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Ψ Brain's Building Blocks
- Overview: Human Brain -

Ψ  Genes: are basic, functional units of heredity, each occupying a specific place on a chromosome. The instructions contained within them produce "you".

   •  The adult brain is a relatively small organ, weighing about 3 pounds.Three major divisions of the brain are recognized:

   1. Forebrain - The paired cerebral hemispheres: the cerebrum.

   2. Midbrain - The brain stem, from which the cranial nerves emerge, consisting of the thalamus & hypothalamus, the midbrain, the pons, & the medulla oblongata.

   3. Hindbrain -The cerebellum a.k.a. "little brain”, plays an important role in the integration of sensory perception & motor output.

Cellular Structure of the brain

   • Neuron: a cell specialized to conduct and generate electrical impulses and to carry information from one part of the brain to another.

   • Glial (GLEE-all) cells: Nerve tissue of the central nervous system other than the signal-transmitting neurons. these cells are found interspersed between the neurons (which transmit the nerve signals) & provides support & insulation to them.

   • Growth of new neurons in human brains is supported by research!

   • Repairing the brain after injury also occurs through rewiring.

   • The Mind-Body question asks how brain & mind influence each other.

Neurons: Structure & Function

•  Link to neuron structure with picture

Three basic structures of the neuron:

   • Cell body: In nerve cells, this is the central portion containing the cell nucleus, from which axons and dendrites sprout. The cell body is primarily concerned with carrying out the life-sustaining functions of a cell.
   • Dendrites: Branched extensions of the nerve cell body which receives signals from other nerve cells. Each nerve cell usually has many dendrites.
   • Axon: The long, hair like extension of a nerve cell that carries a message to a nearby nerve cell.

Axon parts:

   • Myelin sheath: A sheath of white, fatty protein (myelin) that covers and acts as an electrical insulator for nerve fibers.
   • End bulbs (neurotransmitter)

   • The synapse is a tiny gap between the ends of nerve fibers across which nerve impulses pass from one neuron to another; at the synapse, an impulse causes the release of a neurotransmitter, which diffuses across the gap and triggers an electrical impulse in the next neuron.

Nervous System - 2 Parts

   • Peripheral nervous system: The nervous system beyond the brain and spinal cord. The nerves in this system connect the central nervous system (the brain and spinal cord) to sensory organs, body organs, blood vessels, glands and muscles.
      • Has the ability to re grow.

   • Central nervous system: the portion of the vertebrate nervous system consisting of the brain and spinal cord.
      • Re growth or repair of neurons is very limited.

Sending Information

   • Sequence: action potential:
  1. Feeling a sharp object
  2. Axon membrane: chemical gates open
  3. Ions: charged particles
  4. Resting state: Axon's chemical batteries charged by a Sodium pump.
  5. Action potential: sending information
   • Sequence: nerve impulse:
  6. Sending information is done by nerve impulse down the axon.
  7. All-or-None law states the once started the pulse will go all the way.
  8. Nerve impulse notes:
    • Once begun, the impulse goes to end of the axon.
    • The action potential fires at the breaks in the myelin sheath.
  9. End bulbs trigger neurotransmitter release.

General Psychology
Robert C. Gates