Nervous System II

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Nervous System II

• Organization and Evolution

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Sympathetic and Parasympathetic Divisions of the
Autonomic Nervous System

• Nerves emerge from thoracic and lumbar spine
• Preganglionic NT is acetylcholine
• Ganglia are near spinal cord
• Postganglionic NT is norepinephrine (adrenergic
  response)
• Fight or flight response increase heart rate,
  decrease GI tract activity, increase blood
  glucose levels, etc...

• Nerves emerge from cervical and sacral spine
• Preganglionic NT is acetylcholine
• Ganglia are near target organs
• Postganglionic NT is acetylcholine (cholinergic
  response)
• Antagonistic to sympathetic decrease heart rate,
  increase GI tract activity, etc...

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Body mass and Brain mass
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Evolution of the Mammalian Brain
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Brain Vocabulary

• White matter myelinated axons
• Gray matter unmyelinated axons, neuron cell
  bodies and dendrites
• Cerebrospinal fluid circulates through brain and
  spinal cord, serves as shock absorber and
  delivers nutrients, white blood cells and
  hormones
• Meninges 3 layers of tissue that surround and
  protect the brain and spinal cord (Dura mater,
  arachnoid and pia mater)

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Meninges
http//inside.salve.edu/walsh/meninges.gif
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Regions of the Brain

• Hindbrain (brainstem) Medulla oblongata, pons,
  cerebellum, reticular formation
• Midbrain(brainstem) contains the inferior and
  superior colliculi, substantia nigra (dopamine
  production)
• Forebrain(Diencephalon and Telencephalon)
  Thalamus, hypothalamus, suprachiasmatic nucleus,
  cerebrum

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The Hindbrain and Midbrain (Brainstem)

• Medulla oblongata controls autonomic,
  homeostatic functions breathing, heart rate and
  blood vessels, digestion, emesis (vomiting)
• Pons helps regulate breathing, conducts info
  between higher brain spinal cord
• Cerebellum coordination of movement, body
  position, hand-eye coordination
• Reticular formation regulates state of arousal,
  acts as a sensory filter
• Inferior colliculi receives integrates
  auditory info
• Superior colliculi receives integrates visual
  reflexes, some perception

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Brain Cross Section
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Forebrain-Diencephalon (lower part of forebrain)

• Thalamus sorts out sensory input and relays to
  appropriate part of cerebrum
• Hypothalamus homeostatic regulation sets body
  temperature, regulates hunger, thirst, pleasure,
  mating behaviors sexual response,
  fight-or-flight. Conatins the suprachiasmatic
  nucleus (SCN), which regulates circadian rhythms

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The Cerebrum
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Forebrain-Telencephalon (upper part of forebrain)

• Right and Left Cerebral hemispheres more on that
  later
• Corpus callosum connects right hemisphere to
  left. Many sensory and motor nerves cross here,
  so right optic nerve goes to left visual cortex,
  nerves from left motor cortex go to right side of
  body
• Basal ganglia helps coordinate motor responses

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The Cerebral Cortex

• Less than 5 mm thick, but surface area 0.5 m2,
  makes up 80 of total brain mass
• Occipital lobe visual cortex
• Temporal lobe auditory (hearing)and olfactory
  (smell) cortex
• Parietal lobe somatosensory cortex, taste,
  Wernickes area (language comprehension)
• Frontal lobe motor cortex, Brocas area
  (speech), frontal association area (complex
  cognitive processing)

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The Limbic System

• Composed of parts of the thalamus, hypothalamus
  and parts of the cerebral cortex (amygdala,
  hippocampus, olfactory bulb)
• Functional center of emotions and memory
• Fear is particularly associated with the amygdala

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And there is so much more to learn.