Part 1 - Anatomy and Physiology of Nervous System

• Nervous system


  Coordinates all body functions, enabling a person to adapt to changes in internal and external environment
• Main components of the nervous system

  • Nerve cells (neurons)
  • Supporting cells (neuroglia)
• Functional and structural divisions of the nervous system

  • Central nervous system (brain and spinal cord)
  • Peripheral nervous system (cranial nerves and spinal nerves)
• Functional divisions of the peripheral nervous system

  • Somatic nervous system (controls skeletal muscles)
  • Autonomic nervous system (controls visceral organs)
  • Enteric nervous system (controls digestive system)
• Somatic nervous system (SNS)

  Activated when a person experiences a stressful situation, to help the person survive and adapt
• Parasympathetic nervous system (PNS)


  Activated after the SNS, to help the nervous system adjust, survive and recover from whatever situation it has encountered
• Neuron


  The basic conducting cell of the nervous system, highly specialized but cannot reproduce itself
• Main parts of a neuron

  • Soma (cell body)
  • Axon
  • Dendrites
• Axon


  Responsible to allow conduction of impulses away from the cell body
• Myelin sheath


  Responsible to cover and protect the axon, a damaged or peeling myelin sheath will cause impaired impulse conduction
• Dendrites


  Short, thick, diffuse branching processes that receive impulses and conduct them towards the cell body
• Remarkably, the human brain has just as many neurons as would be expected of a generic primate brain of its size and the same overall 1:1 nonneuronal/neuronal ratio as other primates
• Synapse


  The region where communication occurs between 2 neurons or between a neuron and a target cell, via neurotransmitter release
• Types of neuroglia


  • Oligodendrocytes (produce myelin in cranial nerves)
  • Schwann cells (produce myelin in peripheral nervous system)
• At age 20, the average weight of the male brain is approximately 1400 g, and by the age of 65 brain weight is approximately 1300 g. Brain weight for females follows a similar trend, although the total weight is 100–150 g less than that of males.
• Gross structures of the brain

  • Cerebrum
  • Cerebellum
  • Brainstem (pons, medulla, midbrain)
  • Diencephalon (thalamus, hypothalamus, pineal body)
• Corpus callosum


  Responsible to allow communication between the 2 hemispheres of the brain
• Cerebrum


  • Largest part of the brain, consists of right and left hemispheres connected by the corpus callosum, each hemisphere has different lobes
• Frontal lobe


  Influences personality, responsible for judgment, abstract reasoning, social behavior, language expression and motor movement
• Temporal lobe


  Controls hearing, language comprehension, storage and recall of memories, contains the limbic system which controls basic drives
• Parietal lobe


  Principal center for reception and interpretation of sensation, interprets size, shape, distance and texture
• Occipital lobe


  Functions mainly to interpret visual stimuli
• Speech areas in the cerebrum

  • Wernicke's area (responsible for sensory reception of speech)
  • Broca's area (responsible for motor speech)
• Cerebellum


  Second largest brain region, functions to maintain muscle tone, coordinate muscle movement, posture and control balance/equilibrium
• Components of the brainstem

  • Midbrain
  • Pons
  • Medulla oblongata
• Brainstem


  Houses the center for respiration and cardiovascular system
• Midbrain


  Connects with the cerebrum, contains ascending and descending tracts and fibers, exit points for cranial nerves II, III, IV
• Pons


  Connects the cerebellum with the cerebrum, houses the respiratory and cardiovascular centers, exit points for cranial nerves V, VI and VII
• Medulla oblongata


  Most inferior portion of the brainstem, serves as the center for autonomic reflexes to maintain homeostasis, regulate respiratory, vasomotor and cardiac functions, exit points for cranial nerves VIII, IX, X, XI and XII
• Diencephalon


  The thalamus is the relay station of all sensory stimuli towards the brain, the hypothalamus controls body temperature, appetite, water balance, pituitary secretions and sleep-wake cycle
• Basal ganglia and substantia nigra


  A group of subcortical nuclei responsible primarily for motor control, as well as other roles such as motor learning, executive functions and behaviors, and emotions. Parkinson's disease is caused by loss of nerve cells in the substantia nigra resulting in decreased dopamine.
• Pituitary gland


  The master gland that regulates growth, metabolism, and reproduction through the hormones it produces, under the control of the hypothalamus
• Pituitary lobes


  • Anterior lobe (secretes majority of hormones)
  • Posterior lobe (secretes oxytocin and antidiuretic hormone)