nervous functional organization

• Nervous system


  Along with the endocrine system, helps to keep controlled conditions within limits that maintain health and helps to maintain homeostasis
• Nervous system


  Responsible for all our behaviors, memories, and movements

  
• Neurology


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

  • Central nervous system (CNS)
  • Peripheral nervous system (PNS)

  
• Central nervous system (CNS)


  Consists of the brain and the spinal cord
• Brain


  • Receives nerve impulses from the spinal cord and cranial nerves
  • Contains the nerves that carry messages between the brain and the body

  
• Mechanical protective components for the brain

  • Cranium
  • Cranial meninges (continuous with the spinal meninges)
  • Ventricles
• Cranial meninges


  • Dura mater
  • Arachnoid membrane
  • Pia mater
• Dura mater


  The outermost covering, tough, inelastic bag that surrounds the brain & spinal cord
• Arachnoid membrane


  Lies under the dura mater, resembling a spider web
• Pia mater


  The innermost layer, adheres closely to the surface of the brain, separated from the arachnoid by a cerebrospinal fluid-filled space called subarachnoid space
• Blood supply to the brain

  Mainly via the internal carotid & vertebral arteries

  
• Blood-brain barrier (BBB)


  Located at the interface between the capillary wall & brain tissue, protects brain cells from harmful substances & pathogens by preventing passage of many substances from blood into brain tissue

  
• Components of the blood-brain barrier

  • Endothelial cells lining the capillary wall with tight junctions between them
  • Processes of astrocytes (perivascular end-feet) abutting on the capillaries
  • A capillary basement membrane

  
• Functions of the blood-brain barrier

  • Protecting the brain from "foreign substances" (such as viruses and bacteria) in the blood that could injure the brain
  • Shielding the brain from hormones and neurotransmitters in the rest of the body
  • Maintaining a constant environment (homeostasis) for the brain

  
• Cerebrospinal fluid (CSF)


  Formed in the choroid plexuses in all ventricles, offers buoyancy for the brain, protects the brain by cushioning the brain within the skull and acting as a shock absorber, helps in the transport of nutrients and wastes
• The brain is the control center of the body, it controls thoughts, memory, speech and movement, and regulates the function of many organs
• Cerebral hemispheres


  The left & right cerebral hemispheres are split by the deep fissure called the longitudinal fissure that runs in the mid-sagittal position, transverse fissure separates the cerebrum and cerebellum

  
• Cerebral cortex


  The outermost layer, made up of all the gyri, made of gray matter that makes up the conscious brain, consists of neuron cell bodies and short, unmyelinated axons with no fiber tracts, enables us to be aware of ourselves and our sensations, initiate and control voluntary movements and communicate, remember and understand

  
• Major parts of the brain

  • Cerebrum
  • Cerebellum
  • Diencephalon
  • Brain stem

  
• Cerebrum


  Largest part of the brain, divided into several lobes: frontal, parietal, occipital and temporal

  
• Diencephalon


  Extends from the brain stem to the cerebrum & surrounds the 3rd ventricle, includes thalamus, hypothalamus, and epithalamus

  
• Basal ganglia


  Three nuclei deep within each cerebral hemisphere: globus pallidus, putamen, and caudate nucleus, help initiate and terminate movements, suppress unwanted movements and regulate muscle tone

  
• Limbic system


  A ring of structures on the inner border of the cerebrum and floor of the diencephalon, includes cingulate gyrus, hippocampus, dentate gyrus, amygdala, mammillary bodies, thalamus, and the olfactory bulb, governs emotional aspects of behavior, also involved in olfaction and memory

  
• Cerebellum


  Second largest part of the brain, consists of two cerebellar hemispheres, the anterior and posterior lobes control subconscious aspects of skeletal movement, the flocculonodular lobe contributes to the equilibrium and balance, cerebellar peduncles (3 pairs) attach cerebellum to the brain stem

  
• Brain stem


  The part of the brain between the spinal cord and the diencephalon, consists of the medulla oblongata, pons, and midbrain

  
• Spinal cord


  Consists of two enlargements: cervical and lumbar, conus medullaris, cauda equina, filum terminale, dorsal (posterior) root & ventral (anterior) root, dorsal root (posterior) ganglion, spinal nerves
• Protective structures of the spinal cord

  Vertebral column and meninges (dura mater, arachnoid mater, pia mater)
• Neuron


  The basic functional unit of the nervous system, an electrically excitable cell that processes and transmits information by electrical and chemical signaling
• Spinal nerve


  Nerve that exits the spinal cord
• Dorsal root of spinal nerve


  Part of spinal nerve that carries sensory information to the spinal cord
• Ventral root of spinal nerve

  Part of spinal nerve that carries motor information from the spinal cord
• Dorsal root ganglion


  Collection of sensory neuron cell bodies outside the spinal cord
• Central nervous system


  Includes the brain and the spinal cord
• Spinal cord


  Runs through the vertebral foramen and is protected by the vertebral column and meninges
• Protective structures of the spinal cord

  • Vertebral column
  • Meninges
• Layers of meninges


  • Dura mater
  • Arachnoid mater
  • Pia mater
• Dura mater


  Tough (durable) outer layer of meninges
• Arachnoid mater


  Middle layer of meninges with spider-web/leggy appearance
• Pia mater


  Delicate inner layer of meninges that attaches to the spinal cord