Nervous system

• Has two divisions
• Peripheral nervous system (PNS)
• Central nervous system (CNS) - brain, spinal cord
• Functions of the central nervous system

  Sensory input(receives signals from external environment)

  integration(analyze and interpret information)

  motor output(feedback from the CNS ignites movement in the muscles for a response)
• Peripheral nervous system


  somatic and motor divsion
• somatic sensory division


  carries signals from the skeletal muscles, bones and joints
• visceral sensory division


  carries signals from the viscera or internal organs like the heart, lungs, kidneys and so many others
• somatic motor division


  carries signals to the the skeletal system
• visceral motor division


  carries signals to the the internal organs
• The nervous tissue


  has the axons(conductive), dendrites(receptive) and cell body(soma)
• The cell body


  also known as soma. control centre of the nervous tissue/ neuron
• dendrites


  carries signals towards the cell body
• axon


  carries signals away from the cell body
• telodendria


  terminates the axon terminal
• axolemma


  membrane that wraps around the axon
• axon hillock


  makes the axon smaller in order for the myelin sheath to wrap around the axon
• Neuroglial cells in CNS

  astrocytes: support and anchor blood vessels, maintain the extracellular environment, repair damaged tissue.

  oligodendrocytes: insulation and myelination

  microglial cells: act as phagocytes

  ependymal cells: secrete the cerebrospinal fluid
• neuronal synapse


  communication between neurons
• structural types of neuronal synapses

  axosomatic: between the cell body of one neuron and the axon of another neuron

  axodendritic: between dendrite of one neuron and axon of another neuron

  axoaxonic: between axon of one neuron and axon of another neuron
• Presynaptic neuron


  send signals through the axon terminal
• postsynaptic neuron


  receives signals from the cell body, dendrite and axon of another neuron
• synaptic transmission


  transfer of electric/ chemical signals between neurons via a synapse
• electric synapse


  between cells that are electrically joined through gap junctions
• chemical synapse


  they are the majority present in the nervous system
• The CNS


  cerebrum

  cerebellum

  diencephalon

  brain stem
• Cerebrum


  maintains higher mental functions
• sulcus


  shallow groove
• fissure


  deeper grooves
• gyrus


  ridges
• Lobes of the brain


  frontal(planning and executing function)

  parietal(processing and analyzing info)

  insula(internal organs and taste)

  temporal(emotions, sound)

  occipital(vision)
• white matter


  myelinated
• gray matter


  unmyelinated
• Diencephalon


  maintains homeostasis and regulates movements
• Part of the diencephalon

  Thalamus(regulates cortical activity)

  hypothalamus(boss, regulates the ans(involuntary)

  epithalamus(pineal gland that secretes melatonin for the sleep wake cycle)

  subthalamus(controls movement)
• Cerebellum


  plans and coordinates movement
• Lobes of the cerebellum

  anterior

  posterior

  flocculonodular
• Brainstem


  relays information
• part of the brainstem

  midbrain

  pons

  medulla oblongata