Nervous Tissue

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Nervous Tissue
2012-03-01 00:23:21
Nervous Tissue

Nervous tissue
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  1. endocrine system
    communicates by means of chemical messengers (hormones) secreted into the blood
  2. nervous system
    • employs electrical and chemical means to send messages very quickly from cell to cell
    • Three basic steps: 1. thru sensory nerve endings recieves info about changes in body and external environment and messages to the spinal cord and brain, 2. spinal cord and brain process this info, relate it to past experience and determine what response, if any is appropriate to the circumstances, 3. spinal cord and brain issue commands primarily to muscle and gland cells to carry out such responses
  3. neurobiology
    • study of nervous system
    • primary subdisciplines' neuroanatomy and neuropysiology
  4. central nervous system (cns)
    consists of the brain and spinal cord, which are enclosed and protected by the cranium and vertebral column
  5. peripheral nervous system (pns)
    • consists of all the nervous system except the brain and spinal cord
    • composed of nerves and ganglia
    • functionally divided into sensory and motor divisions
  6. nerve
    • bundle of nerve fibrons (axons) wrapped in fibrous connective tissue
    • emerge from teh CNS through foramina of the skull and vertebral column and carry signals to and from other organs of the body.
  7. ganglion
    knotlike swelling in a nerve where the cell bodies of neurons are concentrated
  8. Sensory (afferent) division
    • carries sensory signals from various receptors to the CNS
    • -somatic sensory division carrries signals from receptors in the skin muscles, bones and joints
    • -visceral sensory division carries signals mainly from the viscera of the thoracic and abdominal cavities, such as the heart, lungs, stomach and urinary bladder
  9. Motor (effferent) division
    • carries signals from the CNS to gland and muscle cells that carry out the body's responses
    • -somatic motor division carries signals to the skeletal muscles, produces muscular contractions that are under voluntary control, as well as involuntary muscle contractions called somatic reflexes
    • visceral motor division (autonomic nervous system) carries signals to glands, cardiac, muscle, and smooth muscle. Usually have no voluntary ctrl of these effectorsfurther divisible into sympathetic division and parasympathetic division
  10. Excitabilty
    ability to respond to environmental changes (stimuli)
  11. Conductivity
    neurons respond to stimuli by producing traveling electrical signals that quickly reach other cells at distant locations
  12. Secretion
    when the electrical signal reaches the end of a nerve fiber, the neuron usually secretes a chemical called a neurotransmitter that crosses a small gap between cells and stimulates the next cell
  13. Sensory (afferent)
    • neurons specialized to detect stimuli such as light, heat, pressure, and chemicals and to transmit info about them to the CNS
    • can begin in almost any organ of the body but always end in brain or spinal cord
  14. interneurons (association neurons)
    • lie entirely within the CNS
    • recieve signals from many other neurons and carry ot the integrative function of the nervous system- process, store and retrieve info and make decisions about how to respond to stimuli
    • lie between and interconnect incoming sensory pathways and the outgoing motor pathways of the CNS
  15. Motor (efferent)neurons
    • send signals predominantly to muscle and gland cellls
    • effectors that carry out the body's responses to stimuli
    • most lead to muscle cells
  16. Neurosoma
    • aka soma or cell body
    • centrally located nucleus with a large nucleolus