Nervous system

Nervous system

Functions
1. Sensory input
2. Integration
3. Homeostasis
4. Mental Activity
5. Control of skeletal muscle
Central Nervous System
1. Brain and spinal cord
Peripheral Nervous System
1. 31 pairs of spinal nerves and all neural tissue outside of CNS
  1. 12 Thoratic nerves
  2. 5 Lumbar nerves
  3. 1 coccygeal nerve
  4. 5 sacral nerves
  5. 8 cervical nerves
2. 12 pairs of cranial nerves
3. Afferent division
  1. Sensory info to CNS via ascending pathway
4. Efferent division
  1. Motor info to glands and muscles via descending pathway
  2. Somatic nervous system
    1. Skeletal muscle
  3. Autonomic muscle system
    1. Smooth muscle, Cardiac muscle, Glands
    2. Sympathetic
      1. Ganglion close to CNS
    3. Parasympathetic
      1. Ganglion close to organ
Cellular organisation in neural tissues
1. Neurons
  1. Communication
  2. Large, prominent centrally located nucleus, lot of mitochondria, lot of Nissl bodies (RER) for neurotransmitter production
  3. Axons
    1. Long cell process
    2. Single structure or branch= collateral axons
    3. Carry impulse away from body
  4. Dendrites
    1. Short, highly branching cytoplasmic extenstion
    2. Sensory messengers to be processed
  5. Cytoskeleton
    1. neurofilament- architecture
    2. Microtubules - axinal transport
  6. Synaptic terminals
    1. Synapse communication with other cell
2. Neuroglia
  1. Support, Defence and Myelination (insulation)
  2. Oligodendrocytes
    1. Myelination in CNS
  3. Astroglia
    1. White matter - fibrous astrocyte
    2. Grey matter protoplasmic astrocyte
  4. Microglia
    1. Phagocyte in CNS
  5. Ependymal cells
    1. Cubodial or low columnar lining in central spinal canal, no basement membrane, lining ventricles in cerebrum rest on basement membrane and secrete cerebral spinal fluid
  6. Schwann cells
    1. Myelination in PNS
    2. Support non-myellinated axons which bury themselves into the schwann cell cytoplasm
Functional classifications
1. Sensory
  1. Unipolar - single neuron process from cell body
2. Interneurons
  1. Bipolar neuron - 1 dendrite, 1 axon
3. Motor
  1. Multipolar- single axon, many dendrites
Spinal reflexes
1. Stimulus Receptor Sensory neuron Motor neuron Effectors Response
2. No interneuron in reflex arc of knee jerk
Myelin
1. Spiral of membrane wrapped around axon
2. Increase speed of conduction along axon
3. Space between small units = nodes of Ranvier
4. Multiple sclerosis, myelin of CNS attacked by immune system, destruction results in severe functional deficits, such as paralysis, loss of sensation and/ or loss of coordination

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	Erstellt von Colleen Curley vor fast 9 Jahre