Microbial Diseases of the Nervous System Chapter 22
Terms in this set (60)
The Central Nervous System
Consists of the brian and spinal cord.
The CNS picks up sensory info from the environment, interprets the info and sends impulses to the effectors.
Peripheral Nervous System
Consists of all the nerves that branch off from the brain and spinal cord.
Are the lines of communication b/w the CNS,the various parts of the body and the external environment.
The brain and the spinal cord are covered and protected by...
Continuous membranes called Meninges
The Three Meninges
Dura Mater-outermost layer
Arachnoid Mater- middle layer
Pia Mater-innermost layer
Space b/w the pia mater and the arachnoid mater where CSF circulates.
Cerebral Spinal Fluid (CSF)
Has low levels of complement or circulating antibodies and few phagocytic cells so bacteria can multiply in it with few checks.
Blood vessels (capillaries) that selectively let certain substances enter the brain tissue and keep other substances out
T/F: Drugs cannot cross the blood-brain barrier unless they are soluble
Inflammation of the meninges.
Inflammation of the brain itself.
Inflammation of both the brain and meninges.
Symptoms of Meningitis
A triad of fever, headache and stiff neck. Nausea and vomiting often follow and can progress to convulsions and coma.
Only three bacterial species have caused most of the cases of meningitis and it's relates mortality
Streptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae type B
All three of these pathogens possess
A capsule that protects them from phagocytosis as they replicate rapidly in the bloodstream
An aerobic, gram-negative bacterium that is a common member of the normal throat microbiota.
Hib-caused meningitis occurs mostly in...
children under age 4, especially at about 6 months, when antibody protection provided by the mother weakens.
Caused by Neisseria meningitidis and is an aerobic, gram-negative bacterium with a polysaccharide capsule that is important to its virulence. It is frequently present in the nose and throat
Meningococcal Meningitis Usually occurs in...
Children under 2 years of age; the maternal immunity weakens at about 6 months and leaves them susceptible.
Is a common inhabitant of the nasopharyngeal region, and is gram-positive.
The causative agent of tetanus...
Is and obligatory anaerobic, endospore-forming, gram positive rod. Common in Soil contaminated with animal fecal wastes.
A neurotoxin that enters the CNS via peripheral nerves or the blood. The bacteria themselves do no spread from the infection sight and there is no inflammation.
This blocks the relaxation pathway so that both opposing sets of muscles contract, resulting in the characteristic muscle spasms.
When the muscles of the jaw are affected early during tetanus preventing the mouth from opening.
Spasms of the back muscles cause the head and heels to bow backwards. Can result in a fractured spine.
Death from tetanus results from spasms of the...
Effective vaccines for tetanus have been available since...
The tetanus vaccine is a...
Toxoid-required every 10 years to maintain good immunity
An inactivated toxin that stimulates the formation of antibodies that neutralize the toxin produced by the bacteria.
A form of food poisoning that is caused by Clostridium botulinum- an obligatory anaerobic, endospore-forming gram-positive rod found in soil and many aquatic sediments.
In Anaerobic environments (Sealed cans)
The microorganism produces an endotoxin, a neurotoxin that is highly specific for the synaptic end of the nerve, where it blocks the release of acetylcholine.
Individuals suffering from botulism...
undergo a progressive flaccid paralysis for 1 to 10 days and may die from respiratory and cardiac failure.
Endospores of C. botulinum are recovered with some frequency from _______, and a lethal dose may be as few as 2000 bacteria.
Recommendation for honey...
Do not feed it to infants under 1 year of age because they do not yet have normal intestinal microbiota.
The deadly toxin of botulism (Botox)
Has therapeutic uses for a number of medical conditions, such as chronic headaches, relieving painful muscle contractions in conditions such as cerebral palsy, Parkinson disease and multiple sclerosis.
Mycobacterium leprae is the only bacteria that grows in the PNS and can grow in skin cells.
The more formal name for Leprosy.
Best known as a cause of paralysis. Infected with the poliovirus
The majority of cases are asymptomatic, or exhibit only mild symptoms such as...
Headache, sore throat, fever and nausea.
The poliovirus invades..
The tonsils and the lymph nodes of the neck and ileum (the terminal portion of the small intestine). From the lymph nodes, the virus enters the blood, resulting in viremia.
Is only transient in most cases the infection does not progress past the lymphatic system and clinical disease does not result. If viremia is persistant the virus penetrates the capillary walls and enters the CNS. Once in the CNS, the virus displays a high affinity for never cells.
A disease that almost always results in fatal encephalitis.
Humans are usually infected with the rabies virus from the bite of...
an infected animal-especially dogs.
Rabies proliferates in...
The PNS and moves fatally to the CNS.
The United States, the most common cause of rabies is a varient of the virus found in...
Pathology of Rabies infection
1) Virus enters tissue from saliva of biting animal.
2) Virus replicates in muscle near bite.
3) Virus moves up PNS to CNS.
4) Virus ascends spinal cord.
5) Virus reaches brain and causes fatal encephalitis.
6) Virus eneters salivary glands and other organs of victim.
African trypanosomiasis (or sleeping sickness)
Is a protozoan disease that affects the nervous system.
The disease is caused by 2 subspecies of Trypanosoma brucei that infect humans...
Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense.
This disease is spread by...
tsetse fly vectors.
Symptoms of a chronic form of this disease...
fever, headache, and other symptoms develop that indicate deterioration of the CNS, coma and death are inevitable without effective treatment.
The drug that alters the disease's course and is very toxic...
Melarsoprol-It is so dramatically effective even against late stages of T.b. gambiense that it has been called the resurrection drug.
Several fatal diseases affecting the CNS are caused by...
Explaining a Prion...
A certain protein is normally found on the surface of brain cell neurons and is even found on the surface of certain stem cells in red bone marrow and cells that become neurons.
An abnormally folded protein.
If a normal protein encounters a prion, the normal protein...
changes its shape and also becomes abnormally shaped (a prion). A chain reaction of protein misfolding occurs.
A single infective prion may lead to a cascade of new prions...
which them clump together to form the aggregation of fibrils of misfolded proteins that are found in diseased brains.
Creutzfeldt-Jakob disease (CJD)
is rare and is often occurs in families, an indication of a genetic component.
To sterilize reusable instruments...
A strong solution of sodium hydroxide combined with extended autoclaving at 134 degrees C.
Bovine spongiform encephalopathy (BSE)
Better known as Mad Cow disease. The origin of this disease is usually ascribed to feed supplements contaminated with prions from sheep infected with scrapie, a long-endemic neurological disease.