Chapter 19 - Chapter 19 Infectious Diseases Affecting the...

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Chapter 19 Infectious Diseases Affecting the Nervous System Structure of the nervous system Divided into two parts: Central nervous system (CNS) Brain and Spinal Cord Peripheral nervous system (PNS) Nerves that transfer commands between the CNS and muscles and glands Sensory nerves-carry signals towards the CNS Motor nerves - carry signals away from the CNS Mixed nerves-carry signals both toward and away from the CNS Brain and spinal cord are covered with three membranes – meninges Dura mater – outermost membrane Arachnoid – middle membrane Pia mater innermost membrane Between arachnoid and pia mater there is a space that is filled with a fluid – cerebrospinal fluid in which bacteria can multiply. Portals of Infection of the Central Nervous System CNS is an axenic environment It has no normal microbiota Restricted permeability of blood vessels (no microbes can pass into the CNS) Pathogens may access the CNS: Breaks in the bones and meninges Medical Procedures Traveling through peripheral neurons to the CNS Meningitis An infection of the membranes – meningitis Can be caused by Bacteria Streptococcus pneumoniae Haemophylus influenzae Neisseria meningitidis 50 other species of bacteria Viruses Fungi Protozoa An infection of the brain – encephalitis Bacteria cause disease in two ways Infect cells of the nervous system Meningitis Leprosy Bacteria growing elsewhere release toxins that affect neurons Botulism
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Tetanus Bacterial meningitis Signs and Symptoms Sudden high fever and severe meningeal inflammation Inflamed cranial meninges: severe headache, vomiting, Inflamed spinal meninges: stiff neck, altered muscle control Infection of the brain, or encephalitis, can result in behavioral changes, coma, and death Signs and symptoms may develop rapidly Hemophilus influenza Gr negative bacteria, normal throat microflora. Causes meningitis in children (6 month to 4 years old) Of all bacterial meningitises H. influenzae accounts for most often cases Existing vaccine Neisseria meningitides Gr- cocci (meningococcus) The cells are surrounded by thick capsules that protect them from phagocytosis
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This note was uploaded on 12/13/2011 for the course BIO 0019 taught by Professor Spencer during the Fall '11 term at Broward College.

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Chapter 19 - Chapter 19 Infectious Diseases Affecting the...

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