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40 Cards in this Set
- Front
- Back
What are the two parts of the nervous system.
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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 |
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The brain and spinal cord are covered with three membranes called the? Describe these membranes.
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meninges
-Dura matter – outermost membrane -Arachnoid – middle membrane -Pia meter innermost membrane -Between arachnoid and pia mater there is a space that is filled with a fluid- cerebrospinal fluid in which bacteria can multiply |
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True or false.
The CNS has normal biota. |
FALSE
-CNS is an axenic environment -It has no normal microbiota -Restricted permeability of blood vessels |
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How do pathogens enter the nervous system?
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-Pathogens may access the CNS:
-Breaks in the bones and meninges -Medical procedures -Traveling through peripheral neurons to the CNS |
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What is meningitis? What causes it?
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An inflammation of the meninges.
-An infection of the membranes – meningitis -Can be caused by -Bacteria -Streptococcus pneumonia -Haemophylus influenza -Neisseria meningitides -50 other species of bacteria -Viruses -Fungi -Protozoa -An infection of the brain – encephalitis |
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What are the two ways bacteria can cause disease of the nervous system?
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Infect cells of the nervous system
-Meningitis -Leprosy Bacteria growing elsewhere release toxins that affect neurons -Botulism -Tetanus |
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What are the sign and symptoms of bacterial meningitis?
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-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 |
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What is an infection of the brain called?
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encephalitis
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What is Heamophilus influenzae?
and.. -what does it cause? |
-Gr negative bacteria, normal throat microflora
-Causes meningitis in children (6 months to 4 years old) -Of all bacterial meningitises H. influenza accounts for most often causes -Existing vaccine |
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What is Neisseria meningitidis?
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-Gram negative cocci (meningococcus)
-Normal microbiota in the nose and throat -Begins as a throat infection -Replicate in blood and eventually enter cerebrospinal fluid -The cells are surrounded by thick capsules that protect them from phagocytosis -Produces endotoxin that can cause death in few hours -Vaccine available – not for all serotypes -Treatment: Intravenous injection of antibiotic (Penicillin G) – as soon as possible |
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Describe Streptococcus pneumoniae and what it causes.
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- Gram positive diplococcus
-Causes pneumococcal meningitis in children (1 month to 4 years old). -It is a common flora of the mouth and throat. It also causes pneumonia and ear infections -Mortality rate high (30% in children and 80% in the elderly) -Vaccine available, recommended for infants under the age of 2 |
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Describe Listeriariosis
_ Cause _ Effects _ Treatment |
-Causative agent: Listeria monocytogenes (gr+ rods)
-Infects animals and humans -Source of infection: ingestion of contaminated food (dairy products, meat..) -Affects: -Adults with compromised immune system -Pregnant women especially susceptible -Fetus infected through placenta (abortions, and stillbirths) -Newborns infected through the birth canal -Grows in central nervous system of placenta -Treatment: Penicillin G |
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Describe fungal meningitis.
Important: What its caused by. |
-Fungi rarely infect the CNS
-Cryptococcosis – fungal meningitis -Caused by the Cryptococcus neoformans- a yeast -Found in soil and pigeon droppings -Infection via inhalation -Mycoses may spread from the lungs to the CNS via the blood -Affects especially AIDS patients |
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Describe Naegleria meningoencephalitis
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-Caused by Naegleria fowleri – amaeba.
-The victims are children who swim in ponds and streams -The pathogen infects the nasal mucous membrane and then the brain -The disease is fatal (100%). |
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Describe Arboviral Encephalitis
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-Arboviruses are arthropod-borne viruses
-The virus is transmitted by mosquito to humans and horses -Proliferation of the disease occurs during summer months -Symptoms; Chills, fever, headache, and even death, -Different forms of encephalitis: Western equine encephalitis, Eastern equine encephalitis, St. Luis encephalitis, California encephalitis, Japans B encephalitis |
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describe West Nile Virus
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-A new arbovirus disease
-Infects birds and humans -Symptoms: -Body aches, headache, Polio-like paralysis, and fatal encephalitis (especially in elderly) -Treatment: alleviate symptoms -Prevention involves limiting contact with mosquitos -Use netting and insect repellants -Reduce mosquito numbers by eliminating stagnant water |
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What are prions?
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-Prions are infectious proteins
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what do prions cause?
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-They cause spongiform degeneration of the brain – transmissible spongiform encephalitis
-Abnormally folded prion proteins – transform the normal protein -Unclear why the initial prion misfolds -Prion disease include Sheep scrapie, mad cow disease, and variant Creutzfeldt-Jakob disease |
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Describe Creuzfeldt- Jacob disease
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-Symptoms: altered behavior, dementia, memory loss, senility
-Not communicable disease -Some transmission is possible: -Transplants -Contaminated surgical instruments -Injection of growth hormones from infected pituitary glands -Genetic mutation |
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Describe sheep scrapies.
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-Symptoms; The infected animal scrapes itself against the wall. Loss of motor control- death
-*incase of* Mad cow disease- the animals must be destroyed |
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What causes rabies and how does it enter the nervous system?
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-Caused by rabies virus (rhabdovirus)
-Acquired by the bite of an infected animal (also transmitted by aerosol) -After infection the virus multiplies in skeletal muscles (up to few months) -Then the virus enters the peripheral nerves through which it travels into central nervous system |
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Describe Rabies.
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-Symptoms: spasm of muscles, hydrophobia, biting behavior, excitability, increased salivation, difficulties in swallowing. Damage to nervous system- death.
-Diagnosis: immunofluorescent detection of viral antigens in saliva or brain tissue (dead animal) -Reservoir of infection: dog, cat, skunk, bat, fox, raccoon. -Treatment: 5-6 injection of vaccine + rabies immune globulin -Prevention: Vaccination of dogs and cats |
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what causes Poliomyelitis (Polio)?
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-Caused by polyovirus
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Describe Poliomyelitis (Polio)
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-The infection is initiated with ingestion of the virus (contaminated water)
-Disease starts with the mild symptoms (fever, soar throat, nausea) -Primary area of infection is throat and small intestine. Next, tonsils, lymph nodes, blood and central nervous system -Virus multiples in the motor nerve cells -Cell dies -Severe symptoms: 1% of infected will suffer from paralysis |
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What are the two types of vaccines available for polio?
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-Salk vaccine – used in Europe
-Sabin vaccine – more popular in the U.S. |
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Describe the salk vaccine.
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For Polio
-Salk vaccine – used in Europe -Viruses inactivated with formation -Must be injected -Booster required |
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Describe the sabin vaccine.
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For polio
-Sabin vaccine – more popular in the U.S. -Living attenuated viruses (virus is not killed) -Disadvantage – may cause disease -*Advantage* Lifelong immunity *and booster is not required* |
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What causes tetanus?
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Caused by Clostridium tetani = anaeorobic, endospore forming gr+ rod
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How is tetanus contracted?
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-Contracted by infection of the wound with rusty nails. Clostridium is found in the soil contaminated with animal feces.
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What are the sign/symptons of tetanus and the incubation period?
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-Signs/Symptoms: Tightening of the jaw and neck muscles, followed by fever and muscle spasms
-Incubation period: Five days to fifteen weeks |
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Describe how tetanus occurs.
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-Clostridium spores enter a host through a wound on the skin and then it replicates
-Produces tetanospasmin toxin blocks the release of neurotransmitters -Toxin is: -taken up into the nerve axon and transported to the central nervous system -fixed to the inhibitory motor nerve endings- blocking the inhibitory impulses -The bacterium produces a potent neutroxin that causes uncontrollable muscle contractions – muscle spasms -Cause of death – spasm of respiratory muscles. |
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What is the treatment and prevention of tetanus?
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-Treatment: Human tetanus immunoglobulin penicillin
-Prevention: Vaccination with tetanus toxoid (DTP) |
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What causes botulism?
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Caused by Clostridium botulism
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What is the treatment for botulism?
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-Treatment; antitoxin therapy
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How do people get botulism?
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-Not transmitted from person to person
-Source of infection: home processed foods, vegetables, fruits, meat, fish -Spores can survive at high temperature |
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How does botulism affect the body?
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-Clostridium produces exotoxin (botulinum toxin) – the most poisonous naturally occurring substance- the lethal dose is 1ng/kg
-The toxin blocks the release of acetylcholine -Therefore the muscle remains relaxed – flaccid paralisis |
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Describe infant botulism.
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Infant Botulism
-Infants do not have established normal microflora – infant botulism -Cases reported with honey -should not be given to infants under 1 year of age |
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What causes African trypanosomiasis – sleeping sickness and how is it transmitted?
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Protozoa
-Caused by Trypanosoma brucei gambiense. -It is transmitted by the bite of tsetse fly |
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Describe Sleeping Sickness
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-In early stage the protozoa is found in low numbers in the blood (2-4 years).
-In later stage the pathogen moves to central nervous system -Symptoms; decrease in physical activity and mental acuity, coma, and death. -Difficulty in developing vaccine – the parasite changes the protein coat -Prevention: eliminating tsetse flies |
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What is the treatment for Sleeping sickness?
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-Treatment:
-At early stage: suramin -Late stage (brain infected) arsenic-based drug |