PPT

• Nervous System


  The major controlling, regulatory, and communicating system in the body. It is the center of all mental activity including thought, learning, and memory.
• Nervous System

  • Composed of organs, principally the brain, spinal cord, nerves, and ganglia. These, in turn, consist of various tissues, including nerve, blood, and connective tissue.
• Structure of a typical neuron

  • Dendrite
  • Soma
  • Nucleus
  • Axon
  • Myelin sheath
  • Schwann cell
  • Node of Ranvier
• Four Basic Functions of the Human Nervous System

  • Gathers information both from the outside world and from the inside of the body
  • Transmit information to the processing areas in the brain and spinal cord
  • Processes information to determine the best response
  • Sends information to muscles, glands and organs so they can respond correctly
• Stimuli


  Changes that the nervous system keeps your body working properly despite the constant changing taking place around you
• May responses of the nervous system are voluntary
• Neuron


  The basic functional units of structure and function of the nervous system. It carries the messages/ information through the nervous system in the form of nerve impulses.
• Parts of the Neuron

  • Cell Body
  • Dendrites
  • Axons
  • Axon Terminals
• Cell Body


  The largest part of the neurons which contains the nucleus
• Dendrites


  Tiny, branching, threadlike structures which receive and carry information toward the cell body
• Axons


  Long taillike structure that carries messages away from the cell body
• Parts of the Neuron

  • Myelin Sheath
  • Axon Terminals
  • Schwann cell
  • Node of Ranvier
• Myelin Sheath


  Covers the axon and speeds up the travel of the nerve impulses
• Axon Terminals


  Feather-like fibers at the end of the axon which pass the messages to the dendrites of another neurons
• Schwann cell

  Node of Ranvier, gaps between Schwann cell
• Types of Neurons

  • Sensory
  • Interneuron
  • Motor Neuron
• Sensory Neurons


  Also called the afferent neurons. Function is to receive initial stimuli from sense organs where more receptors are located.
• Interneurons


  Also called the connector neurons or association neurons. Read impulses received from sensory neurons. Found in the spinal cord and brain.
• Motor Neurons


  Also called the efferent neurons. Function is to stimulate effector cells. Through this neurons, the messages from the brain and spinal cord are sent to a muscle cell or gland cell in your body.
• Nerve Impulses


  A wave of chemical and electrical change that is conducted along the membrane of a neuron, which is basically from sensory to interneuron to motor neuron.
• Synapse


  The tiny gap between neurons where nerve impulses are ferried across by a chemical signal/ messenger called neurotransmitter.
• Parts of the Nervous System

  • Central Nervous System: Brain and Spinal Cord
  • Peripheral Nervous System: The nerves in the rest of your body
• Central Nervous System


  Receives sensory information from the nervous system and controls the body's responses. It plays a primary role in receiving information from various areas of the body and then coordinating this activity to produce the body's responses.
• The Brain - 3 Major Areas

  • Cerebrum (telencephalon, diencephalon)
  • Cerebellum
  • Brainstem (midbrain, pons, medulla oblongata)
• Cerebral Cortex - 4 Major Lobes

  • Parietal
  • Frontal
  • Temporal
  • Occipital
• Frontal Lobes


  Associated with higher cognition, voluntary movements, and language
• Occipital Lobes


  Associated with visual processes
• Parietal Lobes


  Associated with processing sensory information
• Temporal Lobes


  Associated with hearing and interpreting sounds as well as the formation of memories
• Diencephalon - 2 Major Parts

  • Thalamus
  • Hypothalamus
• Thalamus


  Relays stimuli received from all sensory neurons to cortex for interpretation. Relays signals from the cerebral cortex to the proper area for further processing.
• Hypothalamus


  Monitors many parameters like temperature, blood glucose levels, various hormone levels. Helps maintain homeostasis. Signals the pituitary via releasing factors. Signals the lower neural centers.
• Cerebellum


  Located behind the brainstem. Helps monitor and regulate movement. Integrates postural adjustments, maintenance of equilibrium, perception of speed, and other reflexes related to fine tuning of movement.
• Brainstem


  • Composed of midbrain, pons, and medulla oblongata
• Brainstem


  Maintains vegetative functioning. Where the respiratory control center and cardiovascular control center are located. Reflexes.
• Protective Structure of Central Nervous System

  • Enclosed in bone (skull and vertebra)
  • Covered with protective tissue known as meninges
  • Immersed in cerebrospinal fluid
• Spinal Cord


  Connects to the brain via the brain stem and then runs down through the spinal canal, located inside the vertebra. Motor commands from the brain travel from the spine to the muscles and sensory information travels from the sensory tissues such as the skin toward the spinal cord and finally up to the brain. The spinal cord contains circuits that control certain reflexive responses and can also generate more complex movements such as walking.
• Parts of the Spine

  • Vertebrae
  • Facet joints
  • Intervertebral disks
  • Spinal cord and nerves
  • Soft tissues
• Five Spine Segments

  • Cervical (neck)
  • Thoracic (middle back)
  • Lumbar (lower back)
  • Sacrum
  • Coccyx (tailbone)
• The length of the spinal cord varies from person to person. According to some estimates, females have a spinal cord of about 43 centimeters (cm), while males have a spinal cord of about 45 cm.