Protection of the Central Nervous System Slide 7.44a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Scalp and skin  Skull and vertebral column  Meninges Figure 7.16a

Protection of the Central Nervous System Slide 7.44b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Cerebrospinal fluid  Blood brain barrier Figure 7.16a

Meninges Slide 7.45a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Dura mater  Double-layered external covering  Periosteum – attached to surface of the skull  Meningeal layer – outer covering of the brain  Folds inward in several areas

Meninges Slide 7.45b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Arachnoid layer  Middle layer  Web-like  Pia mater  Internal layer  Clings to the surface of the brain

Cerebrospinal Fluid Slide 7.46 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Similar to blood plasma composition  Formed by the choroid plexus  Forms a watery cushion to protect the brain  Circulated in arachnoid space, ventricles, and central canal of the spinal cord

Ventricles and Location of the Cerebrospinal Fluid Slide 7.47a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.17a

Ventricles and Location of the Cerebrospinal Fluid Slide 7.47b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.17b

Blood Brain Barrier (what cell again?) Slide 7.48 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Includes the least permeable capillaries of the body  Excludes many potentially harmful substances  Useless against some substances  Fats and fat soluble molecules  Respiratory gases  Alcohol  Nicotine  Anesthesia

Traumatic Brain Injuries Slide 7.49 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Concussion  Slight brain injury  Contusion  Nervous tissue destruction occurs  Nervous tissue does not regenerate  Cerebral edema  Swelling from the inflammatory response  May compress and kill brain tissue

Cerebrovascular Accident (CVA) Slide 7.50 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Commonly called a stroke  The result of a ruptured blood vessel supplying a region of the brain  Brain tissue supplied with oxygen from that blood source dies  Loss of some functions or death may result

Alzheimer’s Disease Slide 7.51 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Progressive degenerative brain disease  Mostly seen in the elderly, but may begin in middle age  Structural changes in the brain include abnormal protein deposits and twisted fibers within neurons  Victims experience memory loss, irritability, confusion and ultimately, hallucinations and death

Spinal Cord Slide 7.52 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Extends from the medulla oblongata to the region of T12  ~17in (42 cm)  31 pairs of spinal nerves extend from vertebral column  Below T12 is the cauda equina (a collection of spinal nerves)  Literal translation: horse’s tail Figure 7.18

Spinal Cord Slide 7.52 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Provides 2-way conduction pathway to and from the brain  Protected and cushioned by meninges  Enlargements occur in the cervical and lumbar regions  Serving upper and lower limbs Figure 7.18

Spinal Cord Anatomy Slide 7.53b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Internal gray matter - mostly cell bodies  Dorsal (posterior) horns-contain interneurons  Ventral (anterior) horns-cell bodies of motor neurons  Lateral horn-cell bodies of motor neurons Figure 7.19

Spinal Cord Anatomy Slide 7.54 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Meninges cover the spinal cord  Nerves leave at the level of each vertebrae  Dorsal root  Associated with the dorsal root ganglia – collections of cell bodies outside the central nervous system  Ventral root  Dorsal and ventral root meet up to form a spinal nerve

Spinal Cord Anatomy Slide 7.53a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Exterior white matter – conduction tracts  composed of myelinated fiber tracts  Posterior column-ascending tracts  Anterior & lateral columns-ascending & descending tracts Figure 7.19

Spinal Cord Anatomy Slide 7.53c Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Central canal filled with cerebrospinal fluid Figure 7.19

MechanoreceptorsPacinian corpusclepressure Meissner’s corpuscletouch Muscle spindlesproprioception Golgi tendon organproprioception NociceptorPain due to trauma ChemoreceptorsNociceptorspain from chemicals ThermoreceptorsCold receptors in epidermis Cold temp (10-30C) Warm receptors in dermisWarm temp (32-48C) NociceptorsVery cold/hot pain

Structure of a Nerve Slide 7.56 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Endoneurium (delicate CT) surrounds each fiber  Groups of fibers are bound into fascicles by perineurium (coarser CT)  Fascicles are bound together by epineurium (tough fibrous sheath) Figure 7.20