if the barrier fails
  to work
• Meningitis inflammation of the meninges
• Encephalitis inflammation of the brain
• Hydrocephalus water on the brain

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The spinal cord
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Location

• Continuous with the lowermost part of the brain
  and extends to the conus terminals
• 31 pairs of spinal nerves connect it with the
  rest of the body

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Actions

• Acts as a conduction pathway and reflex center
• White matter
• Composed of bundles of myelinated nerve fibers
• Gray matter H shaped. Contains neurons,
  neuroglia and cell bodies
• Cell bodies - dendrites, and axon terminals of
  unmyelinated axons, etc.

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Protected by

• Three layers of membranes
• A surrounding fluid - cerebrospinal
• Formed primarily from blood
• Helps in nutrient and waste exchange
• Can be removed during lumbar punction for
  analysis
• Bony spinal column

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Functions

• Sensory tracts carry impulses to the brain
• Motor tracts carry impulses from brain to
  effectors

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Thirty one pairs of nerves

• 8 cervical
• 12 thoracic
• 5 lumbar
• 5 sacral
• 1 coccygeal

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Cauda equina

• Lumbar and sacral roots collectively
• Means horses tail

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This is the

• END of the CNS slide show!!!