NERVOUS LECTURE

• Nervous System


  • Comprises spinal cord and brain
  • Helps regulate 'homeostasis' and integrates all body activities by sensing changes (sensory), interpreting them (integrative) and reacting to them (motor)
• Neurology


  The branch of medical science that deals with the study of normal functioning and disorders of the nervous system
• Neurologist


  Medical specialist in the diagnosis and treatment of disorders of the nervous system
• 3 Main Functions of the Nervous System

  • Receive sensory input from internal and external environment
  • Integration (Integrate the input)
  • Motor output (Respond to stimuli)
• Brain

  • Divided into two hemispheres, the left side and the right side
  • The left and right hemispheres need to integrate
• Motor output


  How the brain reacts to the stimuli
• Central Nervous System

  • Divided into two: the brain and the spinal Cord
  • The adult human brain weighs about 1.3kg body weight, constitutes 2% of total body weight
  • It is a mass of pinkish grey, jelly-like tissue made up of 1 billion neurons and neuroglia
  • It is the control centre for all body activities and human emotions
• Each muscle is innervated by a nerve or neurons. You cannot move a muscle without a neuron
• Neuron


  • Cell of the nervous system
  • Receive input, process input, produce response
  • Require oxygen and glucose (Glucose - gives energy to the body)
• Structure of Neuron

  • Dendrite: receives stimulus from other neurons or sensory receptors
  • Cell body: processes stimulus; contains a nucleus
  • Axon: transmits stimulus to a gland, muscle, organ, or other neuron
• Types of Neurons

  • Multipolar
  • Bipolar
  • Pseudo-unipolar
• Frontal lobe


  • Location: Front
  • Function: Controls, voluntary motor functions and emotions
• Parietal lobe


  • Location: Top
  • Function: Senses
• Occipital lobe


  • Location: Back
  • Function: Vision
• Temporal lobe


  • Location: Side
  • Function: Hearing, smell and memory
• Cerebrum


  • Largest part of the brain, constitutes 85% of total brain weight
• Left Hemisphere


  • Sensory stimulus from right side of body
  • Motor control of right side of body
  • Speech, language and comprehension
  • Analysis and calculations
  • Time and sequencing
  • Recognition of words, letters and numbers
• Right Hemisphere


  • Sensory stimulus from left side of body
  • Motor control of left side of body
  • Creativity
  • Spatial ability
  • Context / perception
  • Recognition of faces, places and objects
• Cerebellum


  • Coordinates movements
  • Controls posture, balance & fine motor movement
  • Involved in motor learning
• Brainstem


  • The most primitive part of the brain
  • Responsible for sustaining the basic functions of life
• Parts of the Brainstem

  • Midbrain
  • Pons
  • Medulla Oblongata
• Diencephalon


  • Situated at the ventro-medial portion of the cerebrum
• Components of Diencephalon

  • Thalamus
  • Epithalamus
  • Hypothalamus
• Thalamus


  • Located: between the brainstem and cerebrum
  • Largest portion of diencephalon
  • Function: influences moods and detects pain
• Epithalamus


  • Location: above thalamus
  • Function: emotional and visceral response to odors
• Hypothalamus

  • Location: below thalamus
  • Controls pituitary gland
  • Function: controls homeostasis, body temp
• Meninges


  Protective wrapping around the brain and spinal cord
• Layers of Meninges

  • Dura Mater
  • Arachnoid
  • Pia Mater
• Sub Arachnoid space

  Between Pia Mater and Arachnoid. Where the Cerebrospinal Fluid lies
• Cerebrospinal Fluid (CSF)


  A clear and colorless fluid produced by the choroid plexuses and found within the ventricles of the brain, subarachnoid space and central canal of the spinal cord
• Ventricles of the Brain

  • Lateral ventricles
  • Third ventricle
  • Fourth ventricle
• Lateral ventricles


  • Found within each cerebral hemispheres
  • Communicates with the 3rd ventricle by means of foramen of Monro
• Third ventricle


  • Small slit cavity located in the center of diencephalons, between 2 thalami
  • Communicates with the 4th ventricle by means of aqueduct of sylvius
• Fourth ventricle


  • Located at the base of ventricle cerebellum and is continuous with the central canal of spinal cord
  • Communicates with the spinal cord by means of 2 openings: Foramen of lushka and Foramen of magendie
• Spinal Cord


  • Starts at the level of foramen magnum to the second lumbar
  • Important conduction pathway for ascending and descending nerve fibers from and to the brain
  • Important center for reflexes; ex. Stretch and withdrawal reflexes
  • The white matter consists of myelinated axons, which form nerve tracts, and the gray matter consists of neuron cell bodies, dendrites, and axons

  
• Peripheral Nervous System (PNS)


  • Lies outside the CNS, consists of spinal and cranial nerves linking the body to the brain and spinal cord
  • Collections of neurons are called ganglia

  
• Divisions of PNS

  • Autonomic nervous system
  • Somatic nervous system

  
• Autonomic nervous system


  Involuntary control of internal organs, blood vessels, smooth and cardiac muscles, consisting of the sympathetic and parasympathetic nervous systems

  
• Somatic nervous system


  Voluntary control of skin, bones, joints, and skeletal muscle
• Components of PNS

  • Cranial nerves
  • Spinal nerves