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Explore the anatomy and functions of the central nervous system, including the brain, spinal cord, and divisions. Learn about the CNS structures, such as the brainstem, cerebellum, diencephalon, and cerebrum. Gain insights into spinal cord pathways, reflexes, and the meninges, as well as conditions like meningitis and the role of cerebrospinal fluid.
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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