nervous system

• nervous system - A group of tissues composed of highly specialized cells

  possessing the characteristics of excitability and

  conductivity. Helps regulate homoestsis
• CENTRAL NERVOUS SYSTEM ➢ consists of brain and spinal cord
• PERIPHERAL NERVOUS SYSTEM ➢ lies outside the CNS, consists of nerves and ganglia
• SOMATIC EFFERENT ➢ Innervation somatic structures, ex. Muscles & skin
• VISCERAL EFFERENT ➢ Innervates involuntary structures ex. Smooth, cardiac muscles, and glands. (ANS)
• Neuron Structures

  • 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
• Multipolar

  - many dendrites and a single axon

   Ex. CNS and most motor neurons
• Bipolar- many dendrites and a single axon

   Ex. CNS and most motor neurons
• Bipolar

  - many dendrites and a single axon

   Ex. CNS and most motor neurons
• GLIAL CELL

   Supporting cells for neurons

   More numerous than neurons
• Astrocytes

   star-shaped

   most abundant

   form blood-brain barrier (BBB)
• Ependymal Cells - produce and circulate cerebrospinal fluid (CSF)
• Microglia - help remove bacteria and cell debris from CNS
• Oligodendrocytes - produce myelin sheath in CNS
• Schwann cells - produce myelin sheath in PNS
• ORG OF NERVOUS TISSUE

  GRAY MATTER - collection of DENDRITES and CELL BODIES

  WHITE MATTER - collection of AXONS and their MYELIN SHEATH
• Spinal cord - Controls both voluntary movements, such as those involved in walking and in speech, and involuntary movements, such as breathing

  and reflex actions.
• BRAIN - The adult human brain weighs about 1.3kg body weight, constitutes 2% of total body wt. It is a mass of pinkish grey, jelly like tissue made up of approximately 100 billion neurons and neuroglia.
• CEREBRUM (BRAIN)

  • largest part of the brain
  • 85% of total brain weight
  • thinking part of the brain
• frontal lobe - largest lobe in the brain, involved in the control of VOLUNTARY motor functions, motivation, mood, aggression, and olfactory reception
• parietal lobe - principal center for reception of most sensory information, responsible for integrating sensory, (sensory speech area) – language comprehension
• temporal lobe - 2nd largest lobe of the brain, involved in olfactory (smell), auditory (hearing), and taste and involved in memory,
• occipital lobe - smallest lobe in the brain, visual reception, visual-spatial processing, movement, and color recognition
• insula - lies within the folds of lateral surfaces, play a role in diverse functions usually linked to emotions
• Primary Sensory Areas - where sensations are perceived
• Primary somatic sensory cortex - process of recognition
• MOTOR FUNCTIONS

  • descending tract
  • begins from the brain and terminate in the

  spinal cord
• Basal Ganglia - group of functionally related nuclei
• Corpus Striatum – deep in cerebrum
• Substantia nigra – in midbrain
• CEREBELLUM (LITTLE BRAIN) - 2nd largest part of brain

  • two hemispheres called cerebellar hemispheres connected by vermis, composed of white and gray matter
• C.BRAINSTEM - most primitive part of the brain, connects the spinal cord and brain and continuation of spinal cord
• Reticular Activating System - special group of neurons in the brainstem
• Midbrain (mesencephalon)

  • most superior and smallest portion of the brainstem
  • serves to connect the forebrain with the hindbrain
• Corpora Quadrigemina (Colliculi) - controls visual reflexes

  • superior colliculi – visual reflexes
  • inferior colliculi – auditory reflex
• Pons - main connection between the cerebellum and

  brainstem

  • passageway from all the nerve fibers coming from and to the brain
  • breathing, swallowing, balance, chewing and salivation
• Medulla Oblongata

  • serves as exits of cranial nerves IX, X, XI, XII
• DIENCEPHALON / INTERBRAIN

  • situated at the ventromedial portion of the

  cerebrum
• Thalamus - largest part, shaped like a yoyo, major relay center

  • influences mood and registers uncomfortable perception of pain (parts of diencephalon)
• Epithalamus - small area, superior and posterior to thalamus

  • involved in emotional and visceral response to odors and the pineal gland ( part of diencephalon)