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Central Nervous System An Overview. Organs & Divisions. Central Nervous System : CNS=brain and spinal cord Peripheral Nervous System : PNS= all nerves Autonomic Nervous System : ANS=automatic responses. Central Nervous System. Brain & Spinal Cord. Divisions of the Brain.
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Organs & Divisions • Central Nervous System: CNS=brain and spinal cord • Peripheral Nervous System: PNS= all nerves • Autonomic Nervous System: ANS=automatic responses
Central Nervous System Brain & Spinal Cord
Divisions of the Brain • Brainstem: Medulla Oblongata, Pons, Midbrain • Cerebellum • Diencephalon: Hypothalmus, Thalmus • Cerebrum
Brainstem: • Lies just above the spinal cord in the following order: • Medulla oblangata:cardiac, respiratory and vasomotor control • Pons: influences respirations • Midbrain: relay for visual and auditory impulses
Diencephalon • Thalmus: responsible for sensations, associates sensations with emotions,(pleasantness, unpleasantness), and arousal or alerting mechanism • Hypothalmus:helps regulate hormones, body temperature, water balance, sleep cycles, control of appetite and many emotions involved in fear, anger, pleasure, sexual arousal and pain. Controls vital functions: heartbeat, constriction & dilation of blood vessels, and contractions of stomach & intestines
Cerebellum • Produces smooth coordinated movements, maintain equillibrium, and sustain normal postures
Cerebrum • Largest portion of the brain, • Convolutions(ridges) called gyri. • Grooves called sulci. • Deep sulci are called fissures. • Divided into 4 major lobes: Frontal, Parietal, Temporal, Occipital • Subdivided according to function.
Spinal Cord • Lies in the vertebral foramen of the vertebra. Extends from the occipital bone to just above the 4th lumbar vertebrae. • Provides 2 way conduction paths to and from the brain. • Ascending Tracts: impulses up to the brain • Descending Tracts: impulses down the cord away from the brain
Spinal Cord • Reflexes: jerk reflexes and withdrawal • Sends impulses to the brain. Sensory impulses travel up to the brain in ascending tracts, and motor impulses travel down the cord in descending tracts. • Injury to the cord transversely results in loss of function, therefore particular anatomical functions are lost. Ex: paralysis.
The Meninges • Tough fluid containing membrane • Spinal meninges form a tubelike covering around the spinal cord and line the vertebral foramen. • 3 layer: Dura Mater (tough mother) outer layer; Pia Mater is the innermost layer; Arachnoid (cobweb like) Mater is between the Pia and Dura.
Meningitis=infection orinflammation • Bacterial vs. Viral/Aseptic • Bacterial: most commonly caused by Neisseria meningitidis (meningococcus), Streptococcus pneumoniae, or Haemophilis influenzae Treatable withantibiotics • Viral/Aseptic: various causes, antibiotics, less deadly
Meningitis • S/S: severe headache, nucal rigidity, (neck stiffness) • Fever, vomiting • *SEEK MEDICAL HELPIMMEDIATELY* • Can be mild and self limiting, to fatal.
Cerebrospinal Fluid (CSF) • Flows in between the Pia mater and Arachnoid mater, as well as ventricles of the brain • Formed in the Choroid Plexus. (network of brain capillaries) and in the ventricles of the brain.
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Peripheral Nervous System The peripheral nervous system is divided into two major parts, 1) somatic nervous system 2) autonomic nervous system