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Brianna Cabrera P.1 Nervous System - Coggle Diagram

- - - - Made up of the brain and spinal cord.
      - Responsible for integration of information and decision-making.
    - - Made up of cranial and spinal nerves that connect the CNS to the rest of the body.
      - Contains sensory (afferent) and motor (efferent) divisions
      - Motor functions
        
        Somatic nervous system controls voluntary skeletal muscles.
        
        Autonomic nervous system controls involuntary effectors (smooth and cardiac muscles and glands).
- - - - Microglia: small cells that function as phagocytes for bacterial cells and cellular debris, and produce scar tissue in sites of injury.
      - Oligodendrocytes: form the myelin sheath around axons in the brain and spinal cord.
      - Ependymal cells: produce cerebrospinal fluid in CNS.
      - Astrocytes: lie between blood vessels and neurons; functions: Structural support
        
        Forms a blood-brain barrier, which protects brain
        tissue from chemical fluctuation and prevents entry of many substances.
    - - Schwann cells: the myelin-producing neuroglia of the PNS.
      - Satellite cells: provide protective coating around cell bodies of
        neurons in the PNS.
  - - - Dendrites conduct impulses toward the cell body; they are short and branching, and they provide the receptive surface for communication with other neurons.
      - The axon conducts impulses away from the cell body; it arises from a thickening extending from the cell body, called the axon hillock.
      - The cell body (soma) contains major organelles including nucleus.
    - - Narrow gaps in the myelin sheath are called nodes of Ranvier.
      - Myelin Sheath increases conduction speed of nerve impulses.
      - Larger axons are enclosed by myelin sheaths; they are called myselinated fibers.
    - - CNS axons are myelinated by oligodendrocytes, which don't have a neurilemma, so they usually do not regenerate.
      - Damaged PNS neurons are able to regenerate their axons
- - - - Carries information from a sensory neuron to a motor neuron.
  - - - Carries instructions from a brain or spinal cord out to effector.
  - - - Carries information from a receptor into the brain or spinal cord.
  - - - Responds to stimulation (or inhibition) by motor neuron and produces reflex or behavioral action.
  - - - Senses specific type of internal or external change.
- - - - Four lobes of the cerebrum are names according to the bones: frontal, parietal, temporal, and occipital lobes.
        
        The surface of the brain are marked as Gyri (singular is gyrus): ridges. Sulci (singular is sulcus):grooves. Fissures are deep groves like the longitudinal and transverse fissure.
- - - - Threshold stimulus is received. Sodium channels in the trigger zone of the axon open.
        
        Sodium ions diffuse inward, depolarizing the axon membrane.Potassium channels in the axon membrane open.
        
        Potassium ions diffuse outward, repolarizing the axon membrane. The resulting action potential causes a local electric
        current that stimulates the adjacent portions of the axon membrane.
        
        A series of action potentials occurs along the axon.
- - - - Sympathetic division: active in conditions of stress or emergency (fight or flight).
        
        Preganglionic fibers in the sympathetic division arise from
        neurons in the gray matter in the thoracic and lumbar regions of the spinal cord (T1 – L2).
        
        Axons exit the spinal cord via ventral roots of spinal nerves. Axons then leave the spinal nerves, and proceed into the
        sympathetic (paravertebral) ganglia, a chain of sympathetic ganglia close to the vertebral column on each side.
        
        They synapse with postganglionic neurons, whose long axons return to spinal nerves and then proceed to a visceral effector.
      - Parasympathetic division: active under normal, restful
        conditions (rest and digest).
        
        Long preganglionic fibers in the parasympathetic division arise
        from the brainstem and sacral region of the spinal cord.
        
        The preganglionic fibers extend outward in cranial or sacral nerves, and synapse in terminal ganglia close to or in visceral effector organs.
        
        Short postganglionic fibers continue into the effector organs
        (muscles or glands).