Nervous System

• Integrative function

  Brain and spinal cord analyze, process, and interpret information to decide the response. Information is stored for body changes
• ANS


  Controls involuntary processes. Contains sensory neurons conveying information from viscera to CNS
• PNS


  Nerve cells reach every part of the body. Carries impulses. Contains spinal nerves
• Nervous system

  • Three main functions: sensory, integrative, motor
• PNS components

  • Somatic Nervous System (SNS)
  • Autonomic Nervous System (ANS)
• Nervous Tissue

  • Neuroglia
  • Neurons
• Organisation of the nervous system

  • Central Nervous System (CNS)
  • Peripheral Nervous System (PNS)
• Cell body


  Metabolic center containing nucleus, cytoplasm, organelles specific to neurons
• Neurons


  Responsible for sensory responses, integrative and motor functions of the nervous system
• Neuron consists of a dendrite, cell body, and axon
• Axon


  Transmitting portion of the cell, transmits nerve impulses away from the cell body
• SNS


  Allows control over skeletal muscles. Contains sensory neurons
• Spinal nerves

  Emerge from the spinal cord, carry impulses to and from the body. Contains sensory and motor (efferent) neurons
• Motor function


  Action/response to stimulus by glandular secretions or muscular contractions
• Sensory function

  Stimulus provokes a response (voluntary/involuntary), can be inside or outside the body
• CNS

  Brain and spinal cord analyze, store information, make decisions, and issue orders. Memories made, thoughts and emotions generated
• Neuroglia


  Support cells in the nervous system, insulate, nurture, protect neurons, maintain homeostasis
• ANS branches

  Sympathetic nervous system and Parasympathetic nervous system work in opposition to maintain homeostasis
• Axon terminals


  Found at the end of the axon, contain synaptic vesicles storing neurotransmitters
• Dendrites


  Receiving portion of the cell, short, branching processes projecting from the cell body
• Anatomy of the Brain

  1. Brain weighs around 1.3kg in an adult

  2. Brain consists of 4 regions: Brain stem, Cerebellum, Diencephalon, Cerebrum
• Surroundings of the Connective Tissue

  • Endometrium surrounds each nerve fiber
  • Perineurium surrounds a group of nerve fibers called fasicles
  • Epineurium binds fasicles together and covers the outer nerve
• Parts of a nerve

  • Neuron
  • Nerve
  • Connective tissue
  • Endometrium
  • Perineurium
  • Epineurium
• Functions of the Spinal Cord

  1. Transports nerve impulses from the periphery of the body to the brain and vice versa

  2. Relieves and integrates information and produces reflex actions
• Multiple sclerosis is an unpredictable disease of the central nervous system that disrupts the flow of information within the brain and body
• MS is a disabling disease where the immune system attacks the protective sheath (myelin) covering nerve fibers, causing communication problems between the brain and the body
• Structure of a nerve

  1. Neuron consists of a dendroid, cell body, and axon

  2. Nerve is a bundle of neurons

  3. Neurons bond together to become a connective tissue
• Classification of nerves

  • Sensory
  • Motor
  • Mixed nerves
• Synaptic vesicles


  • Found at the end of the axon and contain membrane-enclosed sacs
  • Store chemical substances called neurotransmitters that influence other neurons, muscle fibers, or gland cells
• The cause of MS is believed to be a combination of genetic and environmental factors
• Protection of the Brain

  1. Brain is protected by hard bones of the cranium

  2. Brain is surrounded by three layers of connective tissues called meninges

  3. Brain floats in cerebrospinal fluid
• Signs and symptoms of MS

  • Numbness or weakness in limbs
  • Electric shock sensations
  • Tremor
  • Loss of vision
  • Double vision
  • Blurry vision
  • Slurred speech
  • Fatigue
  • Tingling in body parts
  • Problems with sexual, bowel, and bladder function
• Anatomy of the Spinal Cord

  1. Spinal cord has protected spinal messages

  2. Spinal cord is covered by dura mater, arachnoid, and pia mater
• Motor Neuron

  • cell body
  • dendrites
  • axon