Organization of the Nervous System Exercise 7, 18

Main Responsibilities  Detect changes in and around the body  Process incoming sensory information and react accordingly  Orchestrate and integrate all sensory and motor activities  Ultimate goal  maintain homeostasis  Detect changes in and around the body  Process incoming sensory information and react accordingly  Orchestrate and integrate all sensory and motor activities  Ultimate goal  maintain homeostasis

CNS vs. PNS  Central Nervous System (CNS)  brain and spinal cord  Peripheral Nervous System (PNS)  communicates with CNS via cranial and spinal nerves  Central Nervous System (CNS)  brain and spinal cord  Peripheral Nervous System (PNS)  communicates with CNS via cranial and spinal nerves

Peripheral Nervous System  Afferent Division  RECEIVES sensory information and then sends the information to the CNS for processing  Motors responses are generated and PNS carries our the demands via the….  Efferent Division  CARRIES OUT the responses to sensory information  Controls the activities of “effectors” ( muscles and glands of the body)  Somatic Nervous System (conducts motor responses to skeletal muscles)  Autonomic Nervous System (sends commands to the visceral effectors)  Sympathethic  Parasympathetic  Afferent Division  RECEIVES sensory information and then sends the information to the CNS for processing  Motors responses are generated and PNS carries our the demands via the….  Efferent Division  CARRIES OUT the responses to sensory information  Controls the activities of “effectors” ( muscles and glands of the body)  Somatic Nervous System (conducts motor responses to skeletal muscles)  Autonomic Nervous System (sends commands to the visceral effectors)  Sympathethic  Parasympathetic

PNS Nerves  Cranial Nerves  Communicate with the brain  Pass into neck and face through the foramina in the skull  Spinal Nerves  Join spinal cord at intervertebral foramina  Pass into upper and lower limbs of the body  “Mixed” – carry BOTH sensory and motor signals  Cranial Nerves  Communicate with the brain  Pass into neck and face through the foramina in the skull  Spinal Nerves  Join spinal cord at intervertebral foramina  Pass into upper and lower limbs of the body  “Mixed” – carry BOTH sensory and motor signals

A Closer Nervous System Cells  GLIAL CELLS – support, protect, and maintain nerve tissue  Most abundant cells in the nervous system  CNS  production and circulation of cerebrospinal fluid (CSF)  2 types (PNS)  Satellite Cells  Schwann Cells  4 types (CNS)  Oligodendrocytes  form myelin sheath  Microglia  remove microbes and cellular debris from CNS tissue  Ependymal  line the ventricles of the brain and central canal of the spinal cord  Astrocytes  maintain the blood brain barrier (BBB), structural support, regulate ion content, and repair  GLIAL CELLS – support, protect, and maintain nerve tissue  Most abundant cells in the nervous system  CNS  production and circulation of cerebrospinal fluid (CSF)  2 types (PNS)  Satellite Cells  Schwann Cells  4 types (CNS)  Oligodendrocytes  form myelin sheath  Microglia  remove microbes and cellular debris from CNS tissue  Ependymal  line the ventricles of the brain and central canal of the spinal cord  Astrocytes  maintain the blood brain barrier (BBB), structural support, regulate ion content, and repair

A Closer Nervous System Cells  NEURONS - communication cells  Components: dendrites, cell body, axon  Nissl bodies : groups of free ribosomes and RER  NEURONS - communication cells  Components: dendrites, cell body, axon  Nissl bodies : groups of free ribosomes and RER

Telodendria d

Anatomy of the Nerve  Three membranes:  Epineurium – Outer layer  Perineurium – Separates axons into fassicles  Endoneurium – Surrounds each axon  Three membranes:  Epineurium – Outer layer  Perineurium – Separates axons into fassicles  Endoneurium – Surrounds each axon