Nervous 4

• CNS is made up of the brain and spinal cord. It is the principal integrator of the sensory input and motor output. It evaluates incoming stimuli and formulates responses to changes that threaten homeostasis
• The two coverings of the brain and spinal cord

  • bones
  • inner coverings = meninges
• Cranial meninges protect the brain. They consist of the dura mater, arachnoid mater and pia mater
• Dura mater

  • outermost layer
  • tough dense connective tissue
• Arachnoid mater

  • middle layer
  • made of collagen and elastic fibers (looks like spider web)
• Pia meter

  • inner transparent layer (between arachnoid and pia mater)
  • made of collagen and elastic fiber that sticks to the surface of the spinal cord
  • contains numerous blood vessels
• Subarachnoid space is the space where cerebrospinal fluid circulates
• Meningitis is the inflammation of the meninges. It is caused by bacterial or viral infections and can be fatal if left untreated
• CSF is a reservoir of circulating fluid that monitors internal environment. It provides a supportive and protective cushion around the brain (travels within the 4 large ventricles of the brain) and spinal cord
• Brain is the main component of the CNS and the control centre for homeostasis by:

  • receiving input (sensory neurons)
  • processes information (interneurons)
  • sends output (motor neurons)
• The brain is made up of 100 billion neurons and 900 billion neuroglia
• The brain can be divided into 4 major parts

  • brain stem
  • diencephalon
  • cerebellum
  • cerebrum (cortex)
• White matter

  • myelinated axons
  • sends signals
  • found deeper in the brain
• Grey matter:

  • cell bodies, neuroglia, unmyelinated axons
  • processes signals
  • found on outer surface of brain
• The brain stem is the part of the brain between the spinal cord and diencephalon. It is made up of the medulla oblangata, pons and midbrain
• Medulla oblangata controls the basic life support systems

  • cardiovascular: regulate heart rate and BP
  • medullary rhythmicity area: adjust breathing rate
  • reflex integration centre: swallowing, vomiting, coughing, sneezing
• Pons is found above the medulla and below the midbrain. It is a bridge that connects the parts of the brain

  • relays information from one side of cerebellum to other and up to cerebrum
  • helps control breathing, sleeping, swallowing
• Midbrain connects the pons to the diencephalon

  • coordinates muscle movement
  • involved with reflexes that control eye movement
  • center for startle reflex
• Diencephalon is made up of the thalamus, hypothalamus and pineal gland
• Thalamus

  • major relay station for most sensory impulses from spinal cord to cerebral cortex
  • role in maintenance of consciousness (keeping awake)
• Hypothalamus

  • controls the pituitary gland and produces hormones
  • primary connection between nervous and endocrine system
  • control the ANS (smooth and cardiac muscle)
  • regulate emotional and behavioral patterns
  • regulate eating and drinking behavior
• Pineal gland is located just above the midbrain. the body’s circardian clock depends on it by varying the secretion of melatonin
• Cerebellum is located posterior to the midbrain and inferior to the cerebrum
• Functions of cerebellum

  • receive sensory input from muscles, joints, tendons like action and location
  • compare actual movement with intended ones
  • help produce smooth coordinated movements
  • helps execute skilled motor activities
  • maintains posture and balance
• Ataxia: disrupted muscle coordination caused by damage to the cerebellum or by alcohol
• Cerebrum is the area of higher brain function like reading, writing, memories and future plans
• Cerebrum composition

  • outer layer: cerebral cortex (gray matter)
  • inner layer white matter
  • surface folds: gyri
  • groves between gyri: sulci
  • deep grooves: fissures
  • longitunal fissure: divides into right and left hemispheres
  • corpus callosum: connect both hemispheres
• Callosum is a broad band of white matter containing axons that extend between 2 sides
• Each hemisphere has 4 lobes

  • frontal
  • occipital
  • parietal
  • temporal
• 3 types of functional areas in the lobes

  • sensory: receive sensory input (perception of senses)
  • motor area: initiation of movement
  • association area: integration of movement
• Frontal lobes primarily functions

  • primary motor area: voluntary control of muscle contraction (right side controls left side of body)
  • Broca’s speech area: muscle control for speech
  • Premotor area: prepares sequences of complex muscle contractions (planning, preparation)
• Parietal lobe is mainly for sensory and association

  • primary somatosensory: receives sensory input (tactile, temperature, proprioception, pain, itching, tickling)
  • primary gustatory: taste
  • wernicke’s area: interpretation of speech
  • common integration: processing information
• Temporal lobe

  • primary auditory area: sound and perception of what is heard
  • primary olfactory area: receives signals relating to smell and perception of smell
  • auditory association area: interpretation of sound
  • wernicke’s area
• Occipital lobe

  • primary visual area: visual perception
• Limbic system is called the emotional brain. It plays a primary role in pain, pleasure, anger, affection and behavior and a key function in memory development
• Limbic system consists of a ring of structures on inner border of cerebrum and floor of diencephalon
• Hemispheric lateralization: small differences in anatomy and function of both hemispheres
• The left side of the brain is important for language, logic, math and science VS right side of brain is more important for artistic skills, music, spatial and pattern perception