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Nervous and Sensory systems - Coggle Diagram

- - - - The CNS is made up of the brain and the spinal cord. The brain is the largest and most complex portion of the nervous system. It controls perception, movement, sensation, thinking, and many other physiological aspects
  - - - it regulates and maintains homeostasis. The nervous system is fast acting and communicates with cells by electrical Cells of the nervous system
      - Neurons
        
        Each neuron consists of a cell body, soma, with extensions called an axon and one or more (sometimes many) extensions called dendrites.
        
        Dendrites receive electrical nerve impulses and conduct them toward the cell body and the axon.
        
        Axons conduct nerve impulses away from the cell body. Most neurons have a single axon arising from the axonal hillock on the cell body.
        
        Neurons are closely associated with neuroglia
        
        Neuroglia comprise almost half the brain and spinal cord tissue and are much more numerous than neurons. They support, nourish, and protect neurons.
        
        CNS neurons are not able to replace themselves if injured or destroyed, although there may be a few exceptions.
        
        Types of neurons
        
        Sensory (aerent)
        
        Conduct action potentials toward the CNS. Sensory neurons detect the internal and external environments (such as from the skin and viscera) and facilitate motor coordination (such as in joints and muscles).
        
        Motor (eerent)
        
        conduct action potentials away from the CNS toward muscles or glands
        
        Interneuron
        
        Conduct action potentials within the CNS from one neuron to another, primarily between sensory and motor neurons
    - - A cell membrane’s surface is usually electrically charged (polarized) compared with its inner contents. This is due to unequal amounts of positive and negative ions. Adequate stimulation of a neuron causes generation of an electrical impulse in response.
        
        An action potential is a change in neuron membrane polarization and a return to its resting state. An action potential forms a nerve impulse propagated along an axon
    - - Chemical synapses release and receive chemical neurotransmitters. Information is transferred across chemical synapses beginning when an action potential arrives at an axon terminal
      - Electrical synapses are less common than chemical synapses. Electrically coupled neurons allow
        for rapid transmission across electrical synapses
      - The actions of neurotransmitters include effects on sleeping, anger, thinking, hunger, movement, memory, and many other functions.Synaptic transmission is commonly affected by either the enhancing or inhibiting effects of neurotransmitters, their destruction, or the blocking of receptor binding. Anything that reduces neurotransmitter activity may slow the brain’s ability to communicate with the rest of the body